The green June beetle (Cotinis nitida) (Coleoptera: Scarabaeidae): local variation in the beetle’s major avian predators and in the competition for mates

The green June beetle (Cotinis nitida) was observed in northern Virginia for a second and third flight season. The study yielded some results that were consistent with earlier findings, namely that mate-locating beetles were vulnerable to attack by avian predators and matings occurred primarily early in the flight season. Novel findings included the following: (1) blue jays (Cyanocitta cristata) were the major predators, not common grackles (Quiscalus quiscala), (2) some jays appeared to selectively prey on female beetles, (3) competition for mates among male beetles could be so intense that some males attempted to copulate with already mated (unreceptive) females, and (4) the sex ratio of the beetle population feeding on wild blackberries remained near equality late in the flight season despite the fact that the sex ratio of the population of beetles at the emergence site became highly female-biased over time.     

Population biology of Sphaeroma serratum Fabricius (Isopoda,Flabellifera) at the Port of Mar del Plata,Argentina

Variations in size distribution, sex ratio, fecundity and morph frequencies in a population of Sphaeroma serratum were studied year-round. Changes in size distribution are most marked during the breeding season. Growth is arrested during the winter months. Young are produced throughout the summer; these overwinter, reproduce and then die. Differences in size of mature males suggest an effect of the timing of birth on life-span. Females are able to produce two broods. Offspring number is positively correlated with female size. Brood pouch mortality is estimated at 39%. Marked changes in sex ratio within the breeding season are thought to be artifacts due to sexual differences in behaviour. Comparison of reproductive traits of this, and other, populations shows a latitudinal pattern related to the duration of the warm season. Analysis of morph frequencies revealed similarities with European populations so far studied.     

数码卷绕的概念和技术

数码卷绕是在精密卷绕的基础上，引入导丝机构的数字控制方式，得到张力更稳定、纱管成形更完善的最新卷绕技术。文章介绍了高速精密数码卷绕技术的概念、实现原理和应用现状。     

浅析高校图书馆电子阅览室的现状与对策——以山东师范大学图书馆为例

以山东师范大学图书馆为例,介绍了电子阅览室的兴起,阐述了电子阅览室现状及存在的问题,提出了提高电子阅览室使用效率的对策,指出了电子阅览室亟待改进的地方。     

建筑间行人高度处的风环境设计

为使用简单的方法对居住区的风环境进行评价,采用CFD软件模拟,运用正交试验的方法选取模拟的工况.根据模拟的结果,推导出建筑尺寸、建筑间距与建筑通道间行人高度处最大风速比的函数关系式,并且进行实例验证.验证表明:该方法简单可行,对建筑师进行风环境设计具有较好的辅助作用.     

天波雷达对空探测任务下积累时间自适应优化设置研究

针对人工设置天波雷达相干积累时间存在盲目性, 不能充分发挥雷达探测性能的问题, 以空中目标探测为研究对象, 提出了自适应积累时间设置优化方法。首先, 分析了积累时间对天波超视距雷达探测性能的影响。其次, 计算了影响相干积累时间的信号时宽和积累点数的最优值。然后, 提出了自适应设置积累点数的方法。最后, 通过实验证明了本文方法比人工方法更能提高天波雷达探测性能。     

纤维金属层板的拉伸性能研究

GLARE是一种先进的混杂层板材料,由高韧度薄铝合金层和高强度玻璃纤维/环氧树脂层交替铺设而成,具有独特的轻质、耐疲劳、耐冲击、高阻燃性和耐腐蚀属性.系统地对GLARE层板进行了静力拉伸测试,展示了铺层结构和铺层类型对其静力学性能的影响,并对混杂模型的适用性进行了验证.结果显示:采用混杂模型法预测GLARE层的轴向弹性模量具有较高的精度,但进行强度预测时对于部分类型的层板需要考虑纤维的桥接作用.     

捣固焦经济型配煤的应用

结合太化焦化厂炼焦煤现状,科学制定了配煤炼焦实验方案,同时扩大了炼焦煤资源,实现了良好的经济和环保效益。     

基于利用率的纸型外文图书数字化研究

提出将纸型外文图书进行数字化并建成相应的数据库,提供网上浏览和下载服务,以期提高纸型外文图书的利用率,探讨了纸型外文图书数字化工作的重点、难点和问题,并提出了一些可行的对策。     

《科技情报开发与经济》2006年刊载基金论文分析

以《科技情报开发与经济》2006年刊载的基金论文为样本,运用文献计量学的方法统计分析了该刊基金论文的栏目分布、作者合著率、作者群的地域分布等情况,并探讨了基金论文对扩大本刊知名度和影响力的重要作用,提出了吸引基金论文的一些措施。