Impact FactorThe Impact Factor is the most widely referenced quality measure amongst academic publications. It is defined as theratio between citations and recent citable articles published in a journal; the average number of citations received perpublished article. The following is an explanation of how Thomson Reuters calculate Impact Factors.Calculating Impact FactorsCitations in 2007 to articles published in: 2006 187 total citations2005 318 total citationsSum 505Number of articles published in: 2006 54 total articles2005 46 total articlesSum 100Calculation: 505 Total citations to articles published in 2005 and 2006100 Number of articles published in 2005 and 2006The 2007 Impact Factor for the journal is 5.050Impact Factors vary greatly by subject discipline and comparison is only meaningful within the same subject category or group.来自：爱思唯尔论文吧，里面有很多实用的论文投稿写作指南，网站地址一搜便知