全文获取类型
收费全文 | 3687篇 |
免费 | 44篇 |
国内免费 | 49篇 |
专业分类
安全科学 | 94篇 |
废物处理 | 203篇 |
环保管理 | 359篇 |
综合类 | 607篇 |
基础理论 | 797篇 |
环境理论 | 4篇 |
污染及防治 | 1130篇 |
评价与监测 | 327篇 |
社会与环境 | 233篇 |
灾害及防治 | 26篇 |
出版年
2023年 | 37篇 |
2022年 | 133篇 |
2021年 | 146篇 |
2020年 | 68篇 |
2019年 | 61篇 |
2018年 | 139篇 |
2017年 | 142篇 |
2016年 | 187篇 |
2015年 | 115篇 |
2014年 | 177篇 |
2013年 | 267篇 |
2012年 | 201篇 |
2011年 | 238篇 |
2010年 | 169篇 |
2009年 | 155篇 |
2008年 | 179篇 |
2007年 | 153篇 |
2006年 | 110篇 |
2005年 | 139篇 |
2004年 | 180篇 |
2003年 | 174篇 |
2002年 | 111篇 |
2001年 | 87篇 |
2000年 | 46篇 |
1999年 | 43篇 |
1998年 | 21篇 |
1997年 | 31篇 |
1996年 | 20篇 |
1995年 | 28篇 |
1994年 | 19篇 |
1993年 | 9篇 |
1992年 | 11篇 |
1991年 | 18篇 |
1990年 | 9篇 |
1989年 | 11篇 |
1988年 | 5篇 |
1987年 | 14篇 |
1986年 | 8篇 |
1985年 | 10篇 |
1984年 | 12篇 |
1983年 | 11篇 |
1982年 | 5篇 |
1981年 | 7篇 |
1979年 | 8篇 |
1975年 | 3篇 |
1970年 | 3篇 |
1966年 | 3篇 |
1964年 | 4篇 |
1961年 | 3篇 |
1957年 | 3篇 |
排序方式: 共有3780条查询结果,搜索用时 289 毫秒
911.
Alejandro Jim��nez Fern��ndez de Palencia Agust�� P��rez-Foguet 《Sustainability Science》2011,6(1):37-49
This paper examines the challenge of achieving a balance between the implementation of centrally designed pro-poor policies
and the decentralization of responsibilities to local governments in many African countries. It analyzes the implementation
of the Rural Water Supply and Sanitation Program in Tanzania. Key mechanisms for planning and allocating resources are analyzed
at ministry, district, and village levels. Results show that a mixture of policy incoherencies, technical shortcomings and
political influence determine that only a small proportion of funds reaches the underserved areas. We argue that a greater
connection between the bottom-up and top-down planning mechanisms, and a sharp increase of downwards accountability are needed
before decentralized decision-making result in better resources allocation. Meanwhile a bigger intervention from central government
is needed. 相似文献
912.
Jesus Barron-Zambrano Agata Szygula Montserrat Ruiz Ana Maria Sastre Eric Guibal 《Journal of environmental management》2010,91(12):2669-2675
Fixed-bed column studies were carried out to investigate the dynamic sorption of Reactive Black 5 (RB5) onto chitosan. The effect of operating parameters such as initial dye concentration, superficial flow velocity, bed height and particle size on the sorption of RB5 onto chitosan was studied. Column regeneration, dye recovery and the possibility of reusing the regenerated chitosan were also investigated. The results show that both the breakthrough curves and the adsorption parameters of the column were strongly affected by the operating parameters studied. An analysis of the breakthrough curves indicated that adsorption was affected by mass transfer limitations, probably due to intraparticle diffusion. An empirical model was applied to describe the breakthrough curves, while the Bohart–Adams and BDST models were used to determine the operating parameters useful in the process design. Elution of the column with 0.01 mol L?1 NaOH allowed the chitosan to be regenerated and the dye to be recovered and concentrated. The concentration factor was 10. Several cycles of adsorption–elution showed that the regenerated chitosan retained good adsorption efficiency and the elution efficiency was always higher than 80%. 相似文献
913.
914.
915.
Cinema offers a substantial opportunity to share messages with a wide audience. However, there is little research or evidence about the potential benefits and risks of cinema for conservation. Given their global reach, cinematic representations could be important in raising awareness of conservation issues and species of concern, as well as encouraging greater audience engagement due to their heightened emotional impact on viewers. Yet there are also risks associated with increased exposure, including heightened visitor pressure to environmentally sensitive areas or changes to consumer demand for endangered species. Conservationists can better understand and engage with the film industry by studying the impact of movies on audience awareness and behavior, identifying measurable impacts on conservation outcomes, and engaging directly with the movie industry, for example, in an advisory capacity. This improved understanding and engagement can harness the industry's potential to enhance the positive impacts of movies featuring species, sites, and issues of conservation concern and to mitigate any negative effects. A robust evidence base for evaluating and planning these engagements, and for informing related policy and management decisions, needs to be built. 相似文献
916.
