Is a family of three databases: Science Citation Index, Social Science Citation Index and Arts and Humanities Citation Index. Each enables searching for works referenced or cited by other scholars. This is a great place to go for interdisciplinary topic such as environmental ones.

(Searches through citations and the full text)
A core collection of full text articles in the sciences and social sciences, as well as reference works, handbooks and book series. Covers 1997 - current.

(Searches through citations, subject indexing, and abstracts)
This tool searches across the AGRICOLA, ESPM, and EIS databases, and it provides full-text titles from around the world. It includes scholarly journals, trade and industry journals, magazines, technical reports, conference proceedings, government publications, and more. Covers 1960-current.

Access to articles and reports pertaining to agricultural research. This includes animal science, botany, agricultural economics, farm management and more.

(Searches through citations, subject indexing, and some full text)
The place to start to find Geology literature. GeoRef has articles, conference proceedings, maps, reports, and dissertations. Take a look at the thesaurus if you're having trouble finding good keywords. Covers publications from 1785 - present.

(Searches through citations, subject indexing, and some abstracts)
The definitive place to find literature on all aspects of medical research, including clinical practice, administration, and policy. Covers 1950 - current.