【单选题】一般情况下,步进电机的驱动电路,不包括()
【单选题】The number of layers in ISO OSI reference model is __________
【单选题】The OS!(68)model, sometimes also called ISO or 7 layers reference model for communication, has been developed by the International Standards Organization in early 1980' s.
【多选题】纳入一般公共预算本级收入核算的科目分类包括
【单选题】关于动作电位的说法正确的是:()
A.
在外界的刺激下,钠离子通道关闭,钠离子流出细胞,细胞内带负电
B.
在外界的刺激下,钠离子通道打开,钠离子进入细胞,细胞内带正电
C.
在外界的刺激下,钾离子通道打开,钾离子进入细胞,细胞内带正电
D.
在外界的刺激下,钾离子通道关闭,钾离子流出细胞,细胞内带负电
【单选题】等截面梁左端为铰支座,右端与拉杆 BC 相连,如图所示。以下结论中( ) 是错误的。
A.
AB杆的弯矩表达式为M(x)=1/2 q(Lx-x 2 )
B.
挠度的积分表达式为: y(x)=q/2EI ∫[∫-(Lx-x 2 )dx]dx+Cx+D
C.
对应的边解条件为: x=0: y=0; x=L: y=∆L CB (∆L CB =qLa/2EA)
D.
在梁的跨度中央,转角为零 ( 即 x=L/2: y / =0)
【单选题】关于动作电位,下列说法正确的是
A.
动作电位一经产生,便可沿细胞膜作电紧张性扩布
C.
强度大于或等于阈值的刺激,再增加刺激强度能使动作电位的幅度增大
E.
动作电位的形态可因可兴奋细胞种类不同而有明显差异
【判断题】The ISO model provides a conceptual framwork for communication between computers, but the model itself is not a method of comunication.
【单选题】Which statement about ISO model is correct
A.
ISO model is better than TCP/IP model
B.
ISO model has seven layers
C.
ISO model does not use layered structure
D.
Application layer consists of differet software such as Web browsers