You can search amongst: - 36 government databases - 1,850 websites - 200 million pages of U.S. government scientific information including research and development.
Suggestions on how to search Science.gov:
(1) Select the Advanced Search link to the right of the search box
(2) Uncheck the All Sources link to deselect the default of all boxes being checked
(3) Check the box(es) that you are interested in searching (ie, "Health & Medicine")
(4) To further narrow your search, click on the + sign in front of the check box to see all the resources for that topic
(5) As the search completes, you may see a pop up box that asks you to accept all the results. If so, agree to display all results
(6) Browse the left menu subtopics to navigate further into your results
(7) Use the "Sort by" option atop the results to re-sort by other options
Science.gov is an example of a federated search engine. It searches across several databases. This is a great way to get acquainted with and discover government resources. Give it a try and see what you think.