三键

Hydrogen bondings induced from carboxylic groups were intentionally designed at the end of the arm of these star-shaped molecules. The hydrogen bonding positions of the so-perpared star-shaped oligofluorenes were similar to those of trimestic acids which has been intensively studied, and this enlightened us to design these moleucles.

通过羧酸基团，我们将(来源：A3bBCe6论7e文网www.abclunwen.com)氢键作用引入到了星状分子的各条臂上，而这种结构和已被广泛研究的苯三酸体系形成了类似的结构：这也是启发我们设计这个分子结构的原因。

On the basis of the Frontier Orbital Theory and three Bonding Principles, the possibility of reaction of active HOSA^- carbanion on polymerization process of MA by alkali catalyst and the mechanism of anionic polymerization of maleic anhydride were studied.

应用前线轨道理论和成键三原则研究了碱催化条件下马来酸酐均聚过程中α-羟基丁二酸酐碳阴离子活性中间体参与反应的可能性及其阴离子聚合机理。

In the second part, quantum chemical AM1 methods were employedto theoretically investigate the electronic structures of maleic anhydride in ground- and excited-states. On basis of the frontier orbital theoryand three bonding principles, the possibility of reaction of active α-hydroxysuccinic anhydride carbanion and active α-hydroxy-succinic anhydride radical on polymerization process of MArespectively by alkali catalyst and by hydroxyl radical was discussed. Theanionic and radical polymerization of MA discussed also. Theoreticalstudies show that both polymerization products of MA are in the chainstructures, corresponding to the experimental findings.

第二部分用量子化学AM1方法，计算研究了马来酸酐的基态和激发态电子结构；应用前线轨道理论和成键三原则分别探讨了碱催化条件下和羟基自由基引发下马来酸酐均聚合过程中α-羟基丁二酸酐碳阴离子和α-羟基丁二酸酐碳自由基活性中间体参与反应的可能性及由它们引发的马来酸酐阴离子聚合反应机理和自由基引发聚合反应机理；理论研究表明马来酸酐的均聚合产物均为链式结构，与实验事实相相符。

This thesis is concerned with studies on the ring opening reaction catalyzed by gold catalysis via carbon-carbon bond cleavages.

本文主要研究了金催化碳碳键断裂的开环反应，全文共分为三个部分：第一章：对均相金催化研究进行了总结，综述了均相金催化的研究进展。

The instrument can measure the location, size and energy distributing of infrared guidance head imaging facula on the best image plane and off focus plane, displaying the results in data and 3D images with just one tap on the button. It can measure abaxial faculas as well.

它用数据和三维图形显示测量结果，可用于检测红外导引头最佳像面和离焦像面光斑的位置、大小及光能分布，并用于测试轴外视场的光斑，全部检测实现了&一键通&。

The system of drive are all driven by stepping motors.the machine system design includes every free degrees,computation of drive and transmission system .the third and four degree of freedom are performed by the feed screw having the spline of ball bearing which is design specially for robot .with the textual study,it can be believe the user will have an overall understanding to the way of thinking and steps of the machine system.

在机械系统设计上，对每个自由度驱动、传动系统进行了计算与校核，其中第三四自由度有专为机器人设计的带滚珠花键的丝杠来实现。通过本文的学习，相信使用者会对它的机械系统设计的步骤和方法有一定的了解。

The system of drive are all driven by stepping motors.the machine system design includes every free degrees,computation of drive and transmission system .the third and four degree of freedom are performed by the feed screw having the spline of ball bearing which is design specially for robot .with the textual study,it can be believe the user will have an overall understanding to the way of thinking and steps of the machine system.

在机械系统设计上，对每个自由度驱动、传动系统进行了计算与校核，其中第三四自由度有专为机器人设计的带滚珠花键的丝杠来实现。通过本文的学习，相信使用者会对它的机械系统设计的步骤和方法有一定的了解。关键词 SCARA机器人，谐波减速器，机械系统，丝杠

Unlike the modern western flute, which has convenient keys to make sharp or flat notes, Dizi players use 3 basic fingerings per flute.

相对于西方长笛因有多个方便转调的键所不同，每个笛子一般仅可演奏三套指法。

This grinder is adopted 3-coordinates CNC system, with control vertical teed of wheel head, longitudinal move of worktable, and index head revoling. It be able to realize linkage of both move of longitudinal and vertical.

功能 本机床采用三座标数控系统，分别控制磨头垂向运动，工作台纵向运动和分度头回转，其中纵向与垂向运动可实现联动，集操作按钮，编程键及CRT字符显示为一体，便于编程和数据输入。

We found that more than 35 different plasma proteins do not seem to contain interchain disulfide bridges.

我们发现超过三十五种不同的血浆蛋白似乎并不含有分子间的双硫键。

Neither the killing of Mr Zarqawi nor any breakthrough on the political front will stop the insurgency and the fratricidal murders in their tracks.

在对危险的南部地区访问时，他斥责什叶派民兵领导人对中央集权的挑衅行为。

In fact,I've got him on the satellite mobile right now.

实际上 我们已接通卫星可视电话了