问题 单项选择题

关于药品稳定性的正确叙述是()

A.盐酸普鲁卡因溶液的稳定性受温度影响,与pH值无关

B.药物的降解速度与离子强度无关

C.固体制剂的赋形剂不影响药物稳定性

D.t=KCn,n为反应级数,当n=0时,即为零级反应,即-dc/dt=KC0=K,所以零级反应的反应速度与反应物的浓度无关。

E.零级反应的反应速度与反应物浓度无关

答案

参考答案:E

解析:药物稳定与否的根本原因在于自身的化学结构,外界因素则是引起变化的条件。影响药物制剂降解的外界因素主要有pH值、温度、溶剂及其解离常数离子强度,赋形刑或附加剂,水分、氧、金属离子和光线等。盐酸普鲁卡因在水溶液中易水解,水解生成对氨基苯甲酸与二乙胺基乙醇即失去药效。在碱性条件下水解加速,偏酸条件下较稳定。在pH3.4~3.6时最稳定。一般来说,温度升高,反应速度加快。根据质量作用定律,反应速度与反应物浓度之间的关系如下:-dc/

单项选择题 A型题
单项选择题

It is a wise father that knows his own child, but today a man can boost his paternal (fatherly) wisdom— or at least confirm that he’s the kid’s dad. All he needs to do is shell out $30 for paternity testing kit (PTK) at his local drugstore—and another $120 to get the results.

More than 60,000 people have purchased the PTKs since they first became available without prescriptions last year, according to Doug Fogg, chief operating officer of Identigene, which makes the over-the-counter kits. More than two dozen companies sell DNA tests directly to the public, ranging in price from a few hundred dollars to more than $ 2,500.

Among the most popular: paternity and kinship testing, which adopted children can use to find their biological relatives and families can use to track down kids put up for adoption. DNA testing is also the latest rage among passionate genealogists—and supports businesses that offer to search for a family’s geographic roots.

Most tests require collecting cells by swabbing saliva in the mouth and sending it to the company for testing. All tests require a potential candidate with whom to compare DNA.

But some observers are skeptical. "There is a kind of false precision being hawked by people claiming they are doing ancestry testing," says Troy Duster, a New York University sociologist. He notes that each individual has many ancestors—numbering in the hundreds just a few centuries back. Yet most ancestry testing only considers a single lineage, either the Y chromosome inherited through men in a father’s line or mitochondrial DNA, which is passed down only from mothers. This DNA can reveal genetic information about only one or two ancestors, even though, for example, just three generations back people also have six other great-grandparents or, four generations back, 14 other great-great-grandparents.

Critics also argue that commercial genetic testing is only as good as the reference collections to which a sample is compared. Databases used by some companies don’t rely on data collected systematically but rather lump together information from different research projects. This means that a DNA database may have a lot of data from some regions and not others, so a person’s test results may differ depending on the company that processes the results. In addition, the computer programs a company uses to estimate relationships may be patented and not subject to peer review or outside evaluation.

In Paragraphs 1 and 2, the text shows PTK’s ()

A. easy availability

B. flexibility in pricing

C. successful promotion

D. popularity with households