Perhaps you should try some spelling variations:
health impedance » health importance, health temperance, head impedance
defense networks » defense network, dense networks, defenses network
networks system » network system, networked systems
health science » health sciences
systems report » systems support, systems recent, systems transport
health defense » health biodefense, health disease, depth defense
system report » system reform, system support, system reforms

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) OR (health science)) network systems report ) OR ( health defense networks system report ))) OR ( health impedance network synthesis report )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(((( ((health evidence) OR (health science)) network systems report ) or ( health defense networks system report ))) or ( health impedance network synthesis report ))".
• Adding a wildcard symbol may retrieve word variants: (((( ((health evidence) OR (health science)) network systems report ) or ( health defense networks system report ))) or ( health impedance network synthesis report ))*.