全文获取类型
收费全文 | 756篇 |
免费 | 32篇 |
国内免费 | 12篇 |
专业分类
测绘学 | 7篇 |
大气科学 | 41篇 |
地球物理 | 165篇 |
地质学 | 458篇 |
海洋学 | 31篇 |
天文学 | 64篇 |
综合类 | 7篇 |
自然地理 | 27篇 |
出版年
2022年 | 7篇 |
2021年 | 11篇 |
2020年 | 12篇 |
2019年 | 12篇 |
2018年 | 49篇 |
2017年 | 53篇 |
2016年 | 46篇 |
2015年 | 30篇 |
2014年 | 41篇 |
2013年 | 59篇 |
2012年 | 45篇 |
2011年 | 42篇 |
2010年 | 26篇 |
2009年 | 46篇 |
2008年 | 47篇 |
2007年 | 22篇 |
2006年 | 29篇 |
2005年 | 15篇 |
2004年 | 25篇 |
2003年 | 24篇 |
2002年 | 13篇 |
2001年 | 6篇 |
2000年 | 12篇 |
1999年 | 3篇 |
1998年 | 8篇 |
1997年 | 8篇 |
1996年 | 3篇 |
1995年 | 7篇 |
1994年 | 6篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1991年 | 6篇 |
1990年 | 4篇 |
1989年 | 6篇 |
1988年 | 4篇 |
1987年 | 8篇 |
1986年 | 9篇 |
1985年 | 8篇 |
1984年 | 7篇 |
1983年 | 8篇 |
1982年 | 6篇 |
1980年 | 2篇 |
1978年 | 2篇 |
1976年 | 2篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1968年 | 1篇 |
1966年 | 3篇 |
1961年 | 1篇 |
1960年 | 1篇 |
排序方式: 共有800条查询结果,搜索用时 15 毫秒
191.
Tectonometamorphic evolution of an intracontinental orogeny inferred from P–T–t–d paths of the metapelites from the Rehamna massif (Morocco)
下载免费PDF全文
![点击此处可从《Journal of Metamorphic Geology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
P. Wernert K. Schulmann F. Chopin P. Štípská D. Bosch M. El Houicha 《Journal of Metamorphic Geology》2016,34(9):917-940
New petrographic and microstructural observations, mineral equilibria modelling and U/Pb (monazite) geochronological studies were carried out to investigate the relationships between deformation and metamorphism across the Rehamna massif (Moroccan Variscan belt). In this area, typical Barrovian (muscovite to staurolite) zones developed in Cambrian to Carboniferous metasedimentary rocks that are distributed around a dome‐like structure. First assemblages are characterized by the presence of locally preserved andalusite, followed by prograde evolution culminating at 6 kbar and 620 °C in the structurally deepest staurolite zone rocks. This Barrovian sequence was subsequently uplifted to supracrustal levels, heterogeneously reworked at greenschist facies conditions, which was followed locally by static growth of andalusite, indicating heating to 2.5–4 kbar and 530–570 °C. The 206Pb/238U monazite age of 298.3 ± 4.1 Ma is interpreted as minimum age of peak metamorphic conditions, whereas the ages of 275.8 ± 1.7 Ma and 277.0 ± 1.1 Ma date decompression and heating at low pressure, in agreement with previous dating of Permian granitoids intruding the Rehamna massif. The prograde metamorphism occurred during thickening and associated horizontal flow in the deeper crust (S1 horizontal schistosity). The horizontally disposed metamorphic zones were subsequently uplifted by a regional scale antiform during ongoing N–S compression. The re‐heating of the massif follows late massive E–W shortening, refolding and retrograde shearing of all previous fabrics coevally with regionally important intrusions of Permian granitoids. We argue that metamorphic evolution of the Rehamna massif occurred several hundred kilometres from the convergent plate boundaries in the interior of continental Gondwanan plate. The tectonometamorphic history of the Rehamna massif is put into Palaeozoic plate tectonic perspective and Late Carboniferous reactivation of (Devonian)–Early Carboniferous basins formed during stretching of the north Gondwana margin and formation of the Palaeotethys Ocean. The inherited heat budget of these magma‐rich basins plays a role in the preferential location of this intracontinental orogen. It is shown that rapid transition from lithospheric stretching to compression is characterized by specific HT type of Barrovian metamorphism, which markedly differs from similar Barrovian sequences along Palaeozoic plate boundaries reported from Variscan Europe. 相似文献
192.
