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   598篇
  免费   26篇
  国内免费   8篇
安全科学   18篇
废物处理   13篇
环保管理   130篇
综合类   117篇
基础理论   172篇
环境理论   3篇
污染及防治   108篇
评价与监测   38篇
社会与环境   24篇
灾害及防治   9篇
  2023年   10篇
  2022年   9篇
  2021年   20篇
  2020年   27篇
  2019年   25篇
  2018年   27篇
  2017年   29篇
  2016年   31篇
  2015年   35篇
  2014年   24篇
  2013年   48篇
  2012年   38篇
  2011年   56篇
  2010年   31篇
  2009年   21篇
  2008年   30篇
  2007年   32篇
  2006年   30篇
  2005年   20篇
  2004年   10篇
  2003年   18篇
  2002年   11篇
  2001年   4篇
  2000年   4篇
  1999年   9篇
  1998年   5篇
  1997年   5篇
  1996年   3篇
  1995年   3篇
  1994年   6篇
  1993年   2篇
  1992年   1篇
  1986年   1篇
  1984年   2篇
  1983年   1篇
  1982年   1篇
  1977年   1篇
  1966年   1篇
  1962年   1篇
排序方式: 共有632条查询结果,搜索用时 546 毫秒
151.
152.
ABSTRACT

The success of ecological restoration efforts is tightly coupled with the effectiveness of many U.S. environmental policies. Yet scholars have raised questions about the ability of restoration to produce intended results. We use a case study of tidal wetland restoration planning in Oregon to examine how neoliberal environmental governance exercises influence through a set of knowledge politics that produces subpar outcomes. We present three main findings: (1) restoration policies produce a restoration economy based on a conception of wetland as commodity (2) practitioners in this restoration economy exhibit competitive behavior resulting in a piecemeal rather than a landscape approach to restoration; and (3) limited monitoring prevents changes to existing policies. Practitioners offer insight into the challenge of treating wetlands as a commodity and call for more monitoring to challenge the assumptions of hegemonic knowledge practices that reinforce a neoliberal environmental governance regime. The divergent ideas of reflexive practitioners, though not yet manifest as action, show where changes to restoration governance might be possible.  相似文献   
153.
ABSTRACT

The imminent development of a number of offshore wind farms in the Republic of Ireland presents a sizable opportunity to stimulate the Irish economy through the growth of an indigenous and globally competitive offshore wind supply chain. This study uses a value chain analysis to evaluate the economic and employment potential of the offshore wind sector for Ireland. The analysis is based on the expenditure on products and services required to develop an offshore wind farm, the planned capacity of projects in the pipeline, and the ability of Irish companies to supply the sector. Results suggest that by 2030, 2.5–4.5GW of domestic offshore wind development could create between 11,424 and 20,563 supply chain jobs and generate between €763 m and €1.4bn in gross value added. This is the first study to estimate domestic GVA potential for the sector.  相似文献   
154.
ABSTRACT: Successful stream rehabilitation requires a shift from narrow analysis and management to integrated understanding of the links between human actions and changing river health. At study sites in the Puget Sound lowlands of western Washington State, landscape, hydrological, and biological conditions were evaluated for streams flowing through watersheds with varying levels of urban development. At all spatial scales, stream biological condition measured by the benthic index of biological integrity (B‐IBI) declined as impervious area increased. Impervious area alone, however, is a flawed surrogate of river health. Hydrologic metrics that reflect chronic altered streamflows, for example, provide a direct mechanistic link between the changes associated with urban development and declines in stream biological condition. These measures provide a more sensitive understanding of stream basin response to urban development than do treatment of each increment of impervious area equally. Land use in residential backyards adjacent to streams also heavily influences stream condition. Successful stream rehabilitation thus requires coordinated diagnosis of the causes of degradation and integrative management to treat the range of ecological stressors within each urban area, and it depends on remedies appropriate at scales from backyards to regional storm water systems.  相似文献   
155.
156.
