Levocetirizine Dihydrochloride was prepared from benzoyl chloride by acidylation, hydrogenation, cyclization with an overall yield of 8.05 %.以苯甲酰氯为原料,经酰化, 还原, 环合等反应合成左旋西替利嗪盐酸盐,反应总收率为8.05%....
A computer would have been invaluable for this job.一台计算机对这个工作的作用会是无法估计的。The book is an invaluable aid to teachers of literature.这本书对于教授文学的老师来说帮助非常大。If you are a regular reader of Homes & Gardens you will know what an inv...