Library catalogs and databases (such as PubMed and Google Scholar) allow you to save searches and create "alerts." You will thus receive notification when citations, books etc. that meet your search criteria are added to the database.
Save a PubMed Search and Create an E-mail Alert (2 min. video)
How to sign up for email alerts in Google Scholar
In addition, most journals allow you to receive electronic tables of contents ("eTOCs") as new issues come out, or as new articles are posted to their web site.
Keep in mind that you will not be able to access the full text of every article from these journal tables of contents unless the article is open access or otherwise freely provided from the publisher.
Alerts and eTOCs may be set up for delivery via email or RSS feed.
Discussion, Blogs, and E-mail Lists (scroll down)
A compilation of resources to keep up to date in your field and stay connected with public health colleagues. From the Partners in Information Access for the Public Health Workforce.