Google Scholar
Search engine for research articles and abstracts, that Google has indexed, from most major academic publishers and repositories worldwide, including both free and subscription sources.
Natural Sciences Databases and Government Research
arXiv.org
One of the first online scholarly repositories, this re-print server provides “open access to 1,486,542 e-prints in Physics, Mathematics, Computer Science, Quantitative Biology, Quantitative Finance, Statistics, Electrical Engineering and Systems Science, and Economics.” This is perhaps the oldest, and most well-established and respected scholarly open access site.
ChemIDplus
ChemIDplus is a free, web search system that provides access to the structure and nomenclature authority files used for the identification of chemical substances cited in National Library of Medicine (NLM) databases.
ChemSpider
ChemSpider is a free chemical structure database published by the Royal Society of Chemistry that provides text and structure search access to over 100 million structures from hundreds of data sources.
GeneReviews
GeneReviews, an international point-of-care resource for busy clinicians, provides clinically relevant and medically actionable information for inherited conditions in a standardized journal-style format, covering diagnosis, management, and genetic counseling for patients and their families.
PubMed Central
PubMed Central® (PMC) is 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 (NIH/NLM).
Engineering/Technology
Google Patents
Search the patent literature for product designs, ideas, and images. Get a sense of how common products are constructed.
NASA Technical Reports Server
An online database to technical reports published by various NASA centers and programs. Full text PDFs of many NASA technical reports are available from 1958 onward. In addition, full text PDFs of reports from NASA's predecessor, the National Advisory Committee for Aeronautics or NACA are available from 1917-1958.
