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Search Results: 1 - 10 of 32136 matches for " 许朗 "
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农业灌溉用水效率及其影响因素分析——基于安徽省蒙城县的实地调查
,黄莺
资源科学 , 2012,
Abstract: 随着水资源问题的日益严峻,用水效率的提高是节水型社会建设的根本要求,农业灌溉用水是我国的用水大户,测算灌溉用水的技术效率对于制定合理的灌溉用水政策,提高灌溉用水效率尤为重要。本文通过实地调查,运用随机前沿分析方法从农户的微观层面对农业生产的灌溉用水效率进行测算,并在此基础上用Tobit模型对影响灌溉用水效率的因素进行深入分析,结果表明:农户的平均灌溉用水效率仅为0.4821,存在很大的节水潜力,农户种植经验的提高、农业的规模化生产、农户节水意识的增强、井灌方式的推广、节水灌溉技术的采用、灌溉水价的改革等都对提高灌溉用水效率产生积极的影响。
琼脂糖光纤湿度传感器响应特性与温度的关系
Relationship between Temperature and the Response of an Optical Fiber Humidity Sensor Fabricated by Agarose
 [PDF]

, 邓焯泳, 张小康
Applied Physics (APP) , 2013, DOI: 10.12677/APP.2013.32006
Abstract:

本文用琼脂糖水凝胶制作了插入损耗为?0.08 dB、在30%~100% RH相对湿度变化范围的光强变化为15 dB的双包层单模光纤湿度传感器,在25℃~34℃的不同温度条件下,检测了该传感器输出光强随相对湿度的变化。根据饱和水汽压与温度的关系和实验结果,证实了被测气体相对湿度较小时,琼脂糖涂层的吸湿能力强,对温度变化敏感;随着相对湿度的升高,吸湿能力降低。在25℃~34℃的温度变化范围内,被测气体相对湿度分别为30%、90%和100% RH时,传感器对温度的灵敏度分别为0.3 dB/℃、0.1 dB/℃和0 dB/℃。实验结果还证实,琼脂糖在饱和吸收水份后的折射率近似等于康宁光纤包层的。本文研究结果说明,在应用光纤湿度传感器时,必须同时监测被测气体的温度,才能严谨地确定被测气体的相对湿度。

A doubly cladding single-mode fiber humidity sensor with insertion loss of ?0.08 dB and optical power variation of 9.47 dB/% RH in the humidity range from 30% to 100% RH was fabricated by agarose. Its responses to humidity range at the different temperature from 25?C to 34?C were tested with a climatic chamber. Based on the Goff-Gratch formula and the experimental results, it has been confirmed that the agarose coating have a great absorbent capacity in a low relative humidity. The sensor had the sensitivity of 0.3 dB/?C, 0.1 dB/?C and 0 dB/?C at the relative humidity of 30% RH, 90% RH and 100% RH, respectively, in the temperature range from 25?C to 34?C. It has also been confirmed that the refractive index of agarose gel was almost equal that of Corningoptical fiber cladding material. It was concluded that the temperature of measured gas must be simultaneously monitored in the application of optical fiber humidity sensor and accurate determination of the RH of the gas.


基于主成分分析的江苏省水资源承载力研究
,黄莺,刘爱军
长江流域资源与环境 , 2011,
Abstract: 随着水资源短缺和水污染问题的加剧,水资源供需矛盾日益突出,水资源承载力已成为衡量区域可持续发展的一项重要指标。以江苏省水资源承载力为研究对象,运用主成分分析法对江苏省的水资源承载力从时间和空间两个角度进行综合评价。研究表明影响水资源承载力的因子主要包括经济发展因子、人口因子和水资源自然状况因子;2000~2009年,江苏省的水资源承载力整体上呈现出稳步递增的趋势;从空间上来看,江苏省内的水资源承载力存在明显的地区差异,苏南的水资源承载力最大,苏中次之,苏北最小,这主要是受到地区经济发展不平衡和水资源条件的影响。为了保证社会经济的可持续发展,必须合理、高效地利用水资源,充分发挥水资源的承载潜力
社会资本对农户参与灌溉管理改革意愿的影响分析
,罗东玲,刘爱军
资源科学 , 2015,
Abstract: 农户参与是推行参与式灌溉管理改革的关键。本文利用安徽省淠史杭灌区的农户调查资料,运用因子分析法从网络、信任和规范3个维度测算了农户社会资本,并采用二元Logistic模型实证分析了社会资本对农户参与灌溉管理改革意愿的影响。研究表明,1农户对周围人的信任度排序为:德高望重的村民>邻居>村干部;农户的社会网络关系相对较差,接触官方信息和互联网信息的机会较少,传统乡村社会规范对农户行为的约束力在下降,农户更加重视自身个体价值和个人利益的获取;2农户社会资本总指数得分分布呈倒U型,说明拥有中等社会资本的农户数量最多,占样本总数的37.3%;3社会信任指数和社会网络指数均对农户参与灌溉管理改革的意愿有显著的正向影响,而社会规范指数的影响则不显著。因此,政府可以着重从社会信任和社会网络的层面采取措施促进农户的参与意愿,同时加强对农村社会规范的培育。
基于“三农”问题的“产、学、研”结合模式
于习法,孙霞,
科技进步与对策 , 2004,
Abstract: 科学技术是第一生产力。解决“三农”问题必须依靠农业科技的推广与应用。实行产、学、研结合是使农业科技成果迅速转化为生产力的重要措施和途径。对目前产、学、研结合的模式进行了分类,并根据对各种模式的成效分析提出了优化的意见和建议。“三农”问题产、学、研结合模式成效分析
超声化学法制备srf2纳米片自组装微球(英文)
 可?,徐 ,朱俊杰?
无机化学学报 , 2009,
Abstract: 通过简单的超声化学方法制备了srf2纳米片自组装微球。合成的产物通过粉末x射线衍射仪、场发射扫描电子显微镜、透射电子显微镜进行了表征和分析,结果表明这些微球是由规则、有序的纳米片组成。而这些纳米片互相垂直连接组装成微球。研究还发现反应物的浓度,配位剂和ph值对产物的形貌和尺寸有着重要的作用。
Measurement of Irrigation Water Efficiency and Analysis of Influential Factors: An Empirical Study of Mengcheng County in Anhui Province
农业灌溉用水效率及其影响因素分析——基于安徽省蒙城县的实地调查