Cs+ transport experiments carried out in columns packed with uncontaminated Hanford formation sediment from the SX tank farm provide strong support for the use of a multisite, multicomponent cation exchange model to describe Cs+ migration in the Hanford vadose zone. The experimental results indicate a strong dependence of the effective Cs+ Kd on the concentrations of other cations, including Na+ that is present at high to extremely high concentrations in fluids leaking from the Hanford SX tanks. A strong dependence of the Cs+ Kd on the aqueous Cs+ concentration is also apparent, with retardation of Cs+ increasing from a value of 41 at a Cs+ concentration of 10(-4) M in the feed solution to as much as 282 at a Cs+ concentration of 5x10(-7) M, all in a background of 1 M NaNO3. The total cation exchange capacity (CEC) of the Hanford sediment was determined using 22Na isotopic equilibrium exchange in a flow-through column experiment. The value for the CEC of 120 microeq/g determined with this method is compatible with a value of 121.9 microeq/g determined by multi-cation elution. While two distinct exchange sites were proposed by Zachara et al. [Geochim. Cosmochim. Acta 66 (2002) 193] based on binary batch exchange experiments, a third site is proposed in this study to improve the fit of the Cs+-Na+ and Cs+-Ca+ exchange data and to capture self-sharpened Cs+ breakthrough curves at low concentrations of Cs+. Two of the proposed exchange sites represent frayed edge sites (FES) on weathered micas and constitute 0.02% and 0.22% of the total CEC. Both of the FES show a very strong selectivity for Cs+ over Na+ (K(Na-Cs)=10(7.22) and 10(4.93), respectively). The third site, accounting for over 99% of the total CEC, is associated with planar sites on expansible clays and shows a smaller Na+-Cs+ selectivity coefficient of 10(1.99). Parameters derived from a fit of binary batch experiments alone tend to under predict Cs+ retardation in the column experiments. The transport experiments indicate 72-90% of the Cs+ sorbed in experiments targeting exchange on FES was desorbed over a 10- and 24-day period, respectively. At high Cs+ concentrations, where sorption is controlled primarily by exchange on planar sites, 95% of the Cs+ desorption was desorbed. Most of the difficulty in desorbing Cs+ from FES is a result of the extremely high selectivity of these sites for Cs+, although truly irreversible sorption as high as 23% was suggested in one experiment. The conclusion that Cs+ exchange is largely reversible in a thermodynamic sense is supported by the ability to match Cs+ desorption curves almost quantitatively with an equilibrium reactive transport simulation. The model for Cs+ retardation developed here qualitatively explains the behavior of Cs+ in the Hanford vadose zone underneath a variety of leaking tanks with differing salt concentrations. The high selectivity of FES for Cs+ implies that future desorption and migration is very unlikely to occur under natural recharge conditions.  相似文献   
157.
Community involvement is fundamental to the management of multijurisdictional river basins but, in practice, is very difficult to achieve. The Murray-Darling basin, in Australia, and the Mekong River basin in Southeast Asia are both cooperatively managed multijurisdictional river basins where the management authorities have expressed an aim of community involvement. In the Murray-Darling basin vigorous efforts have promoted a culture of community consultation throughout each of the state jurisdictions involved, although true participation has not necessarily been achieved. In the Mekong basin the community is much more diverse and the successes so far have been largely at the local level, involving action in subsections of the basin. These case studies suggest that community involvement in the form of community consultation across large multijurisdictional river basins is achievable, but more comprehensive participation is not necessarily possible.  相似文献   
158.
Concentrations of heavy metals and major ions were measured in precipitation, snowpack, garden soils and vegetables from urban and rural sites in New Brunswick in Atlantic Canada. Atmospheric loading of mercury, lead, cadmium, arsenic, strontium, and vanadium need further assessment. Vanadium concentrations in precipitation, snowpack, soils and vegetables showed an urban influence. Vanadium concentrations in the snowpack ranged between <2.0 ppb at 50 kilometers from the city center to 31.4 ppb in the city. Concentrations of all heavy metals in urban soils were less than CCME remediation guidelines but selected metals exceeded the assessment benchmark non-regulatory guidelines. Major ions were consistently higher in event precipitation than the snowpack. The order of ion elution from the snowpack was NO3 > SO4 > NH4 > H > Mg > Cl > Na > K. Hydrogen ion equivalents were highest in the snowpack and precipitation from urban samples. Mean hydrogen ion concentrations ranged from 11 to 22 eq L-1 in the snowpack compared with 18 to 41 eq L-1 in event precipitation.  相似文献   
159.
Hurricanes cause serious and long-term damage to the Agricultural sectors of Caribbean countries. Bananas and tree crops are defoliated, snapped or uprooted and food crops may be flooded or washed away. Recovery takes time and money as both the production bases and the infrastructure are damaged or destroyed. National economies do not have the resources to expedite recovery without aid. An account is given of the actions taken to estimate losses and prepare rehabilitation plans after Hurricanes David (1979) in Dominica and Allen (1980) in St. Lucia and St. Vincent. The implementation of funding agency-assisted agricultural rehabilitation programmes is also described. Some steps that farmers can take to reduce loss of food are suggested.  相似文献   
160.
This research investigates the reception of the visual representations of a wind farm (WF) development by local stakeholders. Using non-verbal Qmethodology, residents of Lesvos’ island, Greece, sort images according to how these images represented their opinion about the proposed Aegean Link WF project. We found three opinion types. The “Risk Averter” type is focused on the various risks of constructing and operating the Aegean Link wind development. The “Green Developer” type believes that the renewable energy project will benefit both their local community and the environment. The “Realist” type defers to expert knowledge to make decisions about project outcomes and is sceptical of media bias. While the former two types seem to form their visual opinions based on whether they are in favour or against (respectively) of the WF development, the Realist opinion is rather guided by carefully considering whether the visual stimuli are representative of the project’s actual characteristics.  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