全文获取类型
收费全文 | 1340篇 |
免费 | 21篇 |
国内免费 | 19篇 |
专业分类
安全科学 | 86篇 |
废物处理 | 38篇 |
环保管理 | 366篇 |
综合类 | 179篇 |
基础理论 | 337篇 |
环境理论 | 3篇 |
污染及防治 | 246篇 |
评价与监测 | 69篇 |
社会与环境 | 43篇 |
灾害及防治 | 13篇 |
出版年
2023年 | 9篇 |
2022年 | 9篇 |
2021年 | 16篇 |
2020年 | 15篇 |
2019年 | 24篇 |
2018年 | 18篇 |
2017年 | 37篇 |
2016年 | 53篇 |
2015年 | 36篇 |
2014年 | 44篇 |
2013年 | 105篇 |
2012年 | 53篇 |
2011年 | 67篇 |
2010年 | 38篇 |
2009年 | 58篇 |
2008年 | 70篇 |
2007年 | 65篇 |
2006年 | 58篇 |
2005年 | 50篇 |
2004年 | 48篇 |
2003年 | 52篇 |
2002年 | 42篇 |
2001年 | 31篇 |
2000年 | 26篇 |
1999年 | 17篇 |
1998年 | 27篇 |
1997年 | 20篇 |
1996年 | 15篇 |
1995年 | 11篇 |
1994年 | 24篇 |
1993年 | 25篇 |
1992年 | 11篇 |
1991年 | 14篇 |
1990年 | 14篇 |
1989年 | 14篇 |
1988年 | 16篇 |
1987年 | 13篇 |
1986年 | 11篇 |
1985年 | 15篇 |
1984年 | 11篇 |
1983年 | 12篇 |
1982年 | 14篇 |
1981年 | 14篇 |
1980年 | 13篇 |
1979年 | 11篇 |
1978年 | 9篇 |
1977年 | 6篇 |
1976年 | 4篇 |
1973年 | 3篇 |
1967年 | 2篇 |
排序方式: 共有1380条查询结果,搜索用时 31 毫秒
1.
2.
3.
4.
An experimental investigation of explanations for inconsistencies in responses to second offers in double referenda 总被引:1,自引:0,他引:1
Anthony C. Burton Katherine S. Carson Susan M. Chilton W. George Hutchinson 《Journal of Environmental Economics and Management》2003,46(3):472
This paper demonstrates the potential for induced preference experiments to test previously unverified explanations of observed behavior in contingent valuation surveys. The NOAA Panel on Contingent Valuation called for experimental evidence on potential biases in the double referendum format. We test Carson, Groves, and Machina's (Incentives and informational properties of preference questions, Plenary address to the European Association of Resource and Environmental Economists, Oslo, Norway, June 1999) simple cost uncertainty and weighted averaging explanations of inconsistent responses to follow-up offers in such double referenda against a baseline of certainty and truthful preference revelation. The results find evidence to support the Weighted Average hypothesis. Results regarding the cost uncertainty hypothesis are more ambiguous and merit further investigation. 相似文献
5.
Neil Ravenscroft Nigel Curry Susan Markwell 《Journal of Environmental Planning and Management》2002,45(5):715-734
The Countryside and Rights of Way Act 2000 places a duty on highways and national park authorities to establish local access forums (LAFs), to advise on the improvement of public access to land for the purposes of open air recreation and enjoyment. This paper examines these proposals in the context of recent academic and political debates about deliberative democracy, and empirical research on the nature and practice of existing access liaison groups and forums. While demonstrating that the proposed LAFs are consistent with contemporary constructs of participative, if not deliberative democracy, the paper argues that most existing groups and forums fall short of this ideal, in a number of significant respects. The paper proceeds to discuss the extent to which the draft regulations for LAFs in England and Wales address these issues, and concludes by questioning the extent to which such consultative arrangements can contribute to new forms of local governance. 相似文献
6.
7.
8.
