Free Open Access Scientific Databases
PubMed is the free interface that allows a free access to references from Medline and some additional references from journals not indexed in Medline as well as à head of print articles.
PubMed Central allows access to full texts of several millions of references.
PMC Europe allows accesss to full texts of several millions of references an dsometimes that are not available in PMC PubMed Central.
Cochrane Collaboration offers a free or low-cost access to countries in this list: Eligibility for access to Research4Life - Research4Life
Core database provide access to full texts for open access articles and grey literature
This search engine provides access to several academic repositories including thesis and dessertations as well as peer-reviewed articles.
This search engine provides access to thesis and dessertations from French universities.
This search engine from Google provides access to articles and reports from publishers and academic repositories.