铅球成绩与体重、身高关系分析

<正>我们在体育教学中发现这样一种情况:以铅球项目为例,在同等条件训练下,体重轻、个子小的学生,其成绩不如体重大、个子高的同学,也不如具有同等体重个子高的同学。他们虽然经过努力,技术动作也掌握得不错,但要达到良好标准却较难,甚至达到最低标准都有一定的困难;相反,体重大、个子高的学生,他们训练并不怎么努力,技术动作也不够     

Composite structure and properties of the pitcher surface of the carnivorous plant Nepenthes and its influence on the insect attachment system

Pitchers of the carnivorous plant Nepenthes have evolved specialized organs serving the purpose of attracting,capturing,retaining and digesting small animals,mostly insects.They consist of several well distinguishable zones,including a leaf-like lid,a collar-like peristome,a slippery zone and a digestive zone,differing in morphology,microstructure,chemical composition and physical properties.Discriminating zones display different functions,and the combined effects of several zones result in great trapping efficiency.The principal aim of this review is to introduce the structure and physiochemical properties of the pitcher surface,as well as the interaction between the pitcher surface and the insect attachment systems.Combining with our present study,the potential application of the pitcher surface being utilized in bionics to manufacture insect slippery trapping plates is discussed,and the original research direction of the pitcher surface and its application on agricultural pest control is highlighted.