New York--Fighting the momentum of B2BWorks and Engage Business Media, DoubleClick Inc. on Monday introduced Intelligent Targeting InMarket Segments. The product allows marketers to send advertisements based on whether Web users have entered certain keywords within seven days. For example, a marketer seeking to reach automotive mechanics can send advertisements to people who have recently looked up such words as ``carburetor,'' ``fuel valve'' or ``toolboxes.'' The technique is not new as other networks have offered similar services. DoubleClick also reported its Sonar Network has burgeoned over the last three months from 300 sites and 50 advertisers to more than 600 sites and 260 advertisers.