periodicalsn.期刊名词periodical的复数形式.periodicaln.期刊adj.定期的periodically running周期作业periodical directory期刊指南,期刊目录periodical operation周期性操作periodical increment周期生长量periodical escapement周期擒纵机构periodical university刊授大学periodical title page期刊封面Periodical publishing期刊出版periodical moistening周期性湿润periodical networking期刊网络化