自从十七世纪中叶世界上第一种期刊问世以来,期刊的种类迅猛发展。据有关资料统计,全世界的期刊种类目前已超过18万种。期刊以其信息传递快,文献容量大,资料内容新,出版周期短等特点,迅速在传递科技情报、交流学术信息方面发挥极为重要的作用。科学文献的分布具有内在的规律性,其中最基本最普遍的规律是文献聚散规律。其表现为:在某个学科 Since the publication of the first periodical in the world in the mid-seventeenth century, the type of periodical has grown rapidly. According to statistics, the world’s journals now have more than 180,000 species. Periodicals play an extremely important role in transmitting scientific and technological intelligence and exchanging academic information with fast information transmission, large literature capacity, new data content and short publication period. The distribution of scientific literature has an inherent regularity, of which the most basic and most common law is the law of polygamy. Its performance: in a subject