Compared with periodicals, regular periodicals and special periodicals need to put together what they have learned in one aspect and have a longer review period. For the employment criteria of papers, at least the condition of subject matching is added, which makes it more difficult for regular journals of sci journals to contribute than journals. But periodicals are still quite difficult.

Sci special issue is different from supplement. It belongs to the main journal, but it is published around a certain theme of the journal, and its audit requirements are higher than those of the main journal, which makes it more difficult to submit the sci special issue. That is to say, the special issue of sci is more difficult than the regular issue. Papers published in sci special issues and regular journals have high gold content, which is not comparable to sci supplements. The reason why sci has special issues and periodicals is related to whether the papers published in the journals have the same theme.