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目前,我国城市化已进入快速发展阶段,对土地的需求越来越大,城市土地利用过程中的问题也日益突出。如何解决好经济发展与保护土地的关系,实现经济发展与土地资源可持续利用的双赢,是当前亟需解决的问题。以聊城市为例,分析了聊城市城市化的发展状况及土地利用中存在的问题,并提出了解决的措施。 相似文献
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通过对山东半岛城市群就业结构的分析,揭示出山东省城市就业结构的一般规律。从对城市群各城市的分析来看,第一产业的就业人员占据较大比重,城市化水平较低。第二产业的从业人员比重较稳定,第三产业的就业比重总体上升,但其中的传统性行业的就业比重趋于下降而新兴行业比重提高。 相似文献
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本文介绍了我国出口室内加热器类产品中暖风机在型式试验过程中常见的安全问题,指出其普遍存在的不符合标准的条款和产生的原因,并提出了解决问题的技术途径和预防措施. 相似文献
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江苏省张家港市金港中心幼儿园以"培养可持续发展的孩子,造就可持续胜任的教师,创办可持续攀高的园所,实施可持续发展的教育"为目标,在中央教科所"生态体验"课题组的引领下,坚持环境教育以人为本,弘扬"科研引领,环境潜润,体验感悟"的教育思想,将绿色教育全方位渗入幼儿的一日生活。开辟了环保展示厅、生态体验场……在环境中融进绿色的理念,发挥"润物无声胜有声"的教育功能。 相似文献
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After the end of pumping the water level in the observation well starts to recover and the reduced drawdown during the recovery period is named as the residual drawdown. Traditional approaches in analyzing the data of residual drawdown for estimating the aquifer hydraulic parameters are mostly based on the application of superposition principle and Theis equation. In addition, the effect of wellbore storage is commonly ignored in the evaluation even if the test well has a finite diameter. In this article, we develop a mathematical model for describing the residual drawdown with considering the wellbore storage effect and the existing drawdown distribution produced by the pumping part of the test. The Laplace‐domain solution of the model is derived using the Laplace transform technique and the time‐domain result is inverted based on the Stehfest algorithm. This new solution shows that the residual drawdown associated with the boundary and initial conditions are related to the well drawdown and the aquifer drawdown, respectively. The well residual drawdown will be overestimated by the Theis residual drawdown solution in the early recovery part if neglecting the wellbore storage. On the other hand, the Theis residual drawdown solution can be used to approximate the present residual drawdown solution in the late recovery part of the test. 相似文献
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本文以山东省两个经济开发区区域环评为例,分析了各开发区在资源和环境方面的优劣势条件,论证了各开发区规划产业定位的合理性,探讨了开发区产业定位合理性评价的指标体系、调整原则、思路、方法,提出了各开发区产业定位的调整建议,并论证了调整后产业定位的合理性,促进了开发区的可持续发展。 相似文献
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埋地管道的杂散电流干扰是威胁管道安全的严重问题.为模拟在阴极电场中开裂涂层下管线表面的化学和电化学状况,本文设计了一种模拟涂覆层开裂起翘的楔形缝隙装置,研究了缝口控制电位分别为-776mVSCE和-950mVSCE时的阴极电场中,X-42钢在NS4溶液中楔形缝隙内电位、溶液Cl-离子浓度、Ph值的分布;并比较了相同缝口控制电位下阴极极化状态时,三种参数的分布.结果表明,当缝外有阴极电场时,缝内试片与阴极极化时一样受到电力线分布的影响,但各试片的电极电位远远高于外加阴极极化时的电极电位,Ph值也明显低于外加阴极极化时的情况:阴极电场对本体溶液中的氯离子产生了屏蔽作用,使得溶液中的氯离子很难迁移进缝内,所以越深入缝隙,氯离子浓度越小,变化也越不明显;缝外阴极电场的屏蔽作用在一定程度上抑制了缝隙内自催化反应的进行,达到了一定的保护效果. 相似文献
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为研究连云港埒子口海域潮流动力特征及其对周边海岸工程的响应,以及为治理埒子口闸下淤积问题提供参考,建立了基于有限体积法离散二维浅水方程的数值模型。采用实测水文资料对模型率定和验证,应用模型分析埒子口潮流动力特征和建设徐圩港防波堤和灌河口导堤后埒子口海域潮流动力的变化。模拟结果表明,建设工程后潮流动力变化较大,埒子口海域涨急流和落急流方向改变,涨、落潮平均流速均减小,距离工程区域越近,流速变化越大。埒子口海域潮流动力减弱将会加重上游挡潮闸的闸下淤积问题,致使埒子口排水不畅,进而增加沂北地区的洪涝风险,所以,相关部门应及时采取措施,保证埒子口排涝畅通。 相似文献
