Regular issue, called regular issue in English, refers to how many issues a periodical is issued every year. The papers published in several issues have no specific theme and do not affect each other.

Special Issue, called special issue in English, refers to the solicitation activities in a specific research direction. Generally, influential experts in academic circles collect a batch of manuscripts with the latest research results and publish them in a certain issue or scattered in various issues of journals.

2. Subject limitation of 2.SCI papers

The papers published in the main journals of SCI are in line with the direction of this journal. The topic selection direction of SCI journals will be subdivided into different small directions, but it is not limited to which small direction. That is, journal papers are only limited by the direction of the topic, not by the theme.

Papers published in the special issue of SCI must have a specific topic, such as publishing an article about COVID-19. All pages and articles published in this issue must be related to COVID-19.

3.SCI issue number has volume number and issue number, and special issue can have no issue number.

When publishing periodical or special issue of SCI, layout should be arranged. When a special issue accounts for a certain issue of the main issue, the special issue has a volume number and an issue number.