期刊文献+
共找到117篇文章
< 1 2 6 >
每页显示 20 50 100
Effects of Using Softwood Pellet Biochar Prepared at Different Temperatures with Grass Chippings on Retention of Heavy Metals in Contaminated Soils
1
作者 Kyari Umar Dunoma Limin Ma +14 位作者 Xingquan Shu Haiyan Yu weiwei zhang Chengcheng Bu Yong-Sik Wang Jiahong Luo Guangyao Chen Jinpeng Yu Ru zhang Yuchen Han Haoyu Zeng Matthew S. Wisseh Amina Grema Mustafa Mohammad Auwal Saidu Mufidat Mamman Khan 《Open Journal of Polymer Chemistry》 2024年第3期146-166,共21页
Heavy metals have been viewed as hazardous environmental pollutants, and anthropogenic activities due to their high toxicity and persistent nature in the environment. Anthropogenic activities such as artisanal mining,... Heavy metals have been viewed as hazardous environmental pollutants, and anthropogenic activities due to their high toxicity and persistent nature in the environment. Anthropogenic activities such as artisanal mining, industrial activities, improper usage of fertilizers and pesticides, and indiscriminate open waste disposal bring about an increase in the presence of heavy metals in the environment. In the Keffi Metropolis, different elements lead to land contamination which debilitates soil quality, plant survival, human well-being, and the environment as a result of extensive dispersion or quantity of heavy metals in the soil and water. In recent years, biochar has emerged as a promising soil amendment for mitigating heavy metal pollution due to its unique physicochemical properties. This paper provides the effects of softwood pellet biochar on the retention of heavy metals in contaminated soils. A microcosm experiment was carried out to investigate the effects of biochar on the retention of heavy metals in contaminated soils. This research aimed to give an overview of the effects of softwood biochar at different temperatures (550˚C and 700˚C) on the retention of heavy metals and metalloids released from the soil during water inundation. The results show that the addition of organic matter (grass chippings) minimizes heavy metal mobilization. Also, biochar at high temperatures is more effective than those at low temperatures. The expected outcome of the research analysis includes providing insights into the role of biochar in retaining heavy metal contamination and further understanding the use of biochar as a sorbent for the management of contaminated soil. 展开更多
关键词 Softwood Biochar Heavy Metal Contaminated Soil Grass Chips Keffi Metropolis MICROCOSM
在线阅读 下载PDF
Fe稳固的FeOOH@NiOOH电催化剂的大电流极化设计与析氧研究
2
作者 吕青芸 张伟伟 +8 位作者 龙志鹏 王建涛 邹星礼 任伟 侯龙 鲁雄刚 赵玉峰 余兴 李喜 《Chinese Journal of Catalysis》 SCIE CAS CSCD 2024年第7期254-264,共11页
电解水技术是制取高纯度氢气的有效途径,为传统的氢气生产提供了一种可持续的替代方案.其中,开发性能优异的电催化材料是降低电解水制氢成本的关键.析氧反应(OER)由于涉及多个电子转移而导致的动力学缓慢,是克服高过电位的主要挑战.镍... 电解水技术是制取高纯度氢气的有效途径,为传统的氢气生产提供了一种可持续的替代方案.其中,开发性能优异的电催化材料是降低电解水制氢成本的关键.析氧反应(OER)由于涉及多个电子转移而导致的动力学缓慢,是克服高过电位的主要挑战.镍铁羟基/氢氧化物(NiFe(oxy)hydroxides)是近期研究的热点,其在碱性条件下具有极低的OER过电位,部分材料性能甚至超过了贵金属基催化剂,如IrO_(2)和RuO_(2).然而,NiFe(oxy)hydroxides的长期催化稳定性,尤其是在大电流下的长期催化稳定性,成为限制其实际应用的主要问题,这主要是由于铁元素的严重流失导致的.因此,如何有效控制和利用电化学溶解/沉积动力学成为稳定铁位点的关键.为克服该挑战,本文提出了一种大电流极化重构方法来固定活性铁位点.通过在大电流(1.5 A cm^(-2))下对材料进行表面快速极化重构,成功制备了FeOOH@NiOOH(eFNO_(L))电催化剂.eFNO_(L)不仅具有稳定的铁位点,还暴露出高指数晶面,因此eFNO_(L)同时展现出较好的OER催化活性和稳定性.同时,密度泛函理论计算结果表明,与具有低指数晶面的FeNiOOH相比,大电流极化工程制备的分相eFNO_(L)对铁位点表现出更高的结合能,可以有效抑制OER过程中的铁流失,且高指数晶面在改变速率决定步骤和减少吸附能垒上具有更大的优势.电化学测试结果表明,经过优化后的eFNO_(L)催化剂在产生100和500 mA cm^(-2)大电流密度仅需234和27 mV的过电位,并且具有较小的Tafel斜率(35.2 mV dec^(-1)).由于铁位点结合能的提高,eFNO_(L)催化剂在500 mA cm^(-2)的电流密度下能够稳定催化超过100 h,且仅有1.5%的性能衰减,优于近期报道的大多数镍铁基OER催化剂.综上,本文为开发高活性和高稳定性能的催化剂提供了一种有效的大电流电化学重构策略,在电解水制氢领域实现其工业化的大规模应用方面显示出巨大潜力,有望降低可持续电解水制氢成本. 展开更多
关键词 析氧反应 FeOOH@NiOOH 大电流极化重构 高指数晶面 铁位点固定
在线阅读 下载PDF
与45钢对摩材料干摩擦条件下的摩擦学性能
3
作者 张金鹏 张玮炜 +3 位作者 齐瑾 王小静 朱丽慧 金健 《高分子材料科学与工程》 EI CAS CSCD 北大核心 2024年第2期115-123,共9页
