Search engine for biological/medical/epidemiological science literature
Yes, this exists. The portal is called "Pubmed" and looks like this:



This portal allows you to search (have a look into the search-Faq) in various ways as well as getting email alerts, download your searches in different formats and so on. It indexes most (but not all) scientific literature for medicine, biosciences and all related topics and is probably the biggest database in this field. And its free.

Another possibility would be Google Scholar, which is focussed on scientific literature and can also be adapted to your personal needs. However, I usually prefer using Pubmed, but sometimes it is useful as well to use Google Scholar.