对称

The catalytic mechanism of prolinamide phenol on the direct aldol reaction was studied using quantum mechanics theory.

利用量子力学理论研究了脯氨酰胺酚类催化剂催化直接不对称Aldol反应的机理。

In order to examine the catalytic activity of the new catalysts, we have carried out the direct asymmetric Aldol reaction of tetrahydro-4H-thiopyran-4-one with aldehydes.

催化剂的基本结构单元如下：为了检验新型有机催化剂的催化活性，我们研究了硫代四氢吡喃酮和各种醛的直接不对称Aldol反应。

We found that when acetone was used as solvent, in the presence of TFA, cis-4-pyrrodin-1-yl-L-proline could catalyze the direct asymmetric aldol reaction between acetone and 4-nitrobenzaldehyde with 84% ee.

研究发现，该催化剂以丙酮为溶剂时，加入催化剂等当量的三氟乙酸可以较好的催化丙酮与对硝基苯甲醛之间的直接不对称Aldol反应，得到84%的ee值。

The catalytic effects of 1a and 1b on the intermolecular direct asymmetric aldol reaction were evaluated in organic solvents and in water respectively. The activity of 1a was higher than that of 1b.

研究了1a和1b分别在有机相和水中催化分子间直接不对称Aldol反应的性能，发现具有较长烷基链的1a比具有较短链的1b催化活性高。

The key reaction included Aldol condensation,CBS asymmetric reduction and Mitsnobu reaction.

合成过程中的关键反应为Aldol缩合，CBS不对称还原，Mitsnobu反应等。

The purpose of the above mentioned obligations is to relieve the asymmetric information, avoid moral hazard caused by the adhesive, aleatory and continuity nature of insurance contract.

上述义务的根本目的在于缓解双方的信息不对称，避免保险合同的附合性、射幸性以及连续性所带来的道德风险。

Since the method does not need to derive the concrete form of the transformation matrix, making it simple and easy to calculate the results to the eigenvalue problems of the Hamilton with symmetrical form. This algebraic methods is more universal and more effective.

由于该方法不需要求出变换矩阵的具体形式，使得运用此方法求解具有对称形式的Hamilton量的本征值问题变得简单、易计算出结果，该方法更具有普遍性，是一种十分有效的代数方法。

In chapter four, by the concept of negative definite of symmetry interval matrix, methods of analysis of interval matrix and the method of Lyapunov function, the robust absolute stability of Lurie control system with multiple nonlinearities was investigated, and some algebraic sufficient conditions in the form of inequalities of interval matrix were obtained.

在第四章，通过定义对称区间矩阵负定的概念，主要用区间矩阵分析技术和Lyapunov函数方法，研究了具多非线性的区间Lurie控制系统的鲁棒绝对稳定性，我们给出了此类区间Lurie系统鲁棒绝对稳定性的区间矩阵不等式形式的代数充分条件。

By complete discrimination system of polynomial algebraic equation and resultant theory, a symmetry class of quartic systems with stellar node is studied.

利用多项式代数方程的判别系统理论和结式理论，讨论了具有星形结点的一类对称四次系统的代数分类，并对系统进行全局分析。

It is considered, inter alia, as a necessary counterbalance to asymmetric market access in international trade.

特别，作为在国际贸易过程中的非对称的市场准入的一个必要平衡物，它被考虑。

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％。