为选择与45钢对摩的摩擦副材料以适应干摩擦苛刻工况,采用RTEC多功能摩擦试验机,对超高分子量聚乙烯(UHMWPE)、改性聚醚醚酮树脂(改性PEEK)、浸渍呋喃树脂碳石墨(M120K)和浸渍巴氏合金碳石墨(M120B)4种配副材料的摩擦学性能进行测试,并... 为选择与45钢对摩的摩擦副材料以适应干摩擦苛刻工况,采用RTEC多功能摩擦试验机,对超高分子量聚乙烯(UHMWPE)、改性聚醚醚酮树脂(改性PEEK)、浸渍呋喃树脂碳石墨(M120K)和浸渍巴氏合金碳石墨(M120B)4种配副材料的摩擦学性能进行测试,并利用扫描电子显微镜对磨损表面进行观察和分析,从微观角度揭示了4种材料的摩擦磨损机理。结果表明,随着载荷和转速的增加,平均摩擦系数大致呈现出M120B<UHMWPE<改性PEEK<M120K的规律,磨损率则大致呈现出M120B<改性PEEK<M120K<UHMWPE的规律。当载荷增大时,UHMWPE和M120K由磨粒磨损逐渐转变为粘着磨损;改性PEEK以粘着磨损为主并伴随轻微的磨粒磨损;M120B表现出磨粒磨损与粘着磨损共存的形式。当转速增大时,UHMWPE和M120B以磨粒磨损为主并伴随轻微的粘着磨损;改性PEEK和M120K以粘着磨损为主并伴随轻微的磨粒磨损。 展开更多
关键词 45钢对摩材料 干摩擦 摩擦系数 磨损机理
在线阅读 下载PDF
Gut flora in multiple sclerosis:implications for pathogenesis and treatment 被引量:2
4
作者 weiwei zhang Ying Wang +2 位作者 Mingqin Zhu Kangding Liu Hong-Liang zhang 《Neural Regeneration Research》 SCIE CAS CSCD 2024年第7期1480-1488,共9页
Multiple sclerosis is an inflammatory disorder chara cterized by inflammation,demyelination,and neurodegeneration in the central nervous system.Although current first-line therapies can help manage symptoms and slow d... Multiple sclerosis is an inflammatory disorder chara cterized by inflammation,demyelination,and neurodegeneration in the central nervous system.Although current first-line therapies can help manage symptoms and slow down disease progression,there is no cure for multiple sclerosis.The gut-brain axis refers to complex communications between the gut flo ra and the immune,nervous,and endocrine systems,which bridges the functions of the gut and the brain.Disruptions in the gut flora,termed dys biosis,can lead to systemic inflammation,leaky gut syndrome,and increased susceptibility to infections.The pathogenesis of multiple sclerosis involves a combination of genetic and environmental factors,and gut flora may play a pivotal role in regulating immune responses related to multiple scle rosis.To develop more effective therapies for multiple scle rosis,we should further uncover the disease processes involved in multiple sclerosis and gain a better understanding of the gut-brain axis.This review provides an overview of the role of the gut flora in multiple scle rosis. 展开更多
关键词 gut flora gut-brain axis multiple sclerosis PATHOGENESIS treatment
在线阅读 下载PDF
On the longitudinal shifts of the Agulhas retroflection point
5
作者 weiwei zhang Xiaoyi Yang +1 位作者 Wei Zhuang Xiaohai Yan 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2024年第5期16-29,共14页
The Agulhas system is the strongest western boundary current system in the Southern Hemisphere and plays an important role in modulating the Indian-to-Atlantic Ocean water exchange by the Agulhas leakage.It is difficu... The Agulhas system is the strongest western boundary current system in the Southern Hemisphere and plays an important role in modulating the Indian-to-Atlantic Ocean water exchange by the Agulhas leakage.It is difficult to measure in situ transport of the Agulhas leakage as well as the Agulhas retroflection position due to their intermittent nature.In this study,an innovative kinematic algorithm was designed and applied to the gridded altimeter observational data,to ascertain the longitudinal position of Agulhas retroflection,the stability of Agulhas jet stream,as well as its strength.The results show that the east-west shift of retroflection is related neither to the strength of Agulhas current nor to its stability.Further analysis uncovers the connection between the westward extension of Agulhas jet stream and an anomalous cyclonic circulation at its northern side,which is likely attributed to the local wind stress curl anomaly.To confirm the effect of local wind forcing on the east-west shift of retroflection,numerical sensitivity experiments were conducted.The results show that the local wind stress can induce a similar longitudinal shift of the retroflection as altimetry observations.Further statistical and case study indicates that whether an Agulhas ring can continuously migrate westward to the Atlantic Ocean or re-merge into the main flow depends on the retroflection position.Therefore,the westward retroflection may contribute to a stronger Agulhas leakage than the eastward retroflection. 展开更多
关键词 Agulhas system Agulhas leakage retroflection position local wind stress curl
在线阅读 下载PDF
Physiological Mechanism of Exogenous Selenium in Alleviating Mercury Stress on Pakchoi(Brassica campestris L.)
