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681.
辨析持续农业与农业可持续发展的概念,分析中国传统农业中所具有的持续农业的内涵,提出生态农业是实现中国农业可持续发展的根本途径。 相似文献
682.
Environmental Effects of Aquifer Overexploitation: A Case Study in the Highlands of Mexico 总被引:7,自引:0,他引:7
There are several environmental processes occurring under aquifer overexploitation conditions. These processes include groundwater
table decline, subsidence, attenuation and drying of springs, decrease of river flow, and increased pollution vulnerability,
among others processes. Some of these effects have been observed on the Upper Basin of the Lerma River. The Lerma River begins
in the SE of the Valley of Toluca at 2,600 m asl, in the wetland known as Lagoons of Almoloya del Río. This wetland is made
up of a group of lagoons, which are an important aquatic system from an environmental point of view. The water inflow of this
wetland is a discharge of springs, which occur between the fractured volcanic material of the mountain range and granular
volcanic–continental deposits of the Valley of Toluca aquifer. The intensive exploitation of the Valley of Toluca aquifer
to supply urban and industrial water to Mexico City and Toluca began in 1950 and is responsible for a steady decline of piezometric
levels of 1–3.5 m/yr. Other effects of this exploitation—the drying of the wetland, the decrease of river flow and the land
subsidence—caused serious ecological and social impacts. The authorities declared this aquifer as overexploited in order to
reduce the exploitation and preserve the availability of water resources in this important region. 相似文献
683.
684.
利用康平县1959—2008年气象观测资料,分析了康平县近50a气候变化规律特征,论述了增大森林覆盖率对未来气候可能产生的调节作用。结果表明:在全球变暖的大背景下,康平县的气温增高、蒸发量增大、风力减弱、降水量呈下降趋势且干旱少雨期增长;植树造林增加植被覆盖率对防风固沙、改善康平县生态环境有着积极的促进作用,但对降水量的增加作用有限。 相似文献
685.
以青海省互助土族自治县为典型研究案例,根据互助县自然条件、地貌类型、资源状况、生态区位、主导生态系统服务功能以及社会经济发展等情况,按照地域连片、主导功能相对一致的原则,对全县进行生态功能区划,在此基础上再进行全县主体功能区划,在研究区域范围4个生态功能区及4个主体功能区合理划分的基础上,提出了促进区域生态建设的对策和建议。研究结果可为构建互助县国土生态安全格局,保护生态环境、促进当地社会经济发展以及生态文明建设提供参考和安全保障。 相似文献
686.
我国生态环境补偿机制的完善与可持续发展关系探讨 总被引:1,自引:0,他引:1
阐述了我国生态环境价值被低估甚至缺失的状况。分析了我国生态环境价值被低估的表现及生态环境补偿机制的完善与可持续发展的关系。指出政府亟需通过适当的制度安排,从建立健全生态环境的经济补偿机制、经济赔偿机制、经济处罚机制.经济激励机制.加大财政转移支付中生态补偿的力度,积极探索市场化生态环境补偿模式,建立资源环境价值评价体系,建立生态环境保护标准体系等方面,完善生态环境补偿机制,为可持续发展提供重要的制度保障。 相似文献
687.
喀斯特土壤水分变化研究 总被引:5,自引:2,他引:5
土壤含水率的高低与生态变化的关系密切,尤其是在岩溶地区。土壤含水率对生态的影响主要表现在两个方面,其一是含水率的高低可以间接影响岩溶地区的水土流失,对生态的保护有很重要作用;其次是对岩溶地区生态的恢复有重要意义。本文从土壤含水率的实测着手,探索了土壤含水率与植被类型、土壤厚度等方面的关系, 揭示了喀斯特土壤含水率的发育特征与时段变化规律,从而对岩溶地区的生态环境保护提出了建设性意见。 相似文献
688.
689.
690.
Modelling the effects of eutrophication, mitigation measures and an extreme flood event on estuarine benthic food webs 总被引:1,自引:0,他引:1
Alexandra Baeta Nathalie NiquilJoão C. Marques Joana Patrício 《Ecological modelling》2011,222(6):1209-1221
Human-mediated and natural disturbances such as nutrient enrichment, habitat modification, and flood events often result in significant shifts in species composition and abundance that translate into changes in the food web structure. Six mass-balanced models were developed using the “Ecopath with Ecosim” software package to assess changes in benthic food web properties in the Mondego estuarine ecosystem (Portugal). Field, laboratory and literature information were used to construct the models. The main study objective was to assess at 2 sites (a Zostera meadow and a bare sediment area) the effects of: (1) a period of anthropogenic enrichment, which led to excessive production of organic matter in the form of algal blooms (1993/1994); (2) the implementation of mitigation measures, following a long period of eutrophication (1999/2000); and (3) a centenary flood (winter 2000/2001). Different numbers of compartments were identified at each site and in each time period. In general, the Zostera site, due to its complex community, showed a higher number of compartments and a higher level of system activity (i.e. sum of consumptions, respiration, flow to detritus, production, total system throughput, net primary production and system omnivory index). The differences at the two sites in the three time periods in the breakdown of throughput were mainly due to differences in the biomass of the primary producers (higher primary production at the Zostera site). Consumption, respiration and flow to detritus were dominated by the grazers Hydrobia ulvae and Scrobicularia plana at the Zostera and bare sediment sites respectively. At both sites, after recovery measures were implemented there was an increase in S. plana and Hediste diversicolor biomass, consumption, respiration and flows to detritus, and a decrease in H. ulvae biomass and associated flows, which increased again after the flood event. The mass-balanced models showed that the trophic structure of the benthic communities in Mondego estuary was affected differently by each disturbance event. Interestingly, in our study a high system throughput seems to be associated with higher stress levels, which contradicts the idea that higher system activity is always a sign of healthier conditions. 相似文献