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641.
以甘肃定西安家沟小流域为典型研究区,基于TM、ALOS遥感影像解译和地面长期水文数据,深入分析了1997至2010年间流域土地利用变化特征及其产流产沙效应。结果显示,(1)14年间,流域林灌草面积分别增加160.23%、176.33%和80.75%;坡耕地、居民地、裸地和梯田面积分别减少25.57%、0.16%、48.45%和21.52%。以2005年为时间节点,发现前期灌草增加较多、裸地减少明显,后期则是乔木增加比例和坡耕地减少比例更为显著,彰显出不同历史阶段植被恢复的策略变化。(2)流域出口多年平均径流量和输沙量分别由前期的18 249 m3和6 383 kg锐减至后期的2 292 m3和2 267 kg,流域土地利用/覆被有效增加是其主要驱动。(3)春冬季节,由于降雨稀少、径流泥沙的本底值很低,前后两个阶段的水沙输移量差异较小,土地利用/覆被变化的影响相对尚不显著。但在夏秋季节,随着降雨事件增多,土地利用/覆被变化减水减沙的效应趋于显性化。 相似文献
642.
643.
土地利用潜力水平与土地集约利用紧密相关。为充分了解我国土地利用潜力研究状况,从土地利用潜力内涵、分尺度研究内容及特点、研究方法三个方面重点阐述了国内当前的研究状况。以此为基础,提出我国土地利用潜力研究主要存在以下四个方面不足:①研究内容上,以土地利用潜力评价为主,其他研究如潜力来源的分析、土地挖潜措施研究、土地利用潜力与其他学科的交叉略显薄弱;②理论基础与学科借鉴程度较弱;③省级、市级或区县级分尺度研究特色和侧重点不足;④研究结果的应用仍需加强。并提出以下四点展望:①推进理论创新,加强理论借鉴;②推进内容创新,拓宽研究视角;③推进方法与技术创新,促进学科发展;④推进研究结果应用,加强跨领域交叉研究。文章有利于探寻土地利用潜力研究方向和突破口,拓展其研究领域深度与广度,对于我国土地集约利用水平的提升具有重要的实践指导意义。 相似文献
644.
基于RS和GIS技术的区域农田灌溉量预报研究及应用 总被引:2,自引:0,他引:2
区域尺度上开展农田灌溉量预报需要考虑土壤、作物和大气的空间差异性。论文针对农田灌溉现状分别建立了需水量灌溉预报模型和土壤湿润层灌溉预报模型,并在预报模型中引入RS和GIS技术来考虑预报参数的空间差异性,初步实现了区域尺度上250 m分辨率网格化的农田灌溉量预报,并在北京地区冬小麦灌溉量预报中进行了应用。结果表明:北京地区2010年冬小麦6月灌浆期间和11月下旬越冬前冻水的预报灌溉量分别为375 m3/hm2和600 m3/hm2,均较现行农业生产中建议的灌溉量明显偏少,具有节水经济效益潜力。这些结果显示了RS和GIS技术在区域尺度上农田灌溉预报中的良好应用潜力,且预报结论和应用效果能达到较好统一。 相似文献
645.
农业适度规模经营是解决农业资源优化利用最有效的手段之一,也是缩小城乡差距、保障国家稳定的最有力措施。研究以江苏省为例,在对其农业规模化的可能性和必然性论证的基础上,运用非线性模型探讨发达地区在保障粮食自给率达到80%以上的前提下,如何实现农业规模经济的稳定增长及其最适增长空间。结果表明,对于拥有良好农业资源和厚实经济基础的江苏,最适粮食自给率应维持在82.5%~84.9%之间,此时的粮食作物、一般经济作物和高效经济作物最佳用地比为68 ∶20 ∶12。在现有规模化水平上,规模经济的最适增长潜力界于6.40%~7.54%之间。此外,非线性模型能较好地模拟出不同粮食自给率下的江苏省农业规模化曲线,确定不同类型的作物用地空间及经济收益,其结果符合江苏省农业发展的特征,对江苏农业的规模化发展具有较强的辐射性,该方法可用于对类似地区农业资源优化利用分析。 相似文献
646.
