Abstract: Scientific information on the platform of microblog communicates through social relations. Based on the relations among microblog users, such as following, forwarding, commenting and so on, communication network forms, whose structure determines the sources, direction, strength and coverage of information. Quantitative investigation on the structure of this network with the methodology of social network analysis (SNA) provides a new structuralism approach for mechanism studies of science communication with microblog. Structure analysis of communication network could be conducted at four levels, including the structure of whole network, individual position, and sub-network as well as the interaction between sub-networks. The case study of the issues of Genetically Modified food indicates that, 1) public scientific issues communicate through multi-interactional channels in microblog space; 2) the relationship among relevant communicators presents some characteristics of elite-democracy, and 3) actors involved would probably polarize into different groups.

摘要： 微博科学传播通过社会关系进行。微博用户基于关注、转发、评论等关系形成传播网络，网络结构决定信息的来源、方向、强度及范围。运用社会网络分析，定量探究这一网络的结构特征，为微博科学传播机制研究提供了结构主义的新视角。传播网络结构分析从整体结构、个体位置结构、子群结构、子群互动关系结构等四个层次展开。转基因食品议题的案例研究发现：公共科学议题在微博空间中具有多元交互的传播渠道；相关传播主体之间的关系呈现精英民主化特征；往往产生群体两极化的传播效果。

关键词: 科学传播, 机制, 社会网络分析, 微博客, 转基因食品