中文摘要：

政策文件替代计量指标作为一种相对较新的指标,为测度学术成果的社会影响力提供了新方向,具有很高的研究价值。本文基于Altmetric.com公司从2013年1月到2016年6月收集到的所有政策文件替代计量指标数据9万余条,通过统计分析揭示其分布特征,旨在为进一步研究提供基础。研究发现,政策文件替代计量指标的相对覆盖率较低,为1.7%;相对引文指标没有及时性优势,平均时滞长达4.5年;论文层次的分布较为均匀,94%的学术成果仅有1条政策文件提及;期刊层次的分布基本遵循布拉德福定律,EFSA Journal等核心期刊是政策文件参考的主要学术成果来源;保健科学和医学是政策文件提及最多的学科,占据了“半边江山”;具有政策文件替代计量指标的学术成果,其替代计量关注度指数总体处于中等偏上水平,没有明显优势。

英文摘要：

Policy documents altmetrics is a relatively novel indicator which provides a new direction for measuring the societal impact of scientific product. The study reveals the immediacy distribution of policy documents altmetrics, as well as the distribution at article level, journal level and discipline level, and the distribution of Altmetric Attention Score, aiming to provide reference for further application study. The study is based on all policy documents altmetrics data collected by Altmetric. com from January 2013 to June 2016, i. e. more than 90 000 records. Pandas package and Matplotlib package are used for data parsing, statistical analysis and visualization analysis. Results show that： 1） Policy documents altmetrics is of low relative coverage being 1.7% which is two times the coverage measured half a year ago. The absolute number has also grown three times, indicating policy documents are increasingly mentioning and using scientific product and the source of policy documents is also increasing. 2） Policy documents ahmetrics shows no immediacy advantage and the average delay is 4. 5 years, 60%of the policy document mentions occur within 1 to 5 years, the delay peaks at 2 years which takes up 8%. 3） Scientific products are barely mentioned by policy documents even if they do.Distribution in the article level is quite even with 94% of scientific product having only 1 policy document mention. The average frequency is 1.1. 4） Distribution in the journal level generally follows the Bradford＇s law and therefore core journals exist as major sources for policy documents＇ reference. The ranking of core journals is not directly related to journal impact factor, for example, Nature and Science both drop out of top five. Whether or not the scientific product is mentioned in policy document is decided by needs, for example, many policy documents of European Food Safety Authority would reference EFSA Journal. Journals from Medicine and Economy are most frequently mentioned, taking up 24 among the top 30. 5