(1) Paper factor. For example, the delay in publication, the length and type of the paper, and the number of collaborators. Journals with shorter publication time lag are more likely to obtain higher impact factors. If the publishing cycle is long, due to the aging of the literature (more than 2 years), a considerable number of citations are not counted, that is, they do not participate in the calculation of the impact factor, thus reducing the impact factor. A large number of statistical data show that if the published papers are hot topics, short in length and fast in publication, the citation rate will soon reach a peak, leading to a rapid increase in the impact factors of journals and then a rapid decline; Journals that publish complete research papers are cited for a long time, and the impact factors rise for a long time. Some data also show that there is a significant positive correlation between the average number of authors and the total cited frequency of papers.
(2) Periodic factors. Such as the size (number of published papers) and types of periodicals. When calculating the impact factor, the number of published papers is only counted as papers, newsletters and abstracts, and articles in frequently cited columns such as comments, letters and newsletters are not counted. According to experience, the number of papers published in journals is closely related to the impact factors and the total cited frequency. In most cases, journals with few papers are easy to get high impact factors, and the impact factors of these journals will fluctuate greatly year by year; Journals with a large number of papers and a long history often get higher total citation frequency. In addition, it is closely related to other citation indicators, such as annual indicators, cited half-life, regional distribution, fund-paper ratio, periodical scope and circulation. Different periodical sizes and structures will lead to different influencing factors. Generally speaking, the larger the scale of the same type of periodicals, the greater the influence factors of these periodicals; The more "hot" topics or "hot" professional articles contained in a journal, the higher the total citation frequency, and the greater the impact factor of the journal.
(3) subjective factors. For example, the number of journals in different disciplines, average citation times, citation half-life and so on will have an impact on the impact factors and total citation frequency of journals. The impact factor and total cited frequency of journals are based on the relationship between the cited times of papers and the cited times. The citation frequency of a subject depends on two main factors: first, the development characteristics of each subject; Second, the proportion of journals in this discipline in the journals from the database.
Generally speaking, the more source journals of a certain discipline, the greater the total cited frequency and influencing factors of the journals of this discipline. These two factors determine the unbalanced distribution of discipline influencing factors and total cited frequency. Biological journals have always been a striking category of SCI journals, which not only significantly exceeds other disciplines in the number of journals, but also has significant advantages in the total cited frequency and the number of influencing factors, thus indicating the important position of biological sciences in contemporary science. In addition, the impact factors are also influenced by the social coverage of the disciplines involved in the journal in a professional sense. If a sci-tech journal has a small social coverage in the professional sense and few similar journals, then its impact factor cannot be very high.
Different disciplines have different internal scientific research laws, and it is different to cite other people's scientific research results when doing research. These differences will affect the size of impact factors in at least two ways. On the one hand, it is how much others' achievements need to be cited, on the other hand, it is the time when others' achievements are cited. Because the impact factor is generally calculated only according to the literature cited by journals in the last two years, it can be seen that the ranking results based on the distribution of cited years in the last two years are also consistent with the ranking results of journals using the impact factor method, which also shows that the impact factor can not correctly reflect the influence between journals in different disciplines.
Due to historical reasons, the construction and development of different disciplines in a country is unbalanced, even in different branches of the same discipline. Some disciplines are small in scale, but there are many researchers engaged in this discipline, and the capital investment in this discipline is also large, and there are also many related discipline magazines, which will form a scale advantage. However, those smaller disciplines often do not have this scale advantage, so the impact factors and total citation frequency of such journals will not be very high. As far as the development speed of discipline scale is concerned, different disciplines are divided into "cold" and "hot". Due to the needs of the times, the scale of the "hot" discipline has developed rapidly, and the articles of this discipline will be highly cited in its rapid development.