What are some great scientific research databases that have mostly peer-reviewed articles?
It really depends on what branch of science interests you. Since we are a public library, our best resource is Ebsco's MasterFile, the public library's version of their Academic Search Premier. In advanced search (on the left side), you can check the peer-reviewed box to limit your search to peer-reviewed articles. For example, doing so reduces 7,916 results for human genome to 4,384. You will need an active ACL library card to access MasterFile outside of the library. Under Research, select A-Z, then E, Ebsco, and scroll down to MasterFile.
If your interest is academic but you are not a college student, you can get visitor passes to the libraries at both Stanford and Berkeley and some of their libraries do not require them. As you can see at this link, https://searchworks.stanford.edu/ there is a link for searching for databases by subject, including computer science, earth sciences, biology, chemistry, etc. Without a student ID, you would not be able to login remotely, but they would be available in their libraries with the visitor pass. To see how to get access to Stanford's libraries, go to http://library.stanford.edu/using/access-and-privileges, email email@example.com or call (650) 723-1492.