The back dated core journals may be stopped or stopped for some reasons, such as insufficient peer review, poor article quality, loss of editors and so on.
There is a database named China Sci-tech Journals Database (19 15 to 1993) in China academic journals, which contains a large number of back-dated core journals, such as Journal of Tianjin University and Journal of Peking University.
In addition, there are some copies of old periodicals, which can also be found on the electronic resource platform of the library.