Freshwater protected areas are rare even though freshwater ecosystems are among the most imperiled in the world. Conservation actions within terrestrial protected areas (TPAs) such as development or resource extraction regulations may spill over to benefit freshwater ecosystems within their boundaries. Using data from 175 lakes across Ontario, Canada, we compared common indicators of fish‐assemblage status (i.e., species richness, Shannon diversity index, catch per unit effort, and normalized‐length size spectrum slopes) to evaluate whether TPAs benefit lake fish assemblages. Nearest neighbor cluster analysis was used to generate pairs of lakes: inside versus outside, inside versus bordering, and bordering versus outside TPAs based on lake characteristics. The diversity and abundance indicators did not differ significantly across comparisons, but normalized‐length size spectrum slopes (NLSS) were significantly steeper in lakes outside parks. The latter indicated assemblage differences (greater abundances of small‐bodied species) and less‐efficient energy transfer through the trophic levels of assemblages outside parks. Although not significantly different, pollution‐ and turbidity‐tolerant species were more abundant outside parks, whereas 3 of the 4 pollution‐intolerant species were more abundant within parks. Twenty‐one percent of the difference in slopes was related to higher total dissolved solids concentrations and angling pressure. Our results support the hypothesis that TPAs benefit lake fish assemblages and suggest that NLSS slopes are informative indicators for aquatic protected area evaluations because they represent compositional and functional aspects of communities. 相似文献
917.
Jean-Luc de Kok Guy Engelen Roger White Herman G. Wind 《Environmental Modeling and Assessment》2001,6(2):123-132
RaMCo is a prototype version of a decision-support system for coastal-zone management. The model is based on the findings of a multidisiciplinary research program, conducted in Southwest Sulawesi, Indonesia. Different management strategies can be compared on the basis of the short- and long-term consequences. Land-use change has been included in RaMCo in view of the impacts of land-based human activities on the marine environment. The key aspect of the model is a combination of the temporal dynamics of land-use change on the regional (macro-level) scale and spatial dynamics on the local (micro-level) scale. Constrained cellular automata are used to integrate both scale levels. The state changes of the cells depend on the consistency with the macro-scale model, local geographical conditions, and interaction with neighboring cells. In this paper, we discuss the underlying theoretical assumptions of the macro-scale and micro-scale models, some characteristic results for land-use change in the study area, and the validation problem. 相似文献
918.
919.
Guilherme da Silva Bertolaccini Idinei Francisco Pires de Carvalho Filho Gustavo Christofoletti Luis Carlos Paschoarelli 《International journal of occupational safety and ergonomics》2018,24(2):311-315
Introduction. Wheelchair configuration is an important factor influencing the ergonomics of the user–device interface and, from a biomechanical point of view, small changes in chair setup may have a positive influence on the demand on the upper limbs during manual propulsion. This study aimed to investigate the influence of the position of the rear wheels’ axle and the use of accessories on the activity of upper limb muscles during manual wheelchair propulsion. Methods. Electromyography signals of the biceps, triceps, anterior deltoids and pectoralis major were collected for 11 able-bodied subjects in a wheelchair propulsion protocol with four different wheelchair configurations (differing in axle position and the use of accessories) on a straightforward sprint and a slalom course. Results. With accessories, moving the axle forward led to a decrease in the activity of all muscles in both the straightforward sprint (significant differences in triceps, anterior deltoids and biceps) and the slalom course (significant difference in anterior deltoids and biceps). However, when propelling the chair without accessories, no difference was found related to axle position. Conclusion. Changes in wheelchair configuration can influence the ergonomics of manual wheelchair propulsion. Reducing the biomechanical loads may benefit users’ mobility, independence and social participation. 相似文献
920.
Cristina Dutra Vieira Maria Auxiliadora Roque de Carvalho Noil Amorim de Menezes Cussiol Maria Eugênia Alvarez-Leite Simone Gonçalves dos Santos Renata Maria da Fonseca Gomes Marcos Xavier Silva Luiz de Macêdo Farias 《Waste management (New York, N.Y.)》2009,29(4):1388-1391
When developing proper waste management strategies, it is essential to characterize the volume and composition of solid waste. The aim of this work was to evaluate the composition of dental waste produced by three dental health services in Belo Horizonte, Minas Gerais State, Brazil. Two universities, one public and one private, and one public dental health service were selected. Waste collection took place from March to November 2007. During this period, three samples were collected from each dental health service. The total amount of dental waste produced in one day of dental work was manually separated into three categories: infectious and potentially infectious waste, accounting for 24.3% of the total waste; non-infectious waste, accounting for 48.1%; and domestic-type waste, accounting for 27.6% (percentages are for mean weights of solid waste). Our results showed that most of the waste considered as biomedical may be misclassified, consequently making the infectious waste amount appear much larger. In addition, our results suggest that the best waste minimization method is recycling, and they help to define an appropriate waste management system in all three of the dental health services involved in this study. 相似文献