When the search results are not satisfactory-there are too many results, we should reduce the search and improve the accuracy. You can adjust the search formula in the following ways: add restrictions to specific fields and years; For example, if you search for the Qing Dynasty, add 1662-1723 in front. Improve the accuracy of searching nouns-refer to thesaurus, dictionaries, classification tables, glossaries and other tools. Increase the accuracy of retrieval strategy-increase the concept of restriction, increase the use of logical AND and logical NOT in concept groups; Reduce the use of logical OR and eliminate irrelevant concepts; For example: 1, London+London+Ontario. Carry out secondary retrieval in the retrieval results; For example, sign language input is changed to deaf sign language input; Reduce synonyms and related words of the same family; For example, delete one of the titles and topics entered in the keyword. Use field restrictions to limit the search term to one or some fields, or specify auxiliary fields to limit the literature type, language and publishing country of the results; For example, the English language of LA: the document to be retrieved is an English document. Improve the specificity of retrieval questions, add or replace subordinate words or free words with strong specificity, or change from field-level position operator to word-level position operator. Use appropriate positional operators; For example, the input (W) output can detect the input and output. Limit search terms to main fields, such as title field and subject field. Shorten the retrieval cycle, or restrict some publications. For example, search for articles on special education in China.

2. When the search results are unsatisfactory-there are too few results, it is necessary to expand the search and improve the recall rate. You can adjust the search formula in the following ways: check the spelling of search words; For example, the key words entered were originally special education, and the input was special education. Increase the universality of search nouns-refer to thesaurus, dictionaries, classification tables, glossaries and other tools. Expand the retrieval strategy-reduce the use of logical "and" and throw away some secondary or overly specific concepts; Connect synonyms and related words with logical OR, or search with classification number to increase the degree of snare; Such as: overseas Chinese or Chinese. Increase the search database-determine whether other databases cover the topic you want; For example, the retrieved database has changed from a single CNKI to a Wanfang database. Adjust the position operator from strict to loose, for example, from word-level position operator to field-level position operator; For example, information (n) retrieval can detect information retrieval and retrieve information. Cancel some restrictive operators such as field and location operators (or use less restrictive location operators). Use truncation after words with the same stem.