中文摘要：

通过对在线社交网络上图书馆用户生成内容（UGC）的分析,可以从宏观上更好地了解我国图书馆机构关注的热点话题及其演化情况。文章以新浪微博为数据源,获取一定时段我国图书馆微博的内容数据,依据作者主题模型获取候选主题,通过对候选主题进行聚类确定合适的话题数,根据作者主题模型结果计算相邻时间片主题之间的相似度,在此基础上分析主题的演化,最终完成不同图书馆主题分布及演化的差异分析。实证研究结果表明：目前我国图书馆微博主要关注新书推荐、讲座信息、图书馆服务、图书信息等主题;各月份的关注主题差异不大;除了共同关注的图书馆服务、新书推荐等话题之外,上午时段关注音乐和大学生相关话题,下午关注讲座信息和公益话题,晚上时段关注公益和大学生话题。

英文摘要：

Based on topic detection and evolution of library User Generated Content（UGC） from online social networks,one can observe the hot topics and their evolution from a macro perspective. In this paper,the authors extract library corpus from Weibo（microblog） in a certain period. Author-Topic model is used to obtain candidate topics. According to the results of topics clustering,the authors get an appropriate topic number. Then,the authors calculate the similarities between two neighbor topics according to time. Finally,the authors present a comparative analysis of topic evolution between different libraries. The experimental results show that：libraries in China focus on the topics of new arrivals,lecture information,library services,book information and others;topics vary little each month; library Weibos concern the issues about music and college students in the morning, lecture information and public service in the afternoon;public service and college students in the evening in addition to the common topics such as library service,new arrivals.