10 research outputs found

    Impact of Soil and Water Conservation on Agricultural

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     针对水土保持工程实施后农业资源—产业系统的变化情况,运用耦合度模型,对安塞县水土保持系统和农业资源—产业系统及其子系统耦合演变过程进行了分析。结果表明:水土保持和农业资源—产业耦合系统演变过程可划分为4个阶段:Ⅰ.水土保持与农业资源—产业系统协调化发展阶段;Ⅱ.水土保持与农业资源—产业系统耗损发展阶段;Ⅲ.水土保持系统退化限制农业发展阶段;Ⅳ.水土保持系统退化农业系统掠夺式发展阶段。安塞县先后经历了Ⅰ,Ⅱ阶段,目前处于第Ⅱ阶段。由于农业系统内部资源、产业协调耦合效率不高,导致农业系统发展潜伏着较大危机,为此,需要在巩固水土保持成果的前提下,通过农户行为优化和政府政策科学导向调整资源、产业结构,避免资源的结构性剩余,形成农业系统内部良性耦合。 更多还原Abstract:Based on changes of agricultural resources-industry coupling system after taking soil and water conservation(SWC)measures,the coupling process of them in Ansai County was analyzed by utilizing the coupling degree model.The results showed that the coupling evolution process could be divided into 4stages including harmonious development,worn development,damaged soil and water conservation achievements limit the development of agriculturalsystem,and agricultural system development sustainable in the case of damaged soil and water conservation achievements.The coupling relations in Ansai County had experienced the first two stages.At present,thelow coordination degree of resources and industry system indicated that agricultural system developmentlurked in a larger crisis.Therefore,it is necessary to consolidate the achievements of SWC and readjust resources and industrial structure through optimization of farmer behavior and scientific political guiding ofgovernment in order to avoid resource surpluses and finally form a positive coupling system

    Assessment Index System of Construction of Commodity-oriented Ecological Agriculture in Ansai County

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    商品型生态农业是市场经济背景下农业生态经济系统相耦合的结果,可以通过生态环境、农业资源、产业态势、经济效益来表征;文章首次依据其演变过程和效果选择其中的16个具体指标,构建了安塞县商品型生态农业建设效果评价指标体系;基于安塞县1998-2009年相关数据和农业生态经济系统演变特征,运用熵值法和专家咨询相结合的方法确定了指标体系中各个指标的权重

    Evaluation on Ecosystem Service Value of Converting Farmland into

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    基于安塞县12a的统计资料,定量评价了安塞县1999—2010年的退耕林生态系统服务价值,并对其外部性价值进行了权重分析和计算,结果表明:安塞县退耕还林已基本达到改善生态环境的首要目的,为区域生态经济发展提供了巨大的生态系统服务价值,总价值为1 027 352万元,其中外部性价值为540 550万元,占总价值的52.62%;各项功能的价值量排序为:固碳释氧>涵养水源>保育土壤>保护生物多样性>净化环境>森林防护。其中最为重要的固碳释氧主要作用于全国范围内,且总的外部性价值超过了总价值的一半,这表明黄土丘陵沟壑区为黄河中下游地区的生态修复和水土保持贡献了巨大的力量。通过本文的外部性价值计算,估算出安塞县的退耕还林补偿上限应为12 325.5元/(hm2.a)Abstract:Based on statistical data,the value of the Converting Farmland into Forest and Grassland Project ofAnsai County in 12years was quantitatively calculated,also its externalities weight analysis was calculated.The results showed that the Converting Farmland into Forest and Grassland Project of Ansai County has achieved the primary target of improving the ecological environment.This project has provided tremendousvalue for the local area′s ecological and economic development.Total value was 1.037×1010 Yuan.The externality value was 5.41×109 Yuan,accounting for 52.62%of the total value.The service value of the functions of forests was in the order of:carbon fixation and oxygen release>water conservation>soil conservation>species conservation> environmental purification>action of forest against natural calamities.Themost important role was carbon fixation and oxygen release,it played the main role in the nationwide,theexternal value was more than half of the total value,indicating that loess hilly region contributed to the tremendous power of ecological restoration and soil conservation in the middle and lower reaches of the YellowRiver region.Calculated by the the external value,the estimated returning farmland compensation ceiling ofAnsai County was 12 325.5Yuan per hectare

