The role of the dose-interval on the development of tolerance to morphine.
D000818:Animals; D004361:Drug Tolerance; D007279:Injections, Subcutaneous; D008297:Male; D009020:Morphine / Q000008:administration & dosage* / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors
D009020:Morphine