You can do this in two different ways:

1. If you start at the library's homepage and clink on the Journals link, you can search for a specific journal and after entering the journal search within it.

2 You can also use a Database: You would first go to Databases and enter Medline. Once there, you can search for a journal title. Make sure you click the Journal title option instead of author or keyword. Then you can search for a topic and combine both result sets with AND. That will narrow the results to only articles on your topic from the journal you searched for.