不对称

It is demonstrated that the chiral quaternary ammonium salts catalysts exhibit promising catalytic properties for the substrate. Part III: The synthesis and the characterizing of the macroporous aminomethyl resin-supported cinchona alkaloid complexes and the study on its catalytic properties The part consists of two subsections. the macroporous aminomethyl resin -supported cinchona alkaloid complexes were synthesized by the stuff (cinchonine, quinine and macroporous aminomethyl resin). Their structures were characterized by means of elemental analysis, XPS, TG/DTA; the chiral polymer-supported complexes were first used as catalysts for the reduction of ketones. Their catalytic properties for the reduction processes were investigated. The comparison of the products e.e., the conversion of the substrate among different reduction processes was employed with determined by HPLC. The effects of the time, the temperature, the ratio of catalyst to substrate, reaction solvent as well as the recycle times were also discussed.

第三章聚-4-氨甲基苯乙烯负载金鸡纳碱金属络合物的合成与表征及其不对称催化性能研究本章分为两节，以辛可宁和奎宁及聚-4-氨甲基苯乙烯为原料，合成了4种聚-4-氨甲基苯乙烯负载金鸡纳碱络合物催化剂，并对它们的结构用元素分析、X-射线光电子能谱、TG/DTA等几种测试手段进行了表征；首次将所合成的手性高分子负载的金属络合物用于催化芳香酮不对称还原反应，详细研究了所得的手性高分子负载的金属络合物对不同底物的催化性能，用HPLC等分析手段定量检测了还原过程的底物转化率及其产物对映异构体选择性，并考察了反应时间、反应温度、催化剂和底物投料比、反应溶剂和循环次数对催化性能的影响。

This dissertation introduces the specificity and exclusiveness of human capital in Tirole's model to prove the contingence state of the control rights in venture capital excels the one-side control of the enterpriser and the venture capitalist.

根据这一原则，事前信息越重要且不对称程度越大，则人力资本间接定价中越注重甄别，相应报酬绩效敏感性越低；代理人的努力越重要且事后信息不对称程度越大，则人力资本间接定价中激励越重要，因而报酬绩效敏感性越高。

I find that:(1) consistent to the prediction of information asymmetry model,the degree of information asymmetry and ex ante uncertainty is a decreasing function of profitability and offering size.

研究发现：(1)与信息不对称假说一致，盈利能力和发行规模可以降低信息不对称的程度与事前不确定性，与IPO折价率有显著负相关关系。

These dendritic NOBIN derived Schiff base ligands have been applied to titanium catalyzed hetero-Diels-Alder reaction of Danishefshy's diene and aldehydes, affording the corresponding 2-substituted 2, 3-dihydro-4H-pyran-4-one in quantitative yields and excellent enantioselectivities (up to 97. 2%ee). Comparing the reactivities and enantioselectivities of reaction catalyzed by the titanium complexes of these Schiff base ligands, it was found that a series of ligands L〓 were superior to the other three series of ligands L〓, L〓 and L〓, a significant positive NLE and a dendrimer effect existed in the L〓 dendritic catalyst system. The disposition of the dendritic wedges and the dendron size in the ligands were observed to have a significant impact on the enantioselectivity of the reaction.

NOBIN衍生的树枝状大分子希夫碱手性配体与钛形成的配合物在催化不对称杂Diels-Alder反应中的应用将得到的四个系列NOBIN衍生的树枝状希夫碱三齿手性配体与四异丙氧基钛形成的配合物用于催化Danishefsky's diene与醛的不对称杂Diels-Alder反应，通过反应条件的优化，获得了定量的收率和最高达97.2％ee值的对映选择性；考察了这四个系列NOBIN衍生的树枝状希夫碱钛配合物的催化活性和对映选择性，结果发现它们的活性次序依次为L〓≈L〓＞L〓＞L〓，对映选择性次序依次为L〓＞L〓＞L〓＞L〓。

Overcoming the inability of Forcing Decoupling method, this paper presents a new method-To-Step-Additional-Stiffness method to calculate the translation-torsion coupling seismic response of tile symmetric structures with asymmetrically viscous dampers.

摘要克服强行解耦法不能求解对称结构由于不对称安装粘滞消能器而产生平扭耦合地震作用的不足，提出了一种求解该种情况下的平扭耦合地震反应的新方法－两步附加刚度法。

Through establishing the business enterprise trustworthiness with the gene ral model of game and the model of the repeated game,this text discuss es the be havior of business enterprise in the term of dissymmetry information,and gets a conclusion that the business ent...

出现这一矛盾的根源，在于信息的不对称分布，本文通过建立企业诚信的一般博弈模型和重复博弈模型，讨论不对称信息环境下企业的行为选择，得出企业追求长期利益会导致诚信的结论。

Asymmetrical features; a dress with an crooked hemline.

五官不对称的；底边不对称的衣服。

The homeostatic mechanism controlling the choice between self-renewal and differentiation of stem cells is poorly understood.

但是决定发育过程中干细胞对称和不对称分裂的选择机制仍不是很清楚。

Hence retailers can use private label product as a tool to reduce the competition in the horizontal structure.

所以零售商销售自有品牌的原因从水平结构来看，通过利用需求不对称和成本不对称实现价格离散，从而减轻水平结构中的市场竞争。

Further treatment of the Ru nanoparticles with chiral modifier (1S, 2S)-1, 2-diphenyl-1, 2-ethylene-diamirse (1S, 2S-DPEN and KOH in ionic liquid/i-PrOH mixed solvent resulted in a novel immobilized chiral catalyst which can asymmetrically hydrogenate acetophenone and its derivatives.

将此钌纳米粒子与(1S， 2S)-1，2-二苯基乙二胺（简称(1S， 2S)-DPEN）、KOH在离子液体／异丙醇介质中原位生成一种不对称加氢催化剂，用于催化苯乙酮及其衍生物的不对称加氢反应。

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％。