1. Boolean Boolean retrieval
Use Boolean operators to provide for a retrieval logical relationships between search terms
Type: logic (AND, *), or a logic (OR, +), logical negation (NOT, -)
☆ widely used search engine and database
(1) a logical "and" --and; *
And defining a conceptual cross. Since narrow search range and improve precision Document effect
For example: check the related article, "students 'information literacy' aspects
Students and Information Literacy
* Students Information Literacy
(2) a logical "or" --or; +; |
The concept for parallel and complementary. It can broaden the search to improve recall.
For example: to retrieve documents "minor" aspects
Minors or child or teenager
Minors + children + teenagers
(3) a logical "non" --not; -
For repelling between concepts, nothing to eliminate the concept, improve the precision.
For example: Document search "non-alcoholic beverages" aspect
Alcoholic beverages not
Beverages - Alcohol
(4) priority operator "()"
Boolean logic order:
Non-not - and and - or or
But using operator can change the priority order of the normal operation of Boolean logic.
A or B and C
（A or B）and C
For example
Topic: minors alienation study
(Minors or teenagers or children) and behavior and alienation
2. truncation retrieval truncation
You can retrieve a word having the same stem, or root, to improve recall. Common truncation symbol "*", "?", "#", "$", It is a special logical "or" operation
Type: prior to truncation, and an intermediate cut after cut
☆ used for English search engines and databases
（1）computer*
Retrieve comprise computers, computerize, computerise other Documents
（2）*computer
Retrieve comprise computer, minicomputer, microcomputer, etc. Document
（3）wom？n
May comprise retrieved woman, women like document
Tip: truncation symbol must be followed by stem; stems must not cut too short, must be reasonable. Truncation different databases are not the same character, referring to the database description.
3. Precise (Exact) Retrieving
- Two or more words can not be disassembled, are not interchangeable position, with no intervening any character. Different databases are not the same for accurate retrieval requirements, most database use double quotes ""
- For example: Enter "atificial intelligence"
It will not appear in the text retrieved artificial social intelligence and the intelligence of artificial immune system ...... and other articles
4. The position operator (positional operator)
- Also known as proximity search, use locator to specify the positional relationship between search terms, each character adjacent to retrieve the database is not the same, see the instructions before retrieval database.
- To EI, for example :
NEAR word order may be reversed; ONEAR word order can not be reversed; up to n words inserted between ONEAR / n words and word
Wastewater the AND Treat Wastewater Treatment
Wastewater the NEAR Treat Wastewater Treatment
Wastewater the NEAR /. 3 Treat Wastewater
Wastewater ONEAR Treat Wastewater Treatment
Wastewater ONEAR /. 3 Treat Wastewater
Recall AND> NEAR> ONEAR
查准率 AND<NEAR<ONEAR<“ ”
- To the web of science as an example:
NEAR
Up to n words inserted between NEAR / n words and word
Wastewater the AND Treat Wastewater Treatment
Wastewater the NEAR Treat Wastewater Treatment
Wastewater the NEAR /. 3 Treat Wastewater
Recall AND> NEAR> ""
Precision AND <NEAR < ""
The IEEE: W is / n-(variable word order), Pre / n (word order unchanged)
EBSCO: Nn (variable word order), Wn (the same word order)
The SD: W is / n-(variable word order), Pre / n (word order unchanged)
5. Citation Search
- Citation Search also called retrospective search, approach is the use of literature citations retrieved between the relationship between literature and literature.
- By citation searches can be multi-faceted research to understand the situation, the context of the development of retrospective research, find relevant research.