Sulphate, Nitrogen and Base Cation Budgets at 21 Forested Catchments in Canada, the United States and Europe 总被引:1,自引:0,他引:1
Watmough SA Aherne J Alewell C Arp P Bailey S Clair T Dillon P Duchesne L Eimers C Fernandez I Foster N Larssen T Miller E Mitchell M Page S 《Environmental monitoring and assessment》2005,109(1-3):1-36
To assess the concern over declining base cation levels in forest soils caused by acid deposition, input-output budgets (1990s
average) for sulphate (SO4), inorganic nitrogen (NO3-N; NH4-N), calcium (Ca), magnesium (Mg) and potassium (K) were synthesised for 21 forested catchments from 17 regions in Canada,
the United States and Europe. Trend analysis was conducted on monthly ion concentrations in deposition and runoff when more
than 9 years of data were available (14 regions, 17 sites). Annual average SO4 deposition during the 1990s ranged between 7.3 and 28.4 kg ha−1 per year, and inorganic nitrogen (N) deposition was between 2.8 and 13.8 kg ha−1 per year, of which 41–67% was nitrate (NO3-N). Over the period of record, SO4 concentration in deposition decreased in 13/14 (13 out of 14 total) regions and SO4 in runoff decreased at 14/17 catchments. In contrast, NO3-N concentrations in deposition decreased in only 1/14 regions, while NH4-N concentration patterns varied; increasing at 3/14 regions and decreasing at 2/14 regions. Nitrate concentrations in runoff
decreased at 4/17 catchments and increased at only 1 site, whereas runoff levels of NH4-N increased at 5/17 catchments. Decreasing trends in deposition were also recorded for Ca, Mg, and K at many of the catchments
and on an equivalent basis, accounted for up to 131% (median 22%) of the decrease in acid anion deposition. Base cation concentrations
in streams generally declined over time, with significant decreases in Ca, Mg and K occurring at 8, 9 and 7 of 17 sites respectively,
which accounted for up to 133% (median 48%) of the decrease in acid anion concentration. Sulphate export exceeded input at
18/21 catchments, likely due to dry deposition and/or internal sources. The majority of N in deposition (31–100%; median 94%)
was retained in the catchments, although there was a tendency for greater NO3-N leaching at sites receiving higher (<7 kg ha-1 per year) bulk inorganic N deposition. Mass balance calculations show that export of Ca and Mg in runoff exceeds input at
all 21 catchments, but K export only exceeds input at 16/21 sites. Estimates of base cation weathering were available for
18 sites. When included in the mass balance calculation, Ca, Mg and K exports exceeded inputs at 14, 10 and 2 sites respectively.
Annual Ca and Mg losses represent appreciable proportions of the current exchangeable soil Ca and Mg pools, although losses
at some of the sites likely occur from weathering reactions beneath the rooting zone and there is considerable uncertainty
associated with mineral weathering estimates. Critical loads for sulphur (S) and N, using a critical base cation to aluminium
ratio of 10 in soil solution, are currently exceeded at 7 of the 18 sites with base cation weathering estimates. Despite reductions
in SO4 and H+ deposition, mass balance estimates indicate that acid deposition continues to acidify soils in many regions with losses of
Ca and Mg of primary concern.
The U.S. Government's right to retain a non-exclusive, royalty free licence in and to any copyright is acknowledged.
The Canadian Crown reserves the right to retain a non-exclusive, royalty free licence in and to any copyright. 相似文献
9.
Mercury is released to the environment from various anthropogenic and natural sources. This work is a compilation of mercury emissions from anthropogenic sources in Ontario, Canada. The goal of our study was to identify all sources of mercury, and develop an emission inventory of anthropogenic mercury in Ontario. The result of our investigation revealed that combustion of fossil fuels and emissions from landfill sites are two primary sources of mercury to the atmosphere. Other sources of significance are emissions from waste incinerators, various industrial activities, and cement production. Total mercury emission in Ontario is estimated as 4100 kg per year. 相似文献
10.
Gary H. Heinz David S. Miller Brian J. Ebert Kenneth L. Stromborg 《Environmental monitoring and assessment》1994,33(3):175-182
From 1977–1978 to 1990, concentrations of polychlorinated biphenyls (PCBs) and most organochlorine pesticides declined in eggs of red-breasted mergansers (Mergus serrator) nesting on islands in northwestern Lake Michigan. Total PCBs decreased 60% (from 21 ppm in 1977–1978 to 8.5 ppm in 1990) and p,p-DDE decreased 66% (from 6.5 to 2.2 ppm). Dieldrin decreased only 16% (from 0.82 to 0.69 ppm). In 1990, 79.1% of incubated eggs hatched, which was not significantly different from the 83.5% that hatched in 1977–1978.The U.S. Government right to retain a non-exclusive, royalty free licence in and to any copyright is acknowledged. 相似文献