Perhaps you should try some spelling variations:
"net national research : july 2009" » "net educational research : july 2009", "3 national research : july 2009", "2 national research : july 2009", "1 national research : july 2009", "net national research : july 2008", "net national research : july 2007", "net national research : july 2019"
"new vaccine research : july 2009" » "new medicine research : july 2009", "novel vaccine research : july 2009", "anti vaccine research : july 2009", "new vaccine research : july 2008", "new vaccine research : july 2007", "new vaccine research : july 2019"

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("new vaccine research : july 2009") OR ("net national research : july 2009"))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"new vaccine research : july 2009\") OR (\"net national research : july 2009\"))".
• Removing quotes may allow a broader search: (( new vaccine research : july 2009 ) OR ( net national research : july 2009 )).
• Adding a wildcard symbol may retrieve word variants: (("new vaccine research : july 2009") OR ("net national research : july 2009"))*.