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分子生物学家注重冗长的实验数据,而物理学家则习惯于把复杂的系统归结为可有助于了解其全部意义的几个基本原理中。但把这两个学科结合起来并非一件容易的事—— 相似文献
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Many molecules can rotate freely around single bonds and thereby interconvert between different conformations, such as gauche and anti 1,2-disubstituted ethane, a classic example of conformational isomerism. Even though rotation occurs rapidly at room temperature, the product selectivity seen in some reactions has been explained by conformation-dependent reaction mechanisms: if reactant molecules differing only in their conformation are located at different positions on the reaction path, they may undergo different reactions. But a direct verification of this effect is difficult, because the energy barrier separating conformational isomers is so low that under ambient conditions reactants with more than one conformation will be present. But by using temperatures low enough to suppress the interconversion between different conformations, gauche-1-iodopropane ions and anti-1-iodopropane ions have been selectively generated. Here we show that the kinetic energy released during the photodissociation of 1-iodopropane ions depends strongly on the conformation of the ions. Thermodynamic arguments and ab initio calculations indicate that this difference in kinetic energy release results from differences in the reaction mechanism, with gauche-1-iodopropane ions forming 2-propyl ions and anti-1-iodopropane ions forming protonated cyclopropane ions. These findings suggest that the well-known concept of conformation selection forms the basis of a simple scheme for reaction control, thus providing in some cases an attractive alternative for more involved schemes that utilize the phase and pulse shape of laser beams to control chemical reactions. 相似文献
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金昌虎 《沈阳大学学报:自然科学版》2006,18(1):10-13
以证明在线口传内容对口传效果的影响及收信者的特性的作用为目的。通过已有的研究,把口传内容划分为商品信息和个人经验,把口传效果划分为口传受用和口传行为。以大学生为对象,对MP3购买活动和相关在线口传活动进行了268个问卷调查,并用SPSS 10.0统计法进行了分析。研究结果表明:第一,口传信息的受用度使商品资讯更高,口传行为使个人体验资讯更为受用。第二,商品资讯和个人体验对口传内容的效果(口传受用,口传行为)决定于收信者的产品知识,即对在线的口传内容和口传信息受用的关系有调节作用,而且,对口传行为的影响也有调节效果。最后,关联度变数如先前所设的口传内容和口传效果的关系,对它们的关系有调节作用。 相似文献
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LI Xi-zuo HAN Gui-ying KIM Sun-ho 《武汉大学学报:自然科学英文版》2006,11(1):203-210
0 IntroductionTobadaseyd’s o nintfhoer mflaotiwonof s ywsotrekmss t hhraovueg hbe tehne doervgealnoipzead-tion rather than based ontasks .Duetothistrend,work-flowand business process technology has been applied tovarious applications such as ERP, groupwares , E-mar-ketplaces , E-business etc . When business processes areapplied to these applications ,business processes are de-fined by process designers and business process instancesare executed by workflowengines or workflow manage-ment sys… 相似文献
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线性搜索是最优化计算中最普遍应用的方法,文中对Fletcher线性搜索方法作了改进,它具有减少梯度值计算次数的特点,并用数值结果表明了方法的有效性。 相似文献
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Books and archives experience aging which is affected by a variety of factors, such as microorganism, humidity, light and components of paper [1]. Thus, the studies concerning impacts of those factors on paper aging are required. In this paper, an accelerated paper aging was carried out to investigate the effects of acid and metals such as alum, copper ( Ⅱ ) sulfate, copper ( Ⅱ ) chloride, and iron (Ⅲ) chloride on paper aging. It was found that both acid and metals had impacts on paper aging. In particular, paper aging was far more accelerated in case that acid and metals were present in paper at the same time. 相似文献
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金熙哲 《齐齐哈尔大学学报(自然科学版)》2006,22(1):1-6
研究了软件可信成长模型的bayesian推论和模型选择方法。如果用内在错误和错误之间的时间间隔来模化成长模型,在软件开发阶段,可以非常有效的利用其成长模型。本文在解决多重积分问题时利用Gibbs抽样方法来计算出算后分布。一般顺序统计量模型依赖具有扩散算前分布特性的软件。对一般顺序统计量模型依实行了bayesian总体参数的推断,还实行了有效的模型选择方法。模型的设定和判断标准可用于利用方差相乘和的适合度鉴定和趋势鉴定。为了取得相应的值例,本文在分析错误资料时利用了AllenP.NikoraandMichaelR.Lyu[13]提出的SYS2软件错误资料。 相似文献
10.
Minimum information about a microarray experiment (MIAME)-toward standards for microarray data. 总被引:36,自引:0,他引:36
A Brazma P Hingamp J Quackenbush G Sherlock P Spellman C Stoeckert J Aach W Ansorge C A Ball H C Causton T Gaasterland P Glenisson F C Holstege I F Kim V Markowitz J C Matese H Parkinson A Robinson U Sarkans S Schulze-Kremer J Stewart R Taylor J Vilo M Vingron 《Nature genetics》2001,29(4):365-371
Microarray analysis has become a widely used tool for the generation of gene expression data on a genomic scale. Although many significant results have been derived from microarray studies, one limitation has been the lack of standards for presenting and exchanging such data. Here we present a proposal, the Minimum Information About a Microarray Experiment (MIAME), that describes the minimum information required to ensure that microarray data can be easily interpreted and that results derived from its analysis can be independently verified. The ultimate goal of this work is to establish a standard for recording and reporting microarray-based gene expression data, which will in turn facilitate the establishment of databases and public repositories and enable the development of data analysis tools. With respect to MIAME, we concentrate on defining the content and structure of the necessary information rather than the technical format for capturing it. 相似文献