对称中心

This thesis focuses on studying the matrix equa-tion problem systematically, and proposed an abstract algorithm of solving the matrixequation with constraints, and established a strict convergence theory. Using this algo-rithm, we can solve the sets of matrix equation satisfying some constraint conditions,such as symmetric, antisymmetric, centrosymmetric, centroskew symmetric, re?exive,antire?exive, bisymmetric, symmetric and antipersymmetric, symmetric orthogonalsymmetric, symmetric orthogonal antisymmetric, Hermite generalized Hamilton ma-trix;So we can solve the problem with this algorithm, if the set of constrain matrixcan make a subspace in matrix space, and this algorithm also can solve the optimalapproximation and least squares problem. So this abstract algorithm has universal andimportant practical value.

本篇硕士论文系统地研究了此类问题，并找到了求解约束矩阵问题的抽象算法，并建立严格的收敛性理论，利用这一算法可求解约束条件为对称矩阵、反对称矩阵、中心对称矩阵、中心反对称矩阵、自反矩阵、反自反矩阵，对称正交对称矩阵、对称正交反对称矩阵、双中心矩阵、Hermite广义Hamilton矩阵等；可以说只要约束矩阵集合在矩阵空间中构成子空间，都可以考虑用此算法求解，而且这一算法还能把矩阵方程解及其最佳逼近，最小二乘解及其最佳逼近统一处理，因此本文算法有普适性和重要的实用价值。

The disorders in centrosymmetric 1, 4, 6, 7 and 9 may correlate with the observed triboluminescent emissions.

而有对称中心结构的配合物1、4、6、7及9中的无序可能对它们的摩擦发光活性起了很重要的作用。

The generating results of our system were compared with the published,results of DENDRAL and SEMAMI systems, and they were consistent with eachother.

目前本系统对于含C、N、P、S与Si等元素由于不对称中心、不对称轴引起的立体异构和几何异构均能进行穷举生成。

The structure of the compound 〓(1) consists of a pentanuclear molecule which is center-symmetric. One W atom is coordinated by four S atoms and two Cu atom. As expected, the Fe atoms are sandwiched between two staggered pentadiene rings. The most interesting aspect of the structure is that Fe-C-P-Cu-P-Cconstitutes a distorted hexagon and Fe-Cu-W-Cu-Fe is nearly in a line.

结构是以W原子为对称中心含有五个金属原子的线型结构，W原子与四个μ〓-S和两个Cu原子配位；Fe原子在两个戊二烯环中间形成一个三明治夹心结构；Fe〓-C〓-P〓-Cu〓-P〓-C〓-构成扭曲的六边形，由于两边1，1'-双二茂铁配体的作用导致Cu-S键的拉长。

The coordination geometry of the Eu atom is best described as a strongly distorted square-antipyrism.. The two Eu atoms are bridged by two N-oxide oxygen atoms forming a dimeric unit with crystallographic inversions centre. The Eu……Eu distance is 4.2137(9)〓. The two europium atoms and two bridging oxygen atoms is coplanar. The angles of Eu(1)-O(7)-Eu(1A) and O(7)-Eu(1)-O(7A) are 117.82(14)° and 62.18(14)°, respectively. 15 is the first dinuclear triboluminescent lanthanide complex reported.

同时还测定了其摩擦发光光谱与其光致发光光谱，并讨论了晶体结构和摩擦发光活性之间的关系。X-射线结构分析表明，15为有对称中心结构的配合物，每个Eu与三个HTTA的六个O原子和两个PyO的两个O原子形成八配位的四方反锥几何构型，2个N-Oxide O原子桥联两个Eu，形成了一个双核配合物，Eu。。。。

From FEM, the contact stress obeys the semi-ellipse distribution and the Mises stress and shear stress are also consistent with contact mechanics theory, but there exists offset or deflection in the symmetric lines of stress distribution, which originates from tooth bending deformation.

由有限元方法得到的渐开线轮齿的接触应力符合Hertz理论中的半椭圆分布规律，Mises应力和剪应力分布也符合接触力学理论，但应力分布的对称中心存在偏离或者偏斜现象，分析认为，是由于轮齿弯曲变形造成的。

The number of optical isomers is 2n, where n is the number of asymmetric centers.

光学异构体的数量是2 n，在此n是不对称中心的数量。

During the total preparation process, it was inevitable to conduct with the chiral center of prolinamide and the target product would became racemized or even could not be obtained at all.

由于在合成过程中，不可避免的触及不对称中心，发生消旋使产率下降甚至得不到产物，因此本文还研究了D-脯氨酰胺在不同温度、pH值、反应时间下对它的消旋的影响和脱羧机理，这对以后的工业化生产有着极其重要的意义。

The third-order NLO effects exist in all of the optical materials and are irrelevant to their structures.

三阶非线性光学效应不需要材料具有对称中心，因而几乎存在于所有的光学材料中。

For problem II, many references have studied it and obtained its common solutions, symmetric solutions, skew-symmetric solutions and its optimal approximation constrained solution, but the representation of its solutions are complicated.

本文首次采用迭代法系统的研究了它求一般解、对称解、反求解约束矩阵方程及其最佳逼近的迭代法的研究对称解、中心对称解、中心反对称解、自反矩阵解、反自反矩阵解、双对称解、对称次反对称解及其最佳逼近问题，并首次成功地解决了它求中心对称解、中心反对称解、自反矩阵解、反自反矩阵解、双对称解与对称次反对称解及其最佳逼近的问题，拓广和改进了已有的研究成果。

The absorption and distribution of chromium were studied in ryeusing nutrient culture technique and pot experiment.

采用不同浓度K2CrO4(0，0.4，0.8和1.2 mmol/L)的Hoagland营养液处理黑麦幼苗，测定铬在黑麦体内的亚细胞分布、铬化学形态及不同部位的积累。

By analyzing theory foundation of mathematical morphology in the digital image processing, researching morphology arithmetic of the binary Image, discussing two basic forms for the least structure element: dilation and erosion.

通过分析数学形态学在图像中的理论基础，研究二值图像的形态分析算法，探讨最小结构元素的两种基本形态：膨胀和腐蚀；分析了数学形态学复杂算法的基本原理，把数学形态学的部分并行处理理念引入到家实际应用中。