The only difference is that in the RNA copy, thymine is replaced with the closely related base uracil, commonly abbreviated u.

唯一的区别在于，在RNA复制中，胸腺嘧啶被密切联系的、常被缩写为U的碱基尿嘧啶替换。

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Thymine: Organic compound of the pyrimidine family, often called a Base, consisting of a ring containing Both nitrogen and carbon atoms, and a methyl group.

胸腺嘧啶：一种嘧啶类有机化合物，通常叫做基底，由含有氮和碳原子以及甲基的环形物组成。

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