Perhaps you should try some spelling variations:
"research professor" » "research profession", "research processes", "research prozess"
"research problems" » "research progress", "research program"
"research process" » "research progress", "research program", "research proceedings"
"research papers" » "research part"

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: (("research professor") OR ((((((("research process") OR ("research papers"))) OR ("research projects"))) OR ((("research problems") OR ("research project")))))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"research professor\") or (((((((\"research process\") OR (\"research papers\"))) or (\"research projects\"))) or (((\"research problems\") or (\"research project\"))))))".
• Removing quotes may allow a broader search: (( research professor ) or ((((((( research process ) OR ( research papers ))) or ( research projects ))) or ((( research problems ) or ( research project )))))).
• Adding a wildcard symbol may retrieve word variants: (("research professor") or ((((((("research process") OR ("research papers"))) or ("research projects"))) or ((("research problems") or ("research project"))))))*.