全文获取类型
收费全文 | 317篇 |
免费 | 0篇 |
国内免费 | 4篇 |
专业分类
安全科学 | 3篇 |
废物处理 | 4篇 |
环保管理 | 27篇 |
综合类 | 227篇 |
基础理论 | 21篇 |
污染及防治 | 34篇 |
评价与监测 | 4篇 |
社会与环境 | 1篇 |
出版年
2013年 | 4篇 |
2012年 | 4篇 |
2011年 | 6篇 |
2010年 | 5篇 |
2009年 | 5篇 |
2008年 | 7篇 |
2004年 | 5篇 |
2003年 | 4篇 |
2002年 | 6篇 |
2001年 | 5篇 |
2000年 | 5篇 |
1995年 | 6篇 |
1994年 | 4篇 |
1984年 | 5篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1975年 | 5篇 |
1968年 | 4篇 |
1964年 | 3篇 |
1963年 | 6篇 |
1961年 | 9篇 |
1960年 | 7篇 |
1959年 | 5篇 |
1958年 | 11篇 |
1957年 | 6篇 |
1955年 | 6篇 |
1954年 | 5篇 |
1953年 | 3篇 |
1947年 | 3篇 |
1943年 | 5篇 |
1941年 | 5篇 |
1939年 | 4篇 |
1938年 | 5篇 |
1937年 | 4篇 |
1935年 | 4篇 |
1934年 | 4篇 |
1933年 | 4篇 |
1932年 | 5篇 |
1929年 | 3篇 |
1928年 | 6篇 |
1926年 | 3篇 |
1925年 | 3篇 |
1923年 | 6篇 |
1921年 | 3篇 |
1920年 | 3篇 |
1919年 | 5篇 |
1916年 | 3篇 |
1915年 | 3篇 |
1914年 | 6篇 |
1913年 | 5篇 |
排序方式: 共有321条查询结果,搜索用时 0 毫秒
321.
Environmental cross-compliance mitigates nitrogen and phosphorus pollution from Swiss agriculture 总被引:1,自引:0,他引:1
In 1993 the Swiss agricultural policy was revised with – amongst other goals – the objective of improving the environmental performance of agriculture. A voluntary agri-environmental scheme to promote integrated production (IP) was introduced. In 1999 the IP standards were integrated in cross compliance requirements and termed Proof of Ecological Performance (PEP). We evaluated the effectiveness of this policy in terms of reducing diffuse nitrogen (N) and phosphorus (P) pollution of ground and surface water. We combined monitoring schemes covering the reference period from before the introduction of IP/PEP (1990–1992) with the evaluation of cause/effect relationships in selected case-study areas. The evaluation showed an overall reduction of diffuse N and P pollution from agriculture even though some goals were not reached. Nitrate leaching declined, but only a 3–4 mg L−1 reduction was observed rather than the intended decrease of 5 mg L−1. The P pollution of surface waters from agriculture decreased by only 10–30% instead of 50%. The intended reduction of the nitrogen surplus of Swiss agriculture by 33% was not attained, but the P surplus of Swiss agriculture was more than halved. IP/PEP practices that improved N and P management included reduced N and P fertiliser inputs and pig and poultry feedstuffs with reduced N and P contents, both of which are a consequence of the requirement of equilibrated farm nutrient balances, as well as increased use of cover cropping and of conservation tillage systems. 相似文献