The impact factor, often abbreviated IF, is a measure reflecting the average number of citations to articles published in science and social science journals. It is frequently used as a proxy for the relative importance of a journal within its field, with journals with higher impact factors deemed to be more important than those with lower ones. The impact factor was devised by Eugene Garfield, the founder of the Institute for Scientific Information (ISI), now part of Thomson Reuters. Impact factors are calculated yearly for those journals that are indexed in Thomson Reuter's Journal Citation Reports.
In a given year, the impact factor of a journal is the average number of citations to those papers that were published during the two preceding years.[1] For example, the 2008 impact factor of a journal would be calculated as follows:
A = the number of times articles published in 2006 and 2007 were cited by indexed journals during 2008
B = the total number of "citable items" published in 2006 and 2007. ("Citable items" are usually articles, reviews, proceedings, or notes; not editorials or Letters-to-the-Editor.)
提升卡
沉默卡
喧嚣卡
千斤顶
