问题 单项选择题 A1/A2型题

渗透泵型片剂控释的基本原理是()

A.减小溶出

B.减慢扩散

C.片外渗透压大于片内,将片内药物压出

D.片剂膜内渗透压大于片剂膜外,将药物从细孔压出

E.片剂外面包控释膜,使药物恒速释出

答案

参考答案:D

解析:渗透泵型片剂是利用渗透压原理制成的控释片剂,能均匀地恒速释放药物。它是由水溶性药物制成片芯,外面用水不溶性聚合物包衣,形成半透性膜壳,水可渗进膜内,而药物不能渗出。片面用激光开一细孔。当与水接触后,水即渗入膜内,使药物溶解形成饱和溶液,由于膜内外存在很大的渗透压差,使药物溶液由细孔持续流出。所以该片剂控释原理为膜内渗透压大于膜外,将药物从细孔压出。减小溶出、减慢扩散、片外包控释膜及片外渗透压大于片内,均不是渗透泵型片剂控释的基本原理。故答案应选择D。

多项选择题
单项选择题

"In the long run," as John Maynard Keynes observed, "we are all dead. " True. But can the (1) run be elongated in a way that makes the long run (2) And if so, how, and at what cost People have dreamt of (3) since time immemorial. They have sought it since the first alchemist put an elixir of (4) on the same shopping list as a way to turn lead into gold. They have (5) about it in fiction, from Rider Haggard’s "She" to Frank Herbert’s "Dune". And now, with the growth of (6) knowledge that has marked the past few decades, a few researchers believe it might be within (7) .

To think about the question, it is important to understand why organisms-people (8) -age in the first place. People are like machines: they (9) That much is obvious. However, a machine can always be (10) A good mechanic with a stock of spare parts can keep it going (11) . Eventually, no part of the (12) may remain, but it still carries on, like Lincoln’s famous axe that had three new handles and two new blade.

The question, of course, is whether the machine is worth (13) . It is here that people and nature (14) . Or, to put it slightly (15) , two bits of nature disagree with each other. From the individual’s point of view, (16) is an imperative. You cannot reproduce unless you are alive. A fear of death is a sensible evolved response and, since (17) is a sure way of dying, it is no surprise that people want to stop it in its tracks. Moreover, even the appearance of ageing can be (18) . It (19) the range of potential sexual partners who find you attractive-since it is a sign that you are not going to be (20) all that long to help bring up baby-and thus, again, curbs your reproduction.

12()

A.spare

B.original

C.new

D.advanced