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   465篇
  免费   42篇
  国内免费   30篇
安全科学   19篇
废物处理   6篇
环保管理   269篇
综合类   100篇
基础理论   59篇
污染及防治   23篇
评价与监测   25篇
社会与环境   28篇
灾害及防治   8篇
  2023年   4篇
  2022年   2篇
  2021年   10篇
  2020年   10篇
  2019年   15篇
  2018年   16篇
  2017年   18篇
  2016年   15篇
  2015年   24篇
  2014年   21篇
  2013年   35篇
  2012年   25篇
  2011年   22篇
  2010年   21篇
  2009年   29篇
  2008年   23篇
  2007年   27篇
  2006年   21篇
  2005年   17篇
  2004年   17篇
  2003年   16篇
  2002年   15篇
  2001年   16篇
  2000年   16篇
  1999年   9篇
  1998年   10篇
  1997年   10篇
  1996年   8篇
  1995年   5篇
  1994年   4篇
  1993年   3篇
  1992年   4篇
  1991年   2篇
  1990年   1篇
  1989年   3篇
  1988年   8篇
  1987年   2篇
  1986年   5篇
  1984年   4篇
  1983年   3篇
  1982年   4篇
  1980年   3篇
  1979年   7篇
  1978年   1篇
  1977年   2篇
  1974年   2篇
  1972年   1篇
  1971年   1篇
排序方式: 共有537条查询结果,搜索用时 125 毫秒
101.
Resource depletion is of concern to both present and future generations in terms of access to resources. It is a prominent impact category within life cycle assessment (LCA) and sustainability assessment. This paper examines existing resource depletion approaches and indicators in the context of natural gas depletion, and their limitations in modelling the wider environmental consequences of resource consumption. Some existing models assume substitution of scarce fossil fuels with an alternative fossil fuel or mix, but do not consider all of the subsequent change in impacts. An additional methodology is proposed to measure the impact changes when fossil fuel substitution occurs as a result of scarcity. The methodology will demonstrate the effect of resource scarcity for individual processes but also multiple processes which operate at different levels of resource consumption with varying degrees of impacts. The methodology is applied to a scarcity situation of natural gas in Australia, where black coal is substituted for gas. It is first applied to natural gas consumed for electricity generation only. In the second case, the methodology is applied to the substitution of natural gas for both electricity generation and hydrogen production. The varying impacts on emissions to air and water, together with solid waste generation and water depletion, as a result of the substitution are used to reflect the consequences of fossil fuel depletion. The indicators also provide information on the impacts of substitution in each product, thus enabling users to prioritise products based on the impacts produced during natural gas allocation.  相似文献   
102.
邓慧平 《生态环境》2012,21(4):601-605
为了揭示气温变化对西南山区流域森林水文效应的影响,用生物物理/动态植被模型SSiB4/TRIFFID与流域地形指数水文模型TOPMODEL的耦合模型SSiB4T/TRIFFID模拟了西南山区长江上游梭磨河流域森林水文效应对气温变化的响应,分析了气温变化对植被不同演替阶段的流域总径流和总蒸发以及冠层截流蒸发、植被蒸腾和土壤蒸发的影响。结果表明,(1)梭磨河流域森林(常绿针叶林)蒸腾与草和灌木差异小,森林蒸腾潜热比草和灌木仅高1~4 W.m-2,森林冠层截留蒸发高于草和灌木,但土壤蒸发明显低于草和灌木覆盖,森林覆盖流域总蒸发低于草和灌木覆盖甚至低于裸土蒸发,因此增加了流域总径流量,但森林增加径流的作用随土壤蒸发的减小而减小。(2)气温减小1℃将通过减小森林冠层截留蒸发和蒸腾而使森林增加流域总径流量的作用增加;相反,气温增加将增加森林冠层截留蒸发和蒸腾而使森林增加总径流量的作用减小。(3)当温度增加4℃,由于森林总蒸发较草和灌木明显增加,对于较高的土壤蒸发,森林增加总径流量的作用已不明显;对于较低的土壤蒸发,森林减小了流域总径流量。  相似文献   
103.
