电力电子设备的高频辐射损耗

在对电力电子设备的几种损耗进行了分析的基础上，对高频辐射损耗，特别是对开关电容的辐射现象进行了实验验证和机理分析。辐射损耗概念的引入有利于电力电子设备效率的分析和计算。     

双螺旋辊式磨浆机的电气设计

双螺旋辊式磨浆机是国际上造纸行业中的先进磨浆设备，目前国内还没有生产，本文阐述了磨浆机的产量的计算，功率的计算，电气部分的设计原则及特点。     

按序列的分布混沌

引进按序列分布混沌的概念．给出紧度量空间上连续映射按序列分布混沌的一个充分条件，并证明区间连续自映射是混沌的当且仅当它是按某序列分布混沌的     

黄淮海春夏豆区大豆熟期组归属及地理分布概貌

选择256份我国各大豆栽培区代表性地方品种，以国际通用的美国000－X熟期组的48份标准品种为对照，在南京进行分期播种及光照处理试验，制订出与国际相衔接的我国大豆生育期生态类型划分标准，将我国大豆划分为000－Ⅸ熟期；明确我国淮海大豆区春豆归属Ⅰ-Ⅲ组，夏豆归属Ⅱ-Ⅵ组，分析了黄淮海大豆区春夏豆品种熟期组地理分布概貌。     

自动排课系统的模型与实现

本文建立自动排课系统的数学模型,并利用遗传算法进行问题求解。在演化过程中采用了一种新的遗传策略,加速了群体的收敛速度。对本系统做适当的修改,可适用于其它的时间表问题。     

全纳教育中盲用语音导航网络考试系统的设计与实现

论述了采用ASP．NET2．0和C#语言实现B／S模式下语音导航自动化网络考试系统的基本方法。系统利用服务器端C#语言和客户端JavaScript脚本之间的相互调用实现了与客户端用户灵活的语音导航交互功能。解决了B／S模式程序交互性不强的难题,在技术实现上取得了一定的突破。并为全纳教育教学考核提供了一种高效、准确、科学、合理的解决方案。     

Structure of the replicative helicase of the oncoprotein SV40 large tumour antigen

The oncoprotein large tumour antigen (LTag) is encoded by the DNA tumour virus simian virus 40. LTag transforms cells and induces tumours in animals by altering the functions of tumour suppressors (including pRB and p53) and other key cellular proteins. LTag is also a molecular machine that distorts/melts the replication origin of the viral genome and unwinds duplex DNA. LTag therefore seems to be a functional homologue of the eukaryotic minichromosome maintenance (MCM) complex. Here we present the X-ray structure of a hexameric LTag with DNA helicase activity. The structure identifies the p53-binding surface and reveals the structural basis of hexamerization. The hexamer contains a long, positively charged channel with an unusually large central chamber that binds both single-stranded and double-stranded DNA. The hexamer organizes into two tiers that can potentially rotate relative to each other through connecting alpha-helices to expand/constrict the channel, producing an 'iris' effect that could be used for distorting or melting the origin and unwinding DNA at the replication fork.     

25阶非Desarguesian Andre平面的完全分类

本文回答Ｐ．Ｒ．Ｈｕｇｂｏ提出的一个问题：“是否由７个非ｂｅｒｇｕｅｒｅａｎＡｎｄｒｅ拟域坐标的平面可能全部同构？”给出的结论是：有且只有３个２５阶非ＤｅｓａｒｇｕｅｓｉａｎＡｎｄｒｅ平面。     

Fossil jawless fish from China foreshadows early jawed vertebrate anatomy

Most living vertebrates are jawed vertebrates (gnathostomes), and the living jawless vertebrates (cyclostomes), hagfishes and lampreys, provide scarce information about the profound reorganization of the vertebrate skull during the evolutionary origin of jaws. The extinct bony jawless vertebrates, or 'ostracoderms', are regarded as precursors of jawed vertebrates and provide insight into this formative episode in vertebrate evolution. Here, using synchrotron radiation X-ray tomography, we describe the cranial anatomy of galeaspids, a 435-370-million-year-old 'ostracoderm' group from China and Vietnam. The paired nasal sacs of galeaspids are located anterolaterally in the braincase, and the hypophyseal duct opens anteriorly towards the oral cavity. These three structures (the paired nasal sacs and the hypophyseal duct) were thus already independent of each other, like in gnathostomes and unlike in cyclostomes and osteostracans (another 'ostracoderm' group), and therefore have the condition that current developmental models regard as prerequisites for the development of jaws. This indicates that the reorganization of vertebrate cranial anatomy was not driven deterministically by the evolutionary origin of jaws but occurred stepwise, ultimately allowing the rostral growth of ectomesenchyme that now characterizes gnathostome head development.     

瓦韦属10种植物的气孔器类型及其系统学意义

对瓦韦属(Lepisorus)10种代表植物的叶表面结构进行了观察和研究,结果表明瓦韦属中不同植物的叶表皮细胞形状以及垂周壁式样几乎一致;运用表皮细胞长度、宽度、长度与宽度之比,气孔器长度、宽度、长度与宽度比以及气孔指数等变量进行的聚类统计表明,这些特征可以作为该属的一项重要特征,并且这些特征也能在一定程度上反映该属不同植物之间的亲缘关系,但是对瓦韦属植物属下划分意义不大;极细胞型在所研究的物种中均有大量分布.