全文获取类型
收费全文 | 214篇 |
免费 | 10篇 |
国内免费 | 2篇 |
专业分类
测绘学 | 2篇 |
大气科学 | 10篇 |
地球物理 | 58篇 |
地质学 | 91篇 |
海洋学 | 17篇 |
天文学 | 23篇 |
自然地理 | 25篇 |
出版年
2022年 | 2篇 |
2021年 | 6篇 |
2020年 | 3篇 |
2019年 | 5篇 |
2018年 | 4篇 |
2017年 | 9篇 |
2016年 | 8篇 |
2015年 | 7篇 |
2014年 | 13篇 |
2013年 | 16篇 |
2012年 | 15篇 |
2011年 | 21篇 |
2010年 | 11篇 |
2009年 | 16篇 |
2008年 | 12篇 |
2007年 | 10篇 |
2006年 | 10篇 |
2005年 | 4篇 |
2004年 | 7篇 |
2003年 | 11篇 |
2002年 | 4篇 |
2001年 | 1篇 |
2000年 | 4篇 |
1999年 | 7篇 |
1998年 | 3篇 |
1996年 | 4篇 |
1995年 | 1篇 |
1993年 | 2篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 2篇 |
排序方式: 共有226条查询结果,搜索用时 15 毫秒
141.
Patricio Payrola Bosio Jaime Powell Cecilia del Papa Fernando Hongn 《Journal of South American Earth Sciences》2009,28(2):142-154
The Andean foreland basin overlaps the Cretaceous-Paleogene Salta rift basin in northwestern Argentina. Knowledge of the relationship between rift and foreland basins is key to understanding the initial stages of foreland basin development related to Andean shortening. We present a new stratigraphic scheme for the Luracatao Valley, revealing that the Quebrada de los Colorados Formation (Payogastilla Group) lies over the Santa Bárbara Subgroup (Salta Group) through an erosional unconformity that turns into an angular unconformity close to folds and faults recorded in the Santa Bárbara Subgroup. The base of the Quebrada de los Colorados Formation shows growth strata along the west frontal limb of an anticline with Santa Bárbara units in its core. The finding of a mammalian fossil at the base of the Quebrada de los Colorados Formation allows us to assign a Middle-Upper Eocene age to the sedimentation; therefore, the time elapsed between the deposition of the final postrift strata and the beginning of Andean sedimentation was brief and constrained to the Lower-Middle Eocene. This data indicates that the Eocene deformation phase described in other portions of the Puna-Cordillera Oriental transition (e.g., the northern Calchaquí Valley and Aguilar range) is also present in the Luracatao Valley, offering new tools for interpreting the ages and distributions of the initial episodes of sedimentation and deformation related to the Andean shortening. Thus, the Luracatao Valley provides new evidence for tracking the distribution of the Paleogene deformation in northwestern Argentina. 相似文献
142.
A Blocking Markov Chain Monte Carlo Method for Inverse Stochastic Hydrogeological Modeling 总被引:3,自引:2,他引:1
An adequate representation of the detailed spatial variation of subsurface parameters for underground flow and mass transport
simulation entails heterogeneous models. Uncertainty characterization generally calls for a Monte Carlo analysis of many equally
likely realizations that honor both direct information (e.g., conductivity data) and information about the state of the system
(e.g., piezometric head or concentration data). Thus, the problems faced is how to generate multiple realizations conditioned
to parameter data, and inverse-conditioned to dependent state data. We propose using Markov chain Monte Carlo approach (MCMC)
with block updating and combined with upscaling to achieve this purpose. Our proposal presents an alternative block updating
scheme that permits the application of MCMC to inverse stochastic simulation of heterogeneous fields and incorporates upscaling
in a multi-grid approach to speed up the generation of the realizations. The main advantage of MCMC, compared to other methods
capable of generating inverse-conditioned realizations (such as the self-calibrating or the pilot point methods), is that
it does not require the solution of a complex optimization inverse problem, although it requires the solution of the direct
problem many times. 相似文献
143.
Lucien von Gunten Christian Kamenik Marian Fujak Roberto Urrutia 《Journal of Paleolimnology》2012,47(4):583-600
Lake sediment records are underrepresented in comprehensive, quantitative, high-resolution (sub-decadal), multi-proxy climate
reconstructions for the past millennium. This is largely a consequence of the difficulty of calibrating biogeochemical lake
sediment proxies to meteorological time series (calibration-in-time). Thanks to recent methodological advances, it is now
possible. This paper outlines a step-by-step, specifically tailored methodology, with practical suggestions for calibrating
and validating biogeochemical proxies from lake sediments to meteorological data. This approach includes: (1) regional climate
data; (2) site selection; (3) coring and core selection; (4) core chronology; (5) data acquisition; and (6) data analysis
and statistical methods. We present three case studies that used non-varved lake sediments from remote areas in the Central
Chilean Andes, where little a priori information was available on the local climate and lakes, or their responses to climate
variability. These case studies illustrate the potential value and application of a calibration-in-time approach to non-varved
lake sediments for developing quantitative, high-resolution climate reconstructions. 相似文献
144.
