查询词典 geminal

THE FIRST TOTAL SYNTHESIS OF TAXAMAIRIN B Taxamairin B, representive of rare naturally-occuring rearrang-ed 9(10→20)-abeo-8, 11, 13-triene diterpenoids, has been firstsynthesized by a eleven-step route in an overall yield of 8.19%,starting from commercially available catechol and 1,3-cyclohexan-dione. The improved Friedel-Crafts annulation, thermodynamicallycontrolled-geminal pairing methylation, the selective oxidation ofallyl group and the selective reduction of the less-hindrancecarbon-carbon double bond are the key steps.

二。美丽红豆杉素B的全合成研究 1，美丽红豆杉素B的首次全合成以价廉，易得的邻苯二酚和1，3-环己二酮为原料，经过改良的Friedel-Crafts烷基化反应，热力学控制的α，β-不饱和酮结构的α一位双烷基化，烯丙位的选择性氧化，以及选择性还原位阻较小的碳碳双键等十一步反应，以8.19％的总收率首次完成了美丽红豆杉素B的全合成。

The generalized relationship which correlates the geminal coupling constants with the hybrid orbitals, net atomic charges, bond lengths and bond angles had been employed to obtain one concrete relationship for calculation of the geminal coupling constants 2JCaCbH in aromatic systems.

在前文工作的基础上，本文结合MNDO分子轨道方法和最大键级杂化轨道方法研究得到了计算苯及其取代物中孪位偶合常数2JCCH的多元级性关系式。

According to the structure and synthesis character of the geminal dinitro energetic plasticizers,the current situation about the synthesis,the property and application of geminal dinitro aldehyde acetals,esters and ether energetic plasticizers is summarized with 21 references.

从偕二硝基含能增塑剂的结构和合成特点出发，综述了偕二硝基缩醛类、酯类及醚类等含能增塑剂的合成、性能及应用研究现状。

Organic chemistry ; geminal dinitro ; energetic plasticizers ; propellants ; explosives

有机化学；偕二硝基；含能增塑剂；推进剂；炸药

The main research now is focused on the polymerization of difluoramino substituted oxetane monomers, the preparation of neopentyl difluoramino nitrato plasticizers, and the molecular design and synthesis of cyclic N2 nitramino geminal difluoramino oxidizers.

目前该领域的研究工作主要集中在二氟氨基取代环氧丁烷聚合物合成，新戊基二氟氨基硝酸酯增塑剂制备，以及环N2硝胺基偕二氟氨基氧化剂的分子设计与合成上。

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。