Middle and lower reaches The full name of SCI is Science Citation Index, which is a citation database founded by Dr. eugene garfield from institute for scientific information, USA on 1957 in Philadelphia, USA. SCI journal * * * is divided into four regions, Q 1, Q2, Q3 and Q4. Divide the area according to the influence factors from high to low. The first area has the highest impact factor, and the fourth area has the lowest. The third area belongs to the middle and lower reaches of SCI journals. Because of the difficulty of publishing SCI journals, many domestic authors will choose three or four regions to do their best, one in three regions and one in four regions.