全文获取类型
收费全文 | 2190篇 |
免费 | 125篇 |
国内免费 | 139篇 |
专业分类
安全科学 | 98篇 |
废物处理 | 76篇 |
环保管理 | 685篇 |
综合类 | 914篇 |
基础理论 | 205篇 |
环境理论 | 1篇 |
污染及防治 | 86篇 |
评价与监测 | 41篇 |
社会与环境 | 324篇 |
灾害及防治 | 24篇 |
出版年
2024年 | 6篇 |
2023年 | 21篇 |
2022年 | 48篇 |
2021年 | 48篇 |
2020年 | 50篇 |
2019年 | 47篇 |
2018年 | 36篇 |
2017年 | 66篇 |
2016年 | 71篇 |
2015年 | 60篇 |
2014年 | 68篇 |
2013年 | 91篇 |
2012年 | 120篇 |
2011年 | 139篇 |
2010年 | 111篇 |
2009年 | 118篇 |
2008年 | 78篇 |
2007年 | 158篇 |
2006年 | 116篇 |
2005年 | 113篇 |
2004年 | 103篇 |
2003年 | 96篇 |
2002年 | 85篇 |
2001年 | 63篇 |
2000年 | 80篇 |
1999年 | 69篇 |
1998年 | 42篇 |
1997年 | 49篇 |
1996年 | 49篇 |
1995年 | 39篇 |
1994年 | 41篇 |
1993年 | 44篇 |
1992年 | 22篇 |
1991年 | 25篇 |
1990年 | 15篇 |
1989年 | 6篇 |
1988年 | 4篇 |
1986年 | 4篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1982年 | 2篇 |
1980年 | 6篇 |
1979年 | 11篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1975年 | 2篇 |
1973年 | 7篇 |
1972年 | 3篇 |
1971年 | 7篇 |
1970年 | 1篇 |
排序方式: 共有2454条查询结果,搜索用时 15 毫秒
991.
Phil N. Trathan Pablo García‐Borboroglu Dee Boersma Charles‐André Bost Robert J. M. Crawford Glenn T. Crossin Richard J. Cuthbert Peter Dann Lloyd Spencer Davis Santiago De La Puente Ursula Ellenberg Heather J. Lynch Thomas Mattern Klemens Pütz Philip J. Seddon Wayne Trivelpiece Barbara Wienecke 《Conservation biology》2015,29(1):31-41
Cumulative human impacts across the world's oceans are considerable. We therefore examined a single model taxonomic group, the penguins (Spheniscidae), to explore how marine species and communities might be at risk of decline or extinction in the southern hemisphere. We sought to determine the most important threats to penguins and to suggest means to mitigate these threats. Our review has relevance to other taxonomic groups in the southern hemisphere and in northern latitudes, where human impacts are greater. Our review was based on an expert assessment and literature review of all 18 penguin species; 49 scientists contributed to the process. For each penguin species, we considered their range and distribution, population trends, and main anthropogenic threats over the past approximately 250 years. These threats were harvesting adults for oil, skin, and feathers and as bait for crab and rock lobster fisheries; harvesting of eggs; terrestrial habitat degradation; marine pollution; fisheries bycatch and resource competition; environmental variability and climate change; and toxic algal poisoning and disease. Habitat loss, pollution, and fishing, all factors humans can readily mitigate, remain the primary threats for penguin species. Their future resilience to further climate change impacts will almost certainly depend on addressing current threats to existing habitat degradation on land and at sea. We suggest protection of breeding habitat, linked to the designation of appropriately scaled marine reserves, including in the High Seas, will be critical for the future conservation of penguins. However, large‐scale conservation zones are not always practical or politically feasible and other ecosystem‐based management methods that include spatial zoning, bycatch mitigation, and robust harvest control must be developed to maintain marine biodiversity and ensure that ecosystem functioning is maintained across a variety of scales. Contaminación, Pérdida de Hábitat, Pesca y Cambio Climático como Amenazas Críticas para los Pingüinos 相似文献
992.
T. R. McClanahan N. A. J. Graham M. A. MacNeil J. E. Cinner 《Conservation biology》2015,29(2):409-417
The failure of fisheries management among multispecies coral reef fisheries is well documented and has dire implications for the 100 million people engaged in these small‐scale operations. Weak or missing management institutions, a lack of research capacity, and the complex nature of these ecosystems have heralded a call for ecosystem‐based management approaches. However, ecosystem‐based management of coral reef fisheries has proved challenging due to the multispecies nature of catches and the diversity of fish functional roles. We used data on fish communities collected from 233 individual sites in 9 western Indian Ocean countries to evaluate changes in the site's functional composition and associated life‐history characteristics along a large range of fish biomass. As biomass increased along this range, fish were larger and grew and matured more slowly while the abundance of scraping and predatory species increased. The greatest changes in functional composition occurred below relatively low standing stock biomass (<600 kg/ha); abundances of piscivores, apex predators, and scraping herbivores were low at very light levels of fishing. This suggests potential trade‐offs in ecosystem function and estimated yields for different management systems. Current fishing gear and area restrictions are not achieving conservation targets (proposed here as standing stock biomass of 1150 kg/ha) and result in losses of life history and ecological functions. Fish in reefs where destructive gears were restricted typically had very similar biomass and functions to young and low compliance closures. This indicates the potentially important role of fisheries restrictions in providing some gains in biomass and associated ecological functions when fully protected area enforcement potential is limited and likely to fail. Our results indicate that biomass alone can provide broad ecosystem‐based fisheries management targets that can be easily applied even where research capacity and information is limited. Of particular value, is our finding that current management tools may be used to reach key ecosystem‐based management targets, enabling ecosystem‐based management in many socioeconomic contexts. 相似文献
993.
