皮皮学，免费搜题
登录
搜题
【单选题】
Fork-users have historically been( )the minority.A.
on
B.
at
C.
in
D.
with
手机使用
分享
复制链接
新浪微博
分享QQ
微信扫一扫
反馈参考答案：
举一反三
【简答题】Task 1 Generally speaking, business survey, product design and production are the three major steps before the release of a new product. Discuss in pairs: a) What activities are usually included in ea...
【简答题】Unit 18 Beauty I 语境填词 1. I usually have fast food _______ ( 递送 ) to my office. Just came here for a change today. 2. Color choice in this _______ ( 范围 ) are a step up from the small ones in two major ...
【多选题】下列关于膨胀阀的说法错误的是()。
A.
膨胀阀安装在蒸发器的入口处
B.
其作用是将低温、低压的液态制冷剂转化为雾状制冷剂
C.
可根据制冷负荷的大小调节制冷剂的流量
D.
其作用是将雾状制冷剂转化为高温、高压的液态制冷剂
【单选题】Three major documents involved in the fourth step are_________.
A.
a Letter of Intent, Articles of Association and a Charter
B.
a Letter of Intent, a Charter and a contract
C.
Articles of Association, a Charter and a contract
D.
documents of intellectual property rights, patent rights and export numbers
【判断题】Deduction involves a three-step form of reasoning called Syllogism: General Premise ( the initial generalization), Major Premise ( the specific case ), and Conclusion ( the resulting statement).
A.
正确
B.
错误
【单选题】比特币不能成为未来通行货币的原因不包括( )
A.
比特币的总数 2100 万枚， 2014 年全部挖完，总数不再增长
B.
比特币是“去中心化”的，脱离各国央行的监管
C.
比特币是 Hash 函数的解，与商品的价值没有关联，不能反映经济变化
D.
比特币的“分布式记账”技术，网络资源浪费严重
【简答题】儿童文学的作者有 和儿童。
【多选题】下列关于膨胀阀的说法错误的是()。
A.
膨胀阀安装在蒸发器的入口处
B.
其作用是将低温、低压的液态制冷剂转化为雾状制冷剂
C.
可根据制冷负荷的大小调节制冷剂的流量
D.
其作用是将雾状制冷剂转化为温、高压的液态制冷剂
【多选题】Three major feedback mechanisms cooperate in regulating the overall rate of de novo purine nucleotide synthesis and the relative rates of formation of the two end products, adenylate and guanylate.
A.
The first mechanism is exerted on the first reaction that is unique to purine synthesis: transfer of an amino group to PRPP to form 5-phosphoribosylamine. This reaction is catalyzed by the allosteric enzyme glutamine-PRPP amidotransferase, which is inhibited by the end products IMP, AMP, and GMP. AMP and GMP act synergistically in this concerted inhibition. Thus, whenever either AMP or GMP accumulates to excess, the first step in its biosynthesis from PRPP is partially inhibited.
B.
In the second control mechanism, exerted at a later stage, an excess of GMP in the cell inhibits formation of xanthylate from inosinate by IMP dehydrogenase, without affecting the formation of AMP. Conversely, an accumulation of adenylate inhibits formation of adenylosuccinate by adenylosuccinate synthetase, without affecting the biosynthesis of GMP. When both products are present in sufficient quantities, IMP builds up, and it inhibits an earlier step in the pathway; this is another example of the regulatory strategy called sequential feedback inhibition. In the third mechanism, GTP is required in the conversion of IMP to AMP, whereas ATP is required for conversion of IMP to GMP, a reciprocal arrangement that tends to balance the synthesis of the two ribonucleotides.
C.
The final control mechanism is the inhibition of PRPP synthesis by the allosteric regulation of ribose phosphate pyrophosphokinase. This enzyme is inhibited by ADP and GDP, in addition to metabolites from other pathways for which PRPP is a starting point.
D.
all the above.
相关题目：
参考解析：
知识点：
题目纠错 0
发布
