Quertle: Advanced linguistic methods provide relevant results, Power Terms™ allow searching for entire categories
Content - All of PubMed (>2 million full-text), NIH Grants, TOXLINE, and more. Quertle's innovations won an award from the National Library of Medicine.
GoPubMed: From the U.S. National Library of Medicine, PubMed is a great place to find full-text medical journal articles, with more than 19 million available.
Scirus:For scientific information only, Scirus is a comprehensive research tool with more than 460 million scientific items including journal content, courseware, patents, educational websites, and more.
Vadlo:Vadlo is a life sciences search engine offering protocols, tools, and powerpoints for scientific research and discovery. Find what you’re looking for, and then stick around to check out the forums.
Online Journals Search Engine:In this free, powerful scientific search engine, you can discover journals, articles, research reports, and books in scientific publications.
Bioline International:Search Bioline International to get connected with a variety of scientific journals. The search is managed by scientists and librarians as a collaborative initiative between Bioline Toronto and and the Reference Center on Environmental Information.
Directory of Open Access Journals:When you need top-quality journal writings for free, the Directory of Open Access Journals is a great place to check out. You’ll get access to a searchable journal of full-text quality controlled scientific and scholarly journals.
SciCentral:Use SciCentral as your gateway to the best sources in science. This site has a literature search, journals, databases, and other great tools for finding what you need.
Science.gov:In this government science portal, you can search more than 50 databases and 2,100 selected websites from 12 federal agencies. This is an incredible resource for millions of pages of U.S. government science information
Behavioral Brain Science Archive:Check out this searchable archive to find extensive psychology and brain science articles.
PubMed:From the U.S. National Library of Medicine, PubMed is a great place to find full-text medical journal articles, with more than 19 million available.
MedlinePlus:A service of the U.S. National Library of Medicine, Medline Plus offers a powerful search tool and even a dictionary for finding trusted, carefully chosen health information.
Google Scholar provides a simple way to broadly search for scholarly literature. It is designed very similar to the main Google search, but the results are limited to just scholarly resources: peer-reviewed papers, theses, books, abstracts and articles, from academic publishers, professional societies, preprint repositories, universities and other scholarly organizations. One of the key features is that it will show how many times a piece has been cited by other scholarly literature within Google Scholar. It will also give you a link directly to the GALILEO database, such as EBSCOhost, that the article will be in.