全文获取类型
收费全文 | 134篇 |
免费 | 5篇 |
国内免费 | 1篇 |
专业分类
测绘学 | 2篇 |
大气科学 | 29篇 |
地球物理 | 29篇 |
地质学 | 44篇 |
海洋学 | 8篇 |
天文学 | 23篇 |
综合类 | 1篇 |
自然地理 | 4篇 |
出版年
2022年 | 1篇 |
2021年 | 4篇 |
2020年 | 1篇 |
2019年 | 1篇 |
2018年 | 6篇 |
2017年 | 7篇 |
2016年 | 12篇 |
2015年 | 2篇 |
2014年 | 13篇 |
2013年 | 17篇 |
2012年 | 9篇 |
2011年 | 16篇 |
2010年 | 8篇 |
2009年 | 7篇 |
2008年 | 6篇 |
2007年 | 2篇 |
2005年 | 3篇 |
2004年 | 6篇 |
2003年 | 3篇 |
2002年 | 2篇 |
2000年 | 3篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1992年 | 1篇 |
1990年 | 1篇 |
1986年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有140条查询结果,搜索用时 15 毫秒
61.
Hassan Mohamed Hakim Saibi Mohand Bersi Sami Abdelnabi Baher Geith Hamdy Ismaeil Thomas Tindell Hideki Mizunaga 《Arabian Journal of Geosciences》2018,11(21):674
The Um Salatit is a gold occurrence situated in the Central Eastern Desert of Egypt. The studied area is characterized by an intensive imbrication zone of serpentinites and metavolcanic rocks. The integrated use of aeromagnetic and spectral reflectance remote sensing data has proved effective for mapping geology related to ore deposits. Spectral reflectance maps have been produced to discriminate various rocks, such as serpentinites, gabbros, and metavolcanic rocks. 3-D inversion of aeromagnetic data acquired over the Um Salatit study area produced a 3-D magnetic susceptibility model showing magnetic bodies surrounded by less magnetic host rock. The magnetic features are elongated ENE-WSW parallel to the major thrust fault and mapped the Um Salatit serpentinized rocks. Remote sensing data allow investigating surficial geological features and mapping the mineralized areas. Remote results, in conjunction with 3-D inversion of aeromagnetic data, demonstrate that gold occurrence in the study area was effectively restricted to the highly magnetic zone interpreted as host rocks. 相似文献
62.
Sunspots are known to have large, low-lying magnetic canopies, i.e. horizontal magnetic fields overlying a field-free medium, that cover substantial fractions of active region plage. In this paper we consider the influence of such canopies on the inclination of plage magnetic fields. We find that for observations in spectral lines like 5250.2Å the neglect of a sunspot canopy when determining magnetic inclination angles of plage fields can introduce errors exceeding 5–10°. This is particularly true if the observations do not have high spatial resolution. Thus this effect may explain some of the measurements of substantially inclined fields in solar plages. Furthermore we find that the Fe I 15648 Å line is far superior in giving correct flux-tube inclinations in the presence of a sunspot magnetic canopy. Finally, the inversion of full Stokes profiles is shown to produce more reliable results than results obtained by considering only ratios of individual Stokes profile parameters. 相似文献
63.
Christian Azar Kristian Lindgren Michael Obersteiner Keywan Riahi Detlef P. van Vuuren K. Michel G. J. den Elzen Kenneth M?llersten Eric D. Larson 《Climatic change》2010,100(1):195-202
The United Nations Framework Convention on Climate Change (UNFCCC 1992) calls for stabilization of atmospheric greenhouse gas (GHG) concentrations at a level that would prevent dangerous anthropogenic
interference with the climate system. We use three global energy system models to investigate the technological and economic
attainability of meeting CO2 concentration targets below current levels. Our scenario studies reveal that while energy portfolios from a broad range of
energy technologies are needed to attain low concentrations, negative emission technologies—e.g., biomass energy with carbon
capture and storage (BECCS)—significantly enhances the possibility to meet low concentration targets (at around 350 ppm CO2). 相似文献
64.
65.
Mourad Bédir Afif Arbi Sami Khomsi Faten Houatmia Mohamed Naceur Aissaoui 《Arabian Journal of Geosciences》2016,9(19):726
Most of hydrocarbon accumulations within the Gulf of Hammamet foreland basins in eastern Tunisia are reservoired within the Upper Miocene Birsa and Saouaf sandstones. It is the case of Birsa, Tazarka, Oudna, Baraka, Maamoura, Cosmos and Yasmine fields. These sandstones constitute oil and gas fields located on folded and faulted horst anticline highs and described as varying from shoreface to shallow marine and typically exhibit excellent reservoir quality of 30 to 35% porosity and good permeability from 500 to 1100 md. In addition, the fracturing of faults enhanced their reservoir quality potential. However, due to the lack of seismic stratigraphic studies to highlight depositional environment reservoir characterization and distribution, petroleum exploration faces structural and stratigraphic trap types and remains on targeting only high fold closures with limited reserve volumes of hydrocarbons. As an example of the Birsa concession case, syn-sedimentary tectonic structuring and geodynamic evolution during Middle to Upper Miocene Birsa reservoir sequences have guided the distribution of depositional environment of sandstone channel systems around horst and grabens by E-W, NE-SW and N-S strike slip flower faults controlling the subsidence distribution combined with the eustatic sea level variations. Seismic sequence stratigraphy study of Miocene Birsa reservoir horizons, based on the analysis and interpretations of E-W and N-S 3D selected regional lines that were compared and correlated to outcrops and calibrated by well data, permitted to highlight the basin configuration and sequence deposit nature and distribution. Sedimentary infilling of the basin from Langhian Ain Ghrab carbonate to Serravallian Tortonian Birsa and Saouaf sandstone and shale formations is organized in four third-order seismic sequences, limited by regional erosional toplap, onlap and downlap unconformity surfaces and by remarkable chronostratigraphic horizons of forced and normal erosive lowstand and highstand system tracts separated by transgressive and maximum flooding surfaces. Reconstructed sedimentary paleo-environment distribution vary from deltaic fluvial proximal deposits in the northern part of the high central Birsa horst to a delta front and prodelta coastal and shelf shore face and shore line channelized deposits in the surrounding borders of grabens. Distal deposits seem to be distributed from upper to lower slope fans and probably to the basin floor on the flanks of the subsiding grabens. Synthetic predictive paleogeographic depositional reservoir fairway map distribution of Lower, Middle and Upper Birsa sandstone reservoirs highlights four main domains of channelized superposed and shifted reservoirs to explore. 相似文献
66.
