Perhaps you should try some spelling variations:
"research professor" » "research profession", "research processes", "search processor"
"research problems" » "research project", "research program", "research projects"
"research progress" » "research program", "research project", "research projects"
"research prozess" » "research propels", "research processes", "research proteases"
"research process" » "research projects", "research project", "research program"

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