Scholarly (Peer-reviewed) Journals
Articles for Background
Annual Reviews review articles within many scientific disciplines; simple search is full text of article and advanced search can be focused by abstract, article title, author, cited author, full text, keywords, captions.
Nature browsable like print or use advanced search to select specific Nature journals on the NPG platform to search.
Proceedings of the National Academiy of Science of the United States of America PNAS is searchable by title, author, abstract term/keyword, and full-text term/keyword; great for well-written articles on a subject; "PNAS is a general science journal and all papers should be intelligible to a broad scientific audience."
Science browsable like print or use simple search; advanced search for limiting breadth of search.