皮皮学，免费搜题
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【单选题】
关于临产后子宫收缩的特点,下述正确的是
A.
、正常宫缩起自两侧,呈放射状扩散
B.
、正常宫缩是子宫体部随意的,有规律的收缩
C.
、子宫收缩以下下段最强,最持久
D.
、子宫收缩时具有节律性,对称性和极性以及缩复作用
E.
、宫缩时,肌纤维缩短,间歇时松弛仍恢复到原来的长度
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皮皮学刷刷变学霸
举一反三
【单选题】新生皂法
A.
乳剂制备时油相、水相混合后加入到乳化剂中迅速研磨成初乳,再加水稀释的方法
B.
乳剂制备时,使植物油与含碱的水相发生皂化反应,生成新生皂乳化剂,随即进行乳化的方法
C.
乳剂制备时,胶粉与油混合,加入一定量的水乳化成初乳,再逐渐加水至全量的方法
D.
向乳化剂中每次少量交替地加入水或油,边加边搅拌形成乳剂的方法
E.
乳化剂制备时,将油相逐渐加到含乳化剂的水溶液中的方法
查看完整题目与答案
【单选题】根据所学,乳剂制备中的干胶法是如何做
A.
乳剂制备时油相、水相混合后加入到乳化剂中迅速研磨成初乳，再加水稀释的方法
B.
乳剂制备时，使植物油与含碱的水相发生皂化反应，生成新生皂乳化剂，随即进行乳化的方法
C.
乳剂制备时，乳化剂与油混合，加入一定量的水乳化成初乳，再逐渐加水至全量的方法
D.
向乳化剂中每次少量交替地加入水或油，边加边搅拌形成乳剂的方法
E.
乳化剂制备时，将油相逐渐加到含乳化剂的水溶液中的方法
查看完整题目与答案
【单选题】Enzymes that remove nucleotides one at a time from the end of a DNA molecule are called
A.
Ligases
B.
Exonucleases
C.
Endonucleases
D.
Modifying enzymes
查看完整题目与答案
【判断题】Like the chromatin-remodeling complexes, the enzymes that modify histone tails are tightly regulated. They are brought to particular chromatin regions mainly by interactions with proteins that bind to...
A.
正确
B.
错误
查看完整题目与答案
【单选题】我每次出去画画儿,都会采集一些有特色的植物叶子。 问:说话人喜欢做什么?
A.
把叶子拿回家
B.
把叶子画下来
查看完整题目与答案
【单选题】Various chemicals can induce mutations by modifying the nucleotides, causing base deletions or mimicking bases and substituting for them in the DNA chain. An example of the latter is:
A.
acridine
B.
5-bromouracil
C.
mitomycin
D.
nitrous oxide
查看完整题目与答案
【多选题】被列入世界地质公园的花岗岩名山有( )。
A.
黄山
B.
泰山
C.
三清山
D.
龙虎山
E.
雁荡山
查看完整题目与答案
【单选题】乳剂制备时,向乳化剂中每次少量交替加入油或水,边加边搅拌,制成乳剂的方法称为
A.
湿胶法
B.
干胶法
C.
新生皂法
D.
两相交替加入法
E.
机械法
查看完整题目与答案
【单选题】以下哪种处理不能引起细菌的DNA突变？
A.
Base analogs 碱基类似物
B.
DNA modifying agents DNA修饰剂
C.
Intercalating agents 插入剂
D.
氨基酸
查看完整题目与答案
【多选题】How do transcription regulators, general transcription factors, and RNA polymerase gain access to the underlying DNA in highly packed chromosomes?
A.
In eukaryotic cells, activator and repressor proteins can exploit the mechanisms used to package DNA to help turn genes on and of.
B.
Chromatin structure can be altered by chromatin-remodeling complexes and by enzymes that covalently modify the histone proteins that form the core of the nucleosome. Many gene activators take advantage of these mechanisms by attracting such chromatin-modifying proteins to promoters.
C.
For example, the recruitment of histone acetyltransferases promotes the attachment of acetyl groups to selected lysines in the tail of histone proteins; these acetyl groups themselves attract proteins that promote transcription, including some of the general transcription factors. And the recruitment of chromatin-remodeling complexes makes nearby DNA more accessible. These actions enhance the efficiency of transcription initiation.
D.
