| 1 | arXiv | Preprint | Established in 1991, arXiv is an e-print service operated and managed by Cornell University in the fields of physics, mathematics, nonlinear science, computer science and quantum biology. It is the leading open access resource of specific subject areas. |
| 2 | Bielefeld Academic Search Engine | Academic resources | BASE is one of the world's most voluminous search engines especially for academic web resources. BASE is operated by Bielefeld University Library. |
| 3 | DOAJ（Directory of Open Access Journals) | Academic resources | DOAJ is a community-curated online directory that indexes and provides access to high quality, open access, peer-reviewed journals. |
| 4 | Distill |
| Distill is a platform to make machine learning research clear, dynamic and vivid by presenting new notations, visualizations, and mental models. |
| 5 | Exhibition Collections Harvard University Library | Pictures | Open access of Havard Library exhibition collections, including Hedda Morrison's collection, which photographs document lifestyles, trades, handicrafts, landscapes of old China. |
| 6 | National Academies Press (NAP) | Science and Technology | The National Academies Press (NAP) was created by the National Academy of Sciences to publish the reports of the National Academies of Sciences, Engineering, and Medicine of the US. |
| 7 | NASA Astrophysics Data System | Astronomy/ Engineering/ Geophysics | The NASA Astrophysics Data System is a digital library for astronomy and astrophysics. It also covers other subject areas including electrical engineering, geophysics, physics, and instrumentation. |
| 8 | OAlib | Comprehensive | Open Access Library is a search engine covering all fields of open access journals, and articles contributed by scholars. |
| 9 | Project Gutenberg | eBooks of Literature | Project Gutenberg is established by not-for-profit organization in U.S.A. Its data entry and proofreading are done by volunteers and offers free eBook. |
| 10 | ResearchGate | Comprehensive | Founded in 2008 by physicians Dr. Ijad Madisch and Dr. Sören Hofmayer, and computer scientist Horst Fickenscher. Its mission is to connect the world of science and make research open to all. |
| 11 | Scientific Research Publishing (SRP) | Science and Technology | Scientific Research Publishing (SRP) is one of the largest Open Access journal publishers. It is covering a wide range of academic areas of physics, chemistry, medicine, biology, maths, communication, computer, electronics, etc. |
| 12 | SpringerOpen | Comprehensive | The SpringerOpen portfolio has grown tremendously since its launch in 2010, so that it now offers researchers from all areas of science, technology, medicine, the humanities and social sciences. |
| 13 | DSpace@MIT | Institutional Repository | DSpace@MIT is a growing collection of MIT’s research that includes peer-reviewed articles, technical reports, working papers, theses, and more. |
| 14 | Eidgenössische Technische Hochschule Zurich | Institutional Repository | The Research Collection is ETH Zurich's repository for publications and research data.The Research Collection provides a database of scholarly publications produced at ETH Zurich. |
| 15 | University of Cambridge repository | Institutional Repository | The Institutional Repository provides services for open access of University of Cambridge and and digital library collections. |
| 16 | HKUST Institutional Repository | Institutional Repository | The Hongkong University of Science and Technology Institutional Repository collects, preserves, and disseminates the scholarly output created by the HKUST community. |
| 17 | Open Access Theses and Dissertations | Theses and dissertations | Open Access Theses and Dissertations (OATD) is the resource for finding open access graduate theses and dissertations published around the world. |
| 18 | CogPrints | Preprint | CogPrints is an electronic archive for self-archive papers in any area of Psychology, Neuroscience, and Linguistics, and many areas of Computer Science, Medicine, Anthropology. |
| 19 | International Water Association (IWA) | Journal articles and books | International Water Association (IWA) spreads knowledge about the world’s most valuable resource – water. |
| 20 | Engineering Conferences International (ECI) | Full-text articles | Engineering Conferences International (ECI) Digital Archives electronically publishes presented papers, peer-reviewed articles, and other materials (presentations, data sets, video files, etc.) |
| 21 | BioMed Central | Full-text journal articles | BioMed Central(BMC)，a pioneer of open access publishing,has an evolving portfolio of high quality peer-reviewed journals including broad interest titles such as BMC Biology and BMC Medicine. |
| 22 | Free Medical Journals | Full-text journal articles | The Free Medical Journals Site was created to promote the free availability of full text medical journals on the Internet. |
| 23 | PMC（PubMed Central） | Full-text journal articles | PubMed Central is a free full-text archive of biomedical and life sciences journal literature at the U.S. National Institutes of Health. |
| 24 | PLOS | Journal articles | PLOS was founded in 2001 as a nonprofit Open Access publisher, innovator and advocacy organization with a mission to accelerate progress in science and medicine. |
| 25 | SCOAP3 | Full-text journal articles | All articles funded by SCOAP3 appear in the SCOAP3 repository upon publication, alongside the publishers’ own platforms. |
| 26 | HighWire | Full-text journal articles | HighWire provides journals published online with the assistance of HighWire Press, and is an archive of free full-text science. |
| 27 | INSPIRE | Full-text journal articles | INSPIRE is the High Energy Physics information system. It combines the SPIRES database content. |
| 28 | American Association for Cancer Research | Full-text journal articles | From molecules to medicine, from proteomics to prevention, the journals of the AACR cover the entire spectrum of cancer research. |
| 29 | Digital Museum of Shadow | Art | Shadow, commonly known as “shadow & lamp” or “leather-silhouette show”, is one of the oldest forms of folk art in ancient China. This website is based on the shadow puppets collected by the Folk Art Museum of China Academy of Art. |
| 30 | J-STAGE | Comprehensive | Japan Science and Technology Information Aggregator, Electronic，(J-STAGE）is sponsored and developed by Japan Science and Technology Agency by various Japanese science and technology institutions. |
| 31 | ABC-Chemistry | Full-text articles | ABC-Chemistry is directory of free full-text journals in Chemistry and is the researcher's guide to journals. |
| 32 | zbMATH Open | Academic resources | Formerly known as Zentralblatt MATH, it is edited by the European Mathematical Society (EMS), the Heidelberg Academy of Sciences and Humanities, and FIZ Karlsruhe.zbMATH Open has been available as an open access database. |
| 33 | MedXiv | Medicine | MedXiv is open access archive of medical resouces, publishing not peer-reviewed articles in the field of medicine.
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| 34 | BioXiv | Biology | BioXiv is open access archive for publishing not peer-reviewed articles in the field of biology. |
