Perhaps you should try some spelling variations:
"research professionals" » "research professional", "resource professionals", "researching professional", "research professionalals", "research progressionsals", "research protectionals"
"research progression" » "research regression", "research progress", "research progresses"
"research profession" » "research professional", "research progressions", "research protection"
"research professor" » "research process", "research processes", "research prozess"

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