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671.
Frank H. Quinn 《Journal of the American Water Resources Association》1978,14(5):1129-1142
ABSTRACT: The outflows of Lake Superior through the St. Marys River have been modified from natural conditions, initially by the construction of engineering works, such as bridges, and later by the construction of control works and the regulation of the lake. For all practical purposes, the period from 1860 to 1887 represents the natural river conditions. During the period 1888-1900 the regimen was modified by the construction of the International Railroad Bridge and the Chandler-Dunbar Power Canal. In 1901 construction began on the compensating works. Following the completion of the compensating works in August 1921, the Lake Superior outflows were regulated in accordance with the Orders of Approval, 26 and 27 May 1914. A hydrologic response model was developed to simulate the natural Lake Superior regime. The model was run for the 1860–1975 period to simulate natural Lake Superior levels and outflows. The simulated levels were compared with the recorded levels to determine the effect of regulation. It was found that regulation has resulted in a rise in Lake Superior water levels. The simulated natural outflows for the period from 1937 to 1975 were run through the Great Lakes hydrologic response model to analyze the regulation effects on Lakes Michigan-Huron, St. Clair, and Erie. The results show no long-term bias due to regulation. 相似文献
672.
Ned P. Smith 《Journal of the American Water Resources Association》1974,10(5):990-994
ABSTRACT. Temperature recorder data from central Lake Superior obtained from May through July, 1967, are used to describe the spring warming of this deep lake. Data from the 30, 91 and 150 m levels suggest that water descending in the thermal bar spreads lakeward, filling the lake with an increasingly thick layer of maximum density water. Lakeward of the thermal bar, local warming is relatively slow preceeding and following the passage of the reverse thermocline at a given level. 相似文献
673.
利用二维模型求解太湖水质CODMn的研究 总被引:1,自引:0,他引:1
在二维黎曼近似解模型的基础上建立了太湖水质预测模型,并运用该模型对太湖的水质指标CODMn了模拟。模拟的结果跟太湖各监测站的测量值相接近,表明该模型能较好的运用于太湖的水质预测。 相似文献
674.
Environmental Control and Limnological Impacts of a Large Recurrent Spring Bloom in Lake Washington,USA 总被引:3,自引:1,他引:2
A series of statistical analyses were used to identify temporal and spatial patterns in the phytoplankton and nutrient dynamics
of Lake Washington, an mesotrophic lake in Washington State (USA). These analyses were based on fortnightly or monthly samples
of water temperature, Secchi transparency, ammonium (NH4), nitrate (NO3), inorganic phosphorus (IP), total nitrogen (TN), total phosphorus (TP), dissolved oxygen (DO), pH and chlorophyll a (chl a) collected during 1995–2000 from 12 stations. Lake Washington has a very consistent and pronounced annual spring diatom bloom
which occurs from March to May. During this bloom, epilimnetic chl a concentrations peak on average at 10 μg/L, which is 3 times higher than chl a concentrations typically seen during summer stratified conditions. The spring bloom on average comprised 62% diatoms, 21%
chlorophytes and 8% cyanobacteria. During summer stratification, diatoms comprised 26% of the phytoplankton community, chlorophytes
37% and cyanobacteria 25%. Cryptophytes comprised approximately 8% of the community throughout the year. Overall, 6 phytoplankton
genera (i.e., Aulacoseira, Fragilaria, Cryptomonas, Asterionella, Stephanodiscus, and Ankistrodesmus) cumulatively accounted for over 50% of the community. These analyses also suggest that the phytoplankton community strongly
influences the seasonality of NO3, IP, DO, pH and water clarity. According to a MANOVA, seasonal fluctuations explained 40% of the total variability for the
major parameters, spatial heterogeneity explained 10% of variability, and the seasonal-spatial interaction explained 10% of
variability. Distinctive patterns were identified between offshore and inshore sampling stations. The results of our analyses
also suggest that spatial variability was substantial, but much smaller than temporal variability. 相似文献
675.
