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【单选题】
旅客携带中药材、中成药出境,前往国外的,总值限人民币()元A.
300
B.
400
C.
500
D.
600
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参考解析：
知识点：
皮皮学刷刷变学霸
举一反三
【单选题】关于需求曲线,下列说法不正确的是 ( )。
A.
在序数效用论中，需求曲线的推导可以结合价格－消费曲线来完成
B.
需求曲线上的每个点都是能使消费者实现效用最大化的点
C.
一种商品的价格与其需求量间呈反方向变动的关系是由替代效应造成的
D.
在基数效用论与序数效用论中都可以推导出需求曲线
【多选题】How does the pyruvate dehydrogenase (PDH) complex work?
A.
The PDH complex is composed of multiple copies of three enzymes: pyruvate dehydrogenase, E 1 (with its bound cofactor TPP); dihydrolipoyltransacetylase, E 2 (with its covalently bound lipoyl group); and dihydrolipoyl dehydrogenase, E 3 (with its cofactors FAD and NAD).
B.
E1 catalyzes first the decarboxylation of pyruvate, producing hydroxyethyl-TPP, and then the oxidation of the hydroxyethyl group to an acetyl group. The electrons from this oxidation reduce the disulfide of lipoate bound to E 2 , and the acetyl group is transferred into thioester linkage with one –SH group of reduced lipoate.
C.
E 2 catalyzes the transfer of the acetyl group to coenzyme A, forming acetyl-Co E 3 catalyzes the regeneration of the disulfide (oxidized) form of lipoate; electrons pass first to FAD, then to NAD + .
D.
The long lipoyllysyl arm swings from the active site of E 1 to E 2 to E 3 , tethering the intermediates to the enzyme complex to allow substrate channeling.
【单选题】由门电路构成的施密特触发器如图所示，若需改变其回差电压，则下列描述正确的是 。【图片】
A.
增大R 1， 使 R 1> R 2
B.
减小R 2， 使 R 2< R 1
C.
改变R 1 与R 2 的比值，且 R 1< R 2
D.
以上方法均不正确
【简答题】How to map PDH signal into SDH signal?
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