| Three multidisciplinary journals, Nature, Science and PNAS, were selected as samples and the obsolescence for scientific literature and also the measure methods were studied. Both citied and citing data during2000to2011were collected from JCR and WOS respectively. Based on the data, the values of three measures of obsolescence which are half-life, the peak citation age and Price index are calculated in both cited and citing ways. The results showed that aging speed of all three journals is decline and the age range of literature being used currently is expand. The journal with higher influence has lower obsolescence speed in the aspect of being cited. There are many similarities in measurement results of Nature and Science. In addition, there are also theoretical studies about content of indicators, the characteristics of synchronic method and journals as studied objects in this paper.The main innovations in this dissertation include the inquiry into multidisciplinary journals aging and putting forward a new quantitative indicator called declining index according to cumulative percent curve of citation. The rationality of this new indicator is examined as well. |
