全文获取类型
收费全文 | 446篇 |
免费 | 3篇 |
国内免费 | 4篇 |
专业分类
安全科学 | 9篇 |
废物处理 | 12篇 |
环保管理 | 23篇 |
综合类 | 215篇 |
基础理论 | 100篇 |
环境理论 | 1篇 |
污染及防治 | 70篇 |
评价与监测 | 11篇 |
社会与环境 | 11篇 |
灾害及防治 | 1篇 |
出版年
2021年 | 5篇 |
2017年 | 5篇 |
2016年 | 5篇 |
2015年 | 4篇 |
2014年 | 8篇 |
2013年 | 16篇 |
2012年 | 20篇 |
2011年 | 11篇 |
2010年 | 17篇 |
2009年 | 8篇 |
2008年 | 8篇 |
2007年 | 19篇 |
2006年 | 10篇 |
2005年 | 5篇 |
2004年 | 4篇 |
2003年 | 11篇 |
2002年 | 9篇 |
2001年 | 12篇 |
2000年 | 17篇 |
1999年 | 6篇 |
1998年 | 5篇 |
1997年 | 9篇 |
1996年 | 7篇 |
1995年 | 10篇 |
1994年 | 8篇 |
1993年 | 8篇 |
1992年 | 6篇 |
1991年 | 4篇 |
1990年 | 10篇 |
1979年 | 4篇 |
1969年 | 4篇 |
1967年 | 4篇 |
1966年 | 7篇 |
1965年 | 5篇 |
1964年 | 4篇 |
1963年 | 7篇 |
1962年 | 8篇 |
1961年 | 4篇 |
1960年 | 13篇 |
1959年 | 8篇 |
1958年 | 4篇 |
1957年 | 6篇 |
1956年 | 5篇 |
1955年 | 9篇 |
1954年 | 4篇 |
1933年 | 4篇 |
1932年 | 4篇 |
1930年 | 4篇 |
1929年 | 5篇 |
1913年 | 4篇 |
排序方式: 共有453条查询结果,搜索用时 15 毫秒
111.
Dieter Lorenz 《Die Naturwissenschaften》1981,68(1):1-8
After a discussion of the observed phenomena a short account of the very-long-baseline radio interferometry and the redshift controversy is given. The issue of superluminal velocities in the theory of relativity is clarified and a variety of physical models that have been proposed to account for the observed phenomena are discussed. Finally the data of some superluminal sources and their implications are reviewed. 相似文献
112.
Franz Hoffmann 《Die Naturwissenschaften》1980,67(6):301-306
A supplementation of classical plant breeding is now necessary due to the limitations imposed by available genetic variability and the slowness of the method. Therefore, cell culture techniques could play an important role in the future. Using rape seed, in which plants derived from anther culture and in vitro mutagenesis are already field tested, it has been shown that, in this case, somatic genetics is very close to becoming a practical method. For most of the other crop plants, in particular the cereals, no such unconventional breeding techniques have yet been satisfactorily established for commercial use. 相似文献
113.
114.
115.
116.
Herman Friedl Smidt Stefan Englisch Michael Feichtinger Franz Gerzabek Martin Haberhauer Georg Jandl Robert Kalina Michael Zechmeister-Boltenstern Sophie 《Environmental science and pollution research international》2002,9(2):46-52
In the North Tyrolean Limestone Alps a site was investigated over a four-year period (1998–2001) in order to assess the nitrogen saturation status, the nitrogen budget (quantification of the net uptake of nitrogen by the canopy and of the nitrogen mineralization, nitrogen uptake from roots and N2O emission rates, proof of the origin of nitrate in the soil water with stable isotope analyses), and the effects of the actual nitrogen input on ground water quality. The main goals were to quantify the nitrogen input rate, the nitrogen pools in above-ground and below-ground compartments, nitrogen turnover processes in the soil as well as the output into the groundwater and into the atmosphere. The findings are based on continuous and discontinuous field measurements as well as on model results.While nitrogen input exceeded the Critical Loads of the WHO (1995), nitrogen deficiency and nutrient imbalances were verified by needle analyses. The atmospheric input of inorganic nitrogen was higher than the nitrogen output in 50 cm soil depth. A tracer experiment with15N helped to prove that not more than half of the applied nitrate could be discharged. This allows the conclusion that nitrogen is stored in the system and that the site cannot yet be said to be saturated with nitrogen. The same result was also obtained by modelling. In addition, it was proved that the nitrogen discharge did not stem from deposition but from processes within the system. 相似文献
117.
118.
119.
120.