Top 10 journals for "multidisciplinary sciences" as ranked by 5 year impact factor from the 2011 Journal Citation Reports:
To determine if a journal is peer-reviewed:
1. Use Ulrich's (a database about journals) to determine if the journal is peer-reviewed or refereed
Using a database or Ulrich's to determine if a journal is peer-reviewed.
2. Go to the journal's website and look at the article submission guidelines or intructions for authors section or instruction for reviewers to determine if the journal has a peer review process.