AccessScience, McGraw Hill's Online Encyclopedia of Science and Technology, is currently offering a four-week, free trial. This leading, searchable, regularly updated science encyclopedia contains more than 71,000 articles, 115,000 dictionary terms, and hundreds of research updates. Other features include a biography section, In the News, a student center, and links. For four weeks of free, full...

Eric Weisstein's World of Science supplies great, online encyclopedias in astronomy, physics, chemistry, and mathematics, as well as a biography of renowned scientists. Users can find excellent, concise explanations of countless concepts. The website is well linked and, therefore, easy to traverse. Everyone, from grade school students to competent professionals, can utilize this amazing resource...