Searches are case-insensitive as long as lower-case letters are used; upper-case search terms will retrieve only articles where the upper-case term is used. For example, a search for
"thrombin"
will return all articles containing the term, but a search for
"Thrombin"
will generally return articles where Thrombin is the first word in a sentence. In general, you should use lower-case in all of your searches unless you have a specific reason to do otherwise.
Punctuation is not searched and is treated as a space. The only exceptions to this are parentheses "()" and asterisks "*", and the use of a hyphen "-" in author's names. Therefore, the parentheses and the wildcard character have special meaning in the search context and cannot be searched in the text. If a search term includes punctuation (such as a dash "-" or a plus "+"), enclose the whole word in quotation marks to ensure that proper spacing is maintained in the search.