The hydroxyl groups can be changed into esters , ethers , acetals and ketals, etc.最常用的羟基保护基可归纳为三类:酯类 、 醚类和缩醛或缩酮类.Eight acetals ( Ketals ) were synthesized under the optimal conditions.在最佳条件下,合成了八个缩醛 ( 酮 ) 化合物.The yields ...
The yields of other cyclic acetals were between 62.并在此条件下合成了多种环缩醛,收率62.Eight acetals ( Ketals ) were synthesized under the optimal conditions.在最佳条件下,合成了八个缩醛 ( 酮 ) 化合物.The hydroxyl groups can be changed into esters , ethe...
Barely had the bulldozers started when Museum of London archaeologists swooped.推土机刚一启动，伦敦博物馆的考古学家们就蜂拥而至了。Huge rockslides at times bury bulldozers and other machines.有时候巨大岩石崩落埋没了压路机及其他机器.The bulldozers quickly leveled off...
His girlfriend had gone into the witness box and taken the oath.他的女朋友进入证人席并立了誓。The plaintiff's sole witness, a gambler and layabout, was easily discredited.原告唯一的证人嗜赌成性，游手好闲，其证词一下子就被推翻了。The convictions rest solely on...
The Jordanian leader is caught between both sides in the dispute.争论双方使约旦领导人左右为难。The Jordanian leader seemed amenable to attending a conference.约旦领导人似乎愿意参加会议。Even better, the Jordanian people seem eager to welcome outside...
粘连性肠梗阻手术存在危险性吗.Is operation of adhesion sex intestinal obstruction put in dangerous sex.结论螺旋CT扫描及重建对粘连性肠梗阻具有重要诊断价值.Conclusion Spiral CT has an important value in detecting adhesive ileus.粘连性肠梗阻有何临床症状?Does adhesion sex in...
They lacked the scientific personnel to develop the technical apparatus much further.他们缺少能够进一步研发这一技术装置的科研人员。a piece of laboratory apparatus一件实验室仪器A nuclear reactor is the apparatus in which atoms are split.核反应堆是分裂原子的装置....
He walked around the garden and pronounced himself satisfied.他绕着花园走了走，说自己很满意。The aquifer which had once fed the wells was pronounced dry.曾为水井供水的蓄水层正式宣告干涸了。"Getting nowhere fast," pronounced Crosby, "that's what we&#...