This search engine covers articles from many different topics, with a focus on scientific literature.
A preprint network that contains articles from various subjects that are unpublished but uploaded to preprint servers to make their findings immediately available and receive feedback before submission to journals.
"The first multidisciplinary aggregator of Open Access journals and papers. Keep on top of recent discoveries and never hit a paywall."
This search engine can help you "home in on key publications, citation, and results..." on your topic. Once you hone in an article, there are automatic recommendations to other related citations, sorted by influence. It is mostly focused on computer science and neuroscience topics.
An open access repository for research data, including journal articles, datasets, and software. Currently contains mostly scientific research data, but open to all subjects. Affiliated with CERN and OpenAIRE.
Preprint server for biology, contains articles that are unpublished but uploaded to this database to make their findings immediately available and receive feedback before submission to journals.