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【单选题】
《中国药典》(2015年版)鉴别头孢替唑钠采用在272nm波长处测定,吸收系数(E'_)为270~ 300,是利用( )。A.
青霉素类抗生素在PH 4 条件下水解产生青霉烯酸,具有紫外吸收
B.
头孢类药物7-ACA 结构中有共轭体系，具有特征紫外吸收
C.
侧链具有苯环,可产生紫外吸收
D.
头孢类药物的降解产物具有特征紫外吸收
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皮皮学刷刷变学霸
举一反三
【单选题】Some multimeters have a "transistor test" function which provides a known base current and measures the collector current so as to display the transistor's .
A.
AC voltage gain
B.
DC current gain
C.
AC current gain
D.
DC voltage gain
【简答题】display the voltage waveform
【单选题】To write the topic sentence of an opinion paragraph, you should ________.
A.
take a stand on a given topic
B.
state a fact
C.
give the main reason for your opinion
【多选题】Each type of multimeter has its advantages. Used as a voltmeter, ( ) multimeter is usually better because its resistance is much higher, 1 Mega-ohm or 10 Mega-ohm,compared to 200 kilo-ohm for ( ) muli...
A.
an analog
B.
a digital
C.
voltage
D.
current
【多选题】How can we write a successful topic sentence?
A.
Balance the topic sentence.
B.
Introduce yourself.
C.
State your topic sentence clearly.
D.
Give a reasonable opinion.
【单选题】An oscilloscope to display a voltage–time(V/t)graph,a graph of voltage against time. Voltage on the vertical or Y-axis, and time on the horizontal or X-axis.
A.
曲线图
B.
电压-时间
C.
垂直或Y轴
D.
水平或X轴
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