A tag in the Hypertext Markup Language which is not associated with an end tag. The tag <HR> which introduces a horizontal line in a Web page is an example of an empty element.
科学参考收录了60776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。