The Semantic Web is a vision of the current Web where resources have exact meaning assigned in terms of ontologies, thus enabling agents to reason about them. As inconsistencies cannot be treated by standard reasoning approaches, we use Defeasible Logic Programming (DeLP) to reason with possibly inconsistent ontologies. In this article we show how to integrate rules and ontologies in the Semantic Web. We present an approach that can be used to suitably extend the SWRL standard by incorporating classical and default negated literals in SemanticWeb rules in the presence of incomplete and possibly inconsistent information. The rules and ontologies will be interpreted as a DeLP program allowing the rules to reason on top of a set of (possibly inconsistent) ontologies.