Perhaps you should try some spelling variations:
"health evidence network synthesis report" » "health science network synthesis report", "health guidance network synthesis report", "health dence network synthesis report"
health devices » health services, health service, health advice
"head impedance network synthesis report" » "head impedances network synthesis report", "end impedance network synthesis report", "board impedance network synthesis report"
"head impedance network systems report" » "head impedances network systems report", "end impedance network systems report", "board impedance network systems report", "head impedance network system report", "head impedance network systems support", "head impedance network systems recent"
"load impedance network synthesis report" » "ac impedance network synthesis report", "load imbalance network synthesis report"
health device » health service, health services

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: (((("health evidence network synthesis report") OR ("((health device) or (health devices)) network synthesis report"))) OR ((((("head impedance network synthesis report") OR ("load impedance network synthesis report"))) OR ("head impedance network systems report")))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"health evidence network synthesis report\") or (\"((health device) or (health devices)) network synthesis report\"))) or (((((\"head impedance network synthesis report\") OR (\"load impedance network synthesis report\"))) or (\"head impedance network systems report\"))))".
• Removing quotes may allow a broader search: (((( health evidence network synthesis report ) or ( ((health device) or (health devices)) network synthesis report ))) or ((((( head impedance network synthesis report ) OR ( load impedance network synthesis report ))) or ( head impedance network systems report )))).
• Adding a wildcard symbol may retrieve word variants: (((("health evidence network synthesis report") or ("((health device) or (health devices)) network synthesis report"))) or ((((("head impedance network synthesis report") OR ("load impedance network synthesis report"))) or ("head impedance network systems report"))))*.