6
作者 Chengxu Qian Qiangwen Chen +4 位作者 Leiyu Jiang Xiaoyan Yang Shen Rao weiwei zhang Feng Xu 《Phyton-International Journal of Experimental Botany》 SCIE 2024年第5期951-962,共12页
The objective of this study was to explain the physiological mechanisms through which Na_(2)SeO_(3) mitigates the growth and developmental inhibition of pakchoi under HgCl_(2)stress.The results showed that treatment w... The objective of this study was to explain the physiological mechanisms through which Na_(2)SeO_(3) mitigates the growth and developmental inhibition of pakchoi under HgCl_(2)stress.The results showed that treatment with HgCl_(2)(40 mg L^(−1))led to reduced biomass,dwarfing,root shortening,and root tip necrosis in pakchoi.Compared to control(CK),the activities of superoxide dismutase(SOD)and peroxidase(POD)in Hg treatment increased,and the content of malondialdehyde(MDA)also dramatically increased,which negatively impacted the growth of pakchoi.Low concentrations of Na_(2)SeO_(3)(0.2 mg L^(−1))significantly increased the content of soluble sugars compared with control,while chlorophyll,soluble proteins,free amino acids,and vitamin C had no significant changes.The results of the mixed treatments with HgCl_(2)and Na_(2)SeO_(3) suggested that selenium may be able to reduce the toxicity of mercury in pakchoi.The biomass,plant height,root length,chlorophyll content,soluble protein,other physiological indicators,and proline showed significant increases compared with the HgCl_(2)treatment.Additionally,the MDA content and mercury accumulation in pakchoi decreased.Our results revealed the antagonistic effects of selenium and mercury in pakchoi.Thus,a theoretical basis for studying pakchoi’s mercuryexcreted and selenium-rich cultivation technology was provided. 展开更多
关键词 SELENIUM mercury stress PAKCHOI physiological properties antioxidant enzymes
在线阅读 下载PDF
An Immune-Inspired Approach with Interval Allocation in Solving Multimodal Multi-Objective Optimization Problems with Local Pareto Sets
7
作者 weiwei zhang Jiaqiang Li +2 位作者 Chao Wang Meng Li Zhi Rao 《Computers, Materials & Continua》 SCIE EI 2024年第6期4237-4257,共21页
In practical engineering,multi-objective optimization often encounters situations where multiple Pareto sets(PS)in the decision space correspond to the same Pareto front(PF)in the objective space,known as Multi-Modal ... In practical engineering,multi-objective optimization often encounters situations where multiple Pareto sets(PS)in the decision space correspond to the same Pareto front(PF)in the objective space,known as Multi-Modal Multi-Objective Optimization Problems(MMOP).Locating multiple equivalent global PSs poses a significant challenge in real-world applications,especially considering the existence of local PSs.Effectively identifying and locating both global and local PSs is a major challenge.To tackle this issue,we introduce an immune-inspired reproduction strategy designed to produce more offspring in less crowded,promising regions and regulate the number of offspring in areas that have been thoroughly explored.This approach achieves a balanced trade-off between exploration and exploitation.Furthermore,we present an interval allocation strategy that adaptively assigns fitness levels to each antibody.This strategy ensures a broader survival margin for solutions in their initial stages and progressively amplifies the differences in individual fitness values as the population matures,thus fostering better population convergence.Additionally,we incorporate a multi-population mechanism that precisely manages each subpopulation through the interval allocation strategy,ensuring the preservation of both global and local PSs.Experimental results on 21 test problems,encompassing both global and local PSs,are compared with eight state-of-the-art multimodal multi-objective optimization algorithms.The results demonstrate the effectiveness of our proposed algorithm in simultaneously identifying global Pareto sets and locally high-quality PSs. 展开更多
关键词 Multimodal multi-objective optimization problem local PSs immune-inspired reproduction
在线阅读 下载PDF
Fast Evaluation Peanut Oil Quality by Synchronous Fluorescence Spectroscopy and Statistical Analysis 被引量:1
8
作者 weiwei zhang Riqin Lv +1 位作者 Yanhui Sun Haiyang Gu 《Agricultural Sciences》 2021年第5期565-574,共10页
