OpenDOAR – Directory of Open Access Repositories

Multidisciplinary database of open electronic archives

Organic Syntheses

Database of methods for the synthesis of organic compounds

PLoS Journals – Public Library of Science Journals

PLoS Biology, PLoS Medicine, PLoS Computional Biology, PLoS Genetics, PLoS Pathogens, PLoS ONE, PLoS Neglected Tropical

PubMed

Database of the US National Library of Medicine and the US National Institutes of Health

Registry of Open Access Repositories (ROAR)

Institutional and thematic open electronic archives

Science.gov

Research by US federal institutions and agencies

ScienceDirect

Access to the full texts of scientific e-books

Scopus

Polythematic bibliographic and abstract database with tool for tracking citations of articles published in scientific journals

Springer

Access to full texts of scientific journals and e-books

SpringerOpen

Multidisciplinary database published by Springer