全文获取类型
收费全文 | 185篇 |
免费 | 1篇 |
专业分类
安全科学 | 3篇 |
废物处理 | 7篇 |
环保管理 | 6篇 |
综合类 | 109篇 |
基础理论 | 25篇 |
污染及防治 | 26篇 |
评价与监测 | 5篇 |
社会与环境 | 5篇 |
出版年
2019年 | 3篇 |
2018年 | 3篇 |
2016年 | 3篇 |
2013年 | 4篇 |
2011年 | 6篇 |
2010年 | 3篇 |
2009年 | 6篇 |
2008年 | 6篇 |
2007年 | 8篇 |
2006年 | 3篇 |
2005年 | 5篇 |
2003年 | 7篇 |
2002年 | 5篇 |
2000年 | 5篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1997年 | 3篇 |
1996年 | 5篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1986年 | 2篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1974年 | 2篇 |
1969年 | 3篇 |
1967年 | 3篇 |
1965年 | 4篇 |
1964年 | 2篇 |
1963年 | 7篇 |
1962年 | 8篇 |
1961年 | 3篇 |
1960年 | 3篇 |
1959年 | 4篇 |
1958年 | 4篇 |
1957年 | 8篇 |
1956年 | 5篇 |
1954年 | 4篇 |
1950年 | 2篇 |
1940年 | 1篇 |
1939年 | 2篇 |
1938年 | 1篇 |
1934年 | 1篇 |
1932年 | 1篇 |
1924年 | 1篇 |
1920年 | 1篇 |
1919年 | 2篇 |
排序方式: 共有186条查询结果,搜索用时 0 毫秒
71.
72.
Agricultural land use has shifted towards more intensified production because the prices of agricultural products have increased
during the past years. Just a few years ago, voluntary area set-aside was a lucrative alternative in some regions. But nowadays,
land is re-cultivated again, inter alia with biomass crops. Consequently, this affects the soil and nutrient balances in agriculture.
The global changes on the world markets influence agricultural production and thus the water cycle at the regional scale.
In this paper, the regional developments and policy alternatives are discussed for the Elbe River Basin. The paper concludes
that on average, no substantial effects of nitrogen surpluses are expected for the Elbe River Basin due to a continuing decline
in animal herds. However, at the county level, nitrogen surpluses are likely to exceed the maximum threshold of 60 kg nitrogen
per hectare (stipulated in the German Fertiliser Regulation) due to regional concentrations of animal production. A halving
of the threshold to 30 kg per hectare shows that the marginal costs of nitrogen surplus reduction regionally exceeded 10 Euros
per kilogram nitrogen. 相似文献
73.
74.
Begg Katherine Van der Horst Dan 《Mitigation and Adaptation Strategies for Global Change》2004,9(2):181-200
The European Union EU project PROBASE hasexplored a range of possible multi projectstandardised benchmarks as a way ofencouraging projects under Joint Implementation (JI) and the Clean Development Mechanism (CDM)by minimising transaction costs. The aim ofthis paper is to examine the environmentalintegrity of the use of standardisedbaselines and to explore the role ofadditionality. The environmental integritydepends on the uncertainty in emissionreductions, which was estimated bygenerating scenario baselines and comparingthese with the standardised baselines. Thishas allowed a comparison of selected multiproject baselines with the envelope ofuncertainty on the reductions. The projectsincluded a range of electricity supply,heat sector, cogeneration and methane(CH$_{4}$) projects in different countries. Theanalysis showed that the key uncertaintieswere in the technology fuel selection inthe baseline, the continued additionalityof the project emission reductions,uncertainties in some project emissions(e.g. spinning reserve emissions for wind)and data uncertainties. The effect on theestimation of reductions was in the range±12% to ±46% for the electricityprojects and from ±19% to ±57%for the heat and Combined Heat and Power CHP sector projects.Comparison with the envelope of uncertaintyfor the range of projects showed that multiproject electricity sector baselines whichhave been weighted or use high technologyperformance benchmarks (e.g. Organization for Economic Cooperation and Development OECD)can provide conservative estimates buttheir general nature can lead to variationsbetween countries. We would recommend thatthe country-specific context must be takeninto account so that standardised baselinesfor the electricity sector are generated onthe basis of country specificcharacteristics, the project type, andwhether it provides new or existing demand.The conservative scenario produced shouldthen be weighted. Whereas weightings havebeen applied to account for uncertaintiesor to bias towards renewables, we havesuggested a weighting factor of 25% on theelectricity baseline for large projectsbased on an analysis of the effect ofnon-additionality on emission reductionuncertainty. For heat projects, theappropriate benchmark is a technology/fuelbenchmark which is deemed relevant for theheat sector in that (part of the) country.Again we suggest that a weighted sectorbaseline is required to take account of theuncertainties. These recommendations applyto large projects only for a 10-yearcrediting lifetime. 相似文献
75.
76.
77.
78.
79.
80.