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【多选题】
关于电压源与电流源作等效变换,以下说法正确是
A.
所谓等效，只是对电源的外电路而言的，对电源内部则是不等效的 ；
B.
变换电路模型的极性必须一致；
C.
理想电压源与理想电流源不能相互等效变换；
D.
R 0 不限于内阻，可扩展至电阻。
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举一反三
【单选题】既是抗原又是抗体的物质是( )
A.
类毒素
B.
干扰素
C.
生理盐水
D.
细菌外毒素
E.
破伤风抗毒素
查看完整题目与答案
【单选题】What is the common factor of the three sounds: p, k, t?
A.
voiceless
B.
spread
C.
voiced
D.
nasal
查看完整题目与答案
【单选题】既是 抗原又是抗体的物质是
A.
细菌外毒素
B.
类毒素
C.
细菌内毒素
D.
动物免疫血清
E.
青霉素
查看完整题目与答案
【单选题】下列说法或表示方法不正确的是
A.
燃料的燃烧反应都是放热反应
B.
绿色植物进行光合作用时，能把光能转化为化学能
C.
分子的热稳定性主要取决于分子内化学键的键能大小，与分子间作用力无关
D.
已知：N 2 (g)+3H 2 (g) 2NH 3 (g) △H='-92.4' kJ·mol -1 ，则说明相同条件下，在密闭容器中，1 mol N 2 和3 mol H 2 混合充分反应后放热92．4 kJ
查看完整题目与答案
【单选题】----Ms.Carol is not in.Can I take a message? ----( )
A.
Well,I'd prefer to call later.
B.
You'd better not.
C.
Thank you all the same.
D.
That's all right.
查看完整题目与答案
【简答题】What is the common factor of the three sounds:[p] [t] [k] ?A. Voiceless. B. Voiced. C. Spread. D. Nasal.
查看完整题目与答案
【多选题】What are the function of the three different nuclear RNA p olymerases in eukaryotic cells?
A.
Eukaryotes have three RNA polymerases, designated I, II, and III, which are distinct complexes but have certain subunits in common. Each polymerase has a specific function and is recruited to a specific promoter sequence.
B.
RNA polymerase I (Pol I) is responsible for the synthesis of only one type of RNA, a transcript called preribosomal RNA (or pre-rRNA), which contains the precursor for the 18S, 5.8S, and 28S rRNAs. Pol I promoters differ greatly in sequence from one species to another.
C.
The principal function of RNA polymerase II (Pol II) is synthesis of mRNAs and some specialized RNAs. This enzyme can recognize thousands of promoters that vary greatly in sequence. Some Pol II promoters have a few sequence features in common, including a TATA box (eukaryotic consensus sequence TATA(A/T)A(A/T)(A/G)) near base pair −30 and an Inr sequence (initiator) near the RNA start site at +1. However, such promoters are in the minority, and elaborate interactions with regulatory proteins guide Pol II function at many promoters that lack these features.
D.
RNA polymerase III (Pol III) makes tRNAs, the 5S rRNA, and some other small specialized RNAs. The promoters recognized by Pol III are well characterized. Some of the sequences required for the regulated initiation of transcription by Pol III are located within the gene itself, whereas others are in more conventional locations upstream of the RNA start site.
查看完整题目与答案
【单选题】对人体既是抗原又是抗体的物质是
A.
细菌外毒素
B.
马抗破伤风血清
C.
类毒素
D.
HLA
E.
干扰素
查看完整题目与答案
【单选题】既是抗原又是抗体的物质是
A.
细菌
B.
病毒
C.
青霉素
D.
细菌外毒素
E.
动物免疫血清
查看完整题目与答案
【单选题】What time will the staff meeting begin?
A.
At three o'clock.
B.
At half past three.
C.
At half past four.
查看完整题目与答案
相关题目：
【单选题】既是抗原又是抗体的物质是( )
A.
类毒素
B.
干扰素
C.
生理盐水
D.
细菌外毒素
E.
破伤风抗毒素
查看完整题目与答案
【单选题】What is the common factor of the three sounds: p, k, t?
A.
voiceless
B.
spread
C.
voiced
D.
nasal
查看完整题目与答案
【单选题】既是 抗原又是抗体的物质是
A.
细菌外毒素
B.
类毒素
C.
细菌内毒素
D.
动物免疫血清
E.
青霉素
查看完整题目与答案
【单选题】下列说法或表示方法不正确的是
A.
燃料的燃烧反应都是放热反应
B.
绿色植物进行光合作用时，能把光能转化为化学能
C.
分子的热稳定性主要取决于分子内化学键的键能大小，与分子间作用力无关
D.
已知：N 2 (g)+3H 2 (g) 2NH 3 (g) △H='-92.4' kJ·mol -1 ，则说明相同条件下，在密闭容器中，1 mol N 2 和3 mol H 2 混合充分反应后放热92．4 kJ
查看完整题目与答案
【单选题】----Ms.Carol is not in.Can I take a message? ----( )
A.
Well,I'd prefer to call later.
B.
You'd better not.
C.
Thank you all the same.
D.
That's all right.
查看完整题目与答案
【简答题】What is the common factor of the three sounds:[p] [t] [k] ?A. Voiceless. B. Voiced. C. Spread. D. Nasal.
查看完整题目与答案
【多选题】What are the function of the three different nuclear RNA p olymerases in eukaryotic cells?
A.
Eukaryotes have three RNA polymerases, designated I, II, and III, which are distinct complexes but have certain subunits in common. Each polymerase has a specific function and is recruited to a specific promoter sequence.
B.
RNA polymerase I (Pol I) is responsible for the synthesis of only one type of RNA, a transcript called preribosomal RNA (or pre-rRNA), which contains the precursor for the 18S, 5.8S, and 28S rRNAs. Pol I promoters differ greatly in sequence from one species to another.
C.
The principal function of RNA polymerase II (Pol II) is synthesis of mRNAs and some specialized RNAs. This enzyme can recognize thousands of promoters that vary greatly in sequence. Some Pol II promoters have a few sequence features in common, including a TATA box (eukaryotic consensus sequence TATA(A/T)A(A/T)(A/G)) near base pair −30 and an Inr sequence (initiator) near the RNA start site at +1. However, such promoters are in the minority, and elaborate interactions with regulatory proteins guide Pol II function at many promoters that lack these features.
D.
RNA polymerase III (Pol III) makes tRNAs, the 5S rRNA, and some other small specialized RNAs. The promoters recognized by Pol III are well characterized. Some of the sequences required for the regulated initiation of transcription by Pol III are located within the gene itself, whereas others are in more conventional locations upstream of the RNA start site.
查看完整题目与答案
【单选题】对人体既是抗原又是抗体的物质是
A.
细菌外毒素
B.
马抗破伤风血清
C.
类毒素
D.
HLA
E.
干扰素
查看完整题目与答案
【单选题】既是抗原又是抗体的物质是
A.
细菌
B.
病毒
C.
青霉素
D.
细菌外毒素
E.
动物免疫血清
查看完整题目与答案
【单选题】What time will the staff meeting begin?
A.
At three o'clock.
B.
At half past three.
C.
At half past four.
查看完整题目与答案