Looking for information about mass shootings and mental health? Maybe you're trying to find out why bees are mysteriously dying? If the topic you're researching is related to biology, medicine, or other life sciences, you may want to start with PubMed Central (PMC):
archive of full-text journal literature is provided by the National
Institutes of Health's National Library of Medicine. It currently
includes about 3.5 million articles from a variety of sources. It even
offers a special "PubReader" view to make use of the archive easier on
tablets and other small screen devices. An overview and a Users' Guide
are available on the site.