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Seasonal variation in abundance, diel vertical migration and body size of pelagic tunicate Salpa fusiformis in the Southern Yellow Sea 被引量:4
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作者 LIU Yongqin SUN Song ZHANG Guangtao 《Chinese Journal of Oceanology and Limnology》 SCIE CAS CSCD 2012年第1期92-104,共13页
Mass occurrence of Salpafusiformis June 2007. In order to investigate its population was observed in the Southern Yellow Sea in May and recruitment and environmental adaptation, temporal variation of abundance, diel v... Mass occurrence of Salpafusiformis June 2007. In order to investigate its population was observed in the Southern Yellow Sea in May and recruitment and environmental adaptation, temporal variation of abundance, diel vertical migration (DVM) and length frequency distribution of both aggregate and solitary forms were studied with samples collected from eight months during September 2006 to August 2007. S. fusiformis presented in six months other than September and October 2006, and average abundance of aggregate and solitary forms peaked in June and May, respectively. In December, aggregate forms were absent in the bottom layer and performed irregular DVM from surface to 50 m depth, while solitary forms was too scarce to perform diel vertical distribution analysis. Both aggregate and solitary forms presented reverse DVM in May and June. They migrated upwards during daytime and concentrated in surface layer at sunset. The bimodal distribution of aggregate forms was found in April and the average size was largest in this month. In other months, the smaller aggregate forms (1-5 ram) dominated in populations except for May, when the modal size ranged from 2 to 8 mm. The average size of solitary forms was largest in December, followed by April. The skewed nomal distribution of solitary forms was found in May and June, with the modal size of 2-7 mm and 5-13 ram, respectively. 展开更多
关键词 Salpafusiformis SWARM diel vertical migration length frequency Southern Yellow Sea
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关于苏科、人教两教材中压力作用效果与压强问题处理比较研究
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作者 李技 《湖南中学物理》 2017年第4期28-28,54,共2页
初中物理教学中,一般对于压力的作用效果是定性分析,压强则是定量计算,它们实际上不是同一概念。但由于教材的有意或无意的忽视,使得很多学生甚至部分教师认为压强就是压力的作用效果,让人很是遗憾。
关键词 力的作用效果 被压物体
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