BMC - This is a searchable database of 264 open-access, peer-reviewed science, technology, and medical journals. Or, you can browse articles by subject.
ClinicalTrials.gov - This is a registry and results database of approximately 170,000 clinical studies involving human participants conducted around the world. Studies can be searched by topic or location.
Dimensions - Dimensions covers millions of research publications connected by more than 1.8 billion citations, supporting grants, datasets, clinical trials, patents and policy documents. Requires registration for a free account.
DOAJ - Directory of Open Access Journals is a searchable database of over 1,500,000 articles from peer-reviewed, open access scientific and scholarly journals
Free Medical Journals - Has links to over 500 open access medical journals around the world arranged by specialty. Each journal must be searched separately.
Google Scholar - From one place, you can search across many disciplines and sources: articles, theses, books, abstracts and court opinions, from academic publishers, professional societies, online repositories, universities and other web sites.
Highwire - With over 3000 journals and reference works available, Highwire may be searched across all their resources or browsed by specialty. Not all their articles are free; sometimes there is a waiting period before the article is available open access.
Index to Chiropractic Literature - The only exclusively chiropractic database, ICL covers the 1984-present chiropractic literature. Records link to open access content where available.
NCCIH - The National Center for Complementary and Integrative Health contains information for researchers, links to other complementary and alternative resources, and evidence-based information on health conditions and alternative therapies with a searchable interface.
Open Access Library - Search Engine that provides free access to over 2,000,000 academic articles.
PEDro - The Physiotherapy Evidence Database consists of over 27,000 randomized trials, systematic reviews, and practice guidelines in physiotherapy. Besides the abstract, PEDro provides a link to the full text, where possible.
PubMed - Comprises more than 33 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.
PubMed Central - A free full-text archive of biomedical and life sciences journal literature at the U.S. National Institutes of Health's National Library of Medicine .
SciELO - stands for The Scientific Electronic Library Online and is an international research communication program launched in 1998 and implemented through a decentralized network of national collections of peer reviewed journals from 15 countries – 12 from Latin America, Portugal, Spain and South Africa – that jointly publish over 1 thousand journals and about 50 thousand articles per year.
TRIP - The TRIP database contains high-quality, clinically relevant research articles. The user can view the abstracts of the articles, or link to the full-text if the article is linked from PubMed Central, the National Library of Medicine's free full-text database.
Wiley Open Access - a group of open-access, peer-reviewed journals in the science and biomedical fields. It is searchable by journal title or across all journals.