ASM国际出版社
An incredibly valuable resource for mechanical engineering. But the ASM Handbooks are not freely available, not even partially. The Digital
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图书馆、数据库、存储库、分类广告
雅培航空航天技术图书馆
Abbott Aerospace 技术库提供了一个集中式存储库，其中包含超过 17,000 份航空航天结构技术文档和计算工具。
MIL-HDBK-5J 航空航天飞行器结构用金属材料和元件
MIL-HDBK-5J Metallic Materials and Elements for Aerospace Vehicle Structures is the free precursor of MMPDS. This is the last DoD-published
人因工程设计数据摘要
The the Reliability, Maintainability, and Supportability (RMS) Guidebook, a technical publication from the Reliability Information Analysis Center (RIAC). It provides
美国国家标准与技术研究院数字数学函数库（DLMF）
The NIST Digital Library of Mathematical Functions (DLMF) serves as the authoritative, peer-reviewed successor to the Abramowitz and Stegun Handbook
i2p 搜索
i2psearch.com 是一个专门的搜索引擎和目录，旨在索引和发现 I2P（无形互联网项目）中的 “电子网站”。
公共图像库
A great list of free access images and multimedia repositories (check the licenses). In fact these are the sources used
FDA橙皮书：已批准的药品
美国食品药品监督管理局（FDA）的《橙皮书》（正式名称为《具有治疗等效性评价的已批准药品》）是权威的监管数据库。
Europeana 图片和档案搜索
Europeana aggregates and provides access to over 50 million digitized items from more than 3,500 European cultural heritage institutions. The
ChemSpider 化学数据库
109+ million of chemical structures. Free chemical structure database providing fast text and structured search. Search by chemical name, brand,