中国新农村绿化建设的研究现状及趋势

探索了新农村和新农村绿化的含义,总结新农村绿化的研究进展和乡村景观规划、乡村绿地分类、乡村景观评价等新农村绿化建设相关领域的研究现状,揭示了新农村绿化建设的研究趋势,提出了新农村绿化研究将趋于科学化、规范化,数量化方法,乡村景观评价方法将应用于新农村绿化研究领域是我国新农村绿化建设研究的主要趋势.     

江苏省淮山药生产现状与产业发展

通过对江苏省淮山药种植地区主要品种、主体栽培技术、单产水平、种植面积和市场价格等进行生产现状调查,阐述了我省淮山药生产状况,为中长期淮山药产业发展提供参考依据.     

Selectivity of end-Cretaceous marine bivalve extinctions

Analyses of the end-Cretaceous or Cretaceous-Tertiary mass extinction show no selectivity of marine bivalve genera by life position (burrowing versus exposed), body size, bathymetric position on the continental shelf, or relative breadth of bathymetric range. Deposit-feeders as a group have significantly lower extinction intensities than suspension-feeders, but this pattern is due entirely to low extinction in two groups (Nuculoida and Lucinoidea), which suggests that survivorship was not simply linked to feeding mode. Geographically widespread genera have significantly lower extinction intensities than narrowly distributed genera. These results corroborate earlier work suggesting that some biotic factors that enhance survivorship during times of lesser extinction intensities are ineffectual during mass extinctions.