RT Journal Article SR Electronic T1 Emergence of Functional δ-Opioid Receptors Induced by Chronic Morphine JF Molecular Pharmacology JO Mol Pharmacol FD American Society for Pharmacology and Experimental Therapeutics DO 10.1124/mol.105.019109 A1 Junyi Ma A1 Yong Zhang A1 Alex E Kalyuzhny A1 Zhizhong Z Pan YR 2006 UL http://molpharm.aspetjournals.org/content/early/2006/01/06/mol.105.019109.abstract AB