Division of Chinese Academy of Sciences: the top 5% is this kind of 1 area, 6%-20% is area 2, 2 1%-50% is area 3, and the rest is area 4. The division 1-4 area is pyramid-shaped, and the higher the magazine quality;
Thomson Reuters District (ICR): The first 25% (including 25%) is Q 1, the first 25%-50% (including 50%) is Q2, the first 50%-75% (including 75%) is Q3, and the last 75% is Q4. Every subject of JCR is classified according to the influence of journals.
Extended data:
American Science Citation Index (SCI) was founded by institute for scientific information in Philadelphia in 1957, and it is a citation database created and published by institute for scientific information in 196 1 year.
SCI (Science Citation Index), EI (Engineering Index) and ISTP (Science and Technology Conference Index) are three world-famous retrieval systems for scientific documents, which are internationally recognized as the main retrieval tools for scientific statistics and scientific evaluation, among which SCI is the most important. )。
SCI has two partition rules: JCR partition and CAS partition.
According to the impact factor (IF value), all journals of a certain discipline are arranged in descending order according to the impact factor of the previous year, and then divided into four parts (each accounting for 25%), namely Q 1, Q2, Q3 and Q4.
The zoning method of China Academy of Sciences is as follows: the first area journals: the top 5% of the three-year average impact factor of various journals, the second area journals: the top 6% ~ 20%, the third area journals: the top 2 1% ~ 50%, and the fourth area journals: the last 5 1% ~ 100%.
References:
Baidu encyclopedia? Index of scientific citations