Databases A-Z
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OMIM (Online Mendelian Inheritance in Man) (Johns Hopkins University)
OMIM is a comprehensive, authoritative compendium of human genes and genetic phenotypes that is freely available and updated daily. OMIM is authored and edited at the McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, under the direction of Dr. Ada Hamosh. Its official home is
Oncolink (University of Pennsylvania)
OncoLink was founded in 1994 by University of Pennsylvania cancer specialists with a mission to help cancer patients, families, health care professionals and the general public get accurate cancer-related information at no charge. OncoLink contains comprehensive information about specific types of cancer, updates on cancer treatments and news about research advances.
Since 1975, ONS has provided a professional community for oncology nurses, developed evidence-based education programs and treatment information, and advocated for patient care, all in an effort to improve quality of life and outcomes for patients with cancer and their families.  Please note: ONS abstracts are available via CINAHL and the Oncology Nursing Forum (ONF) publication.
Good resource for finding open access graduate theses and dissertations published around the world.

Metadata (information about the theses) comes from over 1100 colleges, universities, and research institutions. OATD currently indexes 4,886,755 theses and dissertations.
Open-i Open Access Biomedical Image Search Engine  (U.S. National Library of Medicine)
Provides access to the images (charts, graphs, clinical images, etc.) and related abstracts from the open source literature, and biomedical image collections. Includes images from PubMed Central® articles; chest x-rays; images from NLM History of Medicine collection; and orthopedic illustrations.

Orphanet  (Orphanet)
Assists in the diagnosis and overview of rare diseases. Provides users with expert summaries, links to reputable resources, and drug information for certain diseases. Orphanet was established in France in 1997 at the advent of the internet in order to gather scarce knowledge on rare diseases so as to improve the diagnosis, care and treatment of patients with rare diseases. This initiative became a European endeavour from 2000, supported by grants from the European Commission: Orphanet has gradually grown to a network of 37 countries, within Europe and across the globe.
OSF Preprints (Open Science Framework)
An open access preprint repository network providing papers in the fields of Architecture, Business, Engineering, Life Science, Physical Science & Mathematics, Arts & Humanities, Education, Law, Medicine & Health Sciences, and Social & Behavioral Sciences.
Ovid Databases (Wolters Kluwer)
Vendor interface that provides access to several resources and databases including Allied and Complementary Medicine (AMED), Health and Psychosocial Instruments (HAPI), MEDLINE, JBI, and PsycINFO.