全麻药对电压门控钙通道的影响主要是()
A.抑制钙内流
B.促进钙内流
C.促进钙失活
D.抑钙外流
E.抑制钙分泌
参考答案:A
某村使用的氮肥是含有杂质的硝酸铵,含氮量为38%;这种氮肥可能含有的杂质是(括号内为杂质的含氮量)( )
A.NH4HCO3(18%)
B.NH4Cl(26%)
C.CO(NH2)2(47%)
D.(NH4)2SO4(21%)
Which of the following observations signals the onset of puberty in male adolescents
A.Appearance of pubic hair.
B.Appearance of axillary hair.
C.Testicular enlargement.
D.Nocturnal emissions.