Science

Some Free Online Resources

National Center for Biotechnology Information

PubMed Bibliographic database of biomedical and veterinary literature; 24+ million citations, some free full-text

Science.gov: Database of U.S. government scientific publications; free full-text

BioMed Central (BMC) Directory of open access journals and selected free full-text articles published by BMC in the fields of biomedical research, medicine, and veterinary medicine; for articles not in collection, use search box or subject tabs and follow links to journal websites

PubAg: Portal to USDA-authored and other highly relevant agricultural research; 40,000+ free full-text articles, bibliographic entries for 340,000+ articles; no subscription required

Multi-Disciplinary

Some Open Access Databases - (Multidisciplinary subjects)

HathiTrust Digital Library

Book and journal content from the collections of a partnership of major research institutions and libraries, digitized and made public; free full-text

Paperity

Collection of articles from 2450+ peer-reviewed open access journals; multidisciplinary; free full-text

Q-Sensei Scholar

Bibliographic database of scholarly books and articles in the Library of Congress, National Library of Medicine, arXiv, IngentaConnect, and Research Papers in Economics (RePEC); multidisciplinary; 40+ million citations; alerts and other tools

HighWire

Portal to 3000+ scholarly journals and other publications partnered with HighWire Press (Stanford University); click "For Researchers" tab to search for articles; some free full-text

Ingenta Connect

Search for articles in 13,500+ scholarly and professional publications on a range of topics; some free full-text

Jurn: Search tool for open access content

DOAJ: Directtory of Open Access Journals