[too rz duh fawrs, -fohrs; French toor duh fawrs] /ËtÊÉrz dÉ ËfÉrs, -ËfoÊrs; French tur dÉ ËfÉrs/ (Show IPA) 1. an exceptional achievement by an artist, author, or the like, that is unlikely to be equaled by that person or anyone else; stroke of genius: Herman Melville's Moby Dick was a tour de force. 2. a particularly adroit maneuver or technique in handling a difficult situation:
edit Nucleobases. Purines make up two of the four nucleobases in DNA and RNA: adenine and guanine. Pyramidines make up the other bases in DNA and RNA: cytosine, thymine (in DNA) and uracil (in RNA).
purine. a heterocyclic compound that is the nucleus of the purine bases (or purines) such as adenine and guanine, which occur in DNA and RNA, and xanthine and hypoxanthine. All living cells contain purines as purine nucleotides. heterocyclic compound that is the nucleus of the purine bases (or purines) such as adenine and guanine, which occur in DNA and RNA, and xanthine and hypoxanthine. All living cells contain purines as purine nucleotides.