<div style="text-align:justify;"> Peanut oil oxidation was to monitor and quantify combining synchronous fluorescence spectroscopy and chemometrics. Peanut oil was subjected to an accelerated oxidation... <div style="text-align:justify;"> Peanut oil oxidation was to monitor and quantify combining synchronous fluorescence spectroscopy and chemometrics. Peanut oil was subjected to an accelerated oxidation testing. The spectral and related chemical indicators were caught during oxidation induce testing. Fluorescence spectra were gained for each sample with simultaneous excitation from 200 to 800 nm and the offsets (Δλ) of 10 to 180 nm during the oxidation process. The results showed the induce period (IP) of the peanut oil was 16.45 h. Parallel factor analysis (PARAFAC) was performed to select the best Δλ interval of 70 nm, which spectral data was the most suitable for interval partial least square (iPLS) and synergy interval PLS (siPLS) modeling and forecast. The study presented all interval selection methods had the better results than the global spectrum modelling. iPLS reached the best into 10 intervals with a ratio of prediction to deviation (RPD) of 2.10. siPLS that separated the whole spectrum into 15 intervals and combined the third intervals (282 to 320 nm, 362 to 400 nm, and 761 to 800 nm) had a ratio of RPD of 2.26. The results showed the optimal siPLS model performed a little better than iPLS. The established model lying on interval selection could improve the prediction accuracy. It could provide a quick, accurate method to monitor oil oxidation process. </div> 展开更多
关键词 Synchronous Fluorescence Spectroscopy Peanut Oil Oxidation Stability CHEMOMETRICS
在线阅读 下载PDF
政治地理、企业内部控制与所得税税负
9
作者 姚圣 张薇薇 《会计论坛》 CSSCI 2018年第1期23-35,共13页
已有文献证明了政治关联对企业所得税税负的影响,但对政治地理的税负效应研究较少,且没有涉及政治地理对企业所得税税负复杂影响的研究。本文通过手工收集中央政治局委员的工作地与出生地信息,构建了政治地理变量,以2013-2015年沪深... 已有文献证明了政治关联对企业所得税税负的影响,但对政治地理的税负效应研究较少,且没有涉及政治地理对企业所得税税负复杂影响的研究。本文通过手工收集中央政治局委员的工作地与出生地信息,构建了政治地理变量,以2013-2015年沪深A股上市公司作为研究样本,检验了政治地理对企业所得税税负的影响,并深入研究内部控制质量对政治地理与企业所得税关系的调节作用。研究结果表明,政治地理的得分越高,公司的企业所得税税负越低,这种效应在国有控股企业中更为显著;内部控制质量会加强政治地理与企业所得税税负的负相关关系,内部控制质量越好,企业所得税税负就越低。 展开更多
关键词 政治地理 企业所得税 企业内部控制
在线阅读 下载PDF
基于微信公众号构建无机化学实验微课平台的研究与探索 被引量:19
10
作者 张玮玮 弓爱君 邱丽娜 《大学化学》 CAS 2020年第3期94-98,共5页
微课是在信息化时代和新教学理念下提出的新型教学模式,针对无机化学实验教学的现状,利用微信公众号构建微课平台,辅助教师进行课堂教学,解决了无机化学实验教学中安全培训、学生预习、学时少及实验内容多、实验药品购买使用受限、不能... 微课是在信息化时代和新教学理念下提出的新型教学模式,针对无机化学实验教学的现状,利用微信公众号构建微课平台,辅助教师进行课堂教学,解决了无机化学实验教学中安全培训、学生预习、学时少及实验内容多、实验药品购买使用受限、不能做有毒实验等问题。通过微课教学还实现了实验内容多样化、演示操作可视化,从而提升学生学习的主观能动性,增强动手能力,规范实验操作流程,便于学生对实验重点难点的掌握,同时增强师生交流,满足各层次学生要求,提高课堂效率。 展开更多
关键词 无机化学实验 微课 微信公众号
在线阅读 下载PDF
Mortality outcomes of low-dose computed tomography screening for lung cancer in urban China:a decision analysis and implications for practice 被引量:10
11
作者 Zixing Wang Wei Han +11 位作者 weiwei zhang Fang Xue Yuyan Wang Yaoda Hu Lei Wang Chunwu Zhou Yao Huang Shijun Zhao Wei Song Xin Sui Ruihong Shi Jingmei Jiang 《Chinese Journal of Cancer》 SCIE CAS CSCD 2017年第8期367-379,共13页
Background: Mortality outcomes in trials of low-dose computed tomography(CT) screening for lung cancer are inconsistent. This study aimed to evaluate whether CT screening in urban areas of China could reduce lung canc... Background: Mortality outcomes in trials of low-dose computed tomography(CT) screening for lung cancer are inconsistent. This study aimed to evaluate whether CT screening in urban areas of China could reduce lung cancer mortality and to investigate the factors that associate with the screening effect.Methods: A decision tree model with three scenarios(low-dose CT screening, chest X-ray screening, and no screening) was developed to compare screening results in a simulated Chinese urban cohort(100,000 smokers aged45-80 years). Data of participant characteristics were obtained from national registries and epidemiological surveys for estimating lung cancer prevalence. The selection of other tree variables such as sensitivities and specificities of low-dose CT and chest X-ray screening were based on literature research. Differences in lung cancer mortality(primary outcome), false diagnoses, and deaths due to false diagnosis were calculated. Sensitivity analyses were performed to identify the factors that associate with the screening results and to ascertain worst and optimal screening effects considering possible ranges of the variables.Results: Among the 100,000 subjects, there were 448,541, and 591 lung cancer deaths in the low-dose CT, chest X-ray, and no screening scenarios, respectively(17.2% reduction in low-dose CT screening over chest X-ray screening and 24.2% over no screening). The costs of the two screening scenarios were 9387 and 2497 false diagnoses and 7and 2 deaths due to false diagnosis among the 100,000 persons, respectively. The factors that most influenced death reduction with low-dose CT screening over no screening were lung cancer prevalence in the screened cohort, lowdose CT sensitivity, and proportion of early-stage cancers among low-dose CT detected lung cancers. Considering all possibilities, reduction in deaths(relative numbers) with low-dose CT screening in the worst and optimal cases were16(5.4%) and 288(40.2%) over no screening, respectively.Conclusions: In terms of mortality outcomes, our findings favor conducting low-dose CT screening in urban China.However, approaches to reducing false diagnoses and optimizing important screening conditions such as enrollment criteria for screening are highly needed. 展开更多
