periodiden.[化]高碘化物periodn.一段时间；周期；时期；课时；学时；句号；月经period of seedling pulling拔秧时期period boundary conditions周期边值问题period division of history历史分期period of social transform社会转型期period of sunspot activity太阳黑子活动周期period of the Ming Dynasty明代period-spectrum relation周谱关系period of beginning mining初采期间period of load development负荷增长期period of free oscillation[电] 自由振荡的周期