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为高效利用水陆两栖植物鸢尾修复污染水体,本研究通过测定不同的丛枝菌根真菌(AMF)与鸢尾构建共生体系的生长指标、土壤理化性质及植物光合作用指标,探讨不同AMF对水生植物鸢尾的促进作用。结果表明:AMF对鸢尾的促进作用主要体现在地上及地下两部分,其中地下部分通过利用其庞大的菌丝网络吸收土壤中的营养物质,进而促进了鸢尾的生长,其中对比无菌剂侵染的空白植物,摩西球囊霉作用的鸢尾对氮元素的吸收率提高71.75%,磷元素的吸收率提高8.36%,而根内球囊霉作用的鸢尾对氮元素的吸收率提高42.55%,磷元素的吸收率提高9.5%;而地上部分则是通过加强叶片气孔导度的开启来调控植物净光合速率与蒸腾速率之间的平衡,进而提高了鸢尾的最优水资源利用率,加快植物的新陈代谢,最终促进植物的生长发育。其中对于鸢尾光合作用的调节摩西球囊霉的促进效果显著好于(P<0.05)根内球囊霉。 相似文献
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The Indus Irrigation System,Natural Resources,and Community Occupational Quality in the Delta Region of Pakistan 总被引:1,自引:0,他引:1
This study examines the impact of an elaborated irrigation system on the natural resources and society in the deltaic part
of the Indus River in Pakistan. Time series information was collected to analyze the ecological and natural resource dynamics,
and their impacts on the structure and quality of the occupations of the people in the Indus delta during pre- and post-irrigation
system development periods. The information was collected through literature review, reconnaissance, structured questionnaire
survey, focus group discussions, and interviews. The findings revealed that the expansion of the irrigation system and the
resulting reduction in the downstream flow had their differential impacts on the various segments of downstream ecology and
society. Some of the resources, for example the agricultural mudflats have been adversely affected due to the accelerated
seawater intrusion that severely impinged on the paddy farms. On the other natural resources like mangroves, the impacts had
been both negative and positive. On one hand, the diversity of the mangroves species had deteriorated while on other hand,
the mangroves have benefited from such development because of the alleviated pressure of camel grazing as a result of the
occupational change on the part of the camel herders. Furthermore, changes in the hydrological regimes had forced the paddy
farmers and camel herders to switch to fishing as an alternative source of employment and income. Considering that currently
about 87% people are already engaged primarily in marine fishery, this scenario is threatening the sustainability of the fishery
resources as well as the livelihoods of all, the traditional and converted fishermen. The findings of the study are therefore
meant to advocate the different treatments which should be accorded to the various segments of the downstream ecology and
society during the planning of any remedial irrigation projects in order to mitigate the adverse impacts of the previous irrigation
development strategies and of any water resources development to be carried out in the future. 相似文献
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农村商品流通是影响农业发展和农民消费的直接因素,完善农村商品流通网络对开拓农村市场,增加农民收入,发展农村经济具有推动作用。首先论述了农村商品流通网络的内涵;其次提出了基于主导要素的3种农村商品流通网络模型,即交易市场主导型、企业组织主导型和流通技术主导型,并对网络主体及其关系等方面进行了分析;最后提出了农村商品流通网络的发展趋势及其相应对策。 相似文献
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长江经济带是世界上最大的内河产业带和制造业基地,建设长江经济带是新时期中国三大国家发展战略之一,积极、有效地保护长江经济带生态环境具有非常重要的战略意义。本研究从识别突出的大气污染防治问题入手,深入分析大气污染的主要驱动力产业与能源结构,以问题为靶向,提出长江经济带的大气污染防治策略。研究结果发现,占国土面积21%的长江经济带排放了全国34%的二氧化硫、32%的氮氧化物、28%的烟粉尘、44%的挥发性有机物、43%的氨,单位面积污染物排放强度是全国平均水平的1.3~2.1倍,污染物排放远超环境容量。长江经济带126个城市中,6项主要大气污染物年平均浓度全部达标的城市比例不到1/3。颗粒物是影响城市达标的主要污染物。长江经济带产业结构偏重和能源消费以煤为主,是造成大气污染排放量的主要源头,是大气污染的主要驱动力。以解决突出的大气环境问题为核心,将环境质量作为大气污染防治的底线,持续推进空气质量改善,重点措施上,从大气污染驱动力着手,提出优化产业与能源结构、深化多污染物协同控制、推进区域联防联控等大气污染防治对策建议。 相似文献