Individual and Institutional Concentration of Leisure Research in North America

The purpose of this article is to identify key characteristics of the community of leisure scholars in North America and to use patterns derived from data about publication activity as a platform for discussing the nature and implications of concentration in leisure research at the individual and institutional levels. The study uses cluster analysis to detect patterns of research and publication activity among 1785 people who were associated with leisure research in North America in the 1990s, concentrating on the slightly smaller number of people (1631) whose names were listed as authors on at least one publication in all editions of 6 research journals and 14 conference proceedings from 1990 to 1999 inclusive. The results demonstrate that leisure research in North America is concentrated at both the individual scholar and institutional levels. For example, at the individual level, less than one-fifth of authors accounted for more than two-thirds of journal articles and conference papers. The implications of these findings are discussed with reference to issues such as the critical mass of scholars and problems of disciplinary isolation detected by previous researchers.     

Industry-region Position and Economic Performance of Travel and Tourism Service Industry: An Agglomeration Perspective

Numerous studies have attempted to examine industry performance from an agglomeration perspective. However, many are still focused on the manufacturing sector. This study examines the travel and tourism service industry's economic position using an agglomeration perspective and whether this relates to its economic performance. This study discovered that, apart from being related to its intra-region position relative to other industries within the region, the economic performance of an industry in a region is also related to its intra-industry position relative to other distributive regions within the industry and to its national geographical concentration. A more significant finding is that regardless of either the intra-industry or intra-region position of the industry in a region, enhancing agglomeration not only increases competition and profit erosion but also improves labour productivity. For employment creation, it is more effective to develop an industry with more uniform national geographical distribution.     

中国蔬菜生产“以水定地”优化布局研究

[目的]文章以中国蔬菜产业布局为研究对象,通过分析蔬菜生产重心演变路径、蔬菜布局地域集中度以及蔬菜生产空间布局与水资源禀赋的拟合度,为优化我国蔬菜生产空间布局、促进农业节水、保障农业用水安全提供参考依据。[方法]采用1995—2018年我国蔬菜产业的相关数据,运用重心模型、集中度指数等方法,对蔬菜生产的区位特征进行研究,并构建蔬菜生产空间布局与水资源禀赋拟合度指标,对蔬菜生产空间布局与水资源禀赋拟合度进行分析。[结果]我国蔬菜生产重心呈现出整体上向西南方向移动的新趋势,蔬菜生产的地域集中度已经达到较高水平,但蔬菜空间布局与水资源禀赋的匹配度不高,导致蔬菜生产过度依赖人工灌溉,消耗甚至是浪费了大量的水资源。[结论]遵循“以水定地”原则,提出蔬菜产业空间布局与水资源禀赋条件优化匹配的政策建议：推进大宗蔬菜生产重心“西南移”,充分利用南方水资源优势,节约北方水资源;推进耐储运蔬菜的“南菜北运”,解决北方消费市场的蔬菜供给问题;推进北方蔬菜生产“转型升级”,转型生产精细时鲜特菜和节水型蔬菜,升级采用微灌、精灌技术,保持北方蔬菜基地经济水平。     

我国产业集中度影响产业工资水平的实证研究

产业集中度是刻画产业市场结构形状和大企业市场控制力的一个标志性概念,系区分市场结构是趋于垄断还是竞争的主要依据。文章以企业盈利能力的高低决定工资水平为理论基础,通过对中国工业36个行业的数据实证研究了产业工资水平与产业集中度之间的相关性,同时对我国的行政垄断对产业工资水平的影响进行了深入探讨。在此基础上,文章提出打破行政垄断行业工资水平过高的局面,大力推进企业收购兼并和资产重组的政策建议。     

市场集中与空间集聚:现代产业组织演进的两条基本路径

市场集中和空间集聚作为现代产业组织演进的两条基本路径,分别从企业内部与企业之间推动产业组织形态的调整与演进。在工业化发展的不同历史时期,二者在产业组织体系中所处的地位与所起的作用是不同的。二者在功能上不能完全互为替代,在发展趋势上呈现相互融合、功能互补的态势。在我国的现阶段,产业的市场集中和空间集聚都有待于得到进一步的发展和壮大。与此同时,应采取积极有效的途径,实现二者的融合发展。     

阿莫西林克拉维酸钾片含量测定方法的改进

为解决实际应用中克拉维酸钾峰与后相邻杂质的分离度达不到要求的问题,建立了一种同时测定阿莫西林克拉维酸钾片中阿莫西林和克拉维酸钾含量的新方法,采用反相高效液相色谱法(RP-HPLC),Ultimate AQ-C_(18)色谱柱(4.6mm×250 mm,5μm),以pH值为4.4的0.05 mol/L磷酸二氢钠缓冲液为流动相,柱温为35℃,流速为1.0mL/min,检测波长为220nm。结果表明:阿莫西林和克拉维酸钾两主峰与相邻杂质得到完全基线分离,分离度大于1.5;克拉维酸钾对照品溶液质量浓度为0.050 0~0.500 1mg/mL时与峰面积的线性关系良好(r=0.999 8),平均回收率(n=9)为100.14%,RSD值为0.24%;阿莫西林对照品溶液质量浓度为0.100 0~1.000 1mg/mL时与峰面积的线性关系良好(r=0.999 9),平均回收率(n=9)为100.45%,RSD值为0.17%。与原有的《中华人民共和国药典》方法相比,新的阿莫西林克拉维酸钾片含量测定方法专属性好,准确度高,操作简便快捷,结果可靠,可作为一种质量控制方法。     

挖泥船挖深能力计算的理论探讨

针对挖泥船"挖深"提出的计算方法不仅考虑到泥泵的吸上性能NPSHr和所挖泥沙的浓度Cv,而且考虑了泥沙的颗粒组成及分布,对所能挖取泥沙或砾石的颗粒大小进行了核算,兼顾了"浓度"和"粒径"的因素,从而对"挖深"提出一种更合理的计算方法。     

顾客集中与管理层治理——基于薪酬契约和代理成本的视角

本文以创业板上市公司为研究样本,从薪酬契约和代理成本的视角,检验了顾客集中与管理层治理的关系。实证分析结果显示,顾客集中度与高管薪酬和代理成本存在显著负相关关系。结果表明：顾客集中显著影响公司薪酬契约,顾客集中降低了高管薪酬;顾客集中降低代理成本,减轻管理层代理冲突问题。这些研究结论丰富了公司治理的理论内容,同时对于缓解公司代理冲突、改善公司治理矛盾具有重要的现实意义。     

直读式粉尘浓度测量仪示值误差的测量不确定度评定

通过粉尘测量仪表检定装置对直读式粉尘浓度测量仪示值误差进行不确度评定。     

基于fluent的综采工作面采空区内瓦斯浓度场研究

本文通过数值模拟采空区内瓦斯浓度场,从理论上确定了瓦斯浓度的分布情况。进而在对综采工作面瓦斯治理提供了科学的理论依据。