对偶基

In the second part of this thesis, a formal [2+2] cycloaddition ketenes and dialkyl azodicarboxylates was studied. We found that by adjusting the substituents in the diazenes, the reaction mode can be completely switched, and furnish four-membered-ring products, aza-b-lactams, the enantioselectivity was up to 91%.

经研究发现，通过对偶氮化合物取代基团的改变，我们可以实现[4+2]环加成反应到[2+2]环加成反应的转变，在手性氮杂环卡宾的作用下，对具有各种取代基的烯酮都可以很好的产率得到氮杂b-内酰胺，其对映选择性最高可以达到91%。

Conductivity of Polyoxyethylene/Poly (2-vinyl pyridine)Blend and Compatibilizing Effect of Lithium Perchlorate;2. Graft terpolymerization of polyoxyethylene macromer with acrylates;3. Then multiblock copolymers was obtained by condensing polyoxyethylene and poly(2 vinylpyridine)with dichloromethane in the presence of potassium hydroxide.

甲基萘锂作为引发剂利用阴离子聚合得到 2 乙烯基吡啶的遥爪双羟基低聚物(P2VP)，然后以二氯甲烷作偶联剂与聚环氧乙烷反应制备P2VP和PEO多嵌段共聚物，考察了反应时间对偶联反应的影响，并对共聚物进行了IR和1H NMR表征，由1H NMR谱的积分曲线得到了共聚物中PEO链段质量分数。

The split between the two groups can hardly be papered over.

这两个团体间的分歧难以掩饰。

This approach not only encourages a greater number of responses, but minimizes the likelihood of stale groupthink.

这种做法不仅鼓励了更多的反应，而且减少跟风的可能性。