Chemical dependency can result from many things: alcohol, caffeine , illegal drugs like cocaine , legal drugs like pain 很多东西会导致化学依耐性的产生：酒精、咖啡因、非法药品，如可卡因，合法药品，如止痛片。
With minim flow velocity of pain killer bump, the department developed the research on the observation of the concentrat开展了微量流速止痛泵临床观察血液中止痛药物浓度的研究。