Specify partial ring names, e.g. "anthra" or partial smiles, "c1ccn*". A wildcard is needed with SMILES, not with names.
The SMILES are obviously ideosyncratic and thus not a reliable way to search. This feature has been provided in the hope that
it may be useful. To search using multiple rings at once, use the (+) button.
NB as of March 13, 2012, only about 10% of the molecules in ZINC have been processed for rings. We expect to have 95% coverage
by April 1, 2012.