arXiv.org is an open access e-print service in the fields of physics, mathematics, computer science, quantitative biology, quantitative finance and statistics.

A comprehensive index, no login required, that is similar to the citation indexes of Web of Science. Each citation provides a list of its references and a citation count plus a list of citing documents. Limited full text, though there is an open access filter on the left. For more full text and formatted citations, take titles found in Dimensions, log into Google Scholar from the library home page, and search for Dimensions titles there.

MathSciNet is a database by the American Mathematical Society (AMS), containing reviews, abstracts and bibliographic information for much of the mathematical sciences literature.

A database of 1,700 full-text journals from scientific, technical and computer science fields.

A database of 1,700 full-text journals from scientific, technical and medical fields.

A portal of different journals covering a wide range of subject areas including materials science & engineering, life & biomedical science, health sciences, and social sciences & humanities.

A multi-disciplinary database with at least some information about most subjects.

Directory of Open Access Journals (DOAJ) is an online directory that indexes and provides access to high quality, open access, peer-reviewed journals. It covers a wide range of different subjects, including technology, medicine, science, social science, education, history, law, philosophy, and so on.

HAL is an open archive where authors can deposit scholarly documents (published or not) from all academic fields. Document types include journal articles, theses, reports, lecture notes, book sections, conference papers, patents and so on.

JSTOR (Journal Storage), is a large archive of back issues of journals across a wide range of academic subjects. While it contains much valuable information, it will not usually be the most up-to-date research.