PubMed is not an Open Access database, but does index free articles from publishers.
PubMed link: https://www.ncbi.nlm.nih.gov/pubmed
Here are links to a few credible open access journal sites. It is by no means complete!
Directory of Open Access Journals: https://doaj.org/
BioMed Central: http://www.biomedcentral.com/
Wiley Open Access (click Journal Information in the info box to go to that journal's site): https://authorservices.wiley.com/open-science/open-access/browse-journals.html
PLOS Medicine: http://journals.plos.org/plosmedicine/
MedKnow Journals: http://www.medknow.com/journals.asp
Here you'll find links to lists of open access databases. This list is by no means comprehensive!
· Howard University A-Z Open Access Databases
· University of Wisconsin Milwaukee Open Access Databases
· Truman State University Open Access Publishing
Oregon State University Databases Available To Everyone
· University of New Hampshire Open Access
A short list of magazines and journals available online.