查询词典 branched chain

The invention concerns a process for preparing heterocyclic carbenes of general formula in which R1, R2, R3 and R4 are identical or different and mean saturated or unsaturated, straight-chain, branched or cyclic, unsubstituted or substituted C1-C10 alkyl, C2-C5 alkylidene, C2-C5 alkylidine, C7-C19 aralkyl or C6-C14 alkyl groups, R3 and R4 can also stand for hydrogen or form jointly anellated, substituted or unsubstituted groups with between 3 and 7 carbon atoms and X stands for carbon or nitrogen, R3 being dropped if X is nitrogen.

本发明涉及一种制备通式Ⅰ的杂环碳烯的方法，其中在通式Ⅰ中，R1、R2、R3和R4是相同的或不同的，并且是饱和的或不饱和的，直链、支链或环状的，未取代或取代的C1－C10－烷基、C2－C5－亚烷基、C2－C5－次烷基、C7－C19－芳烷基或C6－C14－芳基基团，R3和R4可以是氢或它们一起形成具有3－7个碳原子的稠合的、取代或未取代的基团，X是碳或氮，并且当X是氮时，不存在R3。

Long-chain branched polyethylene was obtained using a homogeneous bianary catalyst system composed of late and early transition metal complexes,namely a mixture of bis(α-naphthalidine)-2,3-butanediimine NiBr2 and Cp* TiCl3,as catalyst precursors in the presence of MAO.

合成了一种后过渡金属镍化合物 [二- N ，N′--2 ，3-丁二亚胺镍二溴化物 ][C10H7—NC(CH3)C(CH3)N—C10H7]NiBr2，此化合物在MAO活化下催化乙烯聚合能得到含有末端双键的低分子量聚乙烯，即长链α-烯烃。

The contribution of water concentration on the growth of carbon nanotubes was investigated. Scanning electron microscopy results showed that the grown CNTs in CH4/H2 gas mixure had chain-shaped structure and the diameter was about 40—90nm. With the addition of proper amount of water, the diameter of CNTs became uniform, and the surfaces of nanotubes were fully covered with nano-sized node-like structures. When more water was added, branched carbon nanotubes were synthesized.

场发射扫描电子显微镜结果表明，不加水时，制备出的碳纳米管直径不均匀，分布在40—90nm之间，呈链节状的结构；加入少量水时，制备出的碳纳米管直径比较均匀，集中在70nm左右，表面为瘤状结构；当水的流量进一步增加时，得到的碳纳米管表面光滑，出现了枝状结构。

The presence of iron in CuMnZrO〓 catalyst greatly enhanced the formation of higher alcohols, which were a mixture of straight chain alcohols and branched alcohols .

本论文以具有较好的甲醇合成性能的CuMnZrO〓催化剂为基体添加有促进碳链增长能力的Fe助剂改性得到低碳醇合成催化剂。

The octane number of 5 substances were predicted using the new methods.The results show that the second level group contribution method exhibits significant improvements in accuracy and should be used for estimating the octane number of branched and ring hydrocarbons.In cases of simple straight chain bydrocarbons, however,the first level group contribution method should be used.

用新方法对未参加回归的五种物质的辛烷值进行了预测，结果表明对于含有支链和环的烃应采用第二水平基团法估算其辛烷值，对简单的直链烃采用第一水平基团法估算其辛烷值。

Do not gum up the work by telling mother what we are going to do .

别告诉母亲我们要干的事，那会把事情搞糟的。

In recent years, application of the partial prestressed concrete beam s is developed.

近年来，随着部分预应力砼梁应用的推广，发现我国规范所采用的名义拉应力法的计算结果不稳定。