The search terms are as follows:
1. Topic retrieval: Topic retrieval is carried out in the subject field indexed by CNKI. The content of this field contains all the topics of an article. Features, while embedding tools such as professional dictionaries, subject thesaurus, Chinese-English dictionary, and stop word lists during the retrieval process, and using keyword truncation algorithms to truncate low-relevant or micro-relevant documents.
2. Article abstract search: Article abstract search refers to searching within the scope of article title, keywords, and abstracts. For details, please refer to article title search, keyword search, and abstract search.
3. Keyword search: The scope of keyword search includes Chinese and English keywords given in the original text of the document, as well as keywords indexed by machines after analyzing and calculating the document. The keywords indexed by the machine are based on the analysis of the full text content and combined with professional dictionaries, which solves the problem that the keywords given by the document authors are not comprehensive and accurate enough.
4. Title search: The titles of journals, conferences, dissertations, and collections are the Chinese and English titles of the articles. The titles of newspaper documents include introductions, main titles, and subtitles. The chapter title of the yearbook is the title of the article. The title of the patent is the patent title. The standard title is the Chinese and English standard name. The title of the achievement is the title of the achievement. The chapter title of the ancient book is the volume title.
5. Full-text search: Full-text search refers to searching within the entire text range of the document, including document title, keywords, abstract, text, references, etc.