Perhaps you should try some spelling variations:
"research professor" » "research profession", "research progresson", "search processor"
"research processes" » "research procedures", "research practices", "search process", "research projectes", "research programes", "research paperses"
"research problems" » "research project", "research program"
"research projects" » "research project"
"research progress" » "research program", "research project"
"research prozess" » "research propels", "research proteases", "research proteins"
"research process" » "research project", "research program", "research papers"

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