所有制性质、研发投入与企业社会责任

基于2009—2013年我国493家上市公司的1 132组观测数据,通过数据包络分析计算出上市公司的研发效率,利用独立样本T检验分析国有控股和民营控股的上市公司在社会责任表现以及创新程度方面的差异,再通过一个非平衡面板的多元回归模型,研究企业的研发投入与企业社会责任之间的关系,以及企业的所有制性质对这种关系的影响。研究结果发现:(1)我国国有控股的上市公司的社会责任表现显著优于民营控股的上市公司,但其研发创新投入却不如民营上市公司;(2)企业的研发投入对企业履行社会责任有显著的正向影响;(3)这种正向影响,民营控股上市公司表现得比国有控股上市公司更为显著。基于以上结论,企业(特别是民营企业)可以通过识别研发投入中高社会效益的创新,从而更好地提升本身的社会责任表现。     

自适应非负矩阵分解的人脸识别方法研究

在单样本或者小样本的人脸识别系统中,常常会面临样本数量不足的问题,为解决少样本情况下的分类精度,以及利用原始特征或者目标特点重构的虚拟样本过于单一等问题,提出一种自适应非负矩阵分解（NMF）的人脸识别方法。该方法首先在矩阵分解过程中构造不同矩阵维度和迭代次数参数下的重构样本;然后利用QR分解稀疏表示方法进行人脸分类;最后,通过选取最优参数组合,调整重构样本,直至达到最佳分类效果。在ORL、Yale和AR 3个数据库上的实验结果表明,该算法在最佳参数下,尤其是单样本情况下对比基于原样本方法的准确率平均提高了约5%,最高提高了约10%～15%。     

Sample Sizes and Composition: Their Effect on Recall and Precision in IR Experiments with OPACs

ABSTRACT

This article discusses how samples of records for laboratory IR experiments on OPACs can be constructed so that results obtained from different experiments can be compared. The literature on laboratory IR experiments seems to indicate that the retrieval effectiveness (recall and precision) is affected by the way the samples of records for such experiments are generated. Especially the amount of records and the subject area coverage of the records seems to affect the retrieval effectiveness. This article contains suggestions for the construction of samples for laboratory IR experiments on OPACs and demonstrates that the retrieval effectiveness is affected by different sample size and composition.     

企业信息化对经济增长贡献的实证研究

影响传统企业经济增长的主要因素是资本和劳动,各因素对传统企业产值增加的贡献可借助柯布-道格拉斯生产函数来度量。随着企业信息化浪潮的推动,影响现代企业经济增长的因素不仅仅是资本和劳动,另一个更重要因素是企业信息化投入,信息化投入渗透到资本和劳动两因素中,但该因素对企业经济增长的贡献如何测度,以及如何与劳动、资本两因素对企业经济增长贡献进行比较?基于这一点,在比较几种测度方法基础上,分别调研5个企业取得各自的时间序列数据,提出基于企业信息化投入的企业经济增长模型,并对测得的企业信息化贡献系数从理论和案例两方面进行分析。指出了对处于诺兰模型第二阶段的企业,在实施和评价企业信息化贡献时,参考该模型具有重要意义。     

微波样品处理技术应用进展

综述了微波样品处理技术的原理、特点及应用。     

干燥箱溶样FAAS法测定头发中锌

由干燥箱提供低温环境 ,对头发样品进行消解处理 ,用FAAS法测定人发中锌 .实验结果表明 ,该法具有省时、节约试剂、消解完全等优点 .且本法测定人发中的锌 ,获得满意的精密度、准确度     

法拉第效应实验中样品介质的色散与波长的关系

介绍了在法拉第效应实验中确定样品介质的色散dn／dλ和波长λ之间关系的两种方法。     

Selection procedures in sports: Improving predictions of athletes’ future performance

The selection of athletes has been a central topic in sports sciences for decades. Yet, little consideration has been given to the theoretical underpinnings and predictive validity of the procedures. In this paper, we evaluate current selection procedures in sports given what we know from the selection psychology literature. We contrast the popular clinical method (predictions based on overall impressions of experts) with the actuarial approach (predictions based on pre-defined decision rules), and we discuss why the latter approach often leads to superior performance predictions. Furthermore, we discuss the “signs” and the “samples” approaches. Taking the prevailing signs approach, athletes’ technical-, tactical-, physical-, and psychological skills are often assessed separately in controlled settings. However, for predicting later sport performance, taking samples of athletes’ behaviours in their sports environment may result in more valid assessments. We discuss the possible advantages and implications of making selection procedures in sports more actuarial and sample-based.     

The balance and imbalance of sampling former teachers hidden-by-choice: a snowball in summer

ABSTRACT

In this paper, we explore the challenges inherent in conducting research with a hidden population – how to conduct research with teachers who have left the classroom. Capturing the storied experiences of this group is vital to understanding how to effectively recruit, prepare, support, and sustain teachers in US classrooms for our next generation of students. Although not typically considered vulnerable, this population of “teacher leavers” remains hidden-by-choice because of a voluntary severing of ties with former schools and school districts. In this paper, we chronicle our efforts to identify an appropriate sampling method for this population, our selection of snowball sampling because of the hidden nature of individuals, and our efforts to use snowball sampling to construct a national sample of teacher leavers. We conclude by identifying the resulting areas of balance and imbalance in our sample, their possible explanations, and their subsequent implications for informing thoughtful sampling methodology.     

地质样品的一次阴离子色谱法Hf分离及其MC-ICP-MS分析

本文建立了适合MC-ICP-MS测试地质样品中Hf同位素的一次阴离子交换化学分离方法。使用常规的阴离子交换树脂就可以完成Hf与干扰元素和基体元素的分离,避免了当前广泛采用的多次离子交换柱的麻烦,也无需使用特效树脂,HF处理样品后,也不必使用HClO4赶尽HF.Hf的回收率大于90%,过程空白约为50pg。岩石标样的重复分析表明,该方法简单、快速、经济、有效,尤其适合年轻地质样品Hf同位素组成分析。