两对称

Therelationship of the amount of catalyst and the ee% of product was seen to be negative nonlin-ear. Catalyst 3 was used in the enantioselective addition of diethylzinc to aromatic aldehydesand gave good results. The configuration of products was determined by the configuration ofthe catalysts' chiral carbon linked with hydroxy group. Using β- amino alcohols bearing only one chiral center as catalysts for the enantiose-lective addition were studied. D-N, N-dialkyl-2-amino butanol gave poor catalytic effect be-cause of their structure. The configuration of the product is the same as the catalyst. Anotherkind of β- amino alcohols - phenylglycine derivatives and valine derivatives have chiralcenter on the carbon linked with amino group. Catalyzed by-phenylglycine derivatives 6,7, 9, 10, the reactions gave satisfied results. The optical yields exceeded 80%.

在探讨了含有两个手性中心的β-氨基醇之后，选择了只有一个手性中心的β-氨基醇，一是手性中心为连羟基的手性碳原子：D-N，N-二烷基-2-氨基丁醇；二是手性中心为连氨基的手性碳原子：D-苯基甘氨酸衍生物和L-缬氨酸衍生物。D-2-氨基丁醇的催化效果不太好，这与其结构的空间位阻较小有关系，反应产物与连羟基手性碳构型一致；由苯基甘氨酸和缬氨酸出发合成五种β-氨基醇6-10，研究了不同ee％的-6作用下的二乙基锌-苯甲醛加成反应，发现该催化剂具有不对称放大效应；-7，9，lO的催化效果也比较令人满意，光学产率80％以上，所得产物构型与催化剂构型一致。

Two flat lateral zones 12, parallel to the plane of symmetry X, each of which located near one end of the concave central area 11

两个平的横向区域12，平行于对称面X，各个横向区域12位于靠近凹入中心区域11一端的地方

The results show that the scattered radiant intensity is always symmetric with respect to the polarization plane, and that the scattered intensity is sensitive to the scattering particle size regardless of the incident radiation polarization, and finally, that the vertical components in the scattered light are totally different distribution for two kinds of polarized radiation.

散射粒子直径分别为：1.24μm、0.494μm、0.36μm、0.123μm、0.065μm。以粒子与水技不同比例混合液，作为散射粒子场。所得结果表明，散射光强度总是相对入射光束的偏振面呈对称分布；散射光强度对散射粒子大小敏感而与入射光偏振态无关；散射光中垂直偏振分量在两种光入射下存在完全不同的状态分布。

The original symmetry point and have seriously deviated from, if you want to make a balance between the development of the city, there are two approaches, one is the original economic development of backward areas, for example, to Nancheng huge investment, it's rapid economic growth; also There is a way to move the center to make it balance, if it is still definitely in line for Chang'an Street, Beijing should not balance the development is therefore imperative to the city centers to China.

原来的对称点和已经严重偏离，如果您想之间的平衡发展的城市，有两个办法，一个是原来的经济发展落后地区，例如，南城巨额投资，经济的快速发展增长；也有一种方法可以移动中心，使之平衡，如果它仍然是绝对排在长安街，北京不应该平衡发展，因此必须在城市中心，中国。

The formation mechanism of the screw structures on the surfaces of polytype crystals is discussed according to the theoretical model of anionic coordination polyhedron growth units.

本文用负离子配位多面体生长基元理论模型讨论了多型性晶体表面螺旋结构的形成，提出在多型性晶体中配位多面体呈层状分布，配位多面体的面为层的边界，上、下层负离子配位多面体不是呈镜象对称的，在三方晶系和六方晶系的晶体中是沿晶轴a、b错开，上、下两层负离子配位多面体体呈交叉对应，从而达到稳定平衡。

By use of theory of information asymmetry and principal-agent, the author makes a basic postulation that the incentive in-efficiency and chaos and weakness of accounting control are two main causes of financial statements fraud of Chinese listed corporations.

首先，作者利用信息不对称理论，委托——代理理论等经济理论构造了一个基本假设，即激励的不充分、激励的错位和内部会计控制、外部会计控制的虚化与弱化是中国上市公司财务报告舞弊的两个主要原因。

The fern spore, the original cell of the gametophyte, carries out asymmetrical mitosis to produce a large cell and a small cell. The small cell geminates to a rhizoid by tip growth, and the large cell further divides and develops to become a prothallus.

蕨类植物孢子作为配子体的原始细胞，通过不对称的有丝分裂产生一大一小两个细胞，小细胞萌发出极性生长的假根，大细胞继续分裂发育为原叶体。

We thus give a detailed discussion for QCD factorization involved the complete chirally enhanced power corrections for B decays to two light pseudoscalar mesons. We point out that chirally enhanced corrections can be included consistently in the framework of QCD factorization only if the twist-3 distribution amplitudes are symmetric.

我们仔细讨论了B介子衰变到两个轻的赝标介子中的手征增强修正效应并指出，仅在twist-3波函数对称的条件下，手征增强修正才能被自洽的纳入QCD因子化框架。

The pyran rings were formed in an I_2-induced heterocyclization of hydroxyl and olefin.

分别以14步反应和16步反应为-Benzylpedamide提供两条不同的不对称全合成途径。

Electrical stimulation of the raphe nuclei , amygdala , or some areas of the hypothalamus can elicit defensive behaviors.

两半对称体的类扁桃体中心杏仁核受到电刺激使一些下视丘区域引起自卫行为。

Breath, muscle contraction of the buttocks; arch body, as far as possible to hold his head, right leg straight towards the ceiling (peg-leg knee in order to avoid muscle tension).

呼气，收缩臀部肌肉；拱起身体，尽量抬起头来，右腿伸直朝向天花板（膝微屈，以避免肌肉紧张）。

The cost of moving grain food products was unchanged from May, but year over year are up 8%.

粮食产品的运输费用与5月份相比没有变化，但却比去年同期高8％。