全文获取类型
收费全文 | 213篇 |
免费 | 7篇 |
国内免费 | 3篇 |
专业分类
测绘学 | 4篇 |
大气科学 | 10篇 |
地球物理 | 91篇 |
地质学 | 65篇 |
海洋学 | 13篇 |
天文学 | 20篇 |
综合类 | 2篇 |
自然地理 | 18篇 |
出版年
2022年 | 1篇 |
2021年 | 2篇 |
2020年 | 3篇 |
2019年 | 1篇 |
2018年 | 7篇 |
2017年 | 4篇 |
2016年 | 10篇 |
2015年 | 15篇 |
2014年 | 9篇 |
2013年 | 8篇 |
2012年 | 13篇 |
2011年 | 18篇 |
2010年 | 16篇 |
2009年 | 23篇 |
2008年 | 15篇 |
2007年 | 14篇 |
2006年 | 10篇 |
2005年 | 6篇 |
2004年 | 6篇 |
2003年 | 6篇 |
2002年 | 2篇 |
2001年 | 5篇 |
2000年 | 3篇 |
1999年 | 2篇 |
1998年 | 3篇 |
1997年 | 1篇 |
1996年 | 3篇 |
1994年 | 1篇 |
1992年 | 2篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1973年 | 2篇 |
1972年 | 3篇 |
1969年 | 1篇 |
1963年 | 2篇 |
1949年 | 1篇 |
排序方式: 共有223条查询结果,搜索用时 15 毫秒
21.
Is compression across the northern Apennine fold‐and‐thrust system (Italy) still active? To address this question, we quantified the long‐term rates of migration and shortening of the system along with the measurement errors. Our approach integrates structural geology, seismicity patterns, and statistical treatment of tectonic activity. On the basis of recently published surface and subsurface data, we found a migration rate of 8.85 ± 0.61 mm yr−1. The inception age of individual fold structures follow closely this average rate, indicating that the system has been migrating at a constant rate for the past 17 Myr. Cumulative shortening of the system also increases linearly through time at 2.93 ± 0.31 mm yr−1. The location of the youngest structures in the easternmost portion of the system coincides with a significant peak of seismic moment released by historical earthquakes. We conclude that not only these easternmost thrusts are still active, but also that they generate earthquakes. 相似文献
22.
Karim Kelfoun Pablo Samaniego Pablo Palacios Diego Barba 《Bulletin of Volcanology》2009,71(9):1057-1075
We use a well-monitored eruption of Tungurahua volcano to test the validity of the frictional behaviour, also called Mohr–Coulomb,
which is generally used in geophysical flow modelling. We show that the frictional law is not appropriate for the simulation
of pyroclastic flows at Tungurahua. With this law, the longitudinal shape of the simulated flows is a thin wedge of material
progressively passing, over several hundreds of metres, from an unrealistic thickness at the front (<<1 mm) to some tens of
centimetres. Simulated deposits form piles which accumulate at the foot of the volcano and are more similar to sand piles
than natural pyroclastic deposits. Finally, flows simulated with a frictional rheology are not channelised by the drainage
system, but affect all the flanks of the volcano. In addition, their velocity can exceed 150 m s−1, allowing pyroclastic flows to cross interfluves at bends in the valley, affecting areas that would not have been affected
in reality and leaving clear downstream areas that would be covered in reality. Instead, a simple empirical law, a constant
retarding stress (i.e. a yield strength), involving only one free parameter, appears to be much better adapted for modelling
pyroclastic flows. A similar conclusion was drawn for the Socompa debris avalanche simulation (Kelfoun and Druitt, J Geophys
Res 110:B12202, 2005). 相似文献
23.
The debate concerning the viability of f(R)-gravity as a natural extension of General Relativity could be realistically addressed by using results coming from binary pulsars like PSR 1913 + 16. To this end, we develop a quadrupolar approach to the gravitational radiation for a class of analytic f(R)-models. We show that experimental results are compatible with a consistent range of f(R)-models. This means that f(R)-gravity is not ruled out by the observations and gravitational radiation (in strong field regime) could be a test-bed for such theories. 相似文献
24.
Experimental hydraulic heads and electrical (self-potential) signals associated with a pumping test were used in an inverse model to estimate the transmissivity distribution of a real aquifer. Several works reported in the literature show that there is a relatively good linear relationship between the hydraulic heads in the aquifer and electrical signals measured at the ground surface. In this experimental test field, first, the current coupling coefficient was determined by the best fit between experimental and modeled self-potential signals at the end of the pumping phase. Soon afterward, with the hydraulic heads obtained from the self-potential signals, the transmissivity distribution of the aquifer was conditioned by means an inverse model based on the successive linear estimator (SLE). To further substantiate the estimated T field from the SLE analysis, we analyzed the drawdown rate, the derivative of the drawdown with respect to the ln(t), because the drawdown rate is highly sensitive to the variability in the transmissivity field. In our opinion, these results show that self-potential signals allow the monitoring of subsurface flow in the course of pumping experiments, and that electrical potentials serve as a good complement to piezometric observations to condition and characterize the transmissivity distribution of an aquifer. 相似文献
25.
A new approach to estimate shaft capacity of bored piles in sandy soils, based on numerical analysis, is presented. The topic is relevant as current design methods often largely underestimate the shaft capacity of piles in sands, thus resulting in an over-conservative design. The proposed approach is based on explicitly modelling the thin cylinder of soil surrounding the pile, where strain localization concentrates (shear band), and on the fundamental mechanic behaviour of sandy soils (e.g. dilatancy, softening). This approach is both simple and easy to apply. Results of a broad parametric study involving axially loaded single piles embedded in different sandy soils are presented, highlighting that relative density and grain size distribution mainly affect the shaft capacity. The capability of the procedure to predict shaft friction is checked against data from a well-documented full-scale axial load test on instrumented pile. Some suggestions for calibration and application of the method are also reported. 相似文献
26.
This article focuses on the Montello thrust system in the Eastern Southern Alps as a potential seismogenic source. This system is of particular interest because of its lack of historical seismicity. Nevertheless, the system is undergoing active deformation. We developed a finite‐element model using visco‐elasto‐plastic rheology. The free parameters of the model (essentially, the locking status of the three thrusts included in the study), were constrained by matching the observed horizontal GPS and vertical levelling data. We show that the amount of interseismic fault locking, and thus the seismic potential, is not necessarily associated with the fastest‐slipping faults. More specifically, the locked Bassano thrust has a greater seismic potential than the freely slipping Montello thrust. The findings suggest that faults with subtle evidence of Quaternary activity should be carefully considered when creating seismic hazard maps. 相似文献
27.
Salvatore Erminio Modoni Giuseppe Spagnoli Giovanni Arciero Michela Mascolo Maria Cristina Ochmański Maciej 《Acta Geotechnica》2022,17(11):5073-5087
Acta Geotechnica - Plasticity of clays makes Deep Soil Mixing (DSM) problematic due to the tendency of the material to congest the rotating blades, reduce mixing efficiency and remain... 相似文献
28.
Flood-prone areas assessment using linear binary classifiers based on flood maps obtained from 1D and 2D hydraulic models 总被引:3,自引:0,他引:3
29.
30.