Perhaps you should try some spelling variations:
greatest challenges » greatest challenge, treatment challenges, related challenges
challenges funding » challenges finding, challenge finding, challenges branding
funding among » bonding among, building among, jumping among
3.1 greatest » 3.1 treatment, _ greatest, its greatest
among di » among hiv, among idp, among _
nan yan » nan ya, wang yan, qian yan
yang xi » yang di, yang yi, yang jui
ra 3.1 » era 3.1, ra 4.1, area 3.1

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: ((nan yan) OR (yang xi))ng ra 3.1 greatest challenges funding among di ;~.
• Adding a wildcard symbol may retrieve word variants: ((nan yan) or (yang xi))ng ra 3.1 greatest challenges funding among di ;*.