1, direct method

The method of directly using retrieval tools (systems) to retrieve literature information is the most commonly used method in literature retrieval. It is also divided into sequential investigation, reverse investigation and spot check.

(1) sequential search method

In chronological order, the method of literature information retrieval adopts the retrieval system from far to near. This method can collect systematic documents of a certain discipline and is suitable for document retrieval of larger disciplines. For example, to know the initial age of a subject, we need to know the whole process of its development now, so we can use the sequential search method to start from the initial age and gradually find it in the near future.

(2) Backward search method

Reverse search method is a kind of literature retrieval method which uses retrieval tools from near to far, from new to old, and relative to time. This law focuses on recent literature. Using this method, you can get the latest information as soon as possible.

(3) Sampling method

Spot check method refers to the characteristics of the project, selects the most likely or most likely time period of document information related to the project, and uses retrieval tools to carry out key retrieval.

2, backtracking method

We don't use general retrieval tools, but use the references listed at the end of the existing literature to look for "citations" one by one, which is the simplest way to expand the information sources. You can also trace the "citation" from the found "citation", and get more and more related documents according to the citation relationship between documents like a snowball.

3. Integrated approach

Comprehensive method, also known as circulation method, is a comprehensive application of the above two methods. The comprehensive method should not only use retrieval tools for routine retrieval, but also use the references attached to the literature for retrospective retrieval, and use these two methods alternately in stages and chapters.

That is to say, first, several documents are detected by the retrieval tool (system), and then the reference directories at the end of these documents are used as clues to search, and so on until the requirements are met.

Memory method of literature

1, conversion of search terms

Common transformations are synonyms, synonyms, related words, singular and plural forms and abbreviated forms. If verbs are used, they may have different tenses. Every search word may have many forms of expression. If it is translated from English, there may be many translation methods, so try to find all synonyms and synonyms of all search words.

Related words refer to words that are different from but related to the search term. For example, synonyms of meta-analysis include meta-analysis, meta-analysis and meta-analysis, synonyms include systematic review, and related words are evidence-based medicine.

Step 2 Use word breakers

Although in theory, finding all synonyms and synonyms can expand the search results, it is quite difficult to do so. At this time, you can use the word breaker to help. The common word breaker is "?" And "*" have different meanings in different databases, and the common meaning is "?" Represents 0- 1 character, and "*" represents multiple characters.

3. Use superordinate words, that is, words that refer to a wider range.

Some retrieval systems have keyword channels, and you can select the keywords above. For example, fruit is the superordinate word of apple, and the superordinate word of prostate tumor is prostate disease.

4. Change Boolean operators

That is, changing and concatenating two OR more search terms into OR can increase the number of detections.

5. Change the search term

If the search term is required to be in the title or keyword or subject, and the number of detected records is too small, you can change it to the abstract or full text to increase the number of detected records.

6. Reduce restrictions and increase sub-keywords.

If the previous search has restrictions, relax or cancel the restrictions; If you use the combination of subject words and sub-subject words, see if there are any possible sub-subject words missing.