禁止与磺胺药物同时用的是
A.利多卡因B.普鲁卡因C.丁卡因D.布比卡因E.丙胺卡因
参考答案:B
Although a given waveform may contain frequencies over a very broad range, as a practical matter any transmission system will be able to accommodate only a limited band of (86) . This, in turn, limits the data rate that can be carried on the transmission (87) A square wave has an infinite number of frequency components and hence an infinite (88) However, the peak amplitude of the kth frequency component, kf, is only l/k, so most of the (89) in this waveform is in the first few frequency components. In general, any digital waveform will have (90) bandwidth. If we attempt to transmit this waveform as a signal over any medium, the transmission system will limit the bandwidth that can be transmitted.
(88)是()
A.source
B.bandwidth
C.energy
D.cost
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