You can view and select available search engines via the View -> Engine Selections menu item. When you do this, a dialog with checkboxes will pop up:
You can select or de-select a particular search engine by clicking in the checkbox next to it. Note that, to comply with NCBI's and USPTO's system requirements for large queries, Agilent Literature Search places certain limits on its interaction with these search engines. These limitations are listed along with the descriptions of the search engines below.
Search engines supported in this release of Agilent Literature Search are: