While not specific to the sciences, these databases can be good starting points for research papers. They represent a wide variety of material and can assist with everything from giving a general introduction to a topic to providing scholarly, peer-reviewed articles. They can also be good sources for non major courses.
JSTOR is a digital library of academic journals, books, images, and primary sources.
Articles from scholarly journals, popular magazines and newspapers, in many different subject areas.
These databases are specific to environmental studies or at least to the sciences in general. Here you will find popular articles as well as scholarly, peer-reviewed publications on a wide range of topics in environmental studies and other scientific disciplines.
Sage Research Methods supports research at all levels by providing material to guide users through every step of the research process.