全文获取类型
收费全文 | 771篇 |
免费 | 26篇 |
国内免费 | 1篇 |
专业分类
测绘学 | 23篇 |
大气科学 | 38篇 |
地球物理 | 398篇 |
地质学 | 177篇 |
海洋学 | 22篇 |
天文学 | 123篇 |
综合类 | 1篇 |
自然地理 | 16篇 |
出版年
2021年 | 12篇 |
2019年 | 11篇 |
2018年 | 16篇 |
2017年 | 25篇 |
2016年 | 20篇 |
2015年 | 15篇 |
2014年 | 20篇 |
2013年 | 23篇 |
2012年 | 23篇 |
2011年 | 29篇 |
2010年 | 15篇 |
2009年 | 29篇 |
2008年 | 19篇 |
2007年 | 23篇 |
2006年 | 32篇 |
2005年 | 16篇 |
2004年 | 14篇 |
2003年 | 13篇 |
2002年 | 12篇 |
2001年 | 14篇 |
2000年 | 11篇 |
1999年 | 8篇 |
1997年 | 9篇 |
1996年 | 11篇 |
1994年 | 7篇 |
1993年 | 7篇 |
1992年 | 7篇 |
1991年 | 26篇 |
1990年 | 10篇 |
1989年 | 33篇 |
1988年 | 10篇 |
1987年 | 18篇 |
1986年 | 14篇 |
1985年 | 12篇 |
1984年 | 9篇 |
1983年 | 15篇 |
1982年 | 9篇 |
1981年 | 11篇 |
1980年 | 13篇 |
1979年 | 12篇 |
1978年 | 16篇 |
1977年 | 8篇 |
1976年 | 7篇 |
1975年 | 8篇 |
1974年 | 15篇 |
1973年 | 9篇 |
1972年 | 9篇 |
1971年 | 10篇 |
1969年 | 8篇 |
1960年 | 7篇 |
排序方式: 共有798条查询结果,搜索用时 15 毫秒
11.
Daniel H. Doctor E. Calvin Alexander Jr Metka Petrič Janja Kogovšek Janko Urbanc Sonja Lojen Willibald Stichler 《Hydrogeology Journal》2006,14(7):1171-1191
Karst aquifer components that contribute to the discharge of a water supply well in the Classical Karst (Kras) region (Italy/Slovenia) were quantitatively estimated during storm events. Results show that water released from storage within the epikarst may comprise as much as two-thirds of conduit flow in a karst aquifer following rainfall. Principal components analysis (PCA) and end-member mixing analysis (EMMA) were performed using major ion chemistry and the stable isotopes of water (δ18O, δ2H) and of dissolved inorganic carbon (δ13CDIC) to estimate mixing proportions among three sources: (1) allogenic river recharge, (2) autogenic recharge, and (3) an anthropogenic component stored within the epikarst. The sinking river most influences the chemical composition of the water-supply well under low-flow conditions; however, this proportion changes rapidly during recharge events. Autogenic recharge water, released from shallow storage in the epikarst, displaces the river water and is observed at the well within hours after the onset of precipitation. The autogenic recharge end member is the second largest component of the well chemistry, and its contribution increases with higher flow. An anthropogenic component derived from epikarstic storage also impacts the well under conditions of elevated hydraulic head, accounting for the majority of the chemical response at the well during the wettest conditions. 相似文献
12.
13.
Smoothing the Marmousi Model 总被引:1,自引:0,他引:1
K. Žáček 《Pure and Applied Geophysics》2002,159(7-8):1507-1526
14.
Organic pollutants associated with macromolecular soil organic matter: Mode of binding 总被引:2,自引:0,他引:2
H. H. Richnow R. Seifert J. Hefter M. Link W. Francke G. Schaefer W. Michaelis 《Organic Geochemistry》1997,26(11-12)
A study of ether-linked moieties in macromolecular bound residues of polycyclic aromatic hydrocarbons (PAH) generated in bioremediation experiments was performed using high temperature hydrolysis degradation with subsequent analysis of the products by GC-MS. This hydrolysis reaction was specifically designed to cleave ether bonds including relatively stable diarylether structures. Among the reaction products, aromatic alcohols representing typical microbiologically derived metabolites of PAH were found in addition to natural compounds. Thus, parts of the bound residues appeared to be linked within the macromolecular material by ether bonds. Model experiments with an oxidoreductase enzyme and aromatic alcohols indicate the formation of these ether bonds to be an enzyme-catalysed process. 相似文献
15.
16.
During the 20th century many floods of different intensity and extent have occurred on the Odra River and its tributaries. On the basis of long-term water level observations five major floods, that affected the entire upper and middle Odra River basin, were chosen for further analysis: June 1902, July 1903, August 1977, August 1985 and July 1997. However, hazardous floods were not only those that covered the whole upper and middle Odra River basin, so several local floods were also studied. Detailed historical analysis was made of meteorological conditions, with special emphasis on precipitation patterns and amounts. Then, on the basis of flood peak time occurrence, the stages of flood wave formation were formulated. The natural flood wave of the Odra River is often modified by hydro-technical infrastructure, the development and improvement of which is briefly described in this paper. In conclusion, a comparison of flood wave characteristics such as rising time, falling time, duration, peak flow and volume is presented. 相似文献
17.
18.
19.
20.