周期

• A business cycle can be measured from peak to peak or from trough to trough .
  一个商业周期可以用从高峰到高峰或者从谷底到谷底来测定。
• If the dark period was too short, the photochemical system was not completely regenerated .
  如果暗周期太短，光化学系统不能完全再生。
• It is in fact quite serviceable for seiches of an appreciable magnitude and short period .
  但事实上它对量值大而周期短的假潮还颇适用。
• For geophysical purposes it is customary to use solar rotations of 27. 0 day .
  为适应地球物理学的需要，习惯上以270日为太阳自转周期。
• In order to measure these various cycles accurately, we need a basic time unit .
  为了精确地量度这些变化周期，需要有一个基本的时间单位。
• Another kind of period variation, "glitches," are seen in several pulsars .
  在几个脉冲星中还看到了周期的另一种变化，即“自转突快”现象。
• A high weathercock frequency is essential for the stability of the guidance loop .
  从制导回路的稳定性角度来看，短周期振荡频率高是基本的。
• Equation(4) permits a simple deduction of the relation between the phase velocity and the period .
  用方程（4）可简单推导相速度和周期的关系。
• In vitro analysis must be complemented by studies of the virus replication cycle in plants .
  体外的分析必须辅之以植物体内病毒复制周期的研究。
• A network of about 35 short-period vertical instruments has been installed in the states of u.s.a .
  美国的一些州设置了大约35个短周期垂向仪器。