"Peer review" (or "refereed") means that an article is reviewed by experts in that field before the article gets published. This means that if a scientist writes an article on stem cells, other experts on stem cells will review the article to make sure it’s of high enough quality to be published. The peer review (or referee) process insures that the research described in a journal's articles is sound and of high quality.
Also, peer review can be single-blind (meaning that the reviewers know who wrote the article), or double-blind (meaning that the reviewers do not know who wrote the article). Double-blind peer review is designed to increase objectivity in the review process.
Each database is different. Many databases do not allow you to search for only peer reviewed items.
However, some databases available through GALILEO do give you the option to search for only peer reviewed items:
Other databases separate results so that you can look at only peer reviewed items:
Again, each database is different. Some databases will allow you to click on the Publication Title or Source. This will often show whether an item is peer reviewed:
You can search in Ulrich's Web to see if the article is Referreed (Peer Reviewed).
Then, from the Quick Search menu, choose Title (Exact), type in the Journal Title or Source in which the article appears, and then click on Submit.
Next, look at the record for that journal. If it has a small referee's shirt next to the title, that means that the journal is refereed (peer reviewed).
For further help: Scholarly Journals vs. Trade Magazines vs. Popular Magazines