Perhaps you should try some spelling variations:
resource research » resources research, source research, resource search
research theories » research theory, research themes, research topics
pressure research » present research, pressure release
residue research » residues research, residual research, resident research
rescue research » rescue search, issue research, response research
tissue research » issues research, disease research

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: "((((\"((rescue research) OR (resource research)) theories\") or (((\"((tissue research) OR (pressure research)) series\") or (\"((tissue research) OR (pressure research)) studies\"))))) or (\"residue research theories\"))".
• The words AND, OR and NOT may confuse the search; try adding quotes: "\"((((\\"((rescue research) OR (resource research)) theories\\") or (((\\"((tissue research) or (pressure research)) series\\") or (\\"((tissue research) or (pressure research)) studies\\"))))) or (\\"residue research theories\\"))\"".
• Removing quotes may allow a broader search: (((( ((rescue research) OR (resource research)) theories ) or ((( ((tissue research) or (pressure research)) series ) or ( ((tissue research) or (pressure research)) studies ))))) or ( residue research theories )).