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论作物产量差距与增产途径 被引量:1
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作者 张胜全 耿以工 +1 位作者 黄琴 王志敏 《耕作与栽培》 2009年第1期1-4,共4页
当前,一场新的绿色革命正在全球展开,为了实现粮食可持续高产目标,作物科学家在探索作物产量潜力的同时,正致力于缩小作物产量差距的研究。本文介绍了作物产量差距的基本概念与类型,分析了产量差距形成的原因,综述了作物产量差距的研究... 当前,一场新的绿色革命正在全球展开,为了实现粮食可持续高产目标,作物科学家在探索作物产量潜力的同时,正致力于缩小作物产量差距的研究。本文介绍了作物产量差距的基本概念与类型,分析了产量差距形成的原因,综述了作物产量差距的研究进展,并探讨了资源限制投入条件下缩小作物产量差距的可能途径。 展开更多
关键词 粮食 高产 产量差距 资源投入
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利用产量差距方法进行华北冬小麦产量受气候影响规律的分析——以河北省栾城县为例 被引量:8
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作者 郑娜 刘秀位 王锡平 《中国生态农业学报》 CAS CSCD 北大核心 2014年第2期234-240,共7页
为了进一步分析华北气候要素对小麦产量的影响,基于地处华北腹地的中国科学院栾城农业生态系统试验站,采用逐日作物生长动态模型模拟冬小麦生产潜力(Ymp),并计算其与充分灌溉条件下实际产量(Yh)的产量差距(YG),利用相关分析和逐步回归分... 为了进一步分析华北气候要素对小麦产量的影响,基于地处华北腹地的中国科学院栾城农业生态系统试验站,采用逐日作物生长动态模型模拟冬小麦生产潜力(Ymp),并计算其与充分灌溉条件下实际产量(Yh)的产量差距(YG),利用相关分析和逐步回归分析,进行Yh、YG与不同时段气候因子的关系分析。结果表明,抽穗前日照时数和各温度因子与YG表现为正相关趋势,而抽穗后日照时数、日较差与YG为负相关趋势。说明生育前期较好的光温条件更多地增加生产潜力,而后期光照、日较差增加可以更好地满足冬小麦旺盛生长的需要,更多地提升冬小麦的实际产量。从实际产量来看,整个小麦发育期多个时段的日照时数和气温日较差对Yh呈正相关的影响趋势,表明生长季较高的光照和日较差条件对冬小麦实际产量有利。几乎整个发育期降水量与YG表现出负相关趋势,但与充分灌溉条件的Yh相关不显著,说明降水对YG的影响主要在于对生产潜力的减少作用。只有6月上旬降水量与YG呈显著正相关,与Yh有较弱负相关,说明接近成熟时降水对充分灌溉条件的小麦产量可能有不利影响。 展开更多
关键词 华北平原 冬小麦 产量差距 生产潜力 气候变化
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Normative Versus Perceptual Gap Analysis of Hotel Product Quality as a Service to Tourism in Kenya
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作者 Joe Kibuye Wadawi Frederick Jacobus Herbst Nerine Cecilia Bresler 《Chinese Business Review》 2011年第12期1091-1105,共15页
Kenya's tourism business stagnated from 1991 to 2003 and only registered small but steady grew from 2004. One of the sectors that recorded poor performance as a result of the slow growth of tourism is the hotel busin... Kenya's tourism business stagnated from 1991 to 2003 and only registered small but steady grew from 2004. One of the sectors that recorded poor performance as a result of the slow growth of tourism is the hotel business. Despite this slack, stakeholders in Kenya have not tried to assess the extent to which the quality of this sector may impact on destination preference. The ultimate purpose of this research was to establish the quality gap between the expected and the perceived hotel product/service quality from both the perspective of the tourists and the hotel operators in Kenya. It was motivated by the need to create parameters that can elavate the competitiveness of Kenya's tourism using the hotel product/service quality offer. Descriptive quantitative research design was used to establish the secondary objectives and to assess two propositions set for the study. A sample of 211 tourists and 19 hotel operators in two major tourist provinces of Kenya was used to obtain information regarding normative and perceptive hotel product/service quality. Kenya's only destination marketing organisation, Kenya Tourist Board (KTB) marketers were also surveyed to provide insight on Kenya's destination position with regard to the motivation of tourists to visit Kenya. The study established that although the attractions which make tourists come to Kenya are the unique wildlife safari, beach tourism and the natural scenery, hotel product quality and hospitality plays a vital role in motivating tourists to choose Kenya as the destination to visit. However, this study found out that while the tourists and hotel operators agree on the normative hotel product quality level, there is a significant gap between the normative quality and the perceptual quality registered by tourists who used hotel services. The study established that hotel operators only recognize quality regulatory institutions with statutory and legal authority to incriminate facilities that do not comply with laid down operational requirements such as Hotels and Restaurants Authority and the Local Authority Public Health Department. The study has proposed an integrated framework that may be utilized to build a superior national hotel product/service quality so that the economic potential of tourism is maximized in Kenya. 展开更多
关键词 destination marketing TOURISM COMPETITIVENESS Kenya tourism hotel product/service quality
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Understanding the discrepancy between the quality and yield in the synthesis of carbon nanotubes 被引量:2
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作者 Xiao Zhang Pan Li Hongbo Zhang Jie Liu 《Nano Research》 SCIE EI CAS CSCD 2015年第1期296-302,共7页
High-quality carbon nanotubes (CNTs) are promising materials in many applications. However, current chemical vapor deposition (CVD) methods for CNT synthesis suffer from the discrepancy between the quality and yie... High-quality carbon nanotubes (CNTs) are promising materials in many applications. However, current chemical vapor deposition (CVD) methods for CNT synthesis suffer from the discrepancy between the quality and yield of CNTs: Low-quality CNTs can be synthesized with high yield, while high-quality CNTs can only be synthesized with low yield. Here a CVD method has been designed to synthesize both high-quality and low-quality CNTs using the same combination of catalyst and precursor. As a result, we were able to understand the reasons for the low yield in high-quality CNT synthesis and a method was derived to improve their yield. This understanding is an important step towards high- yield synthesis of high-quality CNTs. 展开更多
关键词 carbon nanotubes chemical vapor deposition high quality high yield catalyst lifetime
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