periodyl[化] 12-羟-9,10-二碘油酸periodn.一段时间；周期；时期；课时；学时；句号；月经periodontal granuloma[医] 牙周肉芽肿period of slack sales销售淡季period of adolescence青春期period of electrolyte电解周期periodontal infection牙周感染periodontal ginivitis根周龈炎period of PN sequence伪码周期periodontitis therapy牙周炎治疗periodontitis simplex单纯性牙周围炎period of angiosperms被子植物时代