百农AK58小麦光合特性的研究     

肖媛  牛立元  茹振钢 《河南科技学院学报》2007,35(3):19-21

在大田条件下,研究了百农AK58及温麦6号、新麦18号、周麦18号 4个小麦品种旗叶的光合作用特性.研究表明:百农AK58、温麦6号、新麦18号和周麦18号旗叶净光合速率/光合有效辐射的拟合系数分别为:0.91,0.59,0.43,0.79;最大净光合速率分别为:22.8μmol·m2·s-1,20.6μmol·m2·s-1,19.4μmol·m2·s-1,21.5μmol·m2·s-1;光补偿点分别为:75.9μmol/(m2·s),24.2μmol/(m2·s),76.9μmol/(m2·s),115.4μmol/(m2·s);CO2补偿点分别为:75.5 μmol/mol,43.7 μmol/mol,75.6 μmol/mol,81.5 μmol/mol.结果表明:百农AK58小麦品种具有较强的耐高温、强光特性和较好的光合生产潜力.  相似文献   

A quadratic programming method for optimal degree reduction of Bezier curves with G^1-continuity     

LU Li-zheng WANG Guo-zhao 《浙江大学学报(A卷英文版)》2007,8(10):1657-1662

This paper presents a quadratic programming method for optimal multi-degree reduction of Bézier curves with G1-continuity. The L2 and l2 measures of distances between the two curves are used as the objective functions. The two additional parameters, available from the coincidence of the oriented tangents, are constrained to be positive so as to satisfy the solvability condition. Finally, degree reduction is changed to solve a quadratic problem of two parameters with linear constraints. Applica  相似文献   

二阶曲线的几何定义与代数定义的等价性     

娄国久 《滨州学院学报》2004,20(4):59-61

建立了有关二阶曲线的 3 个引理,进而论证了二阶曲线的几何定义与代数定度的等价性.  相似文献   

工业用水库兹涅茨曲线分析   总被引：1，自引：0，他引：1  

张兵兵  沈满洪 《资源科学》2016,38(1):102-109

水资源稀缺是21世纪社会经济增长乃至人类生存所面临的重大挑战之一,探索工业水资源利用情况是进一步研究工业水资源节约利用的基础。基于2000-2013年中国31个省份的面板数据,在单位根检验以及协整检验的基础上,对全国以及东、中、西部地区工业水资源利用与工业经济增长之间的关系进行实证检验,结果显示：东部地区二者关系曲线呈现为倒“U”型,且拐点出现在人均工业增加值28 612.150元/人时;中部地区二者关系曲线呈现为“N”型,且拐点分别出现在人均工业增加值15 546.048元/人和35 733.952元/人时;而全国和西部地区二者近似地满足单调递增的关系。经分析,技术创新、结构调整是使工业用水倒“U”型库兹涅茨曲线拐点出现的技术层面的原因,水价提升、水权交易则是其经济激励措施。最后提出应积极进行技术创新、推进产业结构调整以及工业内部行业结构调整,同时适当提升工业用水价格、完善水权交易制度以最终实现工业水资源节约等政策建议。  相似文献   

四维欧氏空间中的向量积运算及其应用     

蔡惠京 《广东广播电视大学学报》2009,18(1):94-98

本文引进四维欧氏空间中三个向量的向量积运算,并讨论这种运算的一些性质。作为应用,将三维欧氏空间中关于曲线的Frenet公式推广到四维欧氏空间,获得了四维欧氏空间中曲线的几个本征参数：曲率、挠率、第三曲率。  相似文献   

广州市城市扩张和经济发展之间的关系   总被引：1，自引：1，他引：0  

郭瑞敏  千怀遂  李明霞  梁圆 《资源科学》2013,35(2):447-454

本文基于广州市1987年-2010年的建成区面积和第二、三产业GDP的统计数据,应用协整分析、库兹涅茨曲线和“脱钩”理论对建成区面积扩张和经济发展之间的关系进行实证研究.结果表明两者之间存在长期协整关系,并得到两者之间的协整方程,通过Granger因果检验,发现两者之间不存在Granger因果关系.通过误差修正模型发现修正系数为负,符合误差修正机制.通过对建成区面积和第二、三产业GDP之关系的库兹涅茨曲线研究,结果表明两者的坐标曲线呈倒“U”型.进一步对建成区面积扩张和第二、三产业GDP进行总量脱钩研究,探究不同发展阶段城市扩张和经济发展的关系.  相似文献   

测地线及其应用   总被引：1，自引：0，他引：1  

张立新 《鞍山师范学院学报》2005,7(4):3-4

介绍了测地线的主要性质,并且给出了它的某些应用.  相似文献   

A comparative study of cross-domain research output and citations: Research impact cubes and binary citation frequencies     

《Journal of Informetrics》2014,8(1):147-161

Across the various scientific domains, significant differences occur with respect to research publishing formats, frequencies and citing practices, the nature and organisation of research and the number and impact of a given domain's academic journals. Consequently, differences occur in the citations and h-indices of the researchers. This paper attempts to identify cross-domain differences using quantitative and qualitative measures. The study focuses on the relationships among citations, most-cited papers and h-indices across domains and for research group sizes. The analysis is based on the research output of approximately 10,000 researchers in Slovenia, of which we focus on 6536 researchers working in 284 research group programmes in 2008–2012.As comparative measures of cross-domain research output, we propose the research impact cube (RIC) representation and the analysis of most-cited papers, highest impact factors and citation distribution graphs (Lorenz curves). The analysis of Lotka's model resulted in the proposal of a binary citation frequencies (BCF) distribution model that describes well publishing frequencies. The results may be used as a model to measure, compare and evaluate fields of science on the global, national and research community level to streamline research policies and evaluate progress over a definite time period.  相似文献   

Components, systems and discontinuities: The case of magnetic recording and playback equipment     

Jeffery Funk 《Research Policy》2009,38(7):1192-1202

Using the history of magnetic recording and playback equipment, this paper explores the relationship between incremental improvements in components and technological discontinuities in systems. It finds that improvements in components have been the major source of all discontinuities in the industry. Focusing just on tape-based systems, all of the basic design approaches had been identified by the late 1950s and thus one of the largest technological challenges for firms has been to modify the design in response to improvements in the magnetic recording density of tape. This paper explores this phenomenon by analyzing data on equipment performance and price, and several design choices for the tape-based equipment. It shows how improvements in the magnetic recording density have changed the tradeoffs that exist between price and different dimensions of performance and between various design choices and thus led to about 10 technological discontinuities in magnetic tape system design.  相似文献   

基于不连续创新的新兴技术形成路径研究   总被引：4，自引：2，他引：2  

宋艳  银路 《研究与发展管理》2007,19(4):31-35,49

基于新兴技术的概念和特点,在前人对技术不连续创新的研究基础上,讨论了新兴技术形成的必要条件是技术进步和应用扩展的不连续的共同作用,由此探讨了新兴技术的形成路径．  相似文献