Rollback,scissor-like closure of the Mongol-Okhotsk Ocean and formation of an orocline:magmatic migration based on a large archive of age dataOA

Tracing the closure of oceans with irregular margins and the formation of an orocline are crucial for understanding plate reconstruction and continental assembly.The eastern Central Asian Orogenic Belt,where the Mongol-Okhotsk orocline is situated,is one of the world’s largest magmatic provinces.Using a large data set of U-Pb zircon ages,we updated the timing of many published igneous rocks,which allowed us to recognize tightly ’folded’ linear Carboniferous-Jurassic magmatic belts that wrap arou...     

个性化图书推荐研究

个性化图书推荐系统通过对用户借阅行为的统计分析,获取用户的兴趣特征,实现由原来的人找书到书找人一对一的个性化图书推荐。现有的图书推荐系统各有侧重,图书推荐算法及评价标准各具优、缺点。未来,图书推荐的研究热点及难点将集中在借阅记录的稀疏性、新图书问题、高校新生问题、用户统计学信息、根据《中国图书馆分类法》计算图书相似性、副本数及借阅规章制度等方面。     

"云娜"台风暴雨的Q矢量与螺旋度诊断分析

利用非地转ω方程说明了Q矢量散度的物理意义,并通过计算台风“云娜”影响过程中的Q矢量散度和高低空螺旋度,分析了这两个物理量的演变特征及其与台风、台风暴雨的关系,指出低层等压面上Q矢量散度场及相对螺旋度对台风暴雨预报具有较好的参考价值。     

地方政府财政科技投入绩效评价模型的突破口研究

介绍了与地方政府财政科技投入绩效工作的中心内容——评价模型相关的5个突破口：模块化、开放性、层次化、图形化以及方法库。     

电子图书对图书馆的影响及对策

电子图书在馆藏和阅读、读者及馆员素质要求、馆舍及设施、读者服务及图书馆评价等方面都对图书馆有重要影响。图书馆人应当正确认识电子图书的影响和作用 ,积极开展电子图书的研究 ,逐步建立电子图书的传播环境 ,开展电子图书利用的馆员及读者培训工作 ,做好其收藏和使用工作。参考文献 6。     

科技期刊假冒网站问题分析及应对策略

专家审稿意见是决定稿件能否被录用的重要依据.为了有效利用专家审稿意见进行稿件处理,文章归纳了专家审稿意见的类型,针对几种典型的审稿意见进行了实例分析,并给出了如何有效利用专家审稿意见的体会.     

基于数字参考咨询适度服务的资源开放获取研究

文章首先提出数字参考咨询适度服务、资源开放获取的概念以及开放获取的条件基础、过程和方式,然后分析数字参考咨询适度服务对开放获取的影响,划分出适度服务区间,以解决资源开放获取的障碍.     

Two decades of suspect evidence for adaptive molecular evolution—negative selection confounding positive-selection signals

There has been a large literature in the last two decades affirming adaptive DNA sequence evolution between species. The main lines of evidence are from (i) the McDonald-Kreitman (MK) test, which compares divergence and polymorphism data, and (ii) the phylogenetic analysis by maximum likelihood (PAML) test, which analyzes multispecies divergence data. Here, we apply these two tests concurrently to genomic data of Drosophila and Arabidopsis. To our surprise, the >100 genes identified by the two tests do not overlap beyond random expectation. Because the non-concordance could be due to low powers leading to high false negatives, we merge every 20–30 genes into a ‘supergene’. At the supergene level, the power of detection is large but the calls still do not overlap. We rule out methodological reasons for the non-concordance. In particular, extensive simulations fail to find scenarios whereby positive selection can only be detected by either MK or PAML, but not both. Since molecular evolution is governed by positive and negative selection concurrently, a fundamental assumption for estimating one of these (say, positive selection) is that the other is constant. However, in a broad survey of primates, birds, Drosophila and Arabidopsis, we found that negative selection rarely stays constant for long in evolution. As a consequence, the variation in negative selection is often misconstrued as a signal of positive selection. In conclusion, MK, PAML and any method that examines genomic sequence evolution has to explicitly address the variation in negative selection before estimating positive selection. In a companion study, we propose a possible path forward in two stages—first, by mapping out the changes in negative selection and then using this map to estimate positive selection. For now, the large literature on positive selection between species has to await reassessment.     

信息技术环境下初中化学教学改革研究

随着信息时代的到来,传统的初中化学课堂教学活动发生了很大改变,越来越多的现代化技术被应用到初中化学教学活动中,极大程度地促进了课堂教学效果的提升.对此,在实践中,初中化学教师必须意识到信息技术对于化学教学改革产生的积极影响,并结合实际教学情况,灵活地应用信息技术优化课堂教学活动,以此促进学生的良好发展.     

论合并高校医学人文课程设置基本原则

独立医学院校与综合性大学或多科性大学合并的目的之一在于加强医学人文教育,合并高校在利用人文社会科学优势促进医学人文课程的优化设置的过程中要坚持综合性原则、关联性原则、协调性原则、整体性原则、重点性原则、实效性原则、适度性原则、专业性原则、探索性原则。