酶的最适PH是A.酶的特征性常数 B.酶促反应速度最大时的pH C.酶最稳定时的pH

题型:单项选择题

问题:

酶的最适PH是

A.酶的特征性常数

B.酶促反应速度最大时的pH

C.酶最稳定时的pH

D.与底物种类无关的参数

E.酶的等电点

考点:临床执业助理医师2004年临床执业助理医师资格考试真题(第一单元)
题型:单项选择题
Coffee has become a popular drink in our culture. Most people have a coffee maker at home for guests who come to visit. It naturally contains caffeine (咖啡因), which people in today’s society have somewhat come to rely on (依靠) to provide them with energy.
In the workplace many people start their day with a cup of coffee, and then continue to drink it until it’s time to go home. Many meetings also begin with a cup of coffee --- which is why so many workplaces now have a steady flow of office coffee.
Coffee is unsurprisingly one of the most traded agricultural products in the world, supporting the economy in many countries. Coffee is made from the roasted(烤,烘,焙) seeds of coffee cherries, which grow on trees in over 70 countries. The seeds are roasted to different degrees depending on the flavors wanted, and then are brewed (泡,煮) to create the coffee drink. Coffee is usually sold already roasted, so that all you have to do is add hot water.
Coffee is labeled according to its appearance --- light, medium light, medium, medium dark, dark, or very dark.
People argue a lot about whether the effect of drinking coffee is positive or negative. Some people think that drinking too much coffee is bad for our health. But you can buy decaffeinated (脱去咖啡因的) coffee, which has a lot less caffeine. Most people, however, would not care  about the negative effects of drinking coffee.
Title: Coffee --- A Modern Trend
The reason for coffee’s popularity
containing caffeine which makes people 小题1: ______
The places where people drink coffee
●providing coffee for 小题2: __________ at home
●drinking coffee 小题3:_____________
 
The coffee-making 小题4: ___________
●made from seeds on coffee trees
●roasted to create coffee drinks
●mixed with 小题5: ________ before it is drunk
The category of coffee
●classified based on its 小题6:__________
 
People’s attitude towards the
小题7: _________ of coffee
●arguing as to whether drinking coffee is小题8: ________
●worrying about the risk of drinking 小题9: __________
●小题10:______ the side effect of drinking coffee
题型:单项选择题

铁路提速为鲜活水产品、新鲜水果和蔬菜的运输提供了有利条件.在鲜活鱼的长途运输中,必须考虑以下几点:水中需要保持适量的O2;及时除去鱼排出的CO2;防止细菌的大量繁殖.现有两种在水中能起供氧灭菌作用的物质是,其性质如下:

过氧化钠(Na2O2):易溶于水,与水反应生成NaOH和O2

过氧化钙(CaO2):微溶于水,与水反应生成Ca(OH)2和O2

根据以上介绍,你认为运输鲜活水产品时选择______加入水中更好?因为______.

题型:单项选择题

哺乳指导中下列不妥的是()

A.宣传母乳喂养好处

B.待下奶后立即哺乳

C.吸吮有助于乳汁分泌

D.告诉产妇开奶越早越好

E.吸吮 * * 可使生乳素增加

题型:单项选择题

社会治安综合治理有政治的、经济的、行政的、教育的、文化的、法律的等手段和措施。()

题型:单项选择题

水与乙醇能形成()混合物,故用蒸馏法不能完全将乙醇中的水除去。

A.共沸

B.络合

C.化合

D.不溶

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