Also some subject-related databases offer good options to search for open access documents. Examples:
arXiv Focus on physics, mathematics, computer sciences
PubMed Central Focus on life sciences
Europe PMC Focus on life sciences
PUBLISSO Focus on life sciences
bioRxiv Focus on biology
PsyArXiv Focus on pychology
SocArXiv Focus on social sciences
peDOCS Focus on educational sciences
Econpaper Focus on economics
The homepage open-access.net offers both general information about Open Access and a lot of specific information how to search open access material (journals, monographs, research data and portals) in different disciplines.
An additional overview how to search for scholarly full texts is accessible on the website of the Technical University of Munich
More information on open access can be found on the university's websites "electronic pulishing".
Phone: +49 941 943-3990