Perhaps you should try some spelling variations:
"tissue research theories" » "tissue research theory", "tissue research themes", "tissue research three", "issues research theories", "pressure research theories", "disease research theories"
"residue research studies" » "residues research studies", "residual research studies", "rescue research studies", "residue research study"
"tissue research topics" » "issues research topics", "pressure research topics", "disease research topics"

Try widening your search to All Fields.

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: (((("tissue research theories") OR ("tissue research topics"))) OR ("residue research studies")).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"tissue research theories\") OR (\"tissue research topics\"))) or (\"residue research studies\"))".
• Removing quotes may allow a broader search: (((( tissue research theories ) OR ( tissue research topics ))) or ( residue research studies )).
• Adding a wildcard symbol may retrieve word variants: (((("tissue research theories") OR ("tissue research topics"))) or ("residue research studies"))*.