全文获取类型
收费全文 | 126篇 |
免费 | 6篇 |
国内免费 | 1篇 |
专业分类
测绘学 | 2篇 |
大气科学 | 2篇 |
地球物理 | 48篇 |
地质学 | 36篇 |
海洋学 | 6篇 |
天文学 | 29篇 |
自然地理 | 10篇 |
出版年
2022年 | 2篇 |
2021年 | 3篇 |
2020年 | 1篇 |
2018年 | 5篇 |
2017年 | 7篇 |
2016年 | 5篇 |
2015年 | 3篇 |
2014年 | 3篇 |
2013年 | 5篇 |
2012年 | 5篇 |
2011年 | 6篇 |
2010年 | 6篇 |
2009年 | 12篇 |
2008年 | 6篇 |
2007年 | 6篇 |
2006年 | 4篇 |
2005年 | 1篇 |
2004年 | 4篇 |
2003年 | 8篇 |
2002年 | 6篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 3篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1991年 | 3篇 |
1989年 | 4篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1983年 | 2篇 |
排序方式: 共有133条查询结果,搜索用时 218 毫秒
131.
The Mendoza River is mainly dependent on the melting of snow and ice in the Upper Andes. Since predicted changes in climate would modify snow accumulation and glacial melting, it is important to understand the relative contributions of various water sources to river discharge. The two main mountain ranges in the basin, Cordillera Principal and Cordillera Frontal, present differences in geology and receive differing proportions of precipitation from Atlantic and Pacific moisture sources. We propose that differences in the origin of precipitation, geology and sediment contact times across the basin generate ionic and stable isotopic signatures in the water, allowing the differentiation of water sources. Waters from the Cordillera Principal had higher salinity and were more isotopically depleted than those from the Cordillera Frontal. Stable isotope composition and salinity differed among different water sources. The chemical temporal evolution of rivers and streams indicated changes in the relative contributions of different sources, pointing to the importance of glacier melting and groundwater in the river discharge. 相似文献
132.
Camilo Valencia Juan Gomez Juan Jaramillo Mario Saenz Juan Vergara 《Studia Geophysica et Geodaetica》2017,61(1):93-114
The problem of diffraction of cylindrical and plane horizontally polarized shear waves (SH waves) by a finite crack embedded in a plane bidimensional elastic full-space is revisited. Particularly, we construct an approximate solution by the addition of independent diffracted terms. In our method the derivation of the fundamental case of a semi-infinite crack obtained as a degenerate case of a generalized wedge is first considered. This result is then used as a building block to compute the diffraction of the main incident waves. The interaction between the opposite edges of the crack is later considered in terms of a series, one term at a time until a desired tolerance is reached. Moreover, we propose a procedure to determine the number of required interactions as a function of frequency. The solution derived with the superposition technique is shown to be effective at low and high frequencies and as shown by comparisons with a direct boundary element method software, highly accurate solutions are obtained after retaining just a few terms of the infinite series. 相似文献
133.
The methodology and errors involved in determining the amount of sediment produced during two (19·5 and 33·2 year) periods by 11 (c. 0·01 − >0·20 km2) gullies within a 4 km2 area in the headwaters of the Waipaoa River basin, New Zealand, using sequential digital elevation models are described. Sediment production from all gullies within the study area was 0·99 ± 0·03 × 106 t a−1 (2480 ± 80 t ha−1 a−1) during the period from 1939 to 1958. It declined to 0·62 ± 0·02 × 106 t a−1 (1550 ± 50 t ha−1 a−1) during the period from 1958 to 1992, when many of the smaller gullies were stabilized by a programme of afforestation, which commenced in 1960. Both figures are very high by global standards. The two largest (the Tarndale and Mangatu) gully complexes together generated 73 and 95 per cent of the sediment in the specified time periods, but the latter amount is equivalent to only c. 5 per cent of the total annual sediment load of the Waipaoa River. © 1998 John Wiley & Sons, Ltd. 相似文献