1,3-二甲基-1,3-二嗪农-2,4,5,6-四酮

尿素

1,3,9-三甲基尿酸

5-amino-1,3-dimethyl-6-sulfanylidene-1,3-diazinane-2,4-dione

8-methoxy-1,3,7-trimethylpurine-2,6-dione