The paper doi number is the paper ID card, which is unique. Once it is made, it will remain unchanged and will not change with the change of the copyright owner or storage address of the digital object it recognizes.

Doi consists of two parts: prefix and suffix, separated by "/". The prefix consists of two parts, one is the directory code, and all doi directories are "10". , that is, all Dior codes start with "10". The other is the registration agency code. Any organization or unit that wants to register doi can apply for registration agency code from IDF. Suffix is the only suffix under a specific prefix, which is assigned by the registration authority to ensure its uniqueness. The suffix can be any alphanumeric code, and its coding scheme is completely specified by the registration agency itself. The suffix can be machine code or existing specification code, such as ISBN number or ISSN number.

The basic structure of doi coding is as follows: doi:10.3969/j.issn.xxxx-xxxx.yyyy.nn.zzz.

journal

Xxxx-xxxx :xxxx-xxxx-xxxx is the serial number of the periodical.

Yyyy: year of publication

Nn: issue number

Zzz: the serial number of the same mid-term paper (that is, the first few articles).