【简答题】样本98, 100 , 98 , 100 , 101 , 103 的样本平均数为( ),的样本方差为( )
【单选题】已知样本为101,98,102,100,99,样本的标准差为( )
【单选题】Signals can be ________.
D.
neither digital nor og
【简答题】样本98,100,98,100,101,103的样本平均数为( ),样本方差为( )。
【多选题】How can extracellular signals regulate the permeability of gap junctions?
A.
Gap junctions in many tissues can be opened or closed in response to extracellular or intracellular signals.
B.
The neurotransmitter dopamine, for example, reduces gap-junction communication between certain neurons in the mammalian retina when secreted in response to an increase in light intensity.
C.
This reduction in gap-junction permeability alters the pattern of electrical signaling and helps the retina switch from using rod photoreceptors, which are good detectors of low light levels, to cone photoreceptors, which detect color and fine detail in bright light.
D.
Gap junctions are dynamic structures that, like conventional ion channels, are gated: they can close by a reversible conformational change in response to extracellular or intracellular sign als . The permeability of gap junctions decreases within seconds, for example, when the intracellular Ca 2+ concentration is raised.
【单选题】某商品的100件样品中,测得的优质品为98件,则样本优质品成数为( )。
【简答题】已知一个样本:98,99,100,101,102.那么这个样本的方差是______.
【单选题】Computers can only recognize( )signals.