1, system classification language-classification index;
2. Subject language (title-title index). Unit word-unit word index, keyword-keyword index, descriptor-descriptor index);
3. Code language (molecular formula, etc.). -Special indexes such as molecular formula index, structural formula-structural index).
Retrieval language is an artificial language created according to the needs of information retrieval, which can uniquely express various concepts that summarize the content of literature information and express the relationship between concepts, which is convenient for systematic arrangement and consistency comparison between indexing language and retrieval terms.
Extended data
According to the principle, retrieval languages can be divided into
1, classification language
A large number of concepts expressing the contents of literature information and retrieval topics are classified and arranged according to their disciplinary nature, which has become a logical system that basically reflects the usual classification system of scientific knowledge, and a retrieval language that uses numbers (classification numbers) to express concepts and their positions in the system, and even to express the relationship between concepts.
China Library Classification is the basis of book classification in China. China Library Classification divides all knowledge categories into Marxism-Leninism and Mao Zedong Thought according to the five-point method. Philosophy; Social science; Natural science; Five categories of comprehensive books. On this basis, a system series consisting of 22 categories is constructed.
2. Topic language
Subject words need to be standardized, and thesaurus is the embodiment of the language of subject words. The words in thesaurus are used as the basis for identifying the content of documents and finding documents.
3. Keyword language
The keywords extracted from the document content, as the identification of the document content and the basis for retrieving the catalogue index, do not need standardization, nor do they need keyword lists as tools for indexing and retrieving books and materials.
4. Natural language
Any word that appears in the literature.
Baidu Encyclopedia-Literature Retrieval
Baidu Encyclopedia-Search Language