共查询到20条相似文献，搜索用时 109 毫秒
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祝智力 《金华职业技术学院学报》2003,3(1):38-39,87
本文阐述了价电子对互斥理论的基本要点和判断分子空间构型的规则；计算出价层电子对数；得到电子对的几何排布，从而判断出分子的几何构型。 相似文献
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李淑兰 《临沂师范学院学报》2001,23(4):44-47
叙述了价层电子对互斥理论的基础规则；计算出价层电子对数，得到了电子几何排布，从而判断出分子的几何2构型；还介绍了孤电子对存在对分子构型及键角的影响。 相似文献
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杂化轨道理论能解释分子的几何构型 ,但不能预测。而价层电子对互斥理论能预测分子的几何构型 ,但不能解释分子的成键情况。两者结合 ,具有一定的互补性 ,可达到处理问题简便、迅速、全面的效果。 相似文献
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杂化轨道理论与价层电子对互斥理论的互补性 总被引：1，自引：0，他引：1
杂化轨道理论能解释但难以预测简单分子的几何构型,价层电子对互斥理论能预测分子的几何构型,但不能解释其成键情况。两结合,具有一定的互补性,可达到处理问题简便、迅速、全面的效果。 相似文献
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使用分子图形软件设计出多种B1N4的同分异构体,然后采用量子化学计算方法的密度泛函理论在B3LYP／6—31G（d）水平下对各个分子进行了全构型优化、谐振频率分析,结果表明有5种构型是势能面上的稳定驻点．对这些构型的几何构型、前线分子轨道和B4N4团簇中原子的成键性质、杂化方式进行了详细地分析．结果表明,B、N原子上加H后有利于分子团簇的稳定． 相似文献
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吐尔逊尼沙·吾买尔 《和田师范专科学校学报》2011,30(2):202-203
有些物质的化学组成相同,但是性质各异。有机化合物的构型和构象就是描述分子的形象的,是指分子中各原子和基团在空间的相对位置。构型和构象是表征分子结构特征的混淆的两个概念。分子几何形象的细微差别对自然界及生命现象都起着难以估计的影响。绝大多数的生命及生理化学过程,是受分子几何形象控制的,因此它不仅是有机化学而且是许多其它相关科学的研究对象。本文主要介绍分子的构造类型、构造异构及其关系。 相似文献
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使用分子图形软件设计出多种B4N4的同分异构体,然后采用量子化学计算方法的密度泛函理论在B3LYP/6-31G(d)水平下对各个分子进行了全构型优化、谐振频率分析,结果表明有5种构型是势能面上的稳定驻点.对这些构型的几何构型、前线分子轨道和B4N4团簇中原子的成键性质、杂化方式进行了详细地分析.结果表明,B、N原子上加H后有利于分子团簇的稳定. 相似文献
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在化学中一个极为活跃的领域是研究各种分子和离子的形状。本文将主要讨论价层电子对互斥模型和杂化理论这两种理论方法在基础上的差别,以及将两者相关联在予言、解释分子构型时的应用和适用范围,这对了解一些分子的几何构型和杂化类型无凝是很有用的. 相似文献
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采用自洽场的HF方法、密度泛函BLYP方法,以及杂化的密度泛函B3LYP方法,利用6-311+G(d)基组对P4团簇的6种异构体进行了几何优化,并以此为基础计算了异构体的振动光谱.然后对上述异构体的几何构型、稳定性,以及振动频率进行了讨论. 相似文献
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Exploratory activity was examined in 4 young baboons with the aim of investigating the type of spatial coding (purely geometric and/or by taking into account the identity of the object) used for the configuration of objects. Animals were individually tested in an outdoor enclosure for their exploratory reactions (contact time and order of spontaneous visits) to changes brought about to a configuration of different objects. Two kinds of spatial changes were made: a modification (1) of the shape of the configuration (by displacement of one object) and (2) of the spatial arrangement without changing the initial shape (exchanging the location of two objects). In the second experiment, the effect of a spatial modification of the global geometry constituted by four identical objects was investigated. Finally, in the third experiment, a substitution of a familiar object with a novel one was performed without changing the objects’ configuration. The baboons strongly reacted to geometrical modifications of the configuration. In contrast, they were less sensitive to modifications of local features that did not affect the initial spatial configuration. Analyses of spontaneous exploratory activities revealed two types of exploratory strategies (cyclic and back-and-forth). These data are discussed in relation to (1) the distinction between the encoding of geometric versus local spatial features and (2) the spatial function of exploratory activity. 相似文献
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目的:用力学实验的方法,对倒、正等腰三角形布局的三枚空心加压螺钉固定头颈型股骨颈骨折进行生物力学比较,确定哪种空间构型生物力学性能好,从而为临床治疗股骨颈骨折提供理论依据.方法:用生物力学机测试比较倒、正等腰三角形空间构型抗压、抗扭性能及最大垂直载荷,实验数据用SPSS10.0统计软件进行t检验,P＜0.05有显著性差异.结果:倒等腰三角形构型在抗压、最大垂直载荷方面优于正等腰三角形组,有显著性差别;抗扭转方面无显著性差别.结论:实验结论支持治疗头颈型股骨颈骨折三枚空心加压螺钉倒等腰三角形构型生物力学效果好. 相似文献
