常见例句双语例句Screening for 2 - bromo-butyric acid as the starting material, after ammonolysis, esterification, ester amine solution, split, five-step cyclization reaction Levetiracetam.筛选以2-溴代丁酸为起始原料，经氨解，酯化，酯胺解，拆分，环合五步反应制得左乙拉西坦。 返回 bromo amine