In a similar way, gene repressor proteins can modify chromatin in ways that reduce the efficiency of transcription initiation. For example, many repressors attract histone deacetylases—enzymes that remove the acetyl groups from histone tails, thereby reversing the positive effects that acetylation has on transcription initiation.
查看完整题目与答案
相关题目：
【单选题】新生皂法
A.
乳剂制备时油相、水相混合后加入到乳化剂中迅速研磨成初乳,再加水稀释的方法
B.
乳剂制备时,使植物油与含碱的水相发生皂化反应,生成新生皂乳化剂,随即进行乳化的方法
C.
乳剂制备时,胶粉与油混合,加入一定量的水乳化成初乳,再逐渐加水至全量的方法
D.
向乳化剂中每次少量交替地加入水或油,边加边搅拌形成乳剂的方法
E.
乳化剂制备时,将油相逐渐加到含乳化剂的水溶液中的方法
查看完整题目与答案
【单选题】根据所学,乳剂制备中的干胶法是如何做
A.
乳剂制备时油相、水相混合后加入到乳化剂中迅速研磨成初乳，再加水稀释的方法
B.
乳剂制备时，使植物油与含碱的水相发生皂化反应，生成新生皂乳化剂，随即进行乳化的方法
C.
乳剂制备时，乳化剂与油混合，加入一定量的水乳化成初乳，再逐渐加水至全量的方法
D.
向乳化剂中每次少量交替地加入水或油，边加边搅拌形成乳剂的方法
E.
乳化剂制备时，将油相逐渐加到含乳化剂的水溶液中的方法
查看完整题目与答案
【单选题】Enzymes that remove nucleotides one at a time from the end of a DNA molecule are called
A.
Ligases
B.
Exonucleases
C.
Endonucleases
D.
Modifying enzymes
查看完整题目与答案
【判断题】Like the chromatin-remodeling complexes, the enzymes that modify histone tails are tightly regulated. They are brought to particular chromatin regions mainly by interactions with proteins that bind to...
A.
正确
B.
错误
查看完整题目与答案
【单选题】我每次出去画画儿,都会采集一些有特色的植物叶子。 问:说话人喜欢做什么?
A.
把叶子拿回家
B.
把叶子画下来
查看完整题目与答案
【单选题】Various chemicals can induce mutations by modifying the nucleotides, causing base deletions or mimicking bases and substituting for them in the DNA chain. An example of the latter is:
A.
acridine
B.
5-bromouracil
C.
mitomycin
D.
nitrous oxide
查看完整题目与答案
【多选题】被列入世界地质公园的花岗岩名山有( )。
A.
黄山
B.
泰山
C.
三清山
D.
龙虎山
E.
雁荡山
查看完整题目与答案
【单选题】乳剂制备时,向乳化剂中每次少量交替加入油或水,边加边搅拌,制成乳剂的方法称为
A.
湿胶法
B.
干胶法
C.
新生皂法
D.
两相交替加入法
E.
机械法
查看完整题目与答案
【单选题】以下哪种处理不能引起细菌的DNA突变？
A.
Base analogs 碱基类似物
B.
DNA modifying agents DNA修饰剂
C.
Intercalating agents 插入剂
D.
氨基酸
查看完整题目与答案
【多选题】How do transcription regulators, general transcription factors, and RNA polymerase gain access to the underlying DNA in highly packed chromosomes?
A.
In eukaryotic cells, activator and repressor proteins can exploit the mechanisms used to package DNA to help turn genes on and of.
B.
Chromatin structure can be altered by chromatin-remodeling complexes and by enzymes that covalently modify the histone proteins that form the core of the nucleosome. Many gene activators take advantage of these mechanisms by attracting such chromatin-modifying proteins to promoters.
C.
For example, the recruitment of histone acetyltransferases promotes the attachment of acetyl groups to selected lysines in the tail of histone proteins; these acetyl groups themselves attract proteins that promote transcription, including some of the general transcription factors. And the recruitment of chromatin-remodeling complexes makes nearby DNA more accessible. These actions enhance the efficiency of transcription initiation.
D.
In a similar way, gene repressor proteins can modify chromatin in ways that reduce the efficiency of transcription initiation. For example, many repressors attract histone deacetylases—enzymes that remove the acetyl groups from histone tails, thereby reversing the positive effects that acetylation has on transcription initiation.
查看完整题目与答案