试论洞庭湖区的洪涝灾害及其减灾对策 总被引:1,自引:1,他引:1
洞庭湖区频繁而严重的洪涝灾害是其孕灾环境的易灾性及承灾体较低的承灾能力共同决定的.减轻洞庭湖区的洪涝灾害应实行“治江、控制四水与洞庭湖本身治理”三位一体的综合整治战略. 相似文献
676.
太湖流域洪涝的激发机制和减灾策略探讨 总被引:1,自引:0,他引:1
太湖流域洪涝灾害的形成包括自然和人为两方面的机制。自然机制有:①年降雨量较大,且降雨时空分布不均,暴雨强度大;②地势周高中低,平原海拔低,河流比降小。人为机制有:①围垦缩小了流域蓄水面积;②地下水开采和高层建筑造成地面沉降;③土地非农业化使地表可渗透性面积减少。并提出洪涝威胁的发展趋势及减灾对策。 相似文献
677.
Deborah H. Lee Thomas E. Croley Frank H. Quinn 《Journal of the American Water Resources Association》1997,33(1):55-69
ABSTRACT: The implications of Lake Ontario regulation under transposed climates with changed means and variability are presented for seasonal and annual time scales. The current regulation plan is evaluated with climates other than the climate for which it was developed and tested. This provides insight into potential conflicts and management issues, development of regulation criteria for extreme conditions, and potential modification of the regulation plan. Transposed climates from the southeastern and south central continental United States are applied to thermodynamic models of the Great Lakes and hydrologic models of their watersheds; these climates provide four alternative scenarios of water supplies to Lake Ontario. The scenarios are analyzed with reference to the present Great Lakes climate. The responses of the Lake Ontario regulation plan to the transposed climate scenarios illustrate several key issues: (1) historical water supplies should no longer be the sole basis for testing and developing lake regulation plans; (2) during extreme supply conditions, none of the regulation criteria can be met simultaneously, priority of interests may change, and new interests may need to be considered, potentially requiring substantial revision to the Boundary Waters Treaty of 1909; (3) revised regulation criteria should be based on ecosystem health and socio-economic benefits for a wider spectrum of interests and not on frequencies and ranges of levels and flows of the historical climate; and (4) operational management of the lake should be improved under the present climate, and under any future climate with more variability, through the use of improved water supply forecasts and monitoring of current hydrologic conditions. 相似文献
678.
Carolyn M. Fonyo William G. Boggess 《Journal of the American Water Resources Association》1989,25(2):309-317
ABSTRACT: The potential for joint public and private action for lake restoration is examined using Lake Apopka, Florida, as a case study. Initial calculations indicate that private incentives alone are inadequate to attract investment in a facility to grow and harvest water hyacinths for conversion to methane gas. However, the private externality of water quality improvement associated with harvesting water hyacinths provides a key linkage between the public's water quality objectives and the private gas producer's actions. In order to establish the potential basis for negotiation, the public's willingness-to-pay for environmental services associated with improved water quality is estimated and compared with the estimated subsidy required to induce private action. A conceptual framework is then presented for coordinating actions between private firms and public water management agencies in order to internalize the private externality of water quality improvement while simultaneously achieving the public and private objectives. Results indicate that the subsidization of water hyacinth production and harvesting compares favorably with alternative means of enhancing the water quality of Lake Apopka. 相似文献
679.
针对湖泊富营养状态Hamming贴近度评价模型存在的“阈值漂移”问题,重新构造了评价参数隶属函数,提出了一种湖泊营养状态Euclid贴近度评价模型,经过对全国23个湖泊富营养状态的实例分析,证明这种评价模型结构合理,评价过程简单,模型通用性好。 相似文献
680.
曾昭华 《环境监测管理与技术》1996,8(5):16-18
根据调查结果,研究了长江中下游地区地下水铅元素的背景特征及其分布规律,并分析了地下水的含水介质成分,氧化还原环境,径流条件及酸碱度对铅元素的分布的影响。 相似文献