    GaAs光电阴极在不同强度光照下的稳定性

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    利用多信息量测试系统分别测试了反射式GaAs光电阴极激活后在0(无光照),33和100 lx白光照射情况下阴极的光电流衰减变化曲线,计算得到其寿命分别为320,160和75 min,阴极稳定性随光照强度的增加而降低,测试了只有光照(100 lx)而无光电流流过阴极时阴极的寿命为100 min.通过比较发现光照比光电流对阴极稳定性的影响更大.还测试了阴极在33 lx光照下量子效率曲线随时间的衰减,发现阴极低能光子的量子效率下降速度更快,导致量子效率曲线形状不断发生变化.基于修正后的反射式阴极量子效率公式对这种变化进行了理论分析,发现与光电子的谷间散射和阴极衰减过程中表面势垒形状的变化有关

    基于CVT变速器的燃油经济性优化潜力研究

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    为了获得某CVT车型速比参数优化对燃油经济性直接改善的潜力,首先,获得了NEDC循环中的发动机运行工况分布特征,市区循环中绝大部分工况都处于最佳燃油经济性曲线以下。随后,根据速比控制方法评估了可以优化的区域,其中市区循环中7%的工况可以优化,市郊循环中部分工况(车速达到70 km/h和100 km/h时),由于速比限值限制无法优化调整。根据仿真结果,仅调整CVT变速器的速比参数,包括调整部分工况至最佳燃油经济性曲线上,或在全部区域内优化,或放宽CVT变速器的速比范围,最大节油潜力的直接贡献达到3.12%

    宝天曼典型森林植被碳库及其分配格局

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    森林类型和群落结构是影响森林植被碳库分配格局的重要因子。拟揭示宝天曼自然保护区栓皮栎林(幼龄)、鹅耳枥林、针叶林和针阔混交林植被碳库及其分配格局,明确森林类型和群落结构对研究区森林植被碳库及其分配格局的影响。采用样地调查法结合木本树种的异速生长方程的方法获得植被碳库,进而划分植物器官碳库以及群落径级。通过单因素方差分析和多重比较的方法,分析林型和群落结构对森林植被碳库及其分配格局的影响。结果表明:(1)栓皮栎林、鹅耳枥林、针叶林和针阔混交林4种林型的总植被碳库分别为54.86、102.22、116.91和132.16 t/hm~2。中龄林和幼龄林间的地上植被碳库、总植被碳库差异显著(P树枝>树根>树叶,栓皮栎林具有最大的根冠比。(2)栓皮栎林、鹅耳枥林和针叶林都以小树[胸径(DBH)鹅耳枥林>针叶林>针阔混交林的趋势,而大树(DBH为50~60 cm)的贡献率则表现为针阔混交林大于其他林型。栓皮栎林中小树对总植被碳库的贡献率为地下大于地上,针阔混交林中大树对植被碳库的贡献率为地上大于地下。建议森林管理应针对不同林型和林龄的特点采取相应的经营方案,以保持较高的植被碳库水平

    洱海蓝藻水华暴发期浮游植物群落变化及影响因素

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    对洱海水质和浮游植物进行了调查,分析了洱海藻类水华暴发季节水质营养水平及浮游植物多样性,并探讨了洱海浮游植物种群演替的环境机制。研究结果表明,洱海蓝藻水华在6—10月份大量暴发,蓝藻数量高达107 cells/L,水华种类为微囊藻(Microcystis)属的一些种,微囊藻在6—10月份占绝对优势,最高可达90%以上。分析5—11月洱海营养水平,其中7月营养水平最高,浮游植物生物量10月份最大(以叶绿素a表示)。使用SPSS里的pearson分析了浮游植物和各理化因子的关系,结果表明相对于其他浮游植物种类,总磷(TP)对微囊藻的影响比较大

    Unemployment and gender relations : occupational trajectories and the experience of job loss among women and men in the metallurgical sector in Campinas (2002 - 2012)

