RT Journal Article SR Electronic T1 System theory of pain and of opiate analgesia: no tolerance to opiates. JF Pharmacological Reviews JO Pharmacol Rev FD American Society for Pharmacology and Experimental Therapeutics SP 355 OP 402 VO 48 IS 3 A1 F C Colpaert YR 1996 UL http://pharmrev.aspetjournals.org/content/48/3/355.abstract AB