Many library database interfaces provide a check box to limit the search results to scholarly or peer-reviewed articles.
Franklin Articles+ has a Peer reviewed limit on the left.
ProQuest -- look for
EBSCO -- look for
Journal Citation Reports analyzes journal citation patterns to determine indicators including total cites, journal impact factor, impact factor without self cites, 5 year impact factor, citable items, cited half-life, citing half-life, and Article Influence Score for journals in the sciences and the social sciences. Options include
indicators include: journal impact factor, journal impact factor contributing items, cited half life, journal relationships, distribution by country, contributions by organization, and many key indicators.