对称

Chiral N,P ligand 5 was examined for the asymmetric allylic alkylation of 1,3-diphenyl-2-propenyl acetate with up to 89% yield and up to 81.6% ee.

化合物5用于钯催化的1，3-二苯基-2-烯丙基乙酸酯的不对称烯丙基烷基化反应，产率为89%，对映体过量最高为81.6% ee。

This thesis focused mainly on studying the role of planar chirality in asymmetric catalysis, synthesizing novel ferrocene ligands and applying them to palladium-catalyzed allylic substitution reactions.

本论文主要是研究二茂铁平面手性在不对称催化反应中的作用，设计合成新型二茂铁配体及其在钯催化烯丙基取代反应中的应用。

At the same time, from the angle of complexity of public information resources management it comprehensively proves insufficiency of the government public information service such as discriminatory service, mandatory service, asymmetrical service and rough service, which not only increase the government management cost but also lead to the structural form rupture of public information resources management at various levels, such as the government and the public, super and subordinate governments, central and local governments, and consequently break the almightiness mythology of government monopoly in public information resources management.

同时，从公共信息资源管理的复杂性角度全面论证了政府公共信息服务的不足，如差别服务、强制服务、不对称服务以及粗糙服务等不仅造成了政府管理成本的攀升，而且也导致政府与公众之间、上下级政府部门之间以及中央与地方之间等不同层面公共信息资源管理的结构型断裂，并在事实上打破了政府垄断公共信息资源管理的全能神话。

Alpha decay half-lives of even-even superheavy element s are calculated in the framework of the effective liquid drop model using the combination of constant asymmetry shape description for the mass transfer and the effective inertia coefficient.

利用有效液滴模型计算了偶偶超重核的α衰变半衰期，计算过程中采用了保持碎片体积守恒的不对称形状描述以及有效惯性系数计算Gamow势垒穿透因子。

Of, relating to, or using an intermittent asymmetrical alternating electric current produced by an induction coil.

法拉第的感应线圈产生的周期性非对称交变电流的或与之有关的，或利用这种电流的

Based on wave propagation feature, this paper analyses 3D seismic migration algorithms such as alternating direction implicit method, LU decomposition method, and inverse operator approach method. The result shows that the alternating direction implicit method is fast but causes distortion in wave field extrapolation and affects image accuracy; however LU decomposition and inverse operator approach methods are fast while holding circular symmetry of wave field, and are promising in oilfield exploration and development.

在波的传播特征分析基础上，对交替方向隐式法、LU分解法、逆算子逼近法等三维地震偏移算法进行了分析研究，结果表明，交替方向隐式法虽然快捷但是在波场外推中明显产生畸变并影响成像的准确性，而LU分解和逆算子逼近法是保持波场圆对称特征前提下的快速算法，在油田勘探开发中具有较好的应用前景。

For accelerating this problem's compute time in parallel computer, we use Saul'yev type asymmetric different scheme and classicality explicit-implicit type to get a new alternating group explicit method for solving diffusion equation.

为便于在并行计算机上计算以加快计算速度，现将第二类saul'yev非对称格式以及古典显、隐式相结合，构造了求解扩散方程的一类交替分组显格式，其基本结构为四点组，并针对内点为偶数的情况，在节点两端点处进行了处理，以提高精度。

It was found that the nonlinear current-voltage curve is the intrinsic property of WO〓 polycrystalline ceramic, and the curve is asymmetrical with very different behavior under applied direct and alternating voltage.

我们发现，非线性是WO〓多晶陶瓷的本征性质，伏安特性曲线是不对称的，而且交直流行为完全不同。

Especially aiming at the asymmetric structure of the cast, the allocation of aluminous liquid during the filling process was presented and the concept of structure mass fraction was inducted.

针对铸件的不对称结构提出了充型过程中铝液的分配问题，引入结构质量分数的概念。

Aim:To observe the amitosis and asymmetric division in subcultured PC12 cells, and to explore the role of amitosis and asymmetric division in tumorigenesis, tumor cell pleomorphism and differentiation.

目的 ：观察传代培养的PC12细胞的无丝分裂和不对称分裂，探讨其在肿瘤发生、肿瘤细胞多形性和细胞分化中的意义。

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％。