From the Search page, you have the option to limit your search using a drop down box to:
If you do not make a selection, the search will be executed using the default option Full file. The search is conducted across the combined Current file and Retrospective file contained in IIBP.
You may also limit your search to Peer Reviewed articles only in the Current file. Click on the check box to make sure that is is selected prior to doing your search. The default option is unchecked.