Scd periodicals belong to Class B periodicals and are scientific citation databases (English name: ScienceCitationDatabase, abbreviated as SCD). China Journal Classification: the classification of current publications in China-publishing level; Core periodicals; Provincial periodicals; National periodicals; CN publications; SCI, SSCI, CSSCI .SCI, SSCI, CSSCI:SCI was founded by institute for scientific information, USA, and contains the authors, titles, source journals, abstracts and keywords of the literature. It can not only evaluate the academic value of articles from the perspective of literature citation, but also establish a reference network for research topics quickly and conveniently. SCI was established in 196 1. After 40 years of development and improvement, it has developed from a single printing type to a powerful electronic, integrated and networked large-scale multidisciplinary comprehensive retrieval system. SSCI is a companion piece of SCI, a social science citation index, and was also founded by institute for scientific information. It is a large-scale retrieval tool, which can be used to analyze the number of social science papers in different countries and regions. CSSCI Chinese Social Science Citation Index (CSSCI) was developed by Nanjing University and is a key research project of the State and the Ministry of Education. The Ministry of Education has regarded CSSCI data as an important assessment index for the evaluation institutions and bases, achievement awards, project establishment and personnel training of colleges and universities nationwide.