【简答题】实验室常利用甲醛法测定(NH 4 ) 2 SO 4 样品中氮的质量分数,其反应原理为:4NH +6HCHO=3H + +6H 2 O+(CH 2 ) 6 N 4 H + [滴定时,1 mol(CH 2 ) 6 N 4 H + 与 l mol H + 相当],然后用NaOH标准溶液滴定反应生成的酸,某兴趣小组用甲醛法进行了如下实验: 步骤I 称取样品1.500g。 步骤II 将样品溶解后,完全转移...
【多选题】What can capping and polyadenylation of eukaryotic mRNA do?
A.
increase the stability of a eukaryotic mRNA molecule
B.
facilitate its export from the nucleus to the cytosol
C.
generally mark the RNA molecule as an mRNA
D.
used by the protein-synthesis machinery to make sure that both ends of the mRNA are present and that the message is therefore complete before protein synthesis begins
【简答题】工业机器人的末端执行器主要有 、 、 等类型。
【单选题】“店铺销售管理系统”按照计划计算机应用的分类属于
【判断题】工业机器人的末端执行器也叫机器人的手部,是类似于人手的结构,不同的末端执行器,一定都具有“手指”
【单选题】“店铺销售管理系统”按照计划计算机应用的分类属于
【简答题】工业机器人的末端执行器有机械式、吸附式和专用工具三类,试分析一下真空吸附末端执行器是如何依靠吸附力抓取物料的。
【多选题】Which statement of the cis-acting elements of eukaryotic gene is correct?
A.
The cis-acting elements are DNA fragments.
B.
The cis-acting elements are proteins.
C.
The cis-acting elements are the regulator of eukaryotic gene transcription.
D.
The cis-acting elements include promoter, upstream promoter elements, enhancer, silencer and so on.