Katrien Heirman Marc De Batist Francois Charlet Jasper Moernaut Emmanuel Chapron Robert Brümmer Mario Pino Roberto Urrutia 《第四纪科学杂志》2011,26(7):665-674
Lago Puyehue is a glacigenic lake in the Chilean Lake District (40°S) with a complex deglaciation history. A detailed seismic–stratigraphic study of its sedimentary infill indicates a much earlier retreat of the glacier from the Lago Puyehue basin than the neighbouring glacier from the Lago Rupanco basin. Because of their close proximity, Rupanco meltwater streams played an important part in the depositional processes of Lago Puyehue. A timing discrepancy between the in‐lake ages of a sediment core and the outer‐lake ages of moraine deposits (re)opens the discussion on the timing of deglaciation in the Southern Hemisphere. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
145.
146.
147.
148.
149.
Multiproxy summer and winter surface air temperature field reconstructions for southern South America covering the past centuries 总被引:2,自引:1,他引:1
R. Neukom J. Luterbacher R. Villalba M. K��ttel D. Frank P. D. Jones M. Grosjean H. Wanner J.-C. Aravena D. E. Black D. A. Christie R. D��Arrigo A. Lara M. Morales C. Soliz-Gamboa A. Srur R. Urrutia L. von Gunten 《Climate Dynamics》2011,37(1-2):35-51
We statistically reconstruct austral summer (winter) surface air temperature fields back to ad 900 (1706) using 22 (20) annually resolved predictors from natural and human archives from southern South America (SSA). This represents the first regional-scale climate field reconstruction for parts of the Southern Hemisphere at this high temporal resolution. We apply three different reconstruction techniques: multivariate principal component regression, composite plus scaling, and regularized expectation maximization. There is generally good agreement between the results of the three methods on interannual and decadal timescales. The field reconstructions allow us to describe differences and similarities in the temperature evolution of different sub-regions of SSA. The reconstructed SSA mean summer temperatures between 900 and 1350 are mostly above the 1901?C1995 climatology. After 1350, we reconstruct a sharp transition to colder conditions, which last until approximately 1700. The summers in the eighteenth century are relatively warm with a subsequent cold relapse peaking around 1850. In the twentieth century, summer temperatures reach conditions similar to earlier warm periods. The winter temperatures in the eighteenth and nineteenth centuries were mostly below the twentieth century average. The uncertainties of our reconstructions are generally largest in the eastern lowlands of SSA, where the coverage with proxy data is poorest. Verifications with independent summer temperature proxies and instrumental measurements suggest that the interannual and multi-decadal variations of SSA temperatures are well captured by our reconstructions. This new dataset can be used for data/model comparison and data assimilation as well as for detection and attribution studies at sub-continental scales. 相似文献
150.
Levels and spatial distribution of polycyclic aromatic hydrocarbons (PAHs) in sediments from Lenga Estuary, central Chile 总被引:1,自引:0,他引:1
Pozo K Perra G Menchi V Urrutia R Parra O Rudolph A Focardi S 《Marine pollution bulletin》2011,62(7):1572-1576
The Lenga Estuary is a small brackish wetland located southwest of San Vicente Bay, Region VIII, Chile. Surface sediment from nine sites in the estuary were analysed for PAHs and compared to Sediment Quality Guidelines (SQG). Sediment samples were freeze dried and soxhlet extracted for 16 h using DCM. Identification and quantification was carried out by HPLC. Organic carbon was also determined. Results showed total PAH concentrations ranged from 290 to 6118 (2025 ± 1975) ng g−1 d.w. (2025 ± 1975). Results for organic carbon percentages ranged from 1% to 7%. Statistical analysis showed a significant positive correlation (Pearson test) between organic carbon percentage PAHs. Comparison of contaminant levels and international Sediment Quality Guidelines (SQG) (ERL and ER) suggested that sediment of the Lenga estuary did not show any ecotoxicologial risk for benthic organisms where high levels of PAHs were detected. Monitoring of this and other contaminants is recommended in Chile. 相似文献