全文获取类型
收费全文 | 153篇 |
免费 | 1篇 |
专业分类
安全科学 | 2篇 |
废物处理 | 6篇 |
环保管理 | 11篇 |
综合类 | 90篇 |
基础理论 | 14篇 |
污染及防治 | 19篇 |
评价与监测 | 3篇 |
社会与环境 | 8篇 |
灾害及防治 | 1篇 |
出版年
2015年 | 2篇 |
2014年 | 3篇 |
2013年 | 5篇 |
2012年 | 3篇 |
2011年 | 2篇 |
2010年 | 6篇 |
2009年 | 7篇 |
2008年 | 6篇 |
2007年 | 4篇 |
2006年 | 3篇 |
2005年 | 3篇 |
2004年 | 4篇 |
2003年 | 6篇 |
2002年 | 6篇 |
2001年 | 3篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1979年 | 2篇 |
1969年 | 1篇 |
1967年 | 1篇 |
1966年 | 2篇 |
1964年 | 1篇 |
1959年 | 1篇 |
1957年 | 2篇 |
1956年 | 2篇 |
1955年 | 4篇 |
1951年 | 3篇 |
1947年 | 1篇 |
1946年 | 1篇 |
1943年 | 3篇 |
1942年 | 1篇 |
1941年 | 2篇 |
1938年 | 3篇 |
1936年 | 3篇 |
1935年 | 1篇 |
1934年 | 6篇 |
1933年 | 5篇 |
1932年 | 3篇 |
1931年 | 2篇 |
1930年 | 3篇 |
1929年 | 2篇 |
1927年 | 4篇 |
1926年 | 4篇 |
1925年 | 2篇 |
1924年 | 4篇 |
1923年 | 2篇 |
1922年 | 2篇 |
1916年 | 1篇 |
排序方式: 共有154条查询结果,搜索用时 0 毫秒
151.
R. Ocampo H. J. Callot P. Albrecht B. N. Popp M. R. Horowitz J. M. Hayes 《Die Naturwissenschaften》1989,76(9):419-421
The authors thank Dr. J. Connan [Société Nationale Elf Aquitaine (Production), Pau, France] for a sample of Julia Creek oil shale and helpful discussions; they also thank the Petroleum Research Fund (PRF 19791-AC2) for financial support. 相似文献
152.
Assessment of the nitrogen and carbon budget of two managed temperate grassland fields 总被引:1,自引:0,他引:1
Christof Ammann Christoph Spirig Jens Leifeld Albrecht Neftel 《Agriculture, ecosystems & environment》2009,133(3-4):150
Greenhouse gas budgets as well as the productivity of grassland systems are closely related to the carbon (C) and nitrogen (N) cycles. Within the framework of the CarboEurope and NitroEurope projects we have measured C and N exchange on the field scale at the grassland site Oensingen previously converted from arable rotation. The site is located on the Swiss Central Plateau and consists of two parallel fields of equal size. One field was subjected to intensive management with average nitrogen input of 230 kg-N ha−1 year−1 and 4–5 cuts per year, and the other to an extensive management with no fertilisation and less frequent cutting. The total C budget of the fields was assessed by measuring the CO2 exchange by eddy covariance and analysing the carbon import by manure application and export by harvest. The N budget of the managed grassland is more complex. Besides the management related import and export, it includes gaseous exchange in many different forms (NO, NO2, HNO3, N2O, NH3, N2) needing different analytical techniques, as well as input by rain and leaching of N-compounds with the soil water. The main (“level-3”) field sites in the NitroEurope project are supposed to measure 95% of the N fluxes at the field scale. For several of the N fluxes specific measurements have been performed for 1 year or longer at the site. Some of the remaining N budget components (dry and wet deposition) could be estimated from results of a national deposition network, while other components (NH3 and N2 emission) were estimated based on literature parameterisations. However, we found indications that the (systematic) uncertainties of these estimated N-fluxes are large and that it is important to make site-specific measurement for all relevant budget components. The suitability of corresponding experimental methods is discussed.Analysis of the C budget over a 6-year period (2002–2007) showed a significant mean difference between the two newly established grassland fields with a likely net carbon loss for the extensive management and a net sequestration for the intensive management. Since the C/N ratio of the soil organic matter of the grassland is constrained in a rather narrow range around 9.3, the change in the soil carbon pool is supposed to be accompanied by a corresponding change in the N storage. This approach provided an alternative method to check the N budget of the two grassland fields derived from the individual N fluxes. 相似文献
153.
Albrecht M 《Die Naturwissenschaften》2007,94(12):951-966
This review gives an introduction into supramolecular chemistry describing in the first part general principles, focusing on terms like noncovalent interaction, molecular recognition, self-assembly, and supramolecular function. In the second part those will be illustrated by simple examples from our laboratories. Supramolecular chemistry is the science that bridges the gap between the world of molecules and nanotechnology. In supramolecular chemistry noncovalent interactions occur between molecular building blocks, which by molecular recognition and self-assembly form (functional) supramolecular entities. It is also termed the "chemistry of the noncovalent bond." Molecular recognition is based on geometrical complementarity based on the "key-and-lock" principle with nonshape-dependent effects, e.g., solvatization, being also highly influential. Self-assembly leads to the formation of well-defined aggregates. Hereby the overall structure of the target ensemble is controlled by the symmetry features of the certain building blocks. Finally, the aggregates can possess special properties or supramolecular functions, which are only found in the ensemble but not in the participating molecules. This review gives an introduction on supramolecular chemistry and illustrates the fundamental principles by recent examples from our group. 相似文献
154.
Burnout is considered to be a long‐term reaction to occupational stress. It is characterized by emotional exhaustion, depersonalization, and diminished personal accomplishment. The most widely used instrument to measure burnout is the Maslach Burnout Inventory (MBI), developed by Maslach and Jackson (1986). From this instrument, Schaufeli and van Dierendonck (1995a) developed a somewhat modified Dutch version: the MBI‐NL. Burnout among dentists has hardly been studied. Since the professions that the MBI‐NL was developed upon are quite different from dentistry, the aim of this study was to test the three‐factor structure of the MBI‐NL against alternative structures among dentists. Both principal components analysis (PCA) and confirmatory factor analysis (CFA) were examined in a representative sample of 709 Dutch general dental practitioners (75 per cent response rate). The three‐factor structure shows the best fit to the underlying data, while other psychometric qualities are very satisfactory. It is concluded that the three‐factor structure of the MBI‐NL is superior to alternative structures, and that the MBI‐NL is a highly suitable instrument to measure burnout among dentists. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献