EFFECTS OF SCALE ON LAND USE AND WATER QUALITY RELATIONSHIPS: A LONGITUDINAL BASIN‐WIDE PERSPECTIVE1
Nancy E. Gove Richard T Edwards Loveday L. Conquest 《Journal of the American Water Resources Association》2001,37(6):1721-1734
ABSTRACT: Human land use is a major source of change in catchments in developing areas. To better anticipate the long‐term effects of growth, land use planning requires estimates of how changes in land use will affect ecosystem processes and patterns across multiple scales of space and time. The complexity of biogeochemical and hydrologic interactions within a basin makes it difficult to scale up from process‐based studies of individual reaches to watershed scales over multiple decades. Empirical models relating land use/land cover (LULC) to water quality can be useful in long‐term planning, but require an understanding of the effects of scale on apparent land use‐water quality relationships. We empirically determined how apparent relationships between water quality and LULC data change at different scales, using LIJLC data from the Willapa Bay watershed (Washington) and water quality data collected along the Willapa and North Rivers. Spatial scales examined ranged from the local riparian scale to total upstream catchment. The strength of the correlations between LTJLC data and longitudinal water quality trends varied with scale. Different water quality parameters also varied in their response to changes in scale. Intermediate scales of land use data generally were better predictors than local riparian or total catchment scales. Additional data from the stream network did not increase the strength of relationships significantly. Because of the likelihood of scale‐induced artifacts, studies quantifying land use‐water quality relationships performed at single scales should be viewed with great caution. 相似文献
647.
Strategic Environmental Assessment of Plans and Programs: A Methodology for Estimating Effects on Biodiversity 总被引:1,自引:0,他引:1
We developed a methodology for biodiversity evaluations within the process of Strategic Environmental Assessment and we applied
it to the estimation of the effect of two Regional Plans of Development on all bird species inhabiting the Castilla y León
region (northwestern Spain). The methodology is based on the evaluation of the effects of main development actions on the
habitat requirements of species. From these evaluations, and from data on the current distribution and population size (number
of individuals) of each species, we estimated the most likely pattern of distribution and population size after the full implementation
of the plans for each species. The impacts of the plans were quantified as the differences between the pre- and postproject
patterns after codifying them to compensate for differences in the quality of the information available among species. Overall,
we conclude that the proposed methodology fulfills the requirements for its use within the SEA process as it allows for the
assessment of cumulative impacts on every species, highlighting the development directions and the habitat types with major
impacts, and ascertaining whether impacts affect species with either low or high conservation and/or economic value. Generalization
of the proposed methodology to other regions or species will require wildlife-habitat models adequate for SEA analyses, so
that we also propose guidelines for the development and validation of these models. 相似文献
648.
FERNANDO TOMÁS MAESTRE GIL 《Environmental management》2001,28(2):149-163
Local scale has an important role in environmental management. In Spain, rapid industrialization has occurred in the last
three decades, leading to substantial changes in socioeconomic relations and resulting in significant environmental degradation.
This paper describes the environmental status of the township of Sax (Alicante, in southeast Spain), which has passed from
agriculture to industrial manufacturing in 50 years. The human population has grown exponentially during the second half of
the 20th century, with a 91% increase from 1955 to 1995, coinciding with strong growth in manufacturing (factories increased
fivefold in the period 1955–1976) and important changes in the working population and land use. Illegal rubbish dumps, water
pollution, forest fires, erosion, and degradation of wildlife habitats are the main outcomes of these dramatic socioeconomic
and demographic changes. The administration has focused on the control of water pollution and waste management, while nongovernmental
organizations have concentrated on the prevention of forest fires and the development of environmental education programs.
These measures are insufficient to manage current environmental degradation, and an environmental management plan for the
study area is discussed. Increasing effort in waste management and industrial wastewater control, changes in land-use policy,
and the creation of an advisory committee to increase public participation in decision-making have been identified as environmental
target objectives for the coming years. 相似文献
649.
二溴次氮基丙酰胺的合成及其性能 总被引:1,自引:0,他引:1
通过实验合成了一种杀菌、阻垢剂——二溴次氮基丙酰胺(DBNPA)。红外及质谱谱图分析表明,产品即为DBNPA。测试了DBNPA在冷却水系统中的杀菌、除粘和缓蚀性能。结果表明,在冷却水系统中投加15mg/L的DBNPA,1h后的杀菌率为99%以上,而且该效果至少可持续48h;4h后就能使冷却塔内的粘泥质量浓度上升至原来的3倍以上;挂片的腐蚀速率由未加药前的0.800mm/a下降至0.052mm/a。 相似文献
650.