Mesoscale physical processes and the distribution and composition of ichthyoplankton on the southern Brazilian shelf break

The southern Brazilian shelf supports the largest fish stocks in the country, and studies on physical–biological processes in the ecology of ichthyoplankton have been recommended to provide a better understanding of the variability of the recruitment of fishing resources. This study is the first to examine the influence of mesoscale physical processes on the distribution of early life stages of fish in this shelf‐break region. Collections of fish eggs and larvae and measurements of temperature and salinity were made at 13 stations along cross‐shelf transects in December 1997. Myctophidae, Bregmacerotidae, Clupeidae, Synodontidae and Engraulidae were the most abundant larvae in the northern region, while Engraulidae and Bregmacerotidae prevailed further south. In situ hydrographic data, NOAA/AVHRR images and merged TOPEX/POSEIDON + ERS‐1/2 satellite altimetry taken during the cruise revealed an anticyclonic eddy dominating the shelf around 31°S. Larval fish abundance was lower at the centre of this feature, suggesting that the eddy advected poorer offshore waters of tropical origin towards the inner shelf‐concentrating the larvae around the eddy.     

DNA和细胞对重离子辐照诱导DNA双链断裂的敏感性比较

用倒转脉冲场凝胶电泳（PIGE）比较研究了50MeV/u^12C^6 辐小鼠B16黑色素瘤细胞及其脱蛋白DNA分子,从而诱导DNA双链断裂（DSB）的辐射敏感性,结果表明,不论辐照脱蛋白DNA还是辐照完整细胞,诱导的DNA片段释放百分比（PR）都随着剂量的增加而增加,在超过40Gy,PR趋向一个近似相同的准阈值－81％,辐照脱蛋白DNA诱导的DSB产额的0．40DSBs/100Mbp/Gy,辐照完整细胞诱导的DSB产额0．19DSBs/100Mbp/Gy,说明脱蛋白DNA分子比完整细胞对重离子辐照要敏感。     

沙棘克隆生长及其生态学意义

克隆生长赋予沙棘生理整合和觅养行为等特性,使其不仅能够适应干旱缺水的环境,并且具有较高的繁殖及生存有效性,通过林缘扩散和林窗更新维持群落持久性及稳定性。同时,沙棘能通过克隆生长产生大量彼此联结的分株,形成庞大的地下网络结构,从而有效地保持水土、防风固沙、稳固土壤基质,并为其他植物的定居创造有利条件。     

台湾桂竹笋─幼竹生长规律研究

台湾桂竹笋─幼竹生长规律研究黄克福，马炳杨（福建林学院林学系，福建南平３５３００１）（莆田县林业局，福建莆田３５１１００）摘要３０个样地材料分析结果表明：台湾桂竹出笋起始期为４月上旬或中旬，持续出笋２０～３０天；退笋率为２３％～３０％，成竹率较高；在...     

试论跨文化交际中文化的负面影响与克服

当今全球化进程使跨文化交际成为一种普遍现象。来自不同民族、国家的人们在相互的交流与合作中容易因为文化差异而导致人际交往失误。文化认同带来的正面效应和文化排斥诱发的负面影响并存。文章详细探讨干预人们交际活动的文化负面影响的几大类表现,包括文化定势、民族中心主义、社会分类等。分析各自的定义、特征、产生的原因,从而积极寻求克服文化负面影响的办法。