The journal impact factor seen in Wang Zhi refers to the journals in the citation database of scientific papers of the Ministry of Science and Technology, that is, the core journals of science and technology in China. The calculation method of the impact factor is the ratio of the number of citations in the journal in recent two years to the number of papers published in the journal in recent two years. Generally speaking, it is the average number of citations of papers published in a journal, which reflects the degree to which papers published in a journal are recognized by other papers (scholars), or reflects the academic influence of a journal.

However, the usual impact factor (IF value) refers to the journals and their impact factors included in American SCI. There are many algorithms for journal impact factors in China, such as China Institute of Sci-tech Information of Ministry of Science and Technology and Chinese Academy of Sciences. The former is divided into core version and extended version, which is of little significance.