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   533篇
  免费   26篇
  国内免费   39篇
安全科学   29篇
废物处理   24篇
环保管理   124篇
综合类   75篇
基础理论   143篇
环境理论   2篇
污染及防治   133篇
评价与监测   45篇
社会与环境   18篇
灾害及防治   5篇
  2023年   9篇
  2022年   5篇
  2021年   14篇
  2020年   11篇
  2019年   17篇
  2018年   21篇
  2017年   21篇
  2016年   39篇
  2015年   31篇
  2014年   27篇
  2013年   32篇
  2012年   20篇
  2011年   42篇
  2010年   37篇
  2009年   26篇
  2008年   41篇
  2007年   28篇
  2006年   18篇
  2005年   15篇
  2004年   17篇
  2003年   21篇
  2002年   17篇
  2001年   4篇
  2000年   6篇
  1999年   1篇
  1998年   3篇
  1997年   12篇
  1996年   15篇
  1995年   7篇
  1994年   4篇
  1993年   5篇
  1992年   8篇
  1991年   4篇
  1990年   2篇
  1989年   2篇
  1987年   3篇
  1985年   2篇
  1984年   1篇
  1983年   1篇
  1982年   3篇
  1981年   2篇
  1979年   2篇
  1978年   2篇
排序方式: 共有598条查询结果,搜索用时 546 毫秒
421.
Al-Mohannadi HI  Hunt CO  Wood AP 《Ambio》2003,32(5):362-366
Qatar has serious water resource problems, following rapid socioeconomic development and massive population increase. Municipal water provision depends on costly and unsustainable desalination. There is little regulation. Native Qataris do not pay a water tariff and migrants pay a subsidized price--approximately one third of the cost of production--so there is little awareness of the true cost of water and use is profligate. This paper discusses trends in water use and identifies issues underlying sustainable water use in Qatar. A questionnaire of respondents chosen to represent Qatari social groups measured awareness and attitudes to water. The results show that previous efforts to control water demand in Qatar, using awareness campaigns, legal restrictions and tariffs, have been ineffectual. The questionnaire evaluated reactions to possible measures to limit uses by raising awareness, using legal restrictions and raising tariffs. From this, a number of policy changes can be suggested, to bring Qatar's water industry towards sustainability.  相似文献   
422.
Climate change is expected to have important impacts on aquatic ecosystems. On the Boreal Shield, mean annual air temperatures are expected to increase 2 to 4°C over the next 50 years. An important challenge is to predict how changes in climate and climate variability will impact natural systems so that sustainable management policies can be implemented. To predict responses to complex ecosystem changes associated with climate change, we used long-term biotic databases to evaluate how important elements of the biota in Boreal Shield lakes have responded to past fluctuations in climate. Our long-term records span a two decade period where there have been unusually cold years and unusually warm years. We used coherence analyses to test for regionally operating controls on climate, water temperature, pH, and plankton richness and abundance in three regions across Ontario: the Experimental Lakes Area, Sudbury, and Dorset. Inter-annual variation in air temperature was similar among regions, but there was a weak relationship among regions for precipitation. While air temperature was closely related to lake surface temperatures in each of the regions, there were weak relationships between lake surface temperature and richness or abundance of the plankton. However, inter-annual changes in lake chemistry (i.e., pH) were correlated with some biotic variables. In some lakes in Sudbury and Dorset, pH was dependent on extreme events. For example, El Nino related droughts resulted in acidification pulses in some lakes that influenced phytoplankton and zooplankton richness. These results suggest that there can be strong heterogeneity in lake ecosystem responses within and across regions.  相似文献   
423.
This analysis presents results based on a five-yearstudy recently supported by the Louisiana Departmentof Transportation and Development (DOTD) in which theacute toxicity, fate and effect of herbicide mixtureson human health and the environment were assessed. Three sites were routinely sprayed by DOTD to killweeds along the roadsides. Two herbicide mixtures wereused, 2,4-D and Roundup, and Garlon 3A and Roundup.Water, vegetation, soil and sediment samples werecollected quarterly for three years and were analyzedfor pesticide content to study the fate and impact ofherbicides in the environment. Results indicate acorrelation between soil type, herbicide type, andpersistence of the herbicide in the environment. Usingthe correlations found in these data, spatial analysisidentified areas where herbicide use may potentiallycause surface water and sediment contamination, basedon soil composition/properties, type of herbicideapplied, and proximity of water bodies to sprayed areas.  相似文献   
424.
425.
