Search Alerts notify you by e-mail when a stored search retrieves new results on a daily, weekly or monthly basis (depending on the database). Generally, one performs a search and then saves the search to create the alert. Although not all databases have alerts, those that do (e.g. Web of Science) usually allow you to set up different kinds of search alerts.
Author Citation Alert - receive a notification each time the author's work has been cited in a database.
If you know the citation or partial citation for an article and need to find the article:
Not all scientific information is published in journals. If you're looking for everything written on a topic, especially recent developments, check these sources to find conference papers, meeting proceedings, and dissertations.