4C principles for selecting a literature database: 1. Content, that is, the content of literature included in the database, involving the subject scope, scientific and technological content of the literature, database type (such as numerical values, facts, abstracts, full text, etc.), and data sources; 2. Coverage, that is, the scope of documents included in the database, involving the time range, geographical scope, institutional source, volume of documents, etc.; 3. currency, that is, the update frequency of the database; 4. charge, that is, the charge of the database, various databases, The charges for various search output methods and formats are different.
The operating environment of this tutorial: Windows 7 system, Dell G3 computer.
Literature database refers to a computer-readable, organized collection of relevant literature information. In the literature database, the literature information is not expressed in traditional text, but in the form of binary encoding, and is stored in the computer in an organized manner according to a certain data structure, so that the computer can recognize and process it. Literature database is the earliest and main processing and retrieval object for online information retrieval through communication networks all over the world.
The content of the literature database corresponds to its traditional literature information. The content and formal characteristics of a book or document form an item after being described. An entry is the basic unit of documentary information. In a literature database, an item is called a record, and a record is also the basic unit that constitutes a literature database. An entry consists of bibliographic items such as article title, author, and subject. The bibliographic items are called fields in the literature database. A field can be subdivided into several subfields. In this way, the literature database is composed of a series of continuous records, fields and sub-fields, and forms a hierarchical tree structure.
4C principles for selecting a literature database
1. Content (database content): Literature content included in the database
The content of the database involves its subject scope, scientific and technological content, database type (such as: numerical values, facts, abstracts, full text, etc.), data sources (such as: journal articles, conference papers, patent documents, scientific and technological reports) wait).
Articles in different fields are included in different databases. Whether you can find the documents you need depends on the database you find.
2. Coverage (database size): the scope of documents included in the database
The size of the database involves its time range, geographical scope, institutional sources, and volume of documents wait.
What years of literature does the database contain, and what types of subjects it contains.
3. Currency: The update frequency of the database
The timeliness of the database update, the frequency and period of the update.
4. Charge: Database charges
The charges for databases are different for various databases, search output methods and formats.
Selection of search points and search terms
The search point corresponds to the field heading in the database, and its basic unit is the search word. The appropriate selection is crucial to the results of the entire search.
The selection of search points mainly includes: topic, category, author, group author, name, number, etc.
The selection of search terms is closely related to the mastery of the search language. In the subject analysis On the basis of this, the concepts related to the topic are converted into search language. In general, priority can be given to the use of standard words, but the number of standard words is limited and the concepts covered are also limited. Moreover, there is no unified word list for each search system and database. In addition, new concepts and new vocabulary are emerging one after another, and the number of new databases is When it comes out, there may not be a standardized vocabulary list.
Therefore, the use of free words is now quite common, or standard words and non-standard words are often combined to express search questions. Most search systems have index dictionaries that can be expanded to provide vocabulary selection.
Formulation of retrieval formula
Retrieval formula (query, formula, profile, statement) is the concrete embodiment of retrieval strategy and is machine-executable A retrieval scheme that combines retrieval units (search words) and correctly expresses the relationship between them, such as logical relationship and positional relationship. The search query can be completed in one go or in multiple steps. The expression of a search term may take many forms for a topic, with various selection, combination, description, limitation, etc. These relationships are reflected through operators. Search formulas can express complex search questions, and systematically organize various search points, different attribute values, and different relationships into one search formula to complete the search task.
Adjustment of retrieval plan
Due to the real-time and interactive nature of computer retrieval, it is possible for users to analyze retrieval results and adjust retrieval plans in a timely manner . In order to obtain a more satisfactory final result, retrieval often requires multiple judgments and multiple modifications. If a step is inappropriate, return to that step and perform it again.
Output of search results
There are many ways to output search results, including display, copy, print, transmission, download, E-mil mail, etc. The output forms include catalog, bibliography, abstract, full text or customized form, etc. You can also Select the search results and output them.
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