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   377篇
  免费   3篇
  国内免费   7篇
安全科学   4篇
废物处理   21篇
环保管理   39篇
综合类   40篇
基础理论   104篇
污染及防治   105篇
评价与监测   55篇
社会与环境   16篇
灾害及防治   3篇
  2023年   2篇
  2022年   17篇
  2021年   8篇
  2020年   11篇
  2019年   8篇
  2018年   12篇
  2017年   15篇
  2016年   18篇
  2015年   14篇
  2014年   20篇
  2013年   34篇
  2012年   23篇
  2011年   36篇
  2010年   22篇
  2009年   17篇
  2008年   26篇
  2007年   22篇
  2006年   13篇
  2005年   13篇
  2004年   4篇
  2003年   6篇
  2002年   8篇
  2001年   7篇
  2000年   4篇
  1999年   2篇
  1998年   5篇
  1997年   1篇
  1996年   3篇
  1995年   1篇
  1994年   2篇
  1993年   3篇
  1992年   3篇
  1991年   1篇
  1990年   1篇
  1989年   1篇
  1988年   1篇
  1986年   1篇
  1985年   1篇
  1982年   1篇
排序方式: 共有387条查询结果,搜索用时 171 毫秒
101.
In tanneries, the phases of conditioning and preparing the hide for tanning, as well as the transportation and fixation of tanning substances, are all carried out in aqueous media. Most of the steps of these processes are carried out with fresh water, which is used as a vehicle for the diffusion of chemical products and the extraction of undesirable materials from the hide. The objective of this study is to provide the minimization of water consumption at tanneries by applying the reuse of water at some stages of the process. Alternatives for water reuse were evaluated through analysis of the process wastewater to determine the concentration of some contaminant parameters. In tests with half-hides, the possibility of reusing the liquors from the 2nd bating washing in the 1st bating washing, and of reusing the liquors from the pre-deliming washing in the pre-deliming operation, was verified. In industrial scale the water reuse from a mixture of bating washings in the deliming and deliming bating was tested successfully. The quality of wet-blue leather analyzed in the systems with and without water reuse did not show any considerable differences and satisfies the tannery specifications. Finally, a mathematical program for mass integration was applied to solve the problem of water reuse in the beamhouse steps.  相似文献   
102.
103.
Part I of this study deals with the primary energy consumption and CO2eq emissions of a 350 tonnes/h construction and demolition waste (CDW) recycling facility, taking into account incorporated, operation and transportation impacts. It concludes that the generated impacts are mostly concentrated in operation and transportation, and that the impacts prevented through material recycling can be up to one order of magnitude greater than those generated.However, the conditions considered for the plant’s operation and related transportation system may, and very likely will, vary in the near future, which will affect its environmental performance. This performance is particularly affected by the plant’s installed capacity, transportation fuel and input CDW mass. In spite of the variations in overall primary energy and CO2eq balances, the prevented impacts are always higher than the generated impacts, at least by a factor of three and maybe even as high as 16 times in particular conditions. The analysis indicates environmental performance for variations in single parameters, except for the plant’s capacity, which was considered to vary simultaneously with all the others. Extreme best and worst scenarios were also generated to fit the results into extreme limits.  相似文献   
104.
Spatio-temporal modeling of benthic biological species   总被引:1,自引:0,他引:1  
The spatial and temporal distribution of the number of benthic species located in an important area under ecological stress (Puerto CALICA, Quintana Roo, Mexico) is analyzed by means of Gaussian Spatial Linear Mixed Models. Following a model-based approach we derive spatial predictions taking into account temporal variations between May 1996 and June 1999. The proposed models were evaluated in terms of their ability to detect the underlying spatial structure for further interpolation. Uncertainty in the prediction could be evaluated by using the Bayesian paradigm. The results can be used as a guide for further environmental management policies in the region.  相似文献   
105.
Carbaryl insecticide was applied by ground spray to plants in urban areas to control a serious insect pest the glassy-winged sharpshooter, Homalodisca coagulata (Say), newly introduced inCalifornia. To assure there are no adverse impacts to human health and the environment from the carbaryl applications, carbaryl was monitored in tank mixtures, air, surface water, foliage and backyard fruits and vegetables.Results from the five urban areas – Porterville, Fresno, Rancho Cordova, Brentwood and Chico – showed there were no significanthuman exposures or impacts on the environment. Spray tank concentrations ranged from 0.1–0.32%. Carbaryl concentrationsin air ranged from none detected to 1.12 g m-3, well below the interim health screening level in air of 51.7 g m-3. There were three detections of carbaryl in surface water nearapplication sites: 0.125 ppb (parts per billion) from a water treatment basin; 6.94 ppb from a gold fish pond; and 1737 ppbin a rain runoff sample collected from a drain adjacent to a sprayed site. The foliar dislodgeable residues ranged from 1.54–7.12 g cm-2, comparable to levels reported forsafe reentry of 2.4 to 5.6 g cm-2 for citrus. Carbarylconcentrations in fruits and vegetables ranged from no detectableamounts to 7.56 ppm, which were below the U.S.EPA tolerance, allowable residue of 10 ppm.  相似文献   
106.
