【单选题】卤代烷与 NaOH 在水-乙醇溶液中进行反应,针对下列现象给出的正确 判断 是: (1) 产物发生 Walden 转化; S N 2 (2) 增加溶剂的含水量反应明显加快; S N 1 (3) 有重排反应; S N 1 (4) 叔卤代烷反应速率大于仲卤代烷; S N 1 (5) 反应只有一步。 S N 2
B.
(2)(3)(4)的现象说明是SN1反应过程
D.
(1)的现象说明产物为一对对映异构体形成的外消旋体。
【简答题】One winter term during college, I took a history class to fulfill a requirement. The professor was a 1 fellow with red hair. He would walk shyly into the room wearing his hooded (带帽的) winter coat, onc...
【单选题】The professor was not able to _____ students, so the English class is not interesting.
【单选题】先求出包括建设期的投资回收期,后求出不包括建设期的投资回收期的方法是( )。
【多选题】卤代烷与 NaOH 在水-乙醇溶液中进行反应,针对下列现象给出的正确 判断 是: (1) 产物发生 Walden 转化; S N 2 (2) 增加溶剂的含水量反应明显加快; S N 1 (3) 有重排反应; S N 1 (4) 叔卤代烷反应速率大于仲卤代烷; S N 1 (5) 反应只有一步。 S N 2
B.
(2)(3)(4)的现象说明是SN1反应过程
D.
(1)的现象说明产物为一对对映异构体形成的外消旋体。
【单选题】The old professor was so versatile that he could ______ almost any subject we studied. (U2—B)
【多选题】卤代烷与 NaOH 在水-乙醇溶液中进行反应,针对下列现象给出的正确 判断 是: (1) 产物发生 Walden 转化; (2) 增加溶剂的含水量反应明显加快; (3) 有重排反应; (4) 叔卤代烷反应速率大于仲卤代烷; (5) 反应只有一步。
B.
(2)(3)(4)的现象说明是SN1反应过程
D.
(1)的现象说明产物为一对对映异构体形成的外消旋体。
【单选题】溶出度检查符合下述条件之一者,可判为符合规定。
A.
6片(粒、袋)中,如有1~2片(粒、袋)低于Q,但不低于Q-10%,且其平均溶出量不低于Q;
B.
6片(粒、袋)中,如有1~2片(粒、袋)低于Q,但不低于Q-20%,且其平均溶出量不低于Q;
C.
6片(粒、袋)中,如有2~3片(粒、袋)低于Q,但不低于Q-10%,且其平均溶出量不低于Q;
D.
6片(粒、袋)中,如有1~2片(粒、袋)低于Q,但不低于Q-5%,且其平均溶出量不低于Q;
E.
6片(粒、袋)中,如有1~2片(粒、袋)低于Q,但不低于Q-15%,且其平均溶出量不低于Q;
【单选题】The old professor was so versatile that he could ______ almost any subject we studied.
【单选题】Professor George was so ______ with his experiments in the laboratory that he often missed lunches.