The h-index: A case of the tail wagging the dog?     

Quentin L. Burrell 《Journal of Informetrics》2013,7(4):774-783

From the way that it was initially defined (Hirsch, 2005), the h-index naturally encourages focus on the most highly cited publications of an author and this in turn has led to (predominantly) a rank-based approach to its investigation. However, Hirsch (2005) and Burrell (2007a) both adopted a frequency-based approach leading to general conjectures regarding the relationship between the h-index and the author's publication and citation rates as well as his/her career length. Here we apply the distributional results of Burrell, 2007a, Burrell, 2013b to three published data sets to show that a good estimate of the h-index can often be obtained knowing only the number of publications and the number of citations. (Exceptions can occur when an author has one or more “outliers” in the upper tail of the citation distribution.) In other words, maybe the main body of the distribution determines the h-index, not the wild wagging of the tail. Furthermore, the simple geometric distribution turns out to be the key.  相似文献   

中国冰雪运动企业空间格局演化特征及影响因素研究     

刘晨月 《武汉体育学院学报》2022,56(2):65-71

冰雪运动企业是冰雪运动产业蓬勃发展的重要载体,探究冰雪运动企业空间格局演化特征及影响因素,对于提升冰雪运动普及程度,促进区域冰雪运动产业集聚发展具有重要意义。以中国冰雪运动企业为研究对象,运用最近邻指数、标准差椭圆和核密度分析法,探索2000年、2005年、2010年、2015年和2020年中国冰雪运动企业的空间格局特征及演化趋势,并借助OLS模型解析影响冰雪运动企业空间布局的核心要素。结果表明:中国冰雪运动企业整体空间布局呈现集聚分布,向外扩散趋势不断减弱而集聚态势日益增强;中国冰雪运动企业分布的热点集聚区主要沿着“西南-东北”方向集中在东北地区、京津冀、长三角及珠三角地区,不同时间节点冰雪运动企业呈现不同分布密度;中国冰雪运动企业空间布局的形成是人口规模、经济实力、产业结构、政策支持、固定资产投资、消费需求、交通条件、雪场数量等多种要素综合作用的结果,且不同区位主导因素有所差异。最后,根据实证研究结论,提出相应对策性建议:借势北京冬奥会东风,冰雪运动产业聚焦空间布局、人才培养、政策扶持、产业融合、数字技术,推动产业高质量可持续发展。  相似文献   

Identification of the activity source of CO2 electroreduction by strategic catalytic site distribution in stable supramolecular structure system     

Sheng-Nan Sun  Ning Li  Jiang Liu  Wen-Xin Ji  Long-Zhang Dong  Yi-Rong Wang  Ya-Qian Lan 《国家科学评论(英文版)》2021,8(3)

Identification of the real catalytic site in CO₂ reduction reaction (CO₂RR) is critical for the rational design of catalysts and the understanding of reactive mechanisms. In this study, the catalytic activity of pyridine-containing materials was for the first time structurally demonstrated in CO₂RR by crystalline supramolecular coordination compounds model system. The system consists of three stable supramolecular coordination compounds (Ni-TPYP, Ni-TPYP-1 and Ni-TPP) with different numbers (4, 2 and 0) of active pyridine groups (i.e. uncoordinated pyridine nitrogen atoms). The electrocatalytic test results show that with the decrease of the number of active pyridine groups, the CO₂RR performance is gradually reduced, mainly showing the reduction of highest FE_CO (99.8%, 83.7% and 25.6%, respectively). The crystallographic, experimental and theoretical evidences prove that the CO₂RR activity is more likely derived from uncoordinated pyridine nitrogen than the electrocatalytic inert metal nickel in porphyrin center. This work serves as an important case study for the identification of electrocatalytic activity of pyridine-containing materials in CO₂RR by simple supramolecular model system.  相似文献   

Exploring the Boundary Conditions of the Redundancy Principle     

Matthew T. McCrudden  Carolyn J. Hushman  Scott C. Marley 《Journal of Experimental Education》2013,81(4):537-554

This experiment investigated whether study of a scientific text and a visual display that contained redundant text segments would affect memory and transfer. The authors randomly assigned 42 students from a university in the southwestern United States in equal numbers to 1 of 2 conditions: (a) a redundant condition, in which participants studied a scientific text that described plate tectonics and a corresponding visual display that contained redundant segments from the text; or (b) a nonredundant condition, in which participants studied the scientific text and a corresponding visual display that lacked the redundant text segments. Embedding redundant text segments within the visual display enhanced performance on 3 measures of memory but not on a measure of transfer. The authors discuss the theoretical and practical implications using the cognitive theory of multimedia learning.  相似文献   

