ETHYLENEUREA2-ImidazolidoneN,N′-Ethyleneurea2-咪唑烷酮2-Oxoimidazolidine环乙烯脲2-Imidazolidone2-imidazolidinone1,3-ethyleneurea2-oxoimidazolidine2-oxomidazolidineethyleneurea2-imidazolidinoneimidazolidin-2-oneethylene ureamonoethyleneurea2-imidazolidoneimidazolid-2-oneN,N'-ethyleneurea