查询词典 ring

Due to the increasingly deep concerns about the cytotoxicity of stannous octoate, which is the most widely used catalyst for synthesizing polyesters derived from lactides (L-LA, D, L-LA, GA) via ring opening polymerization, a lot of new metal complexes of relatively low toxicity including Schiff base–Al complexes, Red-Al were developed and used to initiate the living, stereo-specific, and/or stereo-selective ROP of lactides.

由于合成聚乳酸类生物医用降解材料的最常用的催化剂辛酸亚锡 Sn2的细胞毒性问题已在世界范围内引起日益深切的关注，近年来国内外学者已研究开发出许多性能优异的低毒、非锡金属络合物催化剂（如：位阻西佛碱-Al 络合物， Red-Al 等）用于催化交酯类单体的活性、立构专一性及立构选择性聚合反应。

Microwave-assisted ring-opening polymerizations of DTC were carried successfully with lanthanum chloride (LaCl3) and stannous octoate Sn(Oct2 ascatalyst and the highest weight average molar mass of the obtained PDTC were 66800g/mol and 14600g/mol, respectively.

分别在氯化镧和异辛酸亚锡的催化下，DTC的微波开环聚合反应可以顺利地进行，所得PDTC的重均分子量分别达到66800g／mol和14600g／mol，二者比较而言，氯化镧的催化活性更高。

The grafting of polycaprolcatone on starch by ring-opening polymerization of e -caprolactone was initiated from the starch hydroxyl functions in the presence of a catalyst such as stannous octoate Sn(0ct2, Dibutyltin dilaurate or titanium tetrabutoxide. The grafting ration could reach 16%. IR, X-ray diffraction and DSC were used to investigate the grafting-polymer.

在辛酸亚锡Sn(Oct_2、二月桂酸二丁基锡和钛酸丁酯等催化剂作用下，淀粉羟基引发己内酯单体进行配位聚合，淀粉接枝率可以达到16％，并通过红外光谱、X—ray衍射及DSC等测试手段对反应产物进行了表征。

The star-shaped block copolymers were prepared by ring-opening polymerization of ε-caprolactone in the presence of multiarm PEG using stannous octoate as a catalyst.Based on these star-shaped PEG- b -PCL,soluble macromers terminated with acrylate groups were synthesized.

以辛酸亚锡为催化剂，通过星型聚乙二醇引发ε-己内酯开环聚合，制备了PEG- b -PCL嵌段共聚物，进一步以丙烯酸酯封端，合成了3种水溶性大分子单体。

This purpose of design is a computer simulation ventricle except that electric vector quantity of the heart surrounds the running orbit very much, through the stereoscopic and dynamic way, show the course that the vectorial ring of electricity of heart forms, can make student image, understand electric vector quantity of the heart ocularly; Type the well practical foundation in order to study the kind electric picture.

本设计目的是计算机模拟心室除极心电向量环运行轨迹，通过立体动态的方式，展示心电向量环形成的过程，使学生能够更形象，直观地理解心电向量；为学好心电图打好切实的基础。

The reactions include, organometallic reactions (grignard reaction, organolithium -zinc, and -copper chemistry ), metal catalyzed reactions, mannich reaction, nitration, hydrogenation, azidation, amino-protection reactions, organoalluminum catalyzed beckmann rearrangement, schmidt rearrangement, epoxidation, epoxide ring opening reactions, swern oxidation etc.

这些反应包括：有机金属反应(格利亚反应，有机锂，有机锌和有机铜反应)，金属催化反应堆(suzuki 反应， negish 反应)， mannish 反应，硝化反应，氢化反应，叠氮反应，各种基团的保护和脱保护反应，有机铝催化的贝克曼重排反应，斯密特重排反应，环氧化反应，环氧烷开环反应， swern 氧化反应等。

The resulting organometallics can react with many organic electrophiles,which can tolerate many functional groups. We have synthesized a class of organozinc species and apply them in ring opening of epoxides, affording cis-addition products.

但也因为反应活性低，常常需要在Lewis酸的存在下，或将有机锌试剂用过渡金属络合物转换为相应的有机过渡金属试剂后才可以与多种亲电试剂反应。

The reaction of cyclic b-keto esters with CF3CO2ZnCH2I provides the corresponding ring-expanded products with the advantage of mild condition in moderate to good yields. A simple and efficient procedure has been developed for a variety of 1,3-diketones converted into the corresponding 1,4-diketones and trans-1,2-disubstituted cyclopropanols in high yields. In conclusion, this new type of organozinc reagents has been developed for many useful reaction in organic synthesis.

利用有机锌试剂所具有的双重特性，在新型的Baylis-Hillman反应中，可以直接与炔基酮和醛反应一锅制得多官能团的三取代的顺式烯；在b-酮酯化合物的扩环反应中，取得了重要进展，得到了增加一个碳的扩环产物，&一步法&合成，反应条件温和、环境友好；在1，3-二酮分子中成功地插入1个碳，合成出1，4-二酮和环丙醇，为现代有机合成提供了新的合成方法，具有良好的应用前景。

Keywords: Organozinc reagents; cis-Addition Products; Ring-expansion; Chain-extension

中文关键词：有机锌试剂；环氧的顺式开环；酮酯的扩环；碳链增长

Organozinc reagents; cis-Addition Products; Ring-expansion; Chain-extension

中文主题词：有机锌试剂；环氧的顺式开环；酮酯的扩环；碳链增长

Alternatively, the con- trollers can use the synchronous rectifier itself or loss- less inductor current-sensing methods to provide overload protection with lower power dissipation.

另外，康威特罗勒斯可以使用同步整流器本身或亏损减少电感电流检测方法，以提供低功耗过载保护。

Mr. Dauber's other Schatz hangs in his home movie studio.

多伯把沙兹的另一件作品挂在家里的电影室。