On the misinterpretation of histograms and box plots     

Stephanie Lem  Patrick Onghena  Lieven Verschaffel  Wim Van Dooren 《教育心理学》2013,33(2):155-174

Recent studies have shown that the interpretation of graphs is not always easy for students. In order to reason properly about distributions of data, however, one needs to be able to interpret graphical representations of these distributions correctly. In this study, we used Tversky’s principles for the design of graphs to explain how 125 first-year university students interpreted histograms and box plots. We systematically varied the representation that accompanied the tasks between students to identify how the design principles affected students’ reasoning. Many students displayed misinterpretations of histograms and box plots, despite the fact that they had the required knowledge and time to interpret the representations correctly. We argue that the combination of dual process theories and Tversky’s design principles provides a promising theoretical framework, which leads to various possibilities for future research.  相似文献   

Spatial Ability: A Neglected Talent in Educational and Occupational Settings     

Harrison J. Kell & David Lubinski 《Roeper Review》2013,35(4):219-230

For over 60 years, longitudinal research on tens of thousands of high ability and intellectually precocious youth has consistently revealed the importance of spatial ability for hands-on creative accomplishments and the development of expertise in science, technology, engineering, and mathematical (STEM) disciplines. Yet, individual differences in spatial ability are seldom assessed for educational counseling and selection. Students especially talented in spatial visualization relative to their status on mathematical and verbal reasoning are particularly likely to be underserved by our educational institutions. Evidence for the importance of assessing spatial ability is reviewed and ways to utilize information about individual differences in this attribute in learning and work settings are offered. The literature reviewed stresses the importance of spatial ability in real-world settings and constitutes a rare instance in the social sciences where more research is not needed. What is needed is the incorporation of spatial ability into talent identification procedures and research on curriculum development and training, along with other cognitive abilities harboring differential—and incremental—validity for socially valued outcomes beyond IQ (or, g, general intelligence).  相似文献   

基于市场类型与古诺模型的供应商管理库存实施后的利润分配     

钮浩  刘仲英  张宸 《上海海事大学学报》2008,29(2):62-65

为解决基于市场类型的寡头行为古诺模型的上下游企业合作中的价格制定问题,在供应商管理库存(Vendor Managed Inventory, VMI)能够增加供应链整体利润的基础上,通过经济学市场分类方法,用寡头行为的古诺模型对供应链中处于完全竞争市场的上游与处于寡头垄断市场的下游,在进行利润分配的谈判中对利润分配的工具,即采购价格的形成机制进行研究.指出由于双方所处的市场类型不同导致其议价能力的不同,从而采购价格的形成机制具有独特性,并对其建立定量分析模型.  相似文献   

空间通信系统模拟与QoS性能的研究     

李彪  张灿  付前程 《中国科学院大学学报》2008,25(4):530-537

空间通信链路由于其固有的特点（长传播延迟、可变延迟和高误码率）,对空间通信的服务质量QoS(Quality of Services)提出了新的要求和挑战。提出了空间通信系统模拟的体系结构,实现了基于卫星工具包STK(Satellite Toolkit)的空间通信系统的模拟,并开发了空间通信系统的QoS性能测量软件,同时对QoS性能进行了分析。  相似文献   

评估城市电网供电能力的两个主要问题     

卫宏 《苏州市职业大学学报》2008,19(3):60-63

基于模糊理论对城市电网供电能力进行评估时,需要解决的两个关键问题：一是建立模糊评估隶属函数,二是因各因素的影响程度不同,需确定其权重。介绍了隶属度函数确定的基本方法;并用改进的层次分析法确定权重,该方法将构造判断矩阵的方法进行改进,从根本上消除不一致数据,简化计算过程,得到权重向量。最后通过算例对区域供电能力进行分析,验证了该方法的准确性和可行性。  相似文献   

轮椅竞速100 m速度特征和速度分配的研究   总被引：2，自引：1，他引：1  

程其练  王飚  周美芳  裴艺  熊和平 《北京体育大学学报》2008,31(8)

通过对国内优秀男女轮椅竞速运动员进行的100 m测试和获取的数据,初步探明了100 m的总体竞速特征;并采用聚类分析对100 m全程进行阶段划分;用偏相关分析对阶段速度、全程平均速度的关系进行研究;制定了不同成绩下阶段速度分配表为训练提供模式目标。结论:轮椅竞速100 m的总体速度特征为全程速度处于上升期;100 m全程有三个明显阶段:起动段、起动加速段、加速段;各阶段速度对总成绩都有很大程度的影响;基于样本数据下的速度分配表在实践中有应用价值。  相似文献