关键词 Lung cancer LOW-DOSE CT SCREENING MORTALITY OUTCOME Decision analysis
在线阅读 下载PDF
Cardiac autonomic nerve fiber regeneration in chronic heart failure Do Akt gene-transduced mesenchymal stem cells promote repair? 被引量:13
12
作者 Hongliang Kong Zhanquan Li +7 位作者 Shumei Zhao Li Zhu Yingjun Zhao weiwei zhang GuipingXu Wenjun Hao Huijun Li Guoxian Qi 《Neural Regeneration Research》 SCIE CAS CSCD 2010年第1期28-34,共7页
BACKGROUND: Transplantation of Akt-over-expressing mesenchymal stem ceils (Akt-MSCs) has been shown to repair infarcted myocardium and improve cardiac function. However, little is known about the therapeutic effect... BACKGROUND: Transplantation of Akt-over-expressing mesenchymal stem ceils (Akt-MSCs) has been shown to repair infarcted myocardium and improve cardiac function. However, little is known about the therapeutic effects of Akt-MSCs on cardiac autonomic neuropathy in chronic heart failure (CHF). OBJECTIVE: The present study used adriamycin-induced CHF rat models to observe the effect of Akt-MSCs on cardiac autonomic nervous regeneration and the factors mediating this effect. DESIGN, TIME AND SETTING: A randomized, controlled animal experiment was performed at the Central Laboratory of Basic Medical College, China Medical University, between September 2008 and April 2009. MATERIALS: Rabbit anti-choline acetyltransferase (CHAT), growth associated protein-43 (GAP-43) synaptophysin (SYN) polyclonal antibodies and the secondary antibody (goat anti-rabbit IgG) were purchased from Boster, China. Cat-A-Kit assay system was provided by Amersham, USA. METHODS: (1) Adult rat MSCs were isolated and cultured for the preparation of Akt-MSCs. (2) Forty male Wistar rats were intramyocardially administered adriamycin at 2 mg/kg over 3 days for a total of five times and once a week for additional five times thereafter to establish CHF models. At 2 weeks after final adriamycin treatment, 34 successful CHF rat models were randomized to three groups: Akt-MSCs (n = 11), simple MSCs (s-MSCs, n =11), and control (n = 12). Each group was intravenously administered Akt-MSCs (2x106 cells in 100 IJL PBS), s-MSCs (2×10^6 cells in 100 μL PBS) or equal volume of phosphate buffered saline, once a day for a total of three times. MAIN OUTCOME MEASURES: At 4 weeks after final adriamycin treatment, myocardial norepinephrine (NE) content was detected using a Cat-A-Kit assay system. Myocardial CHAT, SYN and GAP-43 were performed by immunohistochemistry and Western blot analysis. Prior to, 2 and 4 weeks after adriamycin treatment, echocardiographic examination was performed and left ventricular ejection fraction (LVEF) was determined. RESULTS: Myocardial NE content, as well as SYN-positive and GAP-43-positive nerve fiber density and expression, and LVEF, was the greatest in the Akt-MSCs group, followed by the s-MSCs group, and lastly the control group (P 〈 0.05 or P 〈 0.01). ChAT expression was similar between Akt-MSCs and s-MSCs groups, but it was higher compared with the control group (P 〈 0.05). NE contents were negatively correlated to LVEF (r = -0.64, P = 0.015). CONCLUSION: Transplantation of MSCs, in particular Akt-MSCs, promotes cardiac nervous regeneration in failing heart, which might be mediated by GAP-43. 展开更多
关键词 mesenchymal stem cells Akt gene transfection chronic heart failure neural regeneration autonomic nerve system
在线阅读 下载PDF
Exogenous melatonin improves the chilling tolerance and preharvest fruit shelf life in eggplant by affecting ROS-and senescence-related processes 被引量:11
13
作者 Lijun Song Zhuo Tan +5 位作者 weiwei zhang Qiang Li Zhaoxiang Jiang Shuxing Shen Shuangxia Luo Xueping Chen 《Horticultural Plant Journal》 SCIE CAS CSCD 2023年第3期523-540,共18页
Low temperature is the most common abiotic stress factors during the eggplant cultivation in solar greenhouses.Melatonin plays important roles in plant resistance to low temperature.However,the role of melatonin in re... Low temperature is the most common abiotic stress factors during the eggplant cultivation in solar greenhouses.Melatonin plays important roles in plant resistance to low temperature.However,the role of melatonin in regulating chilling tolerance and extending the preharvest shelf life of eggplant fruits is still unknown.In this study,we investigated the effects of exogenous melatonin on eggplant plants and fruits in response to low temperature.Under simulated low-temperature conditions,exogenous melatonin significantly relieved the chilling symptoms of seedlings by reducing reactive oxygen species (ROS) and malondialdehyde (MDA) levels and relative leakage rates.These reductions were caused by higher superoxide dismutase (SOD) and catalase (CAT) activities and increased endogenous polyamine and melatonin levels compared with those in untreated seedlings.Notably,the expression levels of SOD,CAT1/2,and polyamine synthesis genes (ADC and ODC) were also increased by 100μmol·L~(-1)melatonin,as well as those of genes involved in melatonin synthesis (TDC,T5H,SNAT,ASMT,and COMT) and cold regulation (COR1,CBFa/b,and ZAT2/6/12).To further investigate the effects of melatonin on eggplant leaves and fruits under natural low temperature conditions,100μmol·L~(-1)melatonin was sprayed on the functional leaves at three days before commodity maturation.Melatonin significantly alleviated chilling injury in the leaves and pericarp and extended the preharvest shelf life of the fruit by increasing the expression of COR1,CBF,ZAT2/6/12,and API5 and decreasing the expression of senescence-related genes (NCED1/2 and SAG12).Therefore,100μmol·L~(-1)melatonin improved chilling tolerance and fruit shelf life by upregulating ZAT2/6/12 to affect ROS-and senescence-related processes,which provides a reference for alleviating cold stress and extending the preharvest fruit shelf life in eggplant. 展开更多
关键词 EGGPLANT MELATONIN Chilling tolerance Cold regulation Reactive oxygen species Preharvest fruit shelf life
在线阅读 下载PDF
规模化猪场非洲猪瘟防控要点 被引量:4
14
作者 张巍巍 王新 《猪业科学》 2021年第6期100-103,共4页
在我国群众食用的各种肉类中,猪肉占据绝对优势。在肉类消费中,很长时间以来猪肉消费皆处于较大占比。非洲猪瘟于2018年8月进入我国,极大程度干扰到国内生猪养殖,猪肉价格一路上涨,一度接近牛肉。受到猪肉售价提高的影响,其他肉类与菜... 在我国群众食用的各种肉类中,猪肉占据绝对优势。在肉类消费中,很长时间以来猪肉消费皆处于较大占比。非洲猪瘟于2018年8月进入我国,极大程度干扰到国内生猪养殖,猪肉价格一路上涨,一度接近牛肉。受到猪肉售价提高的影响,其他肉类与菜类的售价皆随之提高,也造成了较大的社会影响。在我国,生猪养殖模式上,大多数为集约化养殖,非洲猪瘟的流行在极大程度上威胁到生猪养殖业,导致巨大经济损失。如何防控非洲猪瘟,避免造成较大的损失,文章将从病原来源、发展现状及如何防治等方面进行分析,进而在理论层面上给予防控非洲猪瘟工作以指导,拱筑防控非洲猪瘟城墙。 展开更多
关键词 非洲猪瘟 流行病学 生物安全 消毒剂
在线阅读 下载PDF
The calmodulin-dependent protein kinase II inhibitor KN-93 protects rat cerebral cortical neurons from N-methyl-D-aspartic acid-induced injury 被引量:3
15
作者 Xuewen Liu Cui Ma +5 位作者 Ruixian Xing weiwei zhang Buxian Tian Xidong Li Qiushi Li Yanhui zhang 《Neural Regeneration Research》 SCIE CAS CSCD 2013年第2期111-120,共10页
In this study, primary cultured cerebral cortical neurons of Sprague-Dawley neonatal rats were treated with 0.25, 0.5, and 1.0 μM calmodulin-dependent protein kinase II inhibitor KN-93 after 50 μM N-methyI-D-asparti... In this study, primary cultured cerebral cortical neurons of Sprague-Dawley neonatal rats were treated with 0.25, 0.5, and 1.0 μM calmodulin-dependent protein kinase II inhibitor KN-93 after 50 μM N-methyI-D-aspartic acid-induced injury. Results showed that, compared with N-methyi-D- aspartic acid-induced injury neurons, the activity of cells markedly increased, apoptosis was significantly reduced, leakage of lactate dehydrogenase decreased, and intracellular Ca2+ concentrations in neurons reduced after KN-93 treatment. The expression of caspase-3, phosphorylated calmodulin-dependent protein kinase II and total calmodulin-dependent protein kinase II protein decreased after KN-93 treatment. And the effect was apparent at a dose of 1.0 pM KN-93. Experimental findings suggest that KN-93 can induce a dose-dependent neuroprotective effect, and that the underlying mechanism may be related to the down-regulation of caspase-3 and calmodulin- dependent protein kinase II expression. 展开更多
关键词 neural regeneration brain injury calmodulin-dependent protein kinase II KN-93 N-methyi-D-aspartic acid caspase-3 calcium ion apoptosis NEUROPROTECTION grant-supported paper photographs-containing paper NEUROREGENERATION
在线阅读 下载PDF
Research on data assimilation strategy of turbulent separated flow over airfoil 被引量:4
16
作者 Ying zhang Lin DU +1 位作者 weiwei zhang Zichen DENG 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2022年第4期571-586,共16页
In order to increase the accuracy of turbulence field reconstruction,this paper combines experimental observation and numerical simulation to develop and establish a data assimilation framework,and apply it to the stu... In order to increase the accuracy of turbulence field reconstruction,this paper combines experimental observation and numerical simulation to develop and establish a data assimilation framework,and apply it to the study of S809 low-speed and high-angle airfoil flow.The method is based on the ensemble transform Kalman filter(ETKF)algorithm,which improves the disturbance strategy of the ensemble members and enhances the richness of the initial members by screening high flow field sensitivity constants,increasing the constant disturbance dimensions and designing a fine disturbance interval.The results show that the pressure distribution on the airfoil surface after assimilation is closer to the experimental value than that of the standard Spalart-Allmaras(S-A)model.The separated vortex estimated by filtering is fuller,and the eddy viscosity field information is more abundant,which is physically consistent with the observation information.Therefore,the data assimilation method based on the improved ensemble strategy can more accurately and effectively describe complex turbulence phenomena. 展开更多
