Open Access Library (www.oalib.com) is an academic search engine and publisher. You can download research papers for free and submit your paper to it. It is a shared academic database.

谷歌学术搜索提供可广泛搜索学术文献的简便方法。您可以从一个位置搜索众多学科和资料来源：来自学术著作出版商、专业性社团、预印本、各大学及其他学术组织的经同行评论的文章、论文、图书、摘要和文章。谷歌学术搜索可帮助您在整个学术领域中确定相关性最强的研究。

万方数据知识服务平台-中外学术论文、中外标准、中外专利、科技成果、政策法规等科技文献的在线服务平台。

PubMed® comprises more than 35 million citations for biomedical literature from MEDLINE, life science journals, and online books. Citations may include links to full text content from PubMed Central and publisher web sites.