目的建立一个用于展示和评价肿瘤流行与控制状况的电子地理信息系统。方法收集人口学资料;应用电子计算机W IND OW S平台的M AP-INFO(地图信息)软件,采用数字化图形方式制作天津市街道和乡镇的电子行政区划图;建立分街道和乡镇的肿瘤流...目的建立一个用于展示和评价肿瘤流行与控制状况的电子地理信息系统。方法收集人口学资料;应用电子计算机W IND OW S平台的M AP-INFO(地图信息)软件,采用数字化图形方式制作天津市街道和乡镇的电子行政区划图;建立分街道和乡镇的肿瘤流行病学信息专用数据库,确定相关指标;定义图形区域与数据库的联系,确定图形选择方式。结果合成能直观、快速、准确、清晰地反映肿瘤流行趋势、水平、变化规律和地理分布的天津市多维肿瘤流行病学与电子地理信息图。结论本研究具有多重实用性和优越性,适用于各种卫生事业信息的地理分析,天津市的各区(县)可直接使用本系统。其他的省市和地区都可采用本方法进行分析。展开更多
The effects of nitrogen （N） availability and tree species on the dynamics of carbon and nitrogen at early stage of decomposition of forest litter were studied in a 13-week laboratory incubation experiment. Fresh lit...The effects of nitrogen （N） availability and tree species on the dynamics of carbon and nitrogen at early stage of decomposition of forest litter were studied in a 13-week laboratory incubation experiment. Fresh litter samples including needle litter （Pinus koraiensis） and two types of broadleaf litters （Quercus mongolica and Tilia amurensis） were collected from a broadleaf-korean pine mixed forest in the northern slope of Changbai Mountain （China）. Different doses of N （equal to 0, 30 and 50 kg.ha^-1yr^-1, respectively, as NH4NO3） were added to litter during the experiment period. The litter decomposition rate expressed as mass loss and respiration rate increased significantly with increasing N availability. The mass loss and cumulative CO2-C emission were higher in leaf litter compared to that in needle litter. The dis- solved organic Carbon （DOC） concentrations in litter leachate varied widely between the species, but were not greatly affected by N treatments. Regardless of the N addition rate, both N treatments and species had no significant effect on dissolved organic N （DON） concentrations in litter leachate. About 52-78% of added N was retained in the litter. The percentage of N retention was positively correlated （R^2=0.9 1, p〈0.05） with the litter mass loss. This suggested that a forest floor with easily decomposed litter might have higher potential N sink strength than that with more slowly decomposed litter.展开更多
文摘目的建立一个用于展示和评价肿瘤流行与控制状况的电子地理信息系统。方法收集人口学资料;应用电子计算机W IND OW S平台的M AP-INFO(地图信息)软件,采用数字化图形方式制作天津市街道和乡镇的电子行政区划图;建立分街道和乡镇的肿瘤流行病学信息专用数据库,确定相关指标;定义图形区域与数据库的联系,确定图形选择方式。结果合成能直观、快速、准确、清晰地反映肿瘤流行趋势、水平、变化规律和地理分布的天津市多维肿瘤流行病学与电子地理信息图。结论本研究具有多重实用性和优越性,适用于各种卫生事业信息的地理分析,天津市的各区(县)可直接使用本系统。其他的省市和地区都可采用本方法进行分析。
基金Foundation project： This work was supported by the Knowledge Innova- tion Project of the Chinese Academy of Sciences （KZCX2-YW-416） and the National Natural Science Foundation （90411020）
文摘The effects of nitrogen （N） availability and tree species on the dynamics of carbon and nitrogen at early stage of decomposition of forest litter were studied in a 13-week laboratory incubation experiment. Fresh litter samples including needle litter （Pinus koraiensis） and two types of broadleaf litters （Quercus mongolica and Tilia amurensis） were collected from a broadleaf-korean pine mixed forest in the northern slope of Changbai Mountain （China）. Different doses of N （equal to 0, 30 and 50 kg.ha^-1yr^-1, respectively, as NH4NO3） were added to litter during the experiment period. The litter decomposition rate expressed as mass loss and respiration rate increased significantly with increasing N availability. The mass loss and cumulative CO2-C emission were higher in leaf litter compared to that in needle litter. The dis- solved organic Carbon （DOC） concentrations in litter leachate varied widely between the species, but were not greatly affected by N treatments. Regardless of the N addition rate, both N treatments and species had no significant effect on dissolved organic N （DON） concentrations in litter leachate. About 52-78% of added N was retained in the litter. The percentage of N retention was positively correlated （R^2=0.9 1, p〈0.05） with the litter mass loss. This suggested that a forest floor with easily decomposed litter might have higher potential N sink strength than that with more slowly decomposed litter.
