Perhaps you should try some spelling variations:
vaccine research » medicine research
nation research » national research, action research, inflation research
new vaccine » novel vaccine, anti vaccine
new nation » new national, new action
july 2006 » july 2008, july 2007, july 2009
july 2012 » july 2013

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (( new nation research : july 2006 ) or ( new vaccine research : july 2012 ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( new nation research : july 2006 ) OR ( new vaccine research : july 2012 )).
• Adding a wildcard symbol may retrieve word variants: (( new nation research : july 2006 ) or ( new vaccine research : july 2012 ))*.