施用高效氮肥对农田N2O的减排效果及经济效益分析   总被引:5,自引:0,他引:5       下载免费PDF全文
收集高效氮肥N2O排放资料,利用整合分析法分析高效氮肥对N2O的减排效果.稳定性氮肥排放的N2O是普通肥料的0.66倍,减排效果显著;包膜缓释氮肥N2O排放量为普通氮肥的0.95倍,无显著减排效果.若将全国范围的普通氮肥替换为稳定性氮肥、且用N量不变时,稳定性氮肥在中国农田的N2O减排潜力均值为1.03×108 kgN/a,碳排放交易收入为16.86亿元/a;根据现有市场上稳定性氮肥的价格,每亩地每季补贴4.9元,碳排放交易收入和稳定性氮肥成本增加量相抵.由于稳定性氮肥能有效提高N利用率,保证农作物吸N总量不变时减少用N量,稳定性肥料N利用率提高8个百分点时,N2O减排经济效益(即碳排放交易收入-稳定性氮肥成本增加量)为94亿元/a.  相似文献   
104.
Lu, Haorong, S. Samuel Li, and Jinsong Guo, 2012. Modeling Monthly Fluctuations in Submersion Area of a Dammed River Reservoir: A Case Study. Journal of the American Water Resources Association (JAWRA) 1‐13. DOI: 10.1111/jawr.12003 Abstract: Fluctuations in water submersion of the Three Gorges Reservoir in China have not been explored in spite of their important implications for shoreline erosion and other undesirable consequences. This article aims to quantify the monthly fluctuations in response to changing hydraulic parameters and regional climatic factors. Flow velocity and water levels distributed along the 609‐km long dammed river reservoir are calculated with a one‐dimensional hydrodynamics model. Evaporation of water from the surface of the reservoir is determined using mass transfer‐based methods. Calculated flow velocities and water levels compare well with field data. We show that the water surface slope decreases with rising water level at the dam, and decreases to almost zero during the winter months of water storage when the downstream water level reaches the normal pool level. The submersion area varies between 830 and 1,070 km2 over the year or over 20% of the reservoir zone will experience the annual cycle of dry land and partial or complete submersion. These fluctuations are of relevance to shoreline management and to the prevention and restoration of shoreline erosion. Evaporation is estimated to fluctuate between 1,240 and 26,110 tons of water per month per kilometer length of reservoir channel; this can possibly affect the hydrological budget of the reservoir region. The simple methodologies discussed in this article can easily be applied to other dammed river reservoirs for submersion estimates.  相似文献   
105.
朱媛媛  刘冰  桂海林  李健军  汪巍 《环境科学》2022,43(8):3966-3976
基于生态环境监测和气象观测数据,分析了2016~2020年京津冀13个城市臭氧(O3)浓度特征,讨论了O3污染高发月份日最高温度(Tmax)、日均地面气压(p)、日均地面相对湿度(RH)和日均地面风速(v)等气象要素对O3-8h浓度和O3-8h超标情况的影响规律,并采用AQI级别预报准确率、O3浓度范围预报准确率和O3级别预报准确率等方法,评估了基于神经网络的O3统计预报效果.结果表明,2016~2020年期间京津冀13城市ρ(O3-8h-90per)分别为157.4、177.2、177.3、190.6和175.6μg·m-3,区域臭氧浓度5a上升了11.6%,2016~2019年期间总体呈波动上升趋势,2020年环比下降;2020年与2016年相比,除北京、张家口和承德略有下降外,其他10个城市ρ(O3-8h-90per)上升了6~45.5μg·m-3.O3-8h月均值呈现"两头低,中间高"现象,ρ(O3-8h)在4~9月的月均值超过了100 μg·m-3,在6月最高,为158.10 μg·m-3.城市O3-8h超标率范围为8.6%~19.2%,97.8%的O3-8h超标情况发生在4~9月.区域尺度上O3-8h浓度与日最高温度相关性最强,当Tmax在25~28℃区间时,所有城市开始出现O3-8h超标.O3-8h浓度与日均地面气压呈负相关关系;当RH在60%以下时,大部分城市O3-8h浓度随相对湿度上升缓慢增长;当RH在61%~70%以上时,大部分城市O3-8h浓度随日均相对湿度上升而下降.O3-8h超标时的地面主导风向主要为偏南风,大部城市O3-8h浓度高值易集中出现在2~3m·s-1及以下低风速区间.OPAQ统计模式提前1~9 d预报相关系数范围为0.72~0.86,AQI级别预报平均准确率为67%~86%,O3-8h浓度范围预报平均准确率为63%~84%.在O3-8h超标情况多发的4~9月,模式对O3轻度污染和O3-8h超标情况提前3 d预报准确率分别为69%和66%,可为O3-8h超标管控提供参考依据.  相似文献   
106.
