【单选题】已知一正弦信号源的电压幅值为 10 mV ,初相位为 30 °,频率为 1 000 Hz ,则电压瞬时值表达式为
【单选题】Which of the following cells release histamine
【简答题】已知一正弦信号源的电压幅值为 10 mV ,初相位为 30 °,频率为 50 Hz , 请写出电压瞬时值表达式。
【单选题】Which of the following cells are totipotent cells?
【单选题】Which of the following cells line the stomach?
D.
Absorptive columnar cells
【单选题】已知一正弦信号源的电压幅值为10mV,初相位为30°,频率为100Hz,则电压瞬时值表达式为()。
D.
u(t)=10sin(2000πt+30°)
【单选题】which of the following cells are pluripotent stem cells?
E.
hematopoietic stem cells
【单选题】已知一正弦电压的幅值为10V,初相位为60°,频率为1000 Hz,则电压瞬时值的表达式为________。
A.
u =10√2 sin(314t十60°)V
B.
u =10 √2 sin(2000πt十60 °)V