【简答题】Assume that a 10V voltage drop occurs across an element from terminal 1 to terminal 2 and a current of 5A enters terminal 1. a) Specify the values of v and i for the polarity references shown in Fig....
【单选题】( )是指风景名胜资源集中、自然环境优美、具有一定规模和游览条件,并经县级以上人民政府审定命名、划定范围供人游览、观赏、休息和进行科学文化活动的地域。
【判断题】8w位无符号二进制数可以表示的最大十进制数是256,对吗?
【判断题】风景名胜区是指风景名胜资源集中,环境优美,具有一定规模和范围,可供人们游览、休憩或进行科学文化活动的地区。
【单选题】How many feedback resistors are found in a 3-input voltage summing circuit that is constructed around an op-amp?
【单选题】字符 (char) 型数据在微机内存中的存储形式是 ____.
【简答题】已知Na 2 CO 3 (s)和H 2 O(l)可以生成如下三种水合物:Na 2 CO 3 ·H 2 O(s),Na 2 CO 3 ·7H 2 O(s)和Na 2 CO 3 ·10H 2 O(s)。试求:(1)在大气压力下,与Na 2 CO 3 水溶液和冰平衡共存的水合盐的最大值;(2)在298K时,与水蒸气平衡共存的水合盐的最大值。
【多选题】How do voltage-gated ion channels work?
A.
Voltage-gated ion channels have domains called voltage sensors that are extremely sensitive to changes in the membrane potential: changes above a certain threshold value exert sufficient electrical force on these domains to encourage the channel to switch from its closed to its open conformation.
B.
A change in the membrane potential does not affect how wide the channel is open, but instead alters the probability that it will open. Thus, in a large patch of membrane containing many molecules of the channel protein, one might find that on average 10% of them are open at any instant when the membrane is at one potential, whereas 90% are open after this potential changes.
C.
When one type of voltage-gated ion channel opens, the membrane potential of the cell can change. This in turn can activate or inactivate other voltage-gated ion channels.
D.
Such circuits, which couple the opening of ion channels to changes in membrane potential to the opening of additional ion channels, are fundamental to all electrical signaling in cells.
【判断题】稳压二级管是一种特殊的二极管,它通常工作在反向击穿状态
【单选题】船舶平均吃水等于首吃水与尾吃水之和的0.5倍成立的条件是( )。