关键词 turbulence data assimilation ensemble disturbance strategy large angle of attack separation ensemble transform Kalman filter(ETKF)
在线阅读 下载PDF
中国城市人群低剂量计算机断层扫描筛查肺癌的死亡率结果:决策分析和实践意义 被引量:4
17
作者 Zixing Wang Wei Han +11 位作者 weiwei zhang Fang Xue Yuyan Wang Yaoda Hu Lei Wang Chunwu Zhou Yao Huang Shijun Zhao Wei Song Xin Sui Ruihong Shi Jingmei Jiang 《癌症》 SCIE CAS CSCD 2018年第8期356-370,共15页
背景与目的不同低剂量计算机断层扫描(computed tomography,CT)筛查肺癌试验得出的死亡率结果不一致。本研究旨在评价中国城市CT筛查是否能够降低肺癌死亡率,并探讨影响筛查效果的因素。方法建立了3种场景(低剂量CT筛查、胸部X线筛查和... 背景与目的不同低剂量计算机断层扫描(computed tomography,CT)筛查肺癌试验得出的死亡率结果不一致。本研究旨在评价中国城市CT筛查是否能够降低肺癌死亡率,并探讨影响筛查效果的因素。方法建立了3种场景(低剂量CT筛查、胸部X线筛查和无筛查)的决策树模型来比较模拟的中国城市人群(100,000例年龄45–80岁的吸烟者)的筛查结果。从国家登记和流行病学调查中获得了参与者特征数据并估算了肺癌患病比例。根据文献调研选择了低剂量CT和胸部X线筛查的灵敏度和特异度等其他树变量。计算了3种筛查方法间肺癌死亡率(主要结局)、误诊和误诊导致死亡的差异。通过敏感性分析找出了与筛查结果相关的因素,并确定了在变量可能范围内的最差和最优筛查效果。结果 100,000例研究对象中,低剂量CT、胸部X线和无筛查场景分别有448例、541例和591例肺癌死亡(低剂量CT筛查比胸部X线筛查死亡人数减少17.2%,比无筛查减少24.2%)。100,000例研究对象中,2种筛查场景的代价分别为9387例和2497例误诊及7例和2例误诊导致的死亡。低剂量CT筛查比无筛查的死亡数降低,影响最大的因素是筛查人群的肺癌患病比例、低剂量CT的灵敏度和低剂量CT检出肺癌中早期癌的比例。综合了所有可能性,低剂量CT筛查肺癌的死亡人数(相对数)在最坏和最好情况下分别比无筛查降低了16例(5.4%)和288例(40.2%)。结论就死亡率结局而言,我们的研究结果支持在中国城市人群中进行低剂量CT筛查。然而,急需策略来减少误诊和优化纳入标准等重要筛查条件。 展开更多
关键词 肺癌 低剂量CT 筛查 死亡率结局 决策分析
在线阅读 下载PDF
Targeting EZH1/2 induces cell cycle arrest and inhibits cell proliferation through reactivation of p57CDKN1C and TP53INP1 in mantle cell lymphoma 被引量:2
18
作者 Wei Li Chengfeng Bi +13 位作者 Yating Han Tian Tian Xianhuo Wang Huijing Bao Xiaoying Xu Xuhan zhang Lu Liu weiwei zhang Hai Gao Huaqing Wang Huilai zhang Bin Meng Xi Wang Kai Fu 《Cancer Biology & Medicine》 SCIE CAS CSCD 2019年第3期530-541,共12页
Objective: To explore the effect of dysregulation of epigenetic regulator EZH1 and EZH2 on the proliferation in MCL and the underlying mechanisms.Methods: In this study, we elucidated the role of EZH1 and EZH2 overexp... Objective: To explore the effect of dysregulation of epigenetic regulator EZH1 and EZH2 on the proliferation in MCL and the underlying mechanisms.Methods: In this study, we elucidated the role of EZH1 and EZH2 overexpression by immunohistochemistry and correlated them to clinical outcome in 41 MCL patients.Quantitative real-time PCR and Western blot were applied to confirm the level of EZH1 and EZH2 in well-characterized MCL cell lines which were compared to those of na?ve B cells.Then we manipulated the expression of EZH1 and EZH2 in MCL cells using CRISPR/Cas9 system to directly investigate their functional roles in MCL.We also evaluated the effect of two small molecule selective inhibitors, EPZ005687 and UNC1999, on MCL cell proliferation, cell cycle distribution and apoptosis in vitro.Finally, we performed RNA-sequencing(RNA-Seq) and Chromatin immunoprecipitation(ChIP) assay to further gain insight into the underlying molecular mechanisms.Results: We found that EZH2 protein is overexpressed in approximately half of this cohort of MCL cases.More importantly, the overexpression of EZH2 is associated with poor OS in the patients.Nevertheless, simple EZH2 depletion in vitro has little impact on the viability of MCL cells, predominantly because of the consequent up-regulation of EZH1.Consistently, UNC1999, a dual EZH1/2 inhibitor, unlike the EZH2 selective inhibitor EPZ005687, exerts a potent inhibitory effect on MCL cells.Furthermore, we discover CDKN1C and TP53 INP1 as the two important cell cycle regulators, the expression of which are repressed by EZH1/2 mediated epigenetic regulation and are restored by EZH1/2 dual inhibition.Conclusions: Our study suggests that EZH2 participates in the pathogenesis of MCL which may serve as a potential biomarker for prognosis prediction.The dual inhibition of EZH1/2 is a promising therapeutic strategy for MCL. 展开更多
关键词 MANTLE cell LYMPHOMA EZH1 EZH2 CRISPR/Cas9
在线阅读 下载PDF
Tailoring polymeric composite gel beads-encapsulated microorganism for efficient degradation of phenolic compounds 被引量:2
19
作者 Xueping Liu Ping Xue +3 位作者 Feng Jia Dongya Qiu Keren Shi weiwei zhang 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2021年第4期301-306,共6页