XU Lang,HUANG Ying,
,黄莺

资源科学 , 2012,
Abstract: In the context of problems of water resources becoming increasingly serious, enhancing water use efficiency is the fundamental requirement for building the water-saving society. Agricultural irrigation water is regarded as the major water user in China. It is therefore of great importance to measure the technical efficiency of irrigation water in order to develop reasonable irrigation water policies and improve the irrigation water efficiency. In this paper, stochastic frontier analysis has been performed to measure the irrigation water efficiency from micro-level farmers on the basis of questionnaire surveys. Given the availability and easy-processing of data, the irrigation water of wheat was taken as the primary research objective. A total amount of 250 questionnaires were sent out to investigate the individual behavior of the farmers in their allocation of irrigation water for the wheat in Mengcheng County of Anhui Province. There were 237 valid questionnaires returned. Anhui is one of the major wheat producers of China, so it is of great practical significance to measure the irrigation water efficiency of local wheat on an individual basis. Yield per hm2 is defined as the output. Seed input, chemical input, machinery input, labor input, and irrigation water input are regarded as the essential input variables in building the C-D production function. As the single element efficiency, irrigation water efficiency has been measured based on the technical efficiency in agricultural production of farmers. Results show that both the technical efficiency in agricultural production and the irrigation water efficiency appear to be far less than effective. There is room for improving the efficiency. Meanwhile, the value of irrigation water efficiency is generally lower than the technical efficiency in agricultural production. Thereby, there is large potential for water-saving. As far as the value distribution is concerned, statistics show that the distribution of technical efficiency of agricultural production is more concentrated than the irrigation water efficiency. The distribution of irrigation water efficiency tends to be more dispersed and fluctuant. The Tobit model was used to analyze influential factors affecting the irrigation water efficiency. Results show that the average irrigation water efficiency is just 0.4821; there is still large potential for water-saving. Enhancement of farming experience, extension of agricultural production scale, strengthening of water-saving awareness, promotion of well irrigation, acceleration of water-saving irrigation technologies, as well as the irrigation water price reform can be greatly conducive to improving the irrigation water efficiency.
家庭代际支持对老年人居家养老意愿的影响
Study on the effects of family intergenerational support on elderly’s willingness to choose home-based care mode

郑娟,建强,,苗春霞
- , 2018,
Abstract: 目的 分析家庭代际支持对老年人居家养老意愿的影响,为促进居家养老发展提供对策建议。方法 居家养老意愿现状采用卡方检验进行分析,老年人居家养老意愿影响因素采用二分类Logistic回归分析。结果 仅有296老年人(13.87%)选择居家养老方式。见面频率和子女孝顺程度是影响老年人居家养老选择的重要因素,见面频率较多的老年人选择居家养老的可能性是见面频率较少的老年人的0.041倍;子女不孝顺的老年人选择居家养老的可能性是子女孝顺的老年人的2.113倍。此外,年龄、教育、经济水平、社会保障和健康自评等因素对老年人居家养老意愿有影响。70~79岁和80岁及以上的老年人愿意选择居家养老的可能性是60~69岁老年人的0.509和0.345倍,有社会保障的老年人选择居家养老的可能性是没有社会保障老年人的1.278倍。结论 社区居家养老的发展应该更关注那些没有子女或者与子女情感联系不紧密的老年人。
不锈钢材料砂带磨削试验
王维,潘复生,陈延君,黄云,春霞
重庆大学学报 , 2006, DOI: 10.11835/j.issn.1000-582X.2006.10.022
Abstract: 不锈钢材料具有优良的性能,应用广泛,但属于难磨材料.砂带磨削具有良好的磨削加工性能,笔者采用4种磨料砂带对不锈钢材料进行磨削试验.研究了磨粒与工件在磨削过程中的交互作用机理,讨论了影响材料去除率的因素,用SEM分析了加工表面显微形貌特征,揭示了材料的去除机理和砂带磨损形式.
德甜羊奶果选育
番汝昌,关富,宁东丽,叁卫
热带农业科学 , 2011,
Abstract: 德甜羊奶果是云南省德宏州特有的珍稀水果。该品种于2010年3月30日由云南省园艺植物新品种注册登记办公室组织专家组进行现场鉴定,5月15日登记注册,证书号:云林园植新登第20100006号。该水果营养丰富,鲜果富含维生素C,糖酸比为32.73∶1,是原生种的6.88倍,天然氨基酸含量1.20%,是原生种的1.58倍,且含有镁、钙、铁、硼等9种微量元素。该品种易栽易管病虫害少,丰产早熟经济效益好。种植第二年开始挂果,第四年进入盛果期,盛果期每公顷产鲜果29 040 kg,按批发价10元/kg,六成商品率计算
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