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【简答题】
AT89S51 单片机有 ( ) 个用户中断源 A. 2 B. 3 C. 5 D. 6
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举一反三
【简答题】圆杆试件扭转时,其侧面上各点为_______应力状态.对于铸铁圆杆而言,由于在与轴线成45°的螺旋面上有最大的________应力,同时铸铁的抗__________能力很弱,因而铸铁试件沿此螺旋面断裂.对于低碳钢圆杆而言,横截面上_________应力达到最大,而低碳钢的抗__________能力相对较弱,因此它会在横截面上发生破坏.
【多选题】How are Cdks stably inactivated in G 1 phase?
A.
During early M phase, when mitosis begins, the cell is awash with active cyclin–Cdk complexes. Those S-Cdks and M-Cdks must be disabled by the end of M phase to allow the cell to complete division and to prevent it from initiating another round of division without spending any time in G 1 .
B.
To usher a cell from the upheaval of M phase to the relative tranquility of G 1 , the cell-cycle control machinery must inactivate its inventory of S-Cdk and M-Cdk.
C.
It does so in several ways: by eliminating all of the existing cyclins, by blocking the synthesis of new ones, and by deploying Cdk inhibitor proteins to muffle the activity of any remaining cyclin–Cdk complexes. The use of multiple mechanisms makes this system of suppression robust, ensuring that essentially all Cdk activity is shut down.
D.
This wholesale inactivation resets the cell-cycle control system and generates a stable G 1 phase, during which the cell can grow and monitor its environment before committing to a new round of division.
【单选题】The nitrogen content of a sample is 0.60g. How weigh are proteins in this sample?
A.
16.0g
B.
3.75g
C.
6.40g
D.
6.25g
【单选题】服务员小王不小心将客人的高档衣服扯坏,主动赔偿客人人民币1000元,此时()。
A.
应全部免除小王的赔偿责任
B.
应部分免除小王的赔偿责任
C.
不应免除小王的赔偿责任
D.
可全部或部分免除小王的赔偿责任
【简答题】请简要回答出纳管理的主要功能
【单选题】某二阶欠阻尼系统,当其闭环极点在s平面的分布ωn变大,系统的调节时间变 ;系统的阻尼比ξ变 ;系统的超调量 。
A.
大、小、大
B.
小、大、小
C.
大、不变、不变
D.
小、不变、不变
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