Phenol and its derivatives are highly toxic pollutants in industrial wastewater for the ecological environments,so there is essential attention to develop effective means of removing these harmful substances from wate... Phenol and its derivatives are highly toxic pollutants in industrial wastewater for the ecological environments,so there is essential attention to develop effective means of removing these harmful substances from water.In this work,the microorganism was immobilized into polymeric composite gel beads prepared by the effective recombination of natural abundant chitosan(CS)and industrial polyvinyl alcohol(PVA)for treating phenolic compounds.The degradation rate of 99.5%can be achieved to treat 100 mg·L^(1)of phenol at 30℃using the fresh resultant immobilized microorganism,where only 21.1%degradation rate was obtained by the free microorganism under the identical conditions.The recycling experiments of repeated 90 times to treat 100 mg·L^(1)of phenol displayed that the degradation rate of phenol was stable to 99%with the appearance of beads unchanged significantly,indicating the immobilized microorganism possessed excellent operating stability.Moreover,while the phenol derivatives of 100 mg·L^(1)were treated catalytically including pmethylphenol,catechol,and oaminophenol for 24 h by the immobilized microorganism,the degradation rates were all above 95%.The immobilized microorganism into PVACS polymeric composite with excellent operating stability and degradation activity would provide a feasible solution for treating phenolic compounds in water in industrial applications. 展开更多
关键词 Polymeric composite Immobilization BIOCATALYSIS Phenolic compounds Degradation REUSABILITY
在线阅读 下载PDF
Awareness intervention for Beijing neurologists regarding secondary prevention of cerebral infarction/transient ischemia Cross-sectional investigation 被引量:2
20
作者 Ruihua Ma Chunxue Wang +15 位作者 Xianwei Wang Yuhui zhang Yongjun Wang Yilong Wang Xingquan Zhao Jingjing Li Ying Lu Mingjie Xu Zhuo zhang Li Wang weiwei zhang Lang Lin Jiping Tan Yao Li Ming Wei Hongtao Li 《Neural Regeneration Research》 SCIE CAS CSCD 2008年第3期333-336,共4页
BACKGROUND: Stroke prevention guidelines should be made available application to aid in uniformity, timing, preciseness, and acceptance of disease. OBJECTIVE: To investigate the awareness of neurologists in some Bei... BACKGROUND: Stroke prevention guidelines should be made available application to aid in uniformity, timing, preciseness, and acceptance of disease. OBJECTIVE: To investigate the awareness of neurologists in some Beijing secondary prevention of cerebral infarction/transient ischemia. DESIGN: Cross-sectional study. to neurologists for clinical hospitals of intervention in SETTING: Beijing Tiantan Hospital, Beijing Anzhen Hospital, General Hospital of Beijing Military Area, Command of Chinese PLA, Beijing Chuiyangliu Hospital, Beijing 6^th Hospital, Beijing Hepingli Hospital, and Beijing Daxing District Hospital. PARTICIPANTS: A total of 28 (associate) chief physicians, 58 attending physicians, and 54 resident physicians who engaged in clinical treatment of cerebrovascular diseases were selected from 8 hospitals in Beijing from March to April 2007. All physicians provided informed consent. METHODS: Self-made closed questionnaires were provided for data collection, consisting of 16 questions that were single choice or multiple choice. Specifically, questions 1-7 focused on awareness of blood pressure regulation in different patients and first choice of decompression drug; questions 8-12 focused on awareness of lipid regulation; and questions 13-16 focused on awareness of anti-blood platelet drugs applied in secondary prevention. The scores ranged from 0-100 points, and each question was worth 6.25 points. The scores positively correlated with the awareness rate. To test leveling real-time, the survey lasted for a maximum of 20 minutes. One questionnaire was independently finished by each subject in the survey. MAIN OUTCOME MEASURES: Awareness intervention among neurologists during secondary prevention of cerebral infarction/transient ischemia and questionnaire scores. RESULTS: 140 subjects were included in the final analysis. ① The awareness rate among neurologists for intervention during secondary prevention of cerebral infarction/transient ischemia ranged from 0.7-57.9%, the scores ranged between 0-56 points, and the mean score was 26 points.② Scores of resident physicians were 0-56 points with a mean score of 26 points; attending physicians scored 6-50 points, with a mean score of 26 points; and chief physicians scored 6-50 points, with a mean score of 23 points. There were no significant differences among the various physicians (F = 0.771, t = 0.465, P 〉 0.05). CONCLUSION: Awareness among neurologists of intervention during secondary prevention of cerebral infarction/transient ischemia is not ideal. However, there was no significant difference between professional titles. 展开更多
关键词 secondary prevention cerebral infarction transient ischemic attack cross-sectional study
在线阅读 下载PDF
上一页 1 2 6 下一页 到第
使用帮助 返回顶部