Search for journal articles on most topics. This multi-disciplinary database is a good place to start if you don't know where else to begin. (EBSCO)
Search for journal articles on topics in the arts, humanities, social sciences and some math/science. Most journals have volumes/issues dating from the 19th century to within 3-5 years of present day. (ITHAKA)
Use subject-specific research databases to find more resources, depending on your topic. Here are a few ideas to start...
Search for literature reviews that capture current understandings of topics, including what is well-supported and what is controversial. These articles also set the topic in historical context, highlight the direction of future research, and outline the general significance of the research to society. Subjects are wide-ranging from the science to law to social sciences to politics. (Annual Reviews)
Search for journal articles on topics related to all major fields of philosophy. (EBSCO)