Marcel Kuper Christian Leduc Sylvain Massuel Sami Bouarfa 《Hydrogeology Journal》2017,25(6):1525-1528
This essay introduces a collection of articles that explore the future of groundwater-based agriculture in the Mediterranean from an interdisciplinary perspective, in a context of declining water tables due to intensive groundwater use. The imminent crisis that many groundwater economies face due to very rapid and intense global change may have severe irreversible social, economic and environmental consequences, but could also be the opportunity to make a clear break with current agricultural development models and move towards more sustainable agricultural practices. The Mediterranean region is, therefore, an interesting case for the future of intensive groundwater use, as innovative ideas and practices may emerge and inspire similar groundwater-based agricultural systems around the world. 相似文献
67.
We investigate with 3D hydrodynamical simulations the role played by thermal processes in the dynamical evolution of the interstellarmedium (ISM). A parametric approach of the coolingprocess shows that the observed mass fraction of the cold (< 300 K)and unstable gas (300K < T < 6000K) can not be produced by turbulentcompression or background heating of the medium alone. An analysis of theproperties of the clouds that are formed by the combined effect of the thermal and gravitational instability shows that the cloud’s scaling relations imprinted by the thermal instability (TI) are in good agreementwith observational values. 相似文献
68.
Validation and use of rainfall radar data to simulate water flows in the Rio Escondido basin 总被引:1,自引:1,他引:1
Sami Eleuch Alin Carsteanu Khalidou Bâ Ramata Magagi Kalifa Goïta Carlos Diaz 《Stochastic Environmental Research and Risk Assessment (SERRA)》2010,24(5):559-565
This paper presents a combined validation method of radar-sensed rainfall, using rain gauge data and hydrologic closure, with
an application to the Rio Escondido basin (North-East of Mexico). The space–time scaling behavior of rainfall between rain
gauge and radar scales is compared with the intrinsic variability of rainfall, for a statistical validation of space–time
variability. For hydrological validation purposes, the CEQUEAU model is used to perform rainfall-runoff routing. It provides a basin-wide water balance, to be compared with the measured
water flow at the Villa de Fuentes hydrometric station, for mean-value gauging closure. A good qualitative agreement in terms
of hydrograph shape and timing is obtained between the simulated and the observed water flows, and a multiplicative correction
factor of an initially proposed Z–R relationship is adopted for the watershed under study, which agrees approximately with
other authors’ findings about that relationship. The results are considered particularly useful as a validation-and-correction
methodology of radar rainfall estimates for areas sparsely covered by rain gauges. 相似文献
69.
We use a comparison between the autocorrelation length value in 21-cm hi maps of Holmberg II and the autocorrelation length derived from simulated maps in order to constrain the physical processes that are responsible for the observed distribution of holes and shells in the interstellar medium (ISM) of the galaxy. Our results show that large scale turbulence coupled to a weak cooling can reproduce the value of the autocorrelation length which is observed. 相似文献
70.
Global and regional evolution of short-lived radiatively-active gases and aerosols in the Representative Concentration Pathways 总被引:3,自引:0,他引:3
Jean-Fran?ois Lamarque G. Page Kyle Malte Meinshausen Keywan Riahi Steven J. Smith Detlef P. van Vuuren Andrew J. Conley Francis Vitt 《Climatic change》2011,109(1-2):191-212
In this paper, we discuss the results of 2000?C2100 simulations following the emissions associated with the Representative Concentration Pathways (RCPs) with a chemistry-climate model, focusing on the changes in 1) atmospheric composition (troposphere and stratosphere) and 2) associated environmental parameters (such as nitrogen deposition). In particular, we find that tropospheric ozone is projected to decrease (RCP2.6, RCP4.5 and RCP6) or increase (RCP8.5) between 2000 and 2100, with variations in methane a strong contributor to this spread. The associated tropospheric ozone global radiative forcing is shown to be in agreement with the estimate used in the RCPs, except for RCP8.5. Surface ozone in 2100 is projected to change little compared from its 2000 distribution, a much-reduced impact from previous projections based on the A2 high-emission scenario. In addition, globally-averaged stratospheric ozone is projected to recover at or beyond pre-1980 levels. Anthropogenic aerosols are projected to strongly decrease in the 21st century, a reflection of their projected decrease in emissions. Consequently, sulfate deposition is projected to strongly decrease. However, nitrogen deposition is projected to increase over certain regions because of the projected increase in NH3 emissions. 相似文献