特提斯海变迁对全球动物分布的影响

特提斯海是曾存在于冈瓦纳古陆和劳亚古陆之间的古海洋.特提斯海在其近2亿年的演化历程中,经历了扩张、分裂、收缩直至消亡.本文回顾了特提斯海区域不同动物类群的多样性研究,系统总结了特提斯海演化和变迁对全球动物多样性格局的影响.特提斯海演化通过改变栖息地之间的物理联系,决定了动物的扩散和隔离,进而直接影响了现今全球动物多样性的空间分布和组成;特提斯海的海陆变迁通过改变区域地理和生态环境,如阿尔卑斯-喜马拉雅造山带的形成、淡水生境的出现、中亚地区的干旱化、地中海盐度危机的发生,以及新的洞穴和湖泊生境的形成等,间接影响了特提斯海区域内动物的起源、扩散、分化、存留和灭绝.本文强调了特提斯海的演化和变迁是全球动物多样性演化的重要驱动因素,并揭示了特提斯海区域现今动物多样性格局的形成与地质构造运动之间的潜在联系.     

How do thermophilic proteins deal with heat?

Recent years have witnessed an explosion of sequence and structural information for proteins from hyperthermophilic and thermophilic organisms. Complete genome sequences are available for many hyperthermophilic archaeons. Here, we review some recent studies on protein thermostability along with work from our laboratory. A large number of sequence and structural factors are thought to contribute toward higher intrinsic thermal stability of proteins from these organisms. The most consistent are surface loop deletion, increased occurrence of hydrophobic residues with branched side chains and an increased proportion of charged residues at the expense of uncharged polar residues. The energetic contribution of electrostatic interactions such as salt bridges and their networks toward protein stability can be stabilizing or destabilizing. For hyperthermophilic proteins, the contribution is mostly stabilizing. Macroscopically, improvement in electrostatic interactions and strengthening of hydrophobic cores by branched apolar residues increase the enthalpy change between the folded and unfolded states of a thermophilic protein. At the same time, surface loop deletion contributes to decreased conformational entropy and decreased heat capacity change between the folded and unfolded states of the protein. Received 28 February 2001; received after revision 26 March 2001; accepted 27 March 2001     

叠合梁叠合面抗剪机理分析及抗剪强度计算

本文充分利用已有的研究成果，分析了叠合面的抗剪破坏机理及其影响因素，并列举比较部分规范和研究者的叠合面计算方法，提出今后需要进一步研究的建议．     

Average conditional correlation and tree structures for multivariate GARCH models

We propose a simple class of multivariate GARCH models, allowing for time‐varying conditional correlations. Estimates for time‐varying conditional correlations are constructed by means of a convex combination of averaged correlations (across all series) and dynamic realized (historical) correlations. Our model is very parsimonious. Estimation is computationally feasible in very large dimensions without resorting to any variance reduction technique. We back‐test the models on a six‐dimensional exchange‐rate time series using different goodness‐of‐fit criteria and statistical tests. We collect empirical evidence of their strong predictive power, also in comparison to alternative benchmark procedures. Copyright © 2006 John Wiley & Sons, Ltd.     

基于递归标记和神经网络的红外目标匹配识别

提出了一种红外图像匹配算法。选取实际红外目标,依据图像预处理后的图像,提取对应目标的递归标记,作为BP网络的输入样本,目标的形心为输出样本构建BP神经网络。对网络进行抗干扰训练后,根据目标形心特征进行变分辨率相关匹配。该算法在提高了目标识别率的同时,极大地增强了图像处理的实时性,具有工程实用价值。     

浅谈体能训练的基本原理

体能训练是完成各项运动训练的基础,没有良好的体能,技术、战术的训练必将流于形式。从科学的体能界定出发,依据训练的基本原理加强体能训练,会收到良好的运动训练效果。     

异文化、翻译与变通

在跨语言、跨文化交流时,尤其是在翻译的过程中,人们遇到的最大障碍往往不是语言本身,而是这种语言所依附的、独特的文化。这种文化个性是翻译障碍的主要成因,要逾越这些文化障碍,成功的翻译源语文本,就需要进行适当的变通。变通的方法很多,其中最主要的两种方法就是异化与归化。异化与归化各有优势,也各有欠缺,有时二者同时使用会相得益彰,使翻译文本更贴切、更精彩。     

一类具相互干扰的Leslie捕食与被捕食系统的定性分析

研究一类具有相互干扰的Leslie捕食与被捕食周期系统,得到该系统持久的充分条件以及正周期解的存在且全局稳定的充分条件.     

论全球化与“反全球化”进程中的国家

全球化与“反全球化”是当今时代的两大主要特征,它们既相互矛盾又相互统一,共同作用于时代发展的全过程;发达国家是全球化的主导者和最大受益者,决定着未来全球化的发展趋势和方向;发展中国家是全球化进程中的弱势国家,在全球化的发展过程中始终处于从属地位;发达国家应重新审视其全球化的发展战略,尽量减少或避免全球化带来的负面效应;发展中国家既要利用全球化有利的一面不断发展本国经济,又要利用“反全球化”运动维护经济安全和经济主权。     

一种模糊自适应交互多模型算法

提出了一种模糊自适应交互多模型（FAIMM）算法。该算法通过模糊推理机制，在线调节模型集合中部分模型的参数，使这些模型对不同的目标机动模式有更强的自适应能力，从而使该算法可以采用较少的模型达到很好的跟踪滤波效果，而且避免了传统交互多模型算法的模型冲突问题，大大减少了计算量。最后将该算法与传统的交互多模型算法进行了仿真对比，仿真结果表明，FAIMM算法比传统的交互多模型算法有更好的跟踪性能。