Explanation

• Word: to the search engine, a word is any combination of characters (letters and digits), e.g., hello, H2CO2, and 2001. Punctuation marks and all other symbols are ignored, with the exception of double quotes ("), question marks (?), and asterisks (*), which have special meanings as described below.
• Phrase: a phrase is a sequence of words separated by spaces and enclosed in double quotation marks, e.g., "cat in the hat". This will match cat in the hat and cat, in the hat! (punctuations ignored), but not cat in the red hat.
• Wild cards: a wild card stands for any character (letter or digit) or characters. A question mark (?) will match a single character. An asterisk (*) will match arbitrary number of characters. For example, n??t match with neat and nest, while match colo*r match color, colorer, and colour. Wild cards are especially useful when you are not sure about the spelling of a word, e.g., osteop*osis.
• Note: since by default each search word is treated as a substring (part of a word), there is no need to put wild cards at the beginning or end of a search word. Both physic and physic*, for example, will match physical, physics, and metaphysical.

The rest should be self-explanatory. If you have problems, questions, or comments about the search page, please e-mail the webmaster.

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