Natura 2000 is a network of natural sites whose aim is to preserve species and habitats of relevance in the European Union. The policy underlying Natura 2000 has faced widespread opposition from land users and received extensive support from environmentalists. This paper addresses the ethical framework for Natura 2000 and the probable moral assumptions of its main stakeholders. Arguments for and against Natura 2000 were analyzed and classified according to “strong” or “weak” versions of the three main theories of environmental ethics – anthropocentrism, biocentrism, and ecocentrism. Weak (intergenerational) anthropocentrism was found to underlie the Natura 2000 network itself and the positions of environmentalists, while strong (traditional) anthropocentrism pervaded the positions of economic developers. Land users seemed to fall somewhere between weak and strong anthropocentrism. The paper discusses the relation between ethics and different attitudes towards Natura 2000, highlighting some of the implications for the network’s ongoing implementation. It is shown that Natura 2000 achieves a strong reversal of the burden of proof from conservation to economic development and land use change under anthropocentrism. It is argued that the alleged theoretical divide between anthropocentrism and non-anthropocentrism in relation to the burden of proof does not seem to hold in practice. Finally, it is predicted that the weak versions of anthropocentrism, biocentrism, and ecocentrism, are likely to converge extensively in respect to nature conservation policy measures.“Charting the depths of law and policy disputes yield an understanding of ethical differences.” Paul B. Thompson (2002, p. 189).  相似文献   
107.
We introduce a methodology to infer zones of high potential for the habitat of a species, useful for management of biodiversity, conservation, biogeography, ecology, or sustainable use. Inference is based on a set of sites where the presence of the species has been reported. Each site is associated with covariate values, measured on discrete scales. We compute the predictive probability that the species is present at each node of a regular grid. Possible spatial bias for sites of presence is accounted for. Since the resulting posterior distribution does not have a closed form, a Markov chain Monte Carlo (MCMC) algorithm is implemented. However, we also describe an approximation to the posterior distribution, which avoids MCMC. Relevant features of the approach are that specific notions of data acquisition such as sampling intensity and detectability are accounted for, and that available a priori information regarding areas of distribution of the species is incorporated in a clear-cut way. These concepts, arising in the presence-only context, are not addressed in alternative methods. We also consider an uncertainty map, which measures the variability for the predictive probability at each node on the grid. A simulation study is carried out to test and compare our approach with other standard methods. Two case studies are also presented.  相似文献   
108.
The Amazonian forest is, due to its great size, carbon storage capacity and present-day variability in carbon uptake and release, an important component of the global carbon cycle. Paleo-environmental reconstruction is difficult for Amazonia due to the scarcity of primary palynological data and the mis-interpretation of some secondary data. Studies of lacustrine sediment records have shown that Amazonia has known periods in which the climate was drier than it is today. However, not all geomorphological features such as dunes, and slope erosion, which are thought to indicate rainforest regression, date from the time of the Late Glacial Maximum (LGM) and these features do not necessarily correspond to episodes of forest regression. There is also uncertainty concerning LGM carbon storage due to rainforest soils and biomass estimates. Soil carbon content may decrease moderately during the LGM, whereas rainforest biomass may change considerably in response to changes in the global environment. Biomass per unit area in Amazonia has probably been reduced by the cumulative effects of low CO2 concentration, a drier climate and lower temperatures. As few paleo-vegetation data are available, there is considerable uncertainty concerning the amount of carbon stored in Amazonia during the LGM, which may have corresponded to 44-94% of the carbon currently stored in biomass and soils.  相似文献   
109.
The efficacy of protected areas varies, partly because socioeconomic factors are not sufficiently considered in planning and management. Although integrating socioeconomic factors into systematic conservation planning is increasingly advocated, research is needed to progress from recognition of these factors to incorporating them effectively in spatial prioritization of protected areas. We evaluated 2 key aspects of incorporating socioeconomic factors into spatial prioritization: treatment of socioeconomic factors as costs or objectives and treatment of stakeholders as a single group or multiple groups. Using as a case study the design of a system of no‐take marine protected areas (MPAs) in Kubulau, Fiji, we assessed how these aspects affected the configuration of no‐take MPAs in terms of trade‐offs between biodiversity objectives, fisheries objectives, and equity in catch losses among fisher stakeholder groups. The achievement of fisheries objectives and equity tended to trade‐off concavely with increasing biodiversity objectives, indicating that it is possible to achieve low to mid‐range biodiversity objectives with relatively small losses to fisheries and equity. Importantly, the extent of trade‐offs depended on the method used to incorporate socioeconomic data and was least severe when objectives were set for each fisher stakeholder group explicitly. We found that using different methods to incorporate socioeconomic factors that require similar data and expertise can result in plans with very different impacts on local stakeholders.  相似文献   
110.
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