3,000 to 6,000 words. According to the query of Netease News, for example, there are 4,000 to 5,000 words of SCI papers on cancer, 3,000 to 4,000 words of SCI papers on artificial intelligence and 5,000 to 6,000 words of SCI papers on environmental science. Some studies need a lot of data and experimental verification, so there are many words.