“首日封”的概念、定义、翻译、参考文献-科学参考

单词	首日封
释义	首日封 Encyclopedia 工学集邮品释 first day cover首日封在新邮票发行首日，将该套邮票的全套或单枚贴在特制信封、普通信封或纪念信封的右上角，加盖当日邮政日戳或特制的首日纪念邮戳的信封。
随便看	universal joint universal language universal linear operator universal linear space universal link universal logical system Universal Love universal love/inclusive care universally-applicable judicial interpretations universally axiomatizable class universally Baire set universally beneficial social welfare policies universally catenary ring universally closed mapping universally closed morphism universally equivalent systems universally Japanese ring universally measurable universally measurable set universally optimum programming universally submersive morphism universally valid formula universal machine Universal Machine Readable Catalogue Format universal manifold

科学参考收录了854744条科技类词条，基本涵盖了常见科技类参考文献及英语词汇的翻译，是科学学习和研究的有利工具。