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    Orientador: Angela Maria Carneiro AraujoTese (doutorado) - Universidade Estadual de Campinas, Instituto de Filosofia e Ciências HumanasResumo: O desemprego está relacionado à existência de um excedente de força de trabalho, mas também à atuação das instituições que estruturam o mercado de trabalho para apoiar quem perde sua ocupação em cada sociedade. Além disso, tem importante dimensão subjetiva, pois o/a trabalhador/a sem trabalho pode ou não reconhecer-se como desempregado/a, sendo sua percepção da situação de desemprego e os sentimentos dela decorrentes influenciados pela trajetória profissional e de vida de cada um e cada uma (ou seja, pela relação que cada pessoa desenvolve com o trabalho assalariado, com o(s) coletivo(s) de trabalho e com as empresas por que passou). Neste sentido, as visões sobre o trabalho e sobre o desemprego apresentam diferenças entre mulheres e homens, relacionadas a formas diferenciadas de socialização, às políticas de recursos humanos das empresas (que segregam reiteradamente as mulheres a uma posição secundária no mercado de trabalho) e às políticas públicas que regulamentam o mercado de trabalho e oferecem suporte ao cuidado infantil. Nesta tese investigamos, na perspectiva das relações sociais de gênero, a experiência do desemprego entre os homens e mulheres de uma categoria profissional majoritariamente masculina: a categoria metalúrgica. Procuramos compreender como o desemprego impacta sobre o percurso ocupacional, sobre a vida pessoal, sobre as relações familiares, sobre as estratégias de reinserção no mercado de trabalho e sobre os modelos ideais de comportamento das mulheres e dos homens desta categoriaAbstract: Unemployment is related to the existence of a surplus of labor force, but it is also connected to the performance of institutions that structure the labor market to bolster those who lose jobs in each society. Furthermore, this phenomenon has important subjective dimension, since the unemployed worker may or may not recognized him or herself as such, and one¿s perception depends on each personal and professional path (i.e. it is influenced by the relation that each person develop with paid labor, collective work and also companies). In this sense, there are different points of view of women and men regarding different forms of interaction, gendered human resources policies (which insert women in bottom positions) and public policies that rule the labor market and support childcare. In this thesis we aim to investigate - through the perspective of gender relations - the experience of unemployment among men and women in an environment predominantly male: the metallurgical sector. We seek to understand how unemployment affects distinctively gendered roles of women and men in this sector, as occupational route, personal life, family relations, and strategies of reinsertion into the labor marketDoutoradoCiencias SociaisDoutora em Ciências Sociai

    产量与经济效益共赢的高效生态农业模式:以弘毅生态农场为例

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    化学物质的大量投入以及元素不能循环导致农田生态系统退化,耕地质量和产量均呈下降趋势,食物链受到污染.本研究从低产田开始,通过秸秆养牛、腐熟牛粪还田恢复地力;以物理+生物方法控制虫害;以人工+机械管理杂草,停用农药、化肥和除草剂,同时不用地膜、人工合成激素、转基因种子生产优质安全食品,并在线上与线下销售.10年的长期实验结果表明,所在村庄农田生态环境改善,减少农药用量58.3%;物理+生物控虫效果明显,每盏灯年捕获量从2009年的33 kg下降到2014年的2.1 kg,下降93.8%;年消耗秸秆1000 t,秸秆利用率从1.1%提高到62.5%.有机肥还田提高了土壤生物多样性,有机果园蚯蚓数量317条m~(-2),而普通果园只有16条m~(-2);大量有机肥还田(75 t hm~(-2)),土壤有机质从实验初期的0.7%提高到2.4%.粮食产量从最初的11.43 t hm~(-2)提高到目前的17.43 t hm~(-2),其中冬小麦(Triticum aestivum)、夏玉米(Zea mays)、大豆(Glycine max(Linn.)Merr.)和花生(Arachis hypogaea Linn.)产量分别超出山东省平均水平42.6%,60.9%,32.2%和38.1%.由于质量好,产品已销售往除西藏以外的30个省、市、自治区,经济效益明显,平均每公顷效益是普通农田的3~5倍,带动所在村庄67户农民从事高效生态农业.本研究可为国家制定生态农业发展规划、精准扶贫、农村环境保护等提供科学依据
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