Environmental Agencies require Decision Support Systems, in order to plan Air Quality Policies considering the cost of emission reduction measures and the human health effects (with related social costs). The use of Decision Support Systems is also useful to spread information to general public, explaining the effectiveness of proposed air quality plans. In this paper, a multi-objective approach to control PM10 concentration at a regional level is presented. The problem considers both the internal costs (due to the implementation of emission reduction measures) and the external costs (due to population exposure to high PM10 concentrations). To model PM10 concentrations, a single surrogate model is used for the entire domain, allowing the implementation of a very efficient optimization procedure. The surrogate model is derived through a set of 10 simulations, performed using a Chemistry Transport Model fed with different emission reduction scenarios. The methodology is applied to Northern Italy, a region affected by very high PM10 concentrations that exceed the limit values specified by the EU legislation.  相似文献   
107.
Using Japanese facility-level data from an OECD survey, we estimate the effects of implementation of ISO14001 and publication of environmental reports on the facilities’ environmental performance. While most previous studies focused on an index of emissions toxicity, this study examines three areas of impacts, none of which have been explored in the literature: natural resource use, solid waste generation, and wastewater effluent. The study is also unique in that the effectiveness of ISO14001 is considered in relation to environmental regulations. Our findings are summarized as follows. First, both ISO14001 and report publication help reduce all three impacts; the former appears more effective in all areas except wastewater. Second, environmental regulations do not weaken the effect of ISO14001. Third, assistance programs offered by local governments—a voluntary approach—promote facilities’ adoption of ISO14001. These findings suggest that governments can use command-and-control and voluntary approaches concurrently.  相似文献   
108.
快速城市化地区道路对两侧土地利用影响模式研究   总被引:1,自引:0,他引:1       下载免费PDF全文
基于多时段的卫星影像和土地利用变更调查数据,选取深圳市14条主要道路的代表性影响路段,用城市化影响指数(U)表征道路对土地利用的影响.以社会经济背景、地形条件、道路等级和道路运营年限为道路特征参数,基于相关性和非线性回归分析的方法研究道路对两侧土地利用影响的模式及其成因.研究发现,道路特征参数对两侧土地利用强度的影响表现出显著的差异性,其中,社会经济背景是道路对土地利用影响的主要影响因素,道路运营年限的影响主要表现在道路近距离区域,道路等级在中距离区域,而地形条件影响主要在远距离区域.道路对土地利用的影响模式分为3类,即山峰型、递减型和山谷型,而不同道路特征参数被认为是导致道路影响模式差别的主要原因.根据U值变化的曲线拟合分析得到各道路的影响范围,结果表明,快速路和主干路的影响范围较大,城市化进程起步较早、社会经济发展水平较好的西部地区道路影响范围大于东部.  相似文献   
109.
ABSTRACT: Water resource planning is based primarily on 20th century instrumental records of climate and streamflow. These records are limited in length to approximately 100 years, in the best cases, and can reflect only a portion of the range of natural variability. The instrumental record neither can be used to gage the unusualness of 20th Century extreme low flow events, nor does it allow the detection of low‐frequency variability that may underlie short‐term variations in flow. In this study, tree rings are used to reconstruct mean annual streamflow for Middle Boulder Creek in the Colorado Front Range, a semi‐arid region of rapid growth and development. The reconstruction is based on a stepwise regression equation that accounts for 70 percent of the variance in the instrumental record, and extends from 1703–1987. The reconstruction suggests that the instrumental record of streamflow for Middle Boulder Creek is not representative of flow in past centuries and that several low flow events in the 19th century were more persistent than any in the 20th century. The 1840s to early 1850s period of low flow is a particularly notable event and may have coincided with a period of low flow in the Upper Colorado River Basin.  相似文献   
110.
Science, politics and environmental policy have for several years been encountering social and institutional as well as scientific challenges, national and international. The normative basis of all sciences is pressurised from three sides: by awareness of the public, who claims more transparency and sensibility from the scientific institutions regarding factual or possible impacts of science-based industrial progress; by the industries, which try to speed up and intensify the industrialisation of knowledge; and by the public policies, which want to see the sciences engaged in ways to mitigate unintended consequences of economic, ecological and social developments. At the same time, environmental policy is undergoing a tremendous sea change both in conceptual and practical matters. Since the Brundtland Report in 1987 and accelerated after UNCED 1992, environmental policy has been struggling to become a groundbreaking new paradigm for the capacity of resolving social and political issues as well. Any successful attempt to alter traditional institutional and mental structures in policy-making toward sustainability presupposes a renewed association of co-operation, deliberation and decision making. Results from theory of democracy, studies in science and technology, and evaluation studies in environmental policy and politics can be utilised for this context.  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