全文获取类型
收费全文 | 471篇 |
免费 | 2篇 |
国内免费 | 19篇 |
专业分类
安全科学 | 8篇 |
废物处理 | 6篇 |
环保管理 | 30篇 |
综合类 | 165篇 |
基础理论 | 145篇 |
污染及防治 | 112篇 |
评价与监测 | 12篇 |
社会与环境 | 14篇 |
出版年
2017年 | 5篇 |
2016年 | 10篇 |
2015年 | 9篇 |
2014年 | 5篇 |
2013年 | 23篇 |
2012年 | 17篇 |
2011年 | 22篇 |
2010年 | 13篇 |
2009年 | 15篇 |
2008年 | 20篇 |
2007年 | 25篇 |
2006年 | 32篇 |
2005年 | 21篇 |
2004年 | 9篇 |
2003年 | 16篇 |
2002年 | 14篇 |
2001年 | 10篇 |
2000年 | 6篇 |
1999年 | 20篇 |
1998年 | 10篇 |
1997年 | 10篇 |
1996年 | 12篇 |
1995年 | 7篇 |
1994年 | 9篇 |
1993年 | 7篇 |
1991年 | 4篇 |
1989年 | 5篇 |
1987年 | 3篇 |
1985年 | 3篇 |
1983年 | 6篇 |
1969年 | 3篇 |
1967年 | 2篇 |
1966年 | 7篇 |
1965年 | 4篇 |
1964年 | 8篇 |
1963年 | 7篇 |
1962年 | 2篇 |
1961年 | 5篇 |
1960年 | 6篇 |
1959年 | 3篇 |
1958年 | 3篇 |
1957年 | 6篇 |
1956年 | 3篇 |
1955年 | 5篇 |
1954年 | 4篇 |
1953年 | 7篇 |
1951年 | 2篇 |
1950年 | 2篇 |
1938年 | 2篇 |
1934年 | 2篇 |
排序方式: 共有492条查询结果,搜索用时 49 毫秒
291.
292.
293.
294.
295.
Ludwig Weißflog Klaus Wienhold Klaus-Dieter Wenzel Gerrit Schüürmann 《Environmental Sciences Europe》1994,6(2):75-80
Air pollution in the region Leipzig-Halle was investigated using two-year-old pine needles (Pinus sylvestris L.) at 39 sites of a biomonitoring net covering an area of ca. 7 500 km2. The concentration values of Al, Ca, Cr, Fe, K, Mg, Mn, Pb and V characterize the immission patterns of the period 1990/91. The method is less suited for Cu, Ni and Zn due to the transfer route soil-pine, and for Cd due to the small total content. There are significant spatial and element-specific variations which require distinct evaluation of the pollution situation. The city of Leipzig itself is a significant source for Pb, Cr, Fe and V emission. Mainly as far as the centre of the region is concerned, the Pb concentration values are beyond those of heavily contaminated reference sites. The bioindication system is also applicable for comparable regions in Eastern Europe where the pine is the dominating conifer type. Immission trends can be monitored over ecologically relevant periods of time. 相似文献
296.
297.
298.
299.
300.
Chunyan Liu Jirko Holst Zhisheng Yao Nicolas Brüggemann Klaus Butterbach-Bahl Shenghui Han Xingguo Han Xunhua Zheng 《Agriculture, ecosystems & environment》2009,134(1-2):136-142
We investigated nitric oxide (NO) fluxes at a summer and a winter sheepfold in the Baiyinxile livestock farm, near Xilinhot, Inner Mongolia, which are a typical feature of the regional husbandry. Using a manual static opaque chamber/chemiluminescence measuring system, we intermittently observed fluxes in the summer sheepfold between May 28th and September 26th 2005 and in both winter and summer sheepfolds between March 8th and October 18th 2006. During these periods, mean NO emissions (±S.E., in terms of mass of nitrogen) were 124.0 ± 28.7, 134.6 ± 23.3 (summer sheepfold) and 214.4 ± 79.6 μg NO–N m−2 h−1 (winter sheepfold), respectively, and thus, three magnitudes higher than observed steppe NO emissions in the same region. The NO fluxes were not significantly different between the 2 years, but in summer they were much higher than in spring (p < 0.05). Temperature and moisture of the faeces layer significantly regulated the NO fluxes (p < 0.01). The direct NO emission factor (EF) for faeces and urine excreted in the sheepfolds was 0.7 g NO–Nemitted kg−1 Nexcreted, which was almost 37 times lower than a recently reported N2O EF. We estimated the total NO emission from the sheepfolds of the Baiyinxile livestock farm to be 1.82 ± 0.43 tons NO–N year−1, which accounts to approximately 12.3% of the total NO emission from this steppe region. With the rapid increase of livestock numbers, sheepfold NO emissions may further increase and contribute to high N deposition in confined areas around sheepfolds. 相似文献