苄醇

The effects of molar ratio of benzyl alcohol to acetic acid,reaction time,and the amount of catalyst and its reusability on esterification yield were discussed.

结果表明，乙酸苄酯最适宜的合成工艺条件为：酸醇摩尔比2∶1、催化剂用量3.5%、带水剂用量40%、反应时间6 h。

The results showed that the optimal conditions for synthesis of benzyl acetate were: the molar ratio of acetic acid to benzyl alcohol was 2∶1,the amount of the water carrier was 40%,the amount of the catalyst was 3.5%,and reaction time was 6 h.

结果表明，乙酸苄酯最适宜的合成工艺条件为：酸醇摩尔比2∶1、催化剂用量3.5%、带水剂用量40%、反应时间6 h。

Structural differences among the three gelators are only in the varied amount of methyl groups on the benzene ring.

从分子结构的差异、亲溶剂作用、分子几何构型、相转变热焓以及溶剂极性等方面研究了三种亚苄基山梨醇衍生物凝胶剂在有机溶剂中的自组装和凝胶化机理。

UV spectra of the n -octanol gels formed by the three gelators indicate that the K bands of benzene rings are red shifted. It reveals that the π-π stack is one of the driving forces for the self-assembly of the gelators. The extent of red shifts of K bands depends on the amount of methyl groups in benzene rings which is in accord with the stabilities of the gels formed by such three gelators.

紫外吸收光谱表明，对比其溶液态，三种衍生物聚集体苯环的K带发生红移，表明π-π堆积作用是亚苄基山梨醇衍生物凝胶剂自组装的驱动力之一；红移的幅度随苯环上甲基数量的增加而增加，这与三种衍生物形成的分子凝胶的热稳定性相吻合。

Now, however, all children continue in "comprehensive" schools, and the eleven-plus determines which courses of study the child will follow.

然而现在，所有的孩子都要在综合学校继续学习，所以这次考试只是决定他们将要学习哪些课程。

Cultivatable land , and led to a general recognition that development must not be carried at the cost of agriculture .

城区的迅速扩大在很多情况下侵占了宝贵的可耕地，使人们普遍认识到发展不能以牺牲农业为代价。