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ＳｈａｐｅＯｐｔｉｍａｌＤｅｓｉｇｎｏｆＨｙｄｒｏｄｙｎａｍｉｃＢｅａｒｉｎｇＢａｓｅｄｏｎＤｙｎａｍｉｃＣｈａｒａｃｔｅｒｉｓｔｉｃｓＣｈｅｎＹｕｎｆｅｉ（陈云飞）ＱｉａｎＲｕｉｍｉｎｇ（钱瑞明）（ＤｅｐａｒｔｍｅｎｔｏｆＭｅｃｈａｎｉｃａｌＥｎｇ... 相似文献
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ZITOUNI Bariza BEN MOUSSA Hocine OULMI Kafia 《浙江大学学报(A卷英文版)》2007,8(9):1500-1504
The dimensions and the materials type limit the performance of fuel cell. The increase of the temperature in electrodes and electrolyte of the cell,is due to the over potential of activation (transfer of load),the over potential Ohmic (resistance of polarization),the over potential of reaction (heat released by the chemical reaction) and the over potential of diffusion. In this paper,we studied the thermo-electrical performance of an intermediate temperature solid oxide fuel cell (IT-SOFC) with electrode supported. The aim of this work is to study this increasing temperature of a single cell of an IT-SOFC under the influence of the following parameters: heat sources,functioning temperature and voltages of the cell,geometric configuration and materials type. The equation of energy in one dimension is numerically resolved by using the method of finite volumes. A computing program (FORTRAN) is developed locally for this purpose in order to obtain fields of temperature in every element of the cell. 相似文献
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Dr. Leon H. Spotts 《Journal of Jewish Education》2013,79(3-4):45-47
That Central agencies for Jewish education throughout North America are in difficulty is now an established fact. The challenges facing these agencies relate principally to the two “f's”: function and financing. As the configuration and power structure of Jewish communities have changed, the traditional activities of bureaus and boards of Jewish education have come under intense scrutiny. At the same time, the geometric escalation of Jewish community demands on decreasing financial resources has made it increasingly difficult for bureaus to secure the funding needed to carry out their full array of programs. 相似文献
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从第一性原理出发,对Mon（n=2-12）团簇的最低能量结构和电子性质进行了研究．计算结果表明,Mon的最低能量结构可以看成是在Mon-1的基础上戴帽一个Mo原予生长而成．综合团簇的平均结合能和能隙可知,n=3,6,8,10时团簇的基态稳定性较高． 相似文献
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In three experiments, a new reference memory procedure was used to examine how male rats search for consistently located food in a cue-controlled spatial environment. The animals searched the tops of 24 poles for six hidden baits in an enclosed circular arena containing a fixed configuration of six object landmarks. In Experiment 1, acquisition was faster and overall performance better for theconsistent group (10 rats), in which the six baited poles were fixed relative to the landmarks for each session, than for therandom group (4 rats), in which baited poles were randomly configured. Cue-control tests and computer simulations suggested that the consistent group relied on the landmarks to directly go to the baited poles, whereas the random group used them to employ a response strategy for searching the arena. Experiments 2 and 3 revealed that the number, identity, and geometric configuration of the landmarks were important to the consistent group’s search performance. Overall, these results are most consistent with the use of a geometric representation by male rats which includes information about both the identity and the relative geometry of discrete landmarks in the surrounding spatial environment. 相似文献