The genetic diversity of cen-tral and peripheral popula-tions of ratlike hamster(Cricetulus triton)

The impact of habitat fragmentation and isolation on the genetic diversity of populations has attracted much attention in studies of meta-population and conservation biology. In this work, using the randomly amplified polymorphic DNA (RAPD) technique, we studied the genetic diversity of central, peripheral and peninsular populations of ratlike hamster, which were collected in five locations of the North China Plain and its surrounding areas, in 1999. The study revealed that, ⅰ) the genetic diversity of central population of Raoyang County＞the sub-central populations of Gu'an County and Taikang County＞the peripheral population of Shunyi District＞the peninsular population of Mentougou District; ⅱ) the genetic diversities of the five populations were positively correlated to the nearest distances to the peripheral line of population distribution; ⅲ) there were significant differences of gene frequencies of some RAPD fragments among the five populations. More RAPD fragments disappeared in peripheral populations than in central or sub-central populations. The frequencies of two RAPD fragments were correlated to the latitude. This study clearly indicated that the variation of the genetic diversities of the five populations was caused by edge effect and frag- mentation through the enhanced inbreeding and genetic drift, and thus supported the view that habitat fragmentation and related edge effect reduce the population genetic diversity.     

选择最小方差阈值的判别式方法

本文阐述了选择最小方差阈值的各次累积矩判别式方法,证明了零次矩判别式最小方差阈值选择法在理论上可使统计累积矩的次数降到最低,在实用上可进一步减少运算量。     

我国当前社会保险面临的问题及对策

从制度设计方面、资金供求方面、管理体制方面分析了社会保险面临的困难和问题，提出了完善社会保险体系的思路与对策，即依法扩大社会保险覆盖面。扩大基金筹措渠道，切实加强基金支出管理，加快社会化管理服务步伐。     

信息技术与学科教学的整合需要研究型教师

信息技术与学科的有效整合需要教师具备整合的基本能力，并成为研究型教师。指出教师要不断更新信息技术知识和技能，利用现代教学设施，依据教学实践开展研究，从而探索出有效的整合模式。     

可碰并工业粉尘粒子的空间浓度分布研究

应用C S Wen统计力学的碰并理论 ,通过研究工业粉尘与墙壁之间的作用势力及粘连性质 ,给出了可碰并工业粉尘粒子的空间浓度分布     

论田径课发散思维的训练

根据发散思维与收敛思维的辩证关系 ,论述了田径课培养学生发散思维的 3种方法 ,有利于表现个性 ;全方位地培养学生与老师之间的有效交往能力 ;激发学生潜力 ,发展学生的兴趣 ;在安排时间、搜集资料、自我评价等方面培养了学生独立的学习能力 .     

计算机基础课教学网站开发和建设方案

文章针对计算机基础所面临的不断变化和持续增长 的需求，提出了计算机基础课教学网站的建设方案，介绍了网站的总体结构和创建网站时所使用的主要工具的方法，以及动态WEB的实现技术。     

用ISM分析某集团公司关键性经营战略因素

针对A集团公司经营发展中的问题，采用问卷调查方式，咨询了该公司20位中上层领导。总结出了7个重要因素。应用ISM方法分析这些因素，得出相应的解释结构模型，使影响该集团发展由浅入深的因素层次化。文中认为低层矛盾得以解决，公司深层能力才能得到提高，表层问题也自然迎刃而解，公司才能加速发展。     

A Case－Based System for Construction Project Risk Management

1　IntroductionIn the field of construction,project risk management is a complex and important task.Therefore,it is very important for construction project managers to consider all possiblerisk factors affecting a given construction project. Furthermore,they should examine howthese factors interact in the decision- making process and how to balance subjective beliefsand information in identifying risk and uncertainties,and information,and takingcorrective actions to control the identified risk…     

略论何乔远《名山藏》中人物传记的特色

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