Products of a power plant flue gas desulfurization scrubber are discharged into a pond as sludge consisting of calcite (initial delta13C 3.2-3.8 per thousand), gypsum (initial delta34S 7.6-8.6 per thousand), and aqueous solution. Reducing conditions exist below a boundary that appears to move vertically as a function of changes in pond water level. Under reducing conditions, bacteria partially reduce aqueous sulfate to low-delta34S sulfide, consuming organic carbon and generating low-delta13C bicarbonate. Under oxidizing conditions, sulfide is converted to sulfate, leading to calcite dissolution, gypsum precipitation, and isotopic re-equilibration of remaining calcite with dissolved bicarbonate near the pond surface. The gypsum has delta34S near 6 per thousand, and calcite has delta13C as low as -1.7 per thousand; the changes from initial values correspond to predictions based on isotopic balance and reaction stoichiometry. The pond largely contains the products of bacterial reduction. After the pond is abandoned, these products may adversely affect attempts to revegetate the site. Future bacterial reduction may be best controlled by dewatering and limiting the supply of organic matter in percolating surface water.  相似文献   
426.
Gas-cooled nuclear power plants in the UK release sulphur-35 during their routine operation. The gas is in the form of COS which can be readily assimilated by vegetation. It is therefore necessary to be able to model the uptake of such releases in order to quantify any potential contamination of the food chain. To develop such models experimental data are required. A series of experiments was undertaken to determine the rate of deposition, the partition and subsequent loss of sulphur-35 in crops exposed to CO(35)S. The mass normalised deposition rate was similar for the range of crops tested, while the partition of the (35)S paralleled the growth of crop components. There was no significant loss of radioactivity other than that expected from radioactive decay.  相似文献   
427.
This article introduces the concept of ISO 14001 registration, outlines related assessment processes, and reviews the drivers behind developing an ISO-14001-concordant environmental management system (EMS) and seeking third party registration of that EMS. It focuses on registration strategies for larger organizations and considerations in choosing a registrar, including: auditor qualifications, standards for the conduct of EMS audits, and some issues for audit and registration service providers. The authors conclude that it is beneficial to pursue an ISO-14001-concordant EMS and that the value of the system can be enhanced through registration. However, some thought should be given to choosing the appropriate registrar, in particular to their EMS and audit approaches and to the qualifications of their audit team. Service providers are also cautioned to remember that ISO 14001 is not the same as ISO 9000, and that the registrar's standard of care in the discharge of their work should reflect that. © 1998 John Wiley & Sons, Inc.  相似文献   
428.
429.
Various cleaner production (CP) audits have been conducted in the South African metal finishing industry. These studies have been successful in effecting changes to the general status of the local metal finishing industry. In this paper, the initiatives undertaken by a Danish government sponsored project are detailed. The project included the conducting of in-plant assessments, using a tailor-made tool for CP benchmarking. Details on this tool's operations and typical results are presented. Typical assessments indicated potential water savings of 78%, with chemical savings of approximately 30%. The plant modifications undertaken in order to achieve the CP objectives, are described. The affects of these initiatives on local municipal wastewater treatment works are detailed with specific reference to significant reductions in incoming wastewater-borne heavy metals. The main challenge for companies has been data retrieval for the tool and overcoming social barriers for implementing the improvement options. Recommendations include redesigning the assessment tool.  相似文献   
430.
Worldwide, an increase in flood damage is observed. Governments are looking for effective ways to protect lives, buildings, and infrastructure. At the same time, a large investment gap seems to exist—a big difference between what should necessarily be done to curb the increase in damage and what is actually being done. Decision-makers involved in climate adaptation are facing fundamental (so-called deep) uncertainties. In the course of time, the scientific community has developed a wide range of different approaches for dealing with these uncertainties. One of these approaches, adaptation pathways, is gaining traction as a way of framing and informing climate adaptation. But research shows that “very little work has been done to evaluate the current use of adaptation pathways and its utility to practitioners and decision makers” (Lin et al. 2017, p. 387). With this paper, the authors, as action researchers and practitioners involved in two of the world’s largest real-life applications of this approach in flood risk management, aim to contribute to filling in that gap. Analysis of the experience in the United Kingdom and the Netherlands in long-term planning in flood risk management shows that the adaptation pathways approach is effective in keeping decision processes going forward, to the final approval of a long-term plan, and helps increase awareness about uncertainties. It contributes to political support for keeping long-term options open and motivates decision-makers to modify their plans to better accommodate future conditions. When it comes to implementing the plans, there are still some major challenges, yet to be addressed, amongst others: the timely detection of tipping points in situations with large natural variability, the inclusion of measures that prepare for a switch to transformational strategies, and the retention of commitment of regional and local authorities, non government organizations, and the private sector, to climate adaptation as national policies move from blueprint planning to adaptive plans. In delivering this feedback, the authors hope to motivate the scientific community to take on these challenges.  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