The homepage of most journals have an option to sign up for new content alerts. You will usually have to register. Some publishers allow alerts from multiple publications. Alerting options typically include email or RSS feeds(RSS feeds can be viewed within a browser or mobile aggregator app, see this article for more information).
Journal TOC's is a free service which allows you to sign up for new content alerts for multiple journals. eTOC's from this site do not link directly to full text of articles (video below).
Ovid journals. eTOC's can be sent from journals within the Ovid interface. This has the advantage of allowing immediate full text access to journals within the library's collection, although the Ovid journal list is not comprehensive. You will need to open a personal account.
Navigate to the Ovid page via Library >>Popular databases >> Medline
Choose your institution - this will take you to the Ovid interface.
Log into Ovid (or create an account)
Select the My WorkSpace link in the blue banner at the top of the page.
Choose My eTOCs below the blue banner.
Enter your email on the next page.
From the box that displays select your journal.
Click the Add text or Add HTML button. the selected journal will now appear in the top box of your subscriptions.
When all you journals are selected click the Update button below the selection box.