MottGThe Lens search engine has some new search features available under the menu option "New Structure Search" such as:
Retracted
Cited by Patents
Has Clinical Trial
Has chemical
Under "Query Tools" you can check an
option that your query has a regular expression.
The is also a Query Text Editor shown in the large rectangle in the lower middle of the 2nd image that allows you to interactively edit and validate Boolean queries.
