The first, second, third and fourth zones of sci refer to the division of SCI papers, and there are two types of SCI journals with wide influence: one is the division made by Thomson Reuters (called Thomson Reuters division for short); The second is the division made by the National Science Library of China Academy of Sciences (referred to as the division of Chinese Academy of Sciences). Thomson Reuters branch.

Thomson Reuters publishes a journal citation report (JCR) every year. JCR has counted more than 86,000 SCI journals such as Impact Factor. JCR divides journals into 176 different disciplines. Classify each topic according to the impact factors of journals.

On average, it is divided into four areas: Q 1, Q2, Q3 and Q4. The top 25% (including 25%) of journals with impact factors are divided into Q 1 area, the top 25% ~ 50% (including 50%) is Q2 area, and the top 50% ~ 75% (including 75%) is Q3 area. The number of periodicals in Thomson Reuters is divided into four parts on average.

China Academy of Sciences is divided into six categories: mathematics, physics, chemistry, biology, earth science, astronomy, engineering technology, medicine, environmental science, agriculture and forestry science, social science, management science and comprehensive periodicals. Then, the journal 13 is divided into four grades, that is, four districts. According to the influence factors of various periodicals.

The first 5% is 1 zone, 6% ~ 20% is zone 2, 2 1% ~ 50% is zone 3, and the rest is zone 4. In the branch of Chinese Academy of Sciences, there are few magazines in 1 and 2 areas, and the quality of the magazines is relatively high, which are basically the top journals in this field.