Medicine intermediate N - ethylethylenediamine ( NEED ) was synthesized from acrylamide and ethylamine by addition reaction and Hofmann rearrangement. 以丙烯酰胺为起始原料,经乙胺加成后,再经Hofmann重排两步反应后合成了药物中间体N - 乙基乙二胺 ( NEED ).
人们早已知道，如果材料的表面积足够大，可引起催化反应。It had been known for some time that chemical reactions can be catalyzed by materials with large surface areas.它们对被它们催化的反应有很强的专一性.They are highly specific for the reactions that they catalyze.在...
这一表态称赞了过去一年的变革。The statement salutes the changes of the past year.他向外交部请了一年的假。He took a year'ssabbatical from the Foreign Office.那家公司与前任审计员已打了整整一年的官司。The company has been in litigation with its previous auditors for...
英语伤我千百遍，我待英语如初恋。English has hurt me a thousand times, but I still regard it as my first love.卡车司机安然脱险，但有一位行人受了伤。The lorry driver escaped unhurt, but a pedestrian was injured.她身上有严重的淤伤，嘴唇也破了。She had quite severe bruising ...
穿过丛林的旅行充满了危险.The journey through the jungle was perilous.我们现在已经来到了丛林的边缘.We were now at the margin of the thicket.这种香调唤起森林和丛林的气息.This tone evokes the smell of forests and undergrowth....
Objective: Observation after urethra holmium laser lithotrity treatment ureter upside stone clinical curative effect and security.目的: 观察经尿道钬激光碎石术治疗输尿管上段结石的临床疗效及安全性.Objective To discuss the oncogenesis, clinical manifesta...