全文获取类型
收费全文 | 5307篇 |
免费 | 501篇 |
国内免费 | 476篇 |
专业分类
安全科学 | 276篇 |
废物处理 | 19篇 |
环保管理 | 1502篇 |
综合类 | 1898篇 |
基础理论 | 1189篇 |
环境理论 | 2篇 |
污染及防治 | 239篇 |
评价与监测 | 151篇 |
社会与环境 | 817篇 |
灾害及防治 | 191篇 |
出版年
2024年 | 27篇 |
2023年 | 47篇 |
2022年 | 106篇 |
2021年 | 124篇 |
2020年 | 138篇 |
2019年 | 182篇 |
2018年 | 191篇 |
2017年 | 305篇 |
2016年 | 281篇 |
2015年 | 260篇 |
2014年 | 232篇 |
2013年 | 623篇 |
2012年 | 295篇 |
2011年 | 402篇 |
2010年 | 286篇 |
2009年 | 246篇 |
2008年 | 267篇 |
2007年 | 349篇 |
2006年 | 269篇 |
2005年 | 213篇 |
2004年 | 198篇 |
2003年 | 202篇 |
2002年 | 153篇 |
2001年 | 118篇 |
2000年 | 119篇 |
1999年 | 101篇 |
1998年 | 62篇 |
1997年 | 50篇 |
1996年 | 64篇 |
1995年 | 36篇 |
1994年 | 34篇 |
1993年 | 35篇 |
1992年 | 25篇 |
1991年 | 28篇 |
1990年 | 25篇 |
1989年 | 20篇 |
1988年 | 19篇 |
1987年 | 10篇 |
1986年 | 10篇 |
1985年 | 11篇 |
1984年 | 10篇 |
1983年 | 14篇 |
1982年 | 6篇 |
1981年 | 17篇 |
1980年 | 18篇 |
1979年 | 13篇 |
1978年 | 6篇 |
1977年 | 9篇 |
1975年 | 10篇 |
1971年 | 5篇 |
排序方式: 共有6284条查询结果,搜索用时 203 毫秒
521.
Michael N. Beaulac Kenneth H. Reckhow 《Journal of the American Water Resources Association》1982,18(6):1013-1024
ABSTRACT: Lake and watershed management strategies and recent environmental legislation dictate that nonpoht nutrient sources associated with storm water runoff must be assessed. Accordingly, a nutrient flu assessment for phosphorus and nitrogen is conducted through an extensive literature review of nutrient export studies. These studies are reevaluated. The nutrient export coefficients are screened according to sampling design criteria and compiled according to land use. The ecological mechanisms within each land use influencing the magnitude of nutrient flux are also discussed 相似文献
522.
523.
M. Almar L. Otero C. Santos J. Gonzalez Gallego 《Journal of environmental science and health. Part. B》2013,48(6):769-783
Abstract Glutathione content and glutahione‐dependent enzymes were measured in the liver of two fish species, gudgeon (Gobio gobio) and roach (Rutilus arcasii), from the river Bernesga (Spain) caught downstream and upstream of the waste site of several chemical industries. Animals from contaminated sites display a reduced glutathione concentration and a tendency to the decrease of glutathione S‐transferase activity. Glutathione peroxidase activity was significantly elevated only in the liver of Gobio gobio and glutathione reductase activity in that of Rutilus arcasii. Our data indicate that the glutathione system constitutes a sensitive biochemical indicator of chemical pollution. Relative changes of glutathione and glutathione‐dependent enzymes in both fish species suggest a different susceptibility to toxins. 相似文献
524.
525.
Abstract: Extinctions can leave species without mutualist partners and thus potentially reduce their fitness. In cases where non‐native species function as mutualists, mutualism disruption associated with species’ extinction may be mitigated. To assess the effectiveness of mutualist species with different origins, we conducted a meta‐analysis in which we compared the effectiveness of pollination and seed‐dispersal functions of native and non‐native vertebrates. We used data from 40 studies in which a total of 34 non‐native vertebrate mutualists in 20 geographic locations were examined. For each plant species, opportunistic non‐native vertebrate pollinators were generally less effective mutualists than native pollinators. When native mutualists had been extirpated, however, plant seed set and seedling performance appeared elevated in the presence of non‐native mutualists, although non‐native mutualists had a negative overall effect on seed germination. These results suggest native mutualists may not be easily replaced. In some systems researchers propose taxon substitution or the deliberate introduction of non‐native vertebrate mutualists to reestablish mutualist functions such as pollination and seed dispersal and to rescue native species from extinction. Our results also suggest that in places where all native mutualists are extinct, careful taxon substitution may benefit native plants at some life stages. 相似文献
526.
