问题 单项选择题 B型题

药物分子中引入酰胺基()

A.易与受体蛋白质的羧基结合

B.可与生物大分子形成氢键,增强与受体的结合力

C.增加药物的解离度和水溶性都增加

D.易于通过生物膜

E.增加药物的亲水性,并增加与受体结合力

答案

参考答案:B

解析:构成受体或酶的蛋白质和多肽结构中含有大量的酰胺键,故酰胺类药物易与生物大分子形成氢键,增强与受体的结合力;醚类化合物由于醚中的氧原子有孤对电子,能吸收质子,具有亲水性,碳原子具有亲脂性,使醚类化合物在脂-水交界处定向排布,易于通过生物膜;磺酸基的引入可增加药物的解离度和水溶性,不易通过生物膜,导致生物活性减弱,毒性降低。

单项选择题

The Erie Canal was the first important national waterway built in the US. It crossed New York from Buffalo on Lake Erie Troy to Albany on the Hudson River. It joined the Great Lakes with the Atlantic Ocean. The canal served as a route over which industrial goods could flow into the west, and materials could pour into the east. The Erie Canal helped New York develop into the nation’s largest city.

The building of the canal was paid for entirely by the state of New York. It cost $ 7 143 789, but it soon gained its price many times over. Between 1825, when the canal was opened, and 1882, when toll charges were stopped, the state collected $121461891.

For a hundred years before the Erie was built, people had been talking about a canal which could join the Great Lakes and the Atlantic Ocean. The man who planned the Erie Canal and carried the plan through was De Witt Clinton. Those who were against the canal laughingly called it "Clinton’s Ditch". Clinton talked and wrote about the canal and drew up plans for it. He and Governor Morris went to Washington in 1812 to ask for help for the canal, but they were unsuccessful.

Clinton became governor of New York in 1817, and shortly afterwards, on July 4, 1817, broke ground for the canal in Rome, N.Y. The first part of the canal was completed in 1820. As the canal grew, towns along its course developed fast. The length of the canal is 363 miles.

It can be inferred that()into the Atlantic Ocean.

A. the Great Lakes flow

B. the Hudson River flows

C. Lake Erie flows

D. the Erie Canal flows

问答题