另两个为胸腺嘧啶和胞嘧啶, 即称为嘧啶的单环结构.The other two, thymine and cytosine, are single ring structures called pyrimidines.嘌呤为嘧啶取代或嘧啶为嘌呤所取代,叫做颠换.The substitution of a purine for a pyrimidine, or vice versa is a transversion.本文研究氟脲嘧啶(5—...
Slowly, Prince Ali Yusuf shook his head.阿里·优素福亲王缓慢地摇了摇头.Her last period had been before Yusuf had a divorce: six weeks ago.她上次经期是在约瑟夫协议离婚之前,也就是: 六周前.Yusuf always had a commanding presence , but tonight Suha could tell th...