ADENA R. RISSMAN†† LYNN LOZIER† TOSHA COMENDANT‡ PETER KAREIVA§ JOSEPH M. KIESECKER M. REBECCA SHAW† ADINA M. MERENLENDER 《Conservation biology》2007,21(3):709-718
Abstract: Conservation easements are one of the primary tools for conserving biodiversity on private land. Despite their increasing use, little quantitative data are available on what species and habitats conservation easements aim to protect, how much structural development they allow, or what types of land use they commonly permit. To address these knowledge gaps, we surveyed staff responsible for 119 conservation easements established by the largest nonprofit easement holder, The Nature Conservancy, between 1985 and 2004. Most easements (80%) aimed to provide core habitat to protect species or communities on-site, and nearly all were designed to reduce development. Conservation easements also allowed for a wide range of private uses, which may result in additional fragmentation and habitat disturbance. Some residential or commercial use, new structures, or subdivision of the property were permitted on 85% of sampled conservation easements. Over half (56%) allowed some additional buildings, of which 60% restricted structure size or building area. Working landscape easements with ranching, forestry, or farming made up nearly half (46%) of the easement properties sampled and were more likely than easements without these uses to be designated as buffers to enhance biodiversity in the surrounding area. Our results demonstrate the need for clear restrictions on building and subdivision in easements, research on the compatibility of private uses on easement land, and greater public understanding of the trade-offs implicit in the use of conservation easements for biodiversity conservation. 相似文献
527.
How conservation messages are framed will impact the success of our efforts to engage people in conservation action. This is highly relevant in the private land conservation (PLC) sector given the low participation rates of landholders. Using a case study of PLC schemes targeted at Australian landholders, we present the first systematic analysis of communication strategies used by organisations and government departments delivering those schemes to engage the public. We develop a novel approach for analysing the framing of conservation messages that codes the stated benefits of schemes according to value orientation. We categorised the benefits as flowing to either the landholder, to society, or to the environment, corresponding to the egoistic, altruistic and biospheric value orientations that have been shown to influence human behaviour. We find that messages are biased towards environmental benefits. Surprisingly, this is the case even for market-based schemes that have the explicit objective of appealing to production-focussed landholders and those who are not already involved in conservation. The risk is that PLC schemes framed in this way will fail to engage more egoistically oriented landholders and are only likely to appeal to those likely to already be conservation-minded. By understanding the frame in which PLC benefits are communicated, we can begin to understand the types of people who may be engaged by these messages, and who may not be. Results suggest that the framing of the communications for many schemes could be broadened to appeal to a more diverse group (and thus ultimately to a larger group) of landholders. 相似文献
528.
空间功能识别是确定国土空间规划空间开发保护格局的关键环节,理论和实践意义重大。基于土地利用和地表覆盖现状、精细化DEM、地形单元等基础地理信息,水、生态、环境、灾害等专题数据,社会统计数据等多元信息,利用空间分析、多元统计、计量模型、基于规则的分类模型等技术方法,从多元信息综合集成和自动分类识别的角度,研究构建了一套市县国土空间规划空间主导功能识别的关键技术与方法,并对榆林市域进行空间功能分区。研究表明:本文方法有效将地理实体单元、功能评价指标综合于统一的地域单元,保证了空间功能分类识别的准确性;通过自动分类算法建模,实现空间功能识别的自动化,提高了国土空间规划的客观性和工作效率。 相似文献
529.
Hauke Von Seht 《Local Environment》2013,18(1):23-34
Local environmental policies are sometimes seen as standing in the way of socio-economic progress. Against the background of these concerns, the actual socio-economic impacts of climate protection measures are discussed in this paper. It is structured as follows. First, the concept of primary and secondary effects of climate policies is introduced. Secondly, there is a discussion of financial and economic impacts of local climate policies. Finally, information is given on the consequences of such measures for local energy security and air quality. The main conclusion is that, at least in the field of climate policies, there is a huge potential for local measures that are socioeconomically attractive to local communities. HAUKE VON SEHT, Impactos socio-económicos de políticas del medio ambiente local, un análisis para el campo de protección climática . Las políticas ambientales locales son vistas algunas veces como si estuvieran en la via del progreso socio-económico. En contra de los antecedentes de estos asuntos, los impactos socio-económicos actuales de las medidas de protección climaticas son discutidos en este documento. Está extructurado de la siguiente manera: Primero serán introducidos el concepto de efectos primarios y secundarios de las políticas climáticas. Luego sigue una discusión de impactos económicos y financieros de las políticas climáticas locales, seguido por información de las consecuencias de tales medidas para la calidad del aire y seguridad de energía local. La conclusión principal es que por lo menos en el campo de las políticas climáticas hay un inmenso potencial de medidas locales que son socio-económicamente actractivas a las comunidades locales. 相似文献
530.
This paper contributes to on-going attempts at bringing together two influential ideas in water governance: Integrated Water Resource Management (IWRM) and adaptive governance. In particular, a tension remains between the call in IWRM for the use of formal institutions, such as river basin organisations, to secure public policy integration, and the assumptions in adaptive governance in favour of informal collaboration between essentially independent policy actors. To clarify this relationship, this article draws on theoretical research on public policy integration, and uses these insights in an empirical setting to identify mechanisms that can facilitate effective policy integration for adaptive water governance. The research is based on recent attempts in Scotland to implement IWRM ideas to improve flood management. Several governance mechanisms were adopted to facilitate the integration of flood, water and rural land use policies. Six Scottish policy regimes are analysed using documentary sources and interviews. Results challenge the idea that collaboration should primarily be built on either river basin organisations or informal mechanisms. We identify a mix of informal and statutory-based mechanisms which may secure political and technocratic commitment to policy integration. 相似文献