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Boolean Logic (for advanced users)
  • You can create your own Boolean phrases with any level of parentheses. This will make it possible for you to specify the exact meaning of your search phrase.
  • Only the search terms can be specified in your Boolean phrase; i.e., year of publication and section can only be specified in the drop down lists.
  • Order of precedence: Parentheses, NOT, AND, OR.
  • If you enter “genentech OR amgen AND cancer”, then the logical result will be: “genentech OR (amgen AND cancer)”, because the AND operator is evaluated before the OR. Similarly, if you enter “cancer AND amgen OR genentech”, the result will be the same as above for the same reason.
  • You can force a desired logic by using parentheses. For example, if you want to find what Genentech and Amgen are doing in cancer, you can enter “(genentech OR amgen) AND cancer”.
 Tip 'NOT' = 'And NOT'

 Note Do not use {curly} or [square] brackets - use only (parentheses).

The table shows several examples of natural language searches and their Boolean implementations:
Normal English Boolean Phrase
All articles about Amgen and cancer, and also all article about Genentech and cancer. (amgen AND cancer) OR (genentech AND cancer)
All articles about Amgen and cancer, and also all articles about Genentech. (cancer AND amgen) OR genentech
All articles with the words "amyloid" and "immunization", but without the term "42-amino" (amyloid AND immunization) NOT 42-amino
All articles that are about Amgen and Genentech, but NOT about cancer. (amgen AND genentech) NOT cancer