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311.
312.
1 ThegeneralsituationoftheSouthDongtingLakeWetlandLocatedinthenorthofHunanProvinceandthesouthbankoftheYangtzeRivermiddlereaches ,theDongtingLakeisoneofthefivelargestfreshwaterlakesandofthesevenmostimportantlandscapesofinternationallyimportantwetlandsi… 相似文献
313.
以某高海拔地区污水处理厂的二级生化处理水为研究对象,通过对人工湿地进出水中COD、NH+4-N、TP浓度的变化,研究了水力负荷、气水比两个参数对人工湿地净水效果的影响。结果表明:人工湿地去除生活污水中COD、NH4+-N、TP的最佳水力负荷为0.33 m3/(m2·d)、气水比为3:1,在此最佳试验条件下,COD、NH4+-N、TP的去除率分别可达84%、69%、68%,出水水质满足《地表水环境质量标准》Ⅲ类水质标准。 相似文献
314.
湿地作为一种特珠的生态系统,在固碳方面也起到了举足轻重的作用.本文首先探讨了湿地生态系统的碳循环和碳平衡过程,然后介绍了当前国内外普遍运用的几种碳汇计童方法,包括生物量法、静态箱法、动态箱法、GIS法、同位素法、涡旋相关法、涡度协方差法等,并对这些方法的优缺点进行了分析,对未来湿地碳平衡及碳核算方法的研究进行了展望. 相似文献
315.
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
316.
Agricultural drainage and wetland management in Ontario 总被引:2,自引:0,他引:2
Land drainage is recognized as an integral part of agricultural activity throughout the world. However, the increase in agricultural production has resulted in the loss of wetland functions and values. Therefore, wetland management and agricultural drainage illustrate the conflict between economic development and natural values. This research assesses the approval process for agricultural land drainage in Ontario, Canada, to determine how the benefits of increased agricultural production are balanced against the loss of wetland values. A permit review of drainage applications was conducted from 1978 to 1997 in Zorra Township, Ontario, Canada. Data collection also included the document reviews, interviews with government agencies and wetland evaluation files. The selected criteria include efficiency, equity, consistency and adequacy. The results indicate that while the process is efficient, fundamental problems remain with the bargaining process. 相似文献
317.
The extent of wetland in New Zealand has decreased by approximately 90% since European settlement began in 1840. Remaining
wetlands continue to be threatened by drainage, weeds, and pest invasion. This article presents a rapid method for broad-scale
mapping and prioritising palustrine and estuarine wetlands for conservation. Classes of wetland (lacustrine, estuarine, riverine,
marine, and palustrine) were mapped using Landsat ETM+ imagery and centre-points of palustrine and estuarine sites as ancillary
data. The results shown are for the Manawatu–Wanganui region, which was found to have 3060 ha of palustrine and 250 ha of
estuarine wetlands. To set conservation priorities, landscape indicators were computed from a land-cover map and a digital
terrain model. Four global indicators were used (representativeness, area, surrounding naturalness, and connectivity), and
each was assigned a value to score wetland sites in the region. The final score is an additive function that weights the relative
importance of each indicator (i.e., multicriteria decision analysis). The whole process of mapping and ranking wetlands in
the Manawatu–Wanganui region took only 6 weeks. The rapid methodology means that consistent wetland inventories and ranking
can now actually be produced at reasonable cost, and conservation resources may therefore be better targeted. With complete
inventories and priority lists of wetlands, managers will be able to plan for conservation without having to wait for the
collection of detailed biologic information, which may now also be prioritised. 相似文献
318.
As the discipline of conservation biology evolves and practitioners grow increasingly concerned about how to put results into achievable conservation, it is still unclear the extent to which science drives conservation outcomes, especially across rural landscapes. We addressed this issue by examining the role of science in the protection of a biological corridor. Our focus is on a North American endemic mammal reliant on long distance migration as an adaptive strategy, the pronghorn (Antilocapra americana) of the southern Greater Yellowstone Ecosystem. The role of science in realizing policy change, while critical as a first step, was surprisingly small relative to the role of other human dimensions. In a case study, we strategically addressed a variety of conservation needs beyond science, first by building a partnership between government and private interests and then by enhancing interest in migratory phenomena across a landscape with divergent political ideologies and economic bases. By developing awareness and even people's pride in the concept of corridor conservation, we achieved local, state, and federal acceptance for protection of a 70 km long, 2 km wide pathway for the longest terrestrial migrant in the contiguous United States. Key steps included conducting and publishing research that defined the migration corridor; fostering a variety of media coverage at local, regional, and national levels; conducting public outreach through stakeholder workshops, meetings, and presentations; and meeting with and gaining the support of elected officials. All these contributed to the eventual policy change that created the first federally protected migration corridor in the United States, which in turn stimulated additional conservation actions. On the basis of our experience, we believe conservation scientists can and should step beyond traditional research roles to assist with on‐the‐ground conservation by engaging in aspects of conservation that involve local communities and public policy. Ir Más Allá de la Ciencia para Proteger un Corredor Migratorio de Mamíferos 相似文献
319.
L. ZengG.Q. Chen 《Ecological modelling》2011,222(2):293-300
For the typical case of a pulsed contaminant emission into a free surface wetland flow, a theoretical analysis is presented in this paper for the decay of the depth-averaged concentration under the combined action of ecological degradation and hydraulic dispersion. Based on a first-order reaction model extensively employed in related ecological risk assessment and environmental hydraulic design, the effect of ecological degradation is separated from the hydraulic effect via an exponential transformation for the general formulation for contaminant transport. The speed profile of a fully developed steady flow through the wetland is obtained. A hydraulic dispersion model for the depth-averaged concentration is devised as an extension of Taylor’s classical analysis on dispersion, and corresponding hydraulic dispersivity is obtained by Aris’s method of moments. Analytical solution of depth-averaged concentration is rigorously derived and characterized. For typical pollutant constituents in wastewater emission, the evolution of contaminant cloud in the wetland flow is illustrated by critical length and duration of influenced region with contaminant concentration beyond given environmental standard level, with essential implications for ecological risk assessment and environmental management. 相似文献
320.