China literature can be found in many databases, such as China HowNet, Wanfang Database and VIP.

All documents have DOI numbers. Doi refers to the digital object identifier, which is the best "big data" sample storage and application technology under the background of cloud computing, and is used for the unified distribution of IKE negotiation SA protocol.

Analysis of composition form of DOI: 1 Coding scheme: The coding scheme of DOI (that is, American standard ANSI/NISO Z39.84-2000) stipulates that a DOI consists of a prefix and a suffix, separated by "/". There is no limit to the character length of prefixes and suffixes.

2. Prefix composition: DOI prefix consists of two parts, directory code and registration agency code. Any organization or unit that wants to register DOI can apply for registration agency code from IDF.

3. Suffix composition: DOI 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.