全文获取类型
收费全文 | 851篇 |
免费 | 20篇 |
国内免费 | 12篇 |
专业分类
测绘学 | 9篇 |
大气科学 | 58篇 |
地球物理 | 159篇 |
地质学 | 361篇 |
海洋学 | 62篇 |
天文学 | 164篇 |
综合类 | 3篇 |
自然地理 | 67篇 |
出版年
2021年 | 9篇 |
2020年 | 4篇 |
2019年 | 6篇 |
2018年 | 15篇 |
2017年 | 11篇 |
2016年 | 16篇 |
2015年 | 20篇 |
2014年 | 26篇 |
2013年 | 43篇 |
2012年 | 27篇 |
2011年 | 27篇 |
2010年 | 36篇 |
2009年 | 29篇 |
2008年 | 37篇 |
2007年 | 29篇 |
2006年 | 35篇 |
2005年 | 29篇 |
2004年 | 32篇 |
2003年 | 25篇 |
2002年 | 33篇 |
2001年 | 25篇 |
2000年 | 25篇 |
1999年 | 18篇 |
1998年 | 24篇 |
1997年 | 11篇 |
1996年 | 17篇 |
1995年 | 9篇 |
1994年 | 15篇 |
1993年 | 10篇 |
1992年 | 11篇 |
1991年 | 5篇 |
1990年 | 8篇 |
1989年 | 8篇 |
1988年 | 8篇 |
1987年 | 11篇 |
1986年 | 12篇 |
1985年 | 9篇 |
1984年 | 24篇 |
1982年 | 16篇 |
1981年 | 12篇 |
1980年 | 11篇 |
1979年 | 8篇 |
1978年 | 18篇 |
1977年 | 8篇 |
1976年 | 11篇 |
1975年 | 11篇 |
1974年 | 11篇 |
1973年 | 8篇 |
1972年 | 4篇 |
1971年 | 6篇 |
排序方式: 共有883条查询结果,搜索用时 15 毫秒
821.
Crustal structure beneath western and eastern Iceland from surface waves and receiver functions 总被引:1,自引:0,他引:1
822.
Christel Prudhomme Andy Young Glenn Watts Tracey Haxton Sue Crooks Jennifer Williamson Helen Davies Simon Dadson Stuart Allen 《水文研究》2012,26(7):1115-1118
As climate change may modify the hydrological cycle significantly, understanding the impact on river flow is important because it affects long‐term water resources planning. Here, we describe a high‐resolution British assessment of changes in river flows in the 2050s under 11 different realisations of HadRM3. In winter, river flows may either increase or decrease, with a wide range of possible decreases in summer flow. These results should encourage adaptation that copes with a broad range of future hydrological conditions. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
823.
In a recent Letter, Litvinenko, Forbes, and Priest (1996) claimed that the rate of the very fast flux-pile up reconnection is severely limited by the effects of plasma pressure. They considered however only two-dimensional, zero-vorticity flows. Here we show that this limitation is a feature of these restrictive assumptions and can be removed by relaxing either of them. 相似文献
824.
825.
Sonia Scarselli Guy D. H. Simpson Philip A. Allen Giorgio Minelli Lorenzo Gaudenzi 《地学学报》2007,19(1):74-81
The Marche Apennines (Italy) offer an excellent opportunity to constrain the temporal and spatial relationships between drainage network formation and tectonic activity. Using a combination of field data, seismic lines and boreholes we show that the main deformation phase took place during the Messinian when the area, affected by the Messinian sea level drop, emerged and evolved from marine to continental conditions. The results highlight that during the Messinian emersion a drainage network developed contemporaneously with an increase in tectonic activity that could be related to sea level fall and river erosion. The present‐day river system, which is dominated by transverse rivers that cut straight across the tectonic grain, is located in older Messinian palaeovalleys, even though the region was subsequently covered by water until the late Pliocene–early Pleistocene. 相似文献
826.
827.
Determination of critical shear stress of non‐cohesive soils using submerged jet test and turbulent kinetic energy
下载免费PDF全文
![点击此处可从《地球表面变化过程与地形》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Laboratory tests using Jet Erosion Testing (JET) apparatus, impinging normally on a horizontal boundary, were conducted to determine the critical shear stress (τc) of non‐cohesive soil samples. A three‐dimensional (3D) SonTek/YSI 16 MHz Micro‐Acoustic Doppler Velocimeter (MicroADV) was used to measure turbulent kinetic energy (TKE) at a radial limit of entrainment in the wall jet zone and the measurements were used to calculate τc of the samples. The results showed that TKE increases exponentially with increasing particle size. The τc from this study were comparable (R2 = 0.8) to the theoretical τc from Shields diagram after bed roughness scale ratio (D/ks), due to the non‐uniform bed conditions, was accounted for. This study demonstrated that JET and TKE can be used to determine τc of non‐cohesive soils. The use of JET and TKE was found to be faster and easier when compared to the conventional approach of using flumes. A relationship of TKE at the onset of incipient motion (TKEc) and samples’ D50 developed in this study can be used to predict τc of non‐cohesive soils under similar non‐uniform conditions. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
828.
S.L. Allen 《Astronomische Nachrichten》2008,329(3):298-300
A trivial modification to the XML schema of VOEvent v1.1 allows the inclusion of W3C digital signatures. Signatures enable identification, identification enables trust, and trust enables authorization. Such changes would inhibit abuse of the VOEvent networks. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
829.
830.
Intensity attenuation for active crustal regions 总被引:1,自引:0,他引:1
We develop globally applicable macroseismic intensity prediction equations (IPEs) for earthquakes of moment magnitude M W 5.0?C7.9 and intensities of degree II and greater for distances less than 300?km for active crustal regions. The IPEs are developed for two distance metrics: closest distance to rupture (R rup) and hypocentral distance (R hyp). The key objective for developing the model based on hypocentral distance??in addition to more rigorous and standard measure R rup??is to provide an IPE which can be used in near real-time earthquake response systems for earthquakes anywhere in the world, where information regarding the rupture dimensions of a fault may not be known in the immediate aftermath of the event. We observe that our models, particularly the model for the R rup distance metric, generally have low median residuals with magnitude and distance. In particular, we address whether the direct use of IPEs leads to a reduction in overall uncertainties when compared with methods which use a combination of ground-motion prediction equations and ground motion to intensity conversion equations. Finally, using topographic gradient as a proxy and median model predictions, we derive intensity-based site amplification factors. These factors lead to a small reduction of residuals at shallow gradients at strong shaking levels. However, the overall effect on total median residuals is relatively small. This is in part due to the observation that the median site condition for intensity observations used to develop these IPEs is approximately near the National Earthquake Hazard Reduction Program CD site-class boundary. 相似文献