【单选题】具有一定肾毒性的β一内酰胺类抗生素是( )
【判断题】螺纹的旋向一般都采用左旋,只有在特殊需要情况下才选用右旋。
【单选题】下列关于企业年金的说法,错误的是( )。
【单选题】Which one of the following statement is NOT true about transition state theory?
A.
Transition state theory describes a hypothetical "transition state" that occurs in the space between the reactants and the products in a chemical reaction.
B.
The species that is formed during the transition state is known as the activated complex.
C.
The activated complex exists in a very long time because it has a great store of energy.
D.
The activated complex can either be converted into products, or it can “revert” back to reactants.
【单选题】爱因斯坦指出光与物质有三种相互作用,( )是指处于高能级上的电子状态是不稳定的,它将自发地从高能级跃迁到低能级与空穴复合,同时释放出一个光子。
【判断题】螺纹的旋向一般都采用左旋,只有在特殊需要情况下采选用右旋。( )
【简答题】( ) conformation is the preferred transition state geometry for the E2 elimination
【单选题】很多职工退休后最重要的收入来源将是()。
【简答题】在研究光与物质的相互关系,爱因斯坦指出:光与物质的粒子体系的相互作用主要有哪三种过程?