【简答题】The problem is not _____ so easy as you think. It's far from being settled. A: nearly B; hardly C; almost
【单选题】根据下列选项,回答 197~201 题:
A.
在6-位酰胺侧链的α-位引入极性亲水性基团,如-NH2、-COOH、-SO3H等
B.
将3-位的乙酰氧基以甲基、氯原子取代,增加药效和改变药代动力学性质
D.
将3-位的乙酰基以含N的杂环取代,增加药效和改变药代动力学性质
E.
将7-位的乙酰侧链的a-位引入极性亲水性基团,如NH2、-COOH、SO3H等下列半合成抗生素类药物是由青霉素G或头孢菌素C的结构改造而来,它们分别适合上述的哪-条 第197题:氨苄青霉素( )。
【简答题】Unsurprisingly, articles debunking the story have not traveled nearly as far on social media as the original versions did. The coronavirus epidemic in China surpassed a grim milestone last week with a...
【单选题】“Not nearly as far as I’m going to go” means ______.
A.
I’m still going to work farther away from home
B.
I’m not going to work far away from home
C.
I’m not satisfied with what I’ve done
D.
What I have done is not far from success
【判断题】委托加工的应税消费品收回后出售的不论售价高低,均不再缴纳消费税。
【简答题】A.在6位酰胺侧链的α位引入极性亲水性基团,如-NH2、-COOH、-SO3H等 B.将3位的乙酰氧基以甲基、氯原子取代,增加药效和改变药代动力学性质 C.7位的酰胺侧链上引入噻吩环等杂环 D.将3位的乙酰基以含N的杂环取代,增加药效和改变药代动力学性质 E.在7位酰胺侧链的α位引入极性亲水性基团,如-NH2、-COOH、-SO3H等下列半合成抗生素类药物是由青霉素G或头孢 菌素C的结构改造而来,...
【简答题】某三元酸 (H 3 A) 的解离常数为 p K a1 = 3.96 , p K a2 = 6.00 , p K a3 = 10.02 ,则 0.10 mol/L H 3 A 溶液的 pH 为 _____ , 0.10 mol/L Na 3 A 溶液的 pH 为 ____________ 。