5. A system of discovering and analyzing structures of user groups in a microblog, which comprises a processor, characterized in that the processor is configured to perform the operations of: acquiring information on behavior data of microblog users of a target group; constructing a microblog user association network based on the information on behavior data of the microblog users of the target group; acquiring at least one maximal clique from the microblog user association network; acquiring at least one core clique based on the maximal clique; conducting behavior analysis on the user groups in the microblog based on the acquired maximal clique and/or the acquired core clique, wherein the operation of acquiring at least one maximal clique particularly comprises: acquiring all maximal cliques of the microblog user association network by utilizing a search-triangle based method operated with a certain pruning strategy, and wherein the operation of acquiring at least one core clique particularly comprises: based on the maximal cliques, analyzing a social relation circle of each microblog user and all other microblog users, and filtering out the core cliques of the microblog user association network based on an inclusion-consolidation strategy on the social relation circles, wherein if a social relation circle of one microblog user is not included by any of the other social relation circles, the social relation circle of the one microblog user is filtered out as one of the core cliques.
5. A system of discovering and analyzing structures of user groups in a microblog, which comprises a processor, characterized in that the processor is configured to perform the operations of: acquiring information on behavior data of microblog users of a target group; constructing a microblog user association network based on the information on behavior data of the microblog users of the target group; acquiring at least one maximal clique from the microblog user association network; acquiring at least one core clique based on the maximal clique; conducting behavior analysis on the user groups in the microblog based on the acquired maximal clique and/or the acquired core clique, wherein the operation of acquiring at least one maximal clique particularly comprises: acquiring all maximal cliques of the microblog user association network by utilizing a search-triangle based method operated with a certain pruning strategy, and wherein the operation of acquiring at least one core clique particularly comprises: based on the maximal cliques, analyzing a social relation circle of each microblog user and all other microblog users, and filtering out the core cliques of the microblog user association network based on an inclusion-consolidation strategy on the social relation circles, wherein if a social relation circle of one microblog user is not included by any of the other social relation circles, the social relation circle of the one microblog user is filtered out as one of the core cliques. 6. The system of discovering and analyzing structures of user groups in a microblog according to claim 5 , characterized in that, the operation of acquiring information on behavior data of microblog users of a target group comprises: establishing association relationships among the microblog users by utilizing an association relationship evaluation model, based on the information on behavior data of the microblog users of the target group; and constructing the microblog user association network which is composed of a microblog user used as a node and an association relationship used as an edge, based on the established association relationships among the microblog users.