首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   9345篇
  免费   620篇
  国内免费   425篇
安全科学   1726篇
废物处理   221篇
环保管理   3735篇
综合类   2485篇
基础理论   887篇
环境理论   10篇
污染及防治   260篇
评价与监测   398篇
社会与环境   360篇
灾害及防治   308篇
  2023年   93篇
  2022年   127篇
  2021年   194篇
  2020年   262篇
  2019年   195篇
  2018年   171篇
  2017年   229篇
  2016年   319篇
  2015年   262篇
  2014年   332篇
  2013年   469篇
  2012年   462篇
  2011年   598篇
  2010年   410篇
  2009年   511篇
  2008年   410篇
  2007年   481篇
  2006年   483篇
  2005年   377篇
  2004年   428篇
  2003年   354篇
  2002年   406篇
  2001年   369篇
  2000年   405篇
  1999年   314篇
  1998年   217篇
  1997年   199篇
  1996年   314篇
  1995年   164篇
  1994年   66篇
  1993年   74篇
  1992年   63篇
  1991年   56篇
  1990年   37篇
  1989年   37篇
  1988年   37篇
  1987年   35篇
  1986年   29篇
  1985年   45篇
  1984年   61篇
  1983年   50篇
  1982年   26篇
  1981年   20篇
  1980年   31篇
  1979年   33篇
  1978年   25篇
  1975年   15篇
  1973年   14篇
  1972年   16篇
  1971年   26篇
排序方式: 共有10000条查询结果,搜索用时 265 毫秒
471.
A statistical procedure is developed to adjust natural streamflows simulated by dynamical models in downstream reaches, to account for anthropogenic impairments to flow that are not considered in the model. The resulting normalized downstream flows are appropriate for use in assessments of future anthropogenically impaired flows in downstream reaches. The normalization is applied to assess the potential effects of climate change on future water availability on the Rio Grande at a gage just above the major storage reservoir on the river. Model‐simulated streamflow values were normalized using a statistical parameterization based on two constants that relate observed and simulated flows over a 50‐year historical baseline period (1964–2013). The first normalization constant is a ratio of the means, and the second constant is the ratio of interannual standard deviations between annual gaged and simulated flows. This procedure forces the gaged and simulated flows to have the same mean and variance over the baseline period. The normalization constants can be kept fixed for future flows, which effectively assumes that upstream water management does not change in the future, or projected management changes can be parameterized by adjusting the constants. At the gage considered in this study, the effect of the normalization is to reduce simulated historical flow values by an average of 72% over an ensemble of simulations, indicative of the large fraction of natural flow diverted from the river upstream from the gage. A weak tendency for declining flow emerges upon averaging over a large ensemble, with tremendous variability among the simulations. By the end of the 21st Century the higher‐emission scenarios show more pronounced declines in streamflow.  相似文献   
472.
Devils Lake is a terminal lake located in northeast North Dakota. Because of its glacial origin and accumulated salts from evaporation, the lake has a high concentration of sulfate compared to the surrounding water bodies. From 1993 to 2011, Devils Lake water levels rose by ~10 m, which flooded surrounding communities and increased the chance of an overspill to the Sheyenne River. To control the flooding, the State of North Dakota constructed two outlets to pump the lake water to the river. However, the pumped water has raised concerns about of water quality degradation and potential flooding risk of the Sheyenne River. To investigate these perceived impacts, a Soil and Water Assessment Tool (SWAT) model was developed for the Sheyenne River and it was linked to a coupled SWAT and CE‐QUAL‐W2 model that was developed for Devils Lake in a previous study. While the current outlet schedule has attempted to maintain the total river discharge within the confines of a two‐year flood (36 m3/s), our simulation from 2012 to 2018 revealed that the diversion increased the Sheyenne River sulfate concentration from an average of 125 to >750 mg/L. Furthermore, a conceptual optimization model was developed with a goal of better preserving the water quality of the Sheyenne River while effectively mitigating the flooding of Devils Lake. The optimal solution provides a “win–win” outlet management that maintains the efficiency of the outlets while reducing the Sheyenne River sulfate concentration to ≤600 mg/L.  相似文献   
473.
简要分析了县级环境监测站在监测监察执法垂直管理制度改革后面临的问题,并针对问题提出建议。  相似文献   
474.
