To search for research questions, first, go to the questions page by using the Questions link in the left navigation bar.
Expand the filters and go to the Types filters, selecting the Value and Profile classifications. If you only want to see research questions from your organization, select Custom under Sharing Permissions, too.
Before filtering the list, there were 149,276 results in the question list. After filtering them as shown above, there were 2,399 results. (Those numbers will be different in your account, of course.)