【单选题】有一混合蛋白质溶液,各种蛋白质的 PI 分别是 4.3,5.0,5.4,6.5,7.4 ,电泳时欲使其都泳向正极,缓冲溶液的 pH 应该是
【简答题】如图是部分元素的单质和化合物之间的相互转化关系,部分反应的生成物没有全部列出。已知原料A、M均属于金属氧化物,L是由两种沉淀组成的。F和Y反应能生成一种全部为非金属元素所组成的盐,C的焰色反应呈黄色,M有磁性,反应①中B和C的物质的量之比为3:4。 回答下列问题 (1)反应②的主要用途是:_________________(答一点即可),Y的空间构型为____________。 (2)已知反应③中...
【单选题】有一混合蛋白质溶液,各种蛋白质的PI值分别为:4.6、5.0、5.3、6.7、7.3,电泳时欲使其中四种蛋白质泳向正极,缓冲液的PH应为( )
【单选题】下列原子、离子和分子中属于反磁性的是( )。
【单选题】下列原子、离子和分子中属于反磁性的是()。
【单选题】6) In this digital world, if we want to go to a restaurant we’ve never been to, we will probably ________.
A.
go to the restaurant directly
B.
check other people’s reviews of the restaurant on our smartphones
C.
call the manager of the restaurant before we make a decision
D.
ask friends about the details of the restaurant before a decision
【简答题】Mr. Harris used to work in Dover, but then he changed his work, and he and his wife moved to another town. They did not have many friends there, but they soon met a lot of interesting people, and afte...
【简答题】We’ve been friends ( ) we
met at school.A. until B. ever since C. when D. every time
【单选题】下列部位中,形成的假膜性炎对人体的危险性最大的是