在有机合成中保护羰基的常用试剂是（ ）。
A:
B:
C:
D:
A:
B:
C:
D:
举一反三
- 下列结论不正确的是 A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201810/903dc792ad1c4b8ba36246edced45e2e.png" /> B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201810/b0d73b80b2734bb6b37cd96300e46fa3.png" /> C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201810/b71e248464754f2f9cf39c6c2bef2a49.png" /> D: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201810/dc30dde832db4b9294ee2e29292180dc.png" />
- 以下哪些图片可表示马太效应？ A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201810/9f53557496f648f294946ddeee28f835.png" /> B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201810/fd1d1c8153324ff58fec7e98aafa4765.png" /> C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201810/998d04a09cb545d1aa9cd734208a020f.png" /> D: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201810/c67cb20670694e0ea0e3e63a3d083975.png" />
- 满足下列哪种条件的序列称为共轭反对称序列________________。 A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201810/6f863bbc8ebe4bf6ae1cd9dac3c3ed35.png" /> B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201810/d236b2f70770439e90970575096b4e8a.png" /> C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201810/d6001dee52dd461ea635a85cf670a223.png" /> D: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201810/e93566380bac4600b77f3bc5c90b5971.png" />
- 以下哪个结构流图对应的是IIR滤波器？ A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201810/004c7c38e68d441093257571330500b2.png" /> B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201810/666abf96f5e64a438faf00a0a678434a.png" /> C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201810/7641806854794e039629fe56c2c53424.png" />
- 采用基2-DIT-FFT算法计算序列的N点FFT，假设N=2<sup>M</sup>，那么其运算量大约是_____次复乘运算。 A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201810/f4eef9305dff4dc38c065ce8a8f98084.png" /> B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201810/02067b978eda48d080afe1f467662d70.png" /> C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201810/09ad3334d3924b79bf4b9af181ac2460.png" /> D: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201810/71e43bf1ac5a4917aebbb2de18c0ac42.png" />