If you are signed in, you can save searches permanently. To do so, click on "Save query" above the list of results:
Note: The "Save query" option is only displayed if you are signed in and have submitted a search.
When saving your query, you can receive email notifications when there is an update to the query. To activate this service a message will appear automatically at the top of the page.
The saved searches are stored in "My Favourites"
in the tab "Saved searches".
You can perform the search again by clicking it. You can set up a notification (by RSS or email) using the symbols on the right to keep you informed of newly added documents that match you search.