改革开放以来,随着经济高速发展,大量外来人口涌入珠三角地区。1979─2012年间,珠三角地区的常住人口从1797.42万人增至5681.70万人。大规模的人口增长使得珠三角地区的资源供给压力增大,特别是土地资源。2010年珠三角地区已开发的建设用地面积为8867 km2,其中深圳、东莞等城市的建设用地规模已经接近其土地资源的适宜开发上限,土地资源对人口增长的约束作用也日趋显著。为了评判珠三角地区土地资源压力对人口增长的影响,利用Malthus模型和Logistic模型分别对该地区9个城市的人口变化进行拟合,结果表明,2组模型对2000年前各城市的人口变化均有较高的拟合精度且拟合结果与实际情况较为相近,主要是由于该地区早期发展阶段的资源压力对人口增长的约束作用较小。2000年以后不同城市的Logistic模型与Malthus模型对人口变化预测呈现出不同的趋势,主要与各城市的土地资源压力密切相关。根据2组模型模拟结果的差异和土地资源的压力,将9个城市分为3组。其中深圳、东莞为第一组,这2个城市的人口增速最快、土地资源压力最大,相应的Malthus模型的估计值分别在2003年、2005年超过了实际人口,且其后估计值与实际值的差距逐渐增大。依据Malthus模型2020年深圳、东莞的人口预测值分别为6469.58万人、2386.81万人,这大大超过了这2个城市的资源环境承载极限。这一结果说明在深圳、东莞的人口高速增长已经不可持续,Malthus模型已不能反映其未来人口的变化趋势。第二组包括广州、佛山、珠海和中山4个城市。这组城市的人口增速相对缓慢,Malthus模型的估计值与实际人口较为接近,但2010年以来这4个城市人口的增长呈放缓趋势,Malthus模型估计值逐渐偏大。第三组城市包括人口增速最慢的江门、惠州和肇庆3个城市。这组城市的人口? 相似文献
994.
Bernard Shanks 《Journal of the American Water Resources Association》1977,13(2):255-264
ABSTRACT: Federal planners, in proposing the massive main stem Missouri River water developments in Montana and North Dakota, promised economic and social benefits to the local residents. Five main stem dams, Fort Peck, Garrison, Oahe, Big Bend and Fort Randall, were evaluated for community and rural development effectiveness. Thirty-seven development factors were examined and improvements noted. Only small differences were noted between areas with water developments and the control area. Further analysis revealed that water development benefits moved downstream and to existing urban areas. The Missouri River's rural areas and small communities were not developed significantly by the water projects. Several problems associated with water development policy were illustrated by the study. Cultural differences between planners and the population impacted were ignored. Second, the allocation of social costs was not considered and related to this, serious geographic maldistribution of benefits and costs resulted. The differences between pre-development promises and development performance was dramatic. While the large dams remain as landmarks to engineering prowess, the projects need to be evaluated for their success in meeting humanistic development objectives. Major redevelopment may be warranted by such an ex-post evaluation. 相似文献
995.
996.
简要回顾江苏省“九五”期间环境保护工作取 得的主要成效,总结环保攻坚战的成功经验和教训,提 出“十五”强化环境污染治理和生态保护的对策措施。 相似文献
997.
孙大伟 《辽宁城乡环境科技》2004,24(2):38-39,48
随着人们消费观念的转变,中华鳖和野生鱼类价格的不断上涨,造成了掠夺性捕捞现象,其资源受到严重破坏。为保护中华鳖和野生鱼类资源特设立保护区,实现中华鳖物种恢复、繁衍,保护自然生态平衡。并创造一定的经济价值。 相似文献
998.
本文着重论述内蒙古自治区21世纪水资源可持续利用,水在人口增长和经济发展,农业用水量增加趋势,特别随着西部大开发,现有淡水资源有限,水资源利用将变的越来越复杂和昂贵,水资源的开发和管理,必须考虑节水和改善环境以实现经济可持续发展。 相似文献
999.
Graham A Davis 《Resources Policy》1998,24(4):217-228
Sectoral analysis, a new branch of political science, alleges that mineral extraction creates a socio-political climate that promotes inflexible statism, which in turn leads to substandard development performance. The theory, that mineral economies underperform bureaucratically and economically, is said not only to hold in a post-dictive sense for the mature mineral economies, such as Zambia, but also in a predictive sense for the newer mineral economies, such as Ecuador. This essay reviews and assesses this hypothesis in the light of the empirical evidence comparing mineral production, state capacity, and economic performance. It finds that the sectoralist view is supportable only in selected cases, and is not a general result. 相似文献
1000.
在我国建立水权制度的探讨 总被引:1,自引:0,他引:1
水权制度是水资源法制化管理的模式,与我国的取水许可制度在管理机制和调度方式上均存在区别。在我国建立水权制度是市场经济发展的需求,是一个长期的、循序渐进的、从理论到实践的过程。取水许可证制度是水权管理的基础,前者向后者的转变需要逐步实施,因地制宜。 相似文献