Almoutaz A. El Hassan H. O. Sharif Terrance Jackson Singaiah Chintalapudi 《水文研究》2013,27(24):3394-3408
The need for accurate hydrologic analysis and rainfall–runoff modelling tools has been rapidly increasing because of the growing complexity of operational hydrologic and hydraulic problems associated with population growth, rapid urbanization and expansion of agricultural activities. Given the recent advances in remote sensing of physiographic features and the availability of near real‐time precipitation products, rainfall–runoff models are expected to predict runoff more accurately. In this study, we compare the performance and implementation requirements of two rainfall–runoff models for a semi‐urbanized watershed. One is a semi‐distributed conceptual model, the Hydrologic Engineering Center‐Hydrologic Modelling System (HEC‐HMS). The other is a physically based, distributed‐parameter hydrologic model, the Gridded Surface Subsurface Hydrologic Analysis (GSSHA). Four flood events that took place on the Leon Creek watershed, a sub‐watershed of the San Antonio River basin in Texas, were used in this study. The two models were driven by the Multisensor Precipitation Estimator radar products. One event (in 2007) was used for HEC‐HMS and GSSHA calibrations. Two events (in 2004 and 2007) were used for further calibration of HEC‐HMS. Three events (in 2002, 2004 and 2010) were used for model validation. In general, the physically based, distributed‐parameter model performed better than the conceptual model and required less calibration. The two models were prepared with the same minimum required input data, and the effort required to build the two models did not differ substantially. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
193.
El Mohtar Chadi Jaffal Hamza Miller Anna Kate Ward Katie 《Geotechnical and Geological Engineering》2022,40(9):4473-4485
Geotechnical and Geological Engineering - Permeation grouting is a ground improvement method commonly used for strengthening and/or reducing permeability of soils with minimal disturbance to the... 相似文献
194.
Mohamed W. ALI-BIK Suranjan GHOSH N. PRABHAKAR Said H. Abd El RAHIM Hilmy E. MOUSSA 《《地质学报》英文版》2022,96(5):1545-1565
The Sa''al Metamorphic Complex (SMC; southern Sinai) encompasses the oldest arc rocks in the Arabian–Nubian Shield, comprising two non-consanguineous metavolcanic successions (the Agramiya Group and the Post-Ra''ayan Formation) separated by the metasediments of the Ra''ayan Formation. It experienced three distinct deformational events (D1–D3) and two low-medium grade regional metamorphic events (M1–M2). The Agramiya Group and the Ra''ayan Formation experienced all tectonometamorphic events (D1–D3 and M1–M2), whereas the Post-Ra''ayan volcanic rocks were only affected by the D3 and M2 events. D1 is an extensional event and is connected to the late Rodinia break-up (~Tonian; 900–870 Ma). The M1 metamorphism variably affected the older Agramiya Group, the rhyolitic tuffs experiencing lower to upper greenschist facies conditions and the basic and intermediate volcanic rocks undergoing amphibolite facies metamorphism. The Ra''ayan Formation metasediments experienced upper greenschist to amphibolite facies metamorphism. The upper greenschist facies M2 affected the youngest Post-Ra''ayan volcanic rocks and other stratigraphic successions. The compressive D2 and D3 events were coeval with the accretion of dismembered terranes in the assembly of Gondwana. D2 can be linked to the Tonian–Cryogenian arc-arc assembly (~880–760 Ma; in Elat and Sinai), whereas D3 and the accompanying M2 is constrained to 622–600 Ma (Ediacaran). 相似文献
195.
196.
Microscopic impactor debris in the soil around Kamil crater (Egypt): Inventory,distribution, total mass,and implications for the impact scenario
下载免费PDF全文
![点击此处可从《Meteoritics & planetary science》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Luigi Folco Massimo D'Orazio Agnese Fazio Carole Cordier Antonio Zeoli Matthias van Ginneken Ahmed El‐Barkooky 《Meteoritics & planetary science》2015,50(3):382-400
We report on the microscopic impactor debris around Kamil crater (45 m in diameter, Egypt) collected during our 2010 geophysical expedition. The hypervelocity impact of Gebel Kamil (Ni‐rich ataxite) on a sandstone target produced a downrange ejecta curtain of microscopic impactor debris due SE–SW of the crater (extending ~300,000 m2, up to ~400 m from the crater), in agreement with previous determination of the impactor trajectory. The microscopic impactor debris include vesicular masses, spherules, and coatings of dark impact melt glass which is a mixture of impactor and target materials (Si‐, Fe‐, and Al‐rich glass), plus Fe‐Ni oxide spherules and mini shrapnel, documenting that these products can be found in craters as small as few tens of meters in diameter. The estimated mass of the microscopic impactor debris (<290 kg) derived from Ni concentrations in the soil is a small fraction of the total impactor mass (~10 t) in the form of macroscopic shrapnel. That Kamil crater was generated by a relatively small impactor is consistent with literature estimates of its pre‐atmospheric mass (>20 t, likely 50–60 t). 相似文献
197.
198.
199.
M. El Sawwaf 《Geotechnical and Geological Engineering》2010,28(4):