In this work we present a method for risk-informed decision-making in the physical asset management context whereby risk evaluation and cost-benefit analysis are considered in a common framework. The methodology uses quantitative risk measures to prioritize projects based on a combination of risk tolerance criteria, cost-benefit analysis and uncertainty reduction metrics. There is a need in the risk and asset management literature for a unified framework through which quantitative risk can be evaluated against tolerability criteria and trade-off decisions can be made between risk treatment options. The methodology uses quantitative risk measures for loss of life, loss of production and loss of property. A risk matrix is used to classify risk as intolerable, As Low As Reasonably Practicable (ALARP) or broadly tolerable. Risks in the intolerable and ALARP region require risk treatment, and risk treatment options are generated. Risk reduction benefit of the treatment options is quantified, and cost-benefit analysis is performed using discounted cashflow analysis. The Analytic Hierarchy Process is used to derive weights for prioritization criteria based on decision-maker preferences. The weights, along with prioritization criteria for risk reduction, tolerance criteria and project cost, are used to prioritize projects using the Technique for Order Preference by Similarity to Ideal Solution. The usefulness of the methodology for improved decision-making is illustrated using a numerical example.  相似文献   
475.
With the development of the city, the number of establishments that are proposed or under construction is increasing year by year, and if they are industries that handle flammable, explosive, toxic, harmful, and dangerous substances, the public safety will face great threats, which will bring great challenges to emergency rescue work. Therefore, providing reasonable solutions to the problem of location selection of emergency supplies repositories are necessary for improving the emergency response efficiency in chemical industrial parks. A mathematical model for location selection of emergency supplies repositories in emergency logistics management are presented considering more actual factors. The optimization objectives of the model are to minimize total transport length and cost. And then a Variable Weighted Algorithm is designed to solve the model, where an auxiliary function was constructed with different methods of building weighting factors based on the theory and method of solving multi-objective optimization problems in operational research. Simulation results show the effectiveness and feasibility of the models and algorithms presented in this paper.  相似文献   
476.
随着近年来大量农村污水处理设施的新建,项目污水处理设施面广、点多、单体规模小、污染物浓度变化大、经营困难等问题凸显,如何突破困境找到一条相对适合分散式污水处理设施的运营管理十分必要。本文提出了集约化管理创新探索,在生产标准化管理、人力资源管理、安全管理、设备设施管理及物资管理等方面全方位的总结了运营管理经验,为分散式污水处理设施管理提供了参考和借鉴。  相似文献   
477.
孟庆峰 《环境与发展》2020,(2):26-26,28
本文首先介绍了我国当前的河湖水环境现状,分析了我国水资源存在的一系列问题,主要问题包括水体污染和富营养化;河湖面积严重萎缩,河湖水的功能逐渐退化;难以降解的有机污染物污染量加大。有针对性地提出了改善我国河湖水环境的管理以及治理模式,进一步落实了保护河湖水环境工作,加强水资源周围生态环境的文明建设,实现河湖水环境的可持续发展。  相似文献   
478.
杨静 《环境与发展》2020,(1):238-239
在第二次全国污染源普查的基础上,利用污染源普查期间配置的软硬件,开发市级区域环境污染源管理平台,进行污染源数据的年度更新,拓展污染源普查软件应用,实现环境管理及环境执法移动终端的应用。拓展二污普一张图的功能,利用移动客户端机动实时及地定位导航等为环境管理执法和环境突发事件应急处置提供技术支持。  相似文献   
479.
陈雪松 《环境与发展》2020,(2):229-229,231
随着环境问题的日益突出,环境保护以及环境治理越来越迫切,由于造成环境污染问题的因素特别多,在对污染原因没有明确了解的情况下,盲目的着手进行环境污染治理工作,将会很难达到预期的治理效果。因此,作者从环境污染治理工程管理入手,进一步探索导致环境污染问题日益严重的根本原因,并详细分析加强环境污染治理工程管理的有效方略,旨在提高我国环境污染治理工程管理水平。  相似文献   
480.
生活垃圾分类回收管理措施正在我国各大城市全面实施。通过对瑞典生活垃圾层级管理和4种处理方式的介绍,对瑞典垃圾回收再利用效果进行分析,为我国推进生活垃圾分类回收再利用工作,提供可借鉴经验和参考。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号