Perhaps you should try some spelling variations:
treatment challenges » greatest challenges, recent challenges, recruitment challenges
present challenges » current challenges, assessment challenges
wang yang » wang yan, wang liang, wang yanling
min hong » amin hong, tin hong, min hyoung
yang xi » yang di, yang yi, yang jui
hong g » hong ng, hong w, hong 7
ya 3 » a 3, 2a 3, 4a 3

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((wang yang) or (yang xi))ng ya 3 ((treatment challenges) OR (present challenges)) min hong g ;~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((wang yang) OR (yang xi))ng ya 3 ((treatment challenges) OR (present challenges)) min hong g ;.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((wang yang) or (yang xi))ng ya 3 ((treatment challenges) OR (present challenges)) min hong g ;".
• Adding a wildcard symbol may retrieve word variants: ((wang yang) or (yang xi))ng ya 3 ((treatment challenges) OR (present challenges)) min hong g ;*.