Perhaps you should try some spelling variations:
"acute respiratory testing" » "acute respiratory gating", "acute respiratory training", "acute respiratory patterning"
"cycle regulatory functions" » "cycle regulation functions", "gene regulatory functions", "cycle regulatory function"

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: (("cycle regulatory functions") OR ("acute respiratory testing")).
• Removing quotes may allow a broader search: (( cycle regulatory functions ) or ( acute respiratory testing )).
• Adding a wildcard symbol may retrieve word variants: (("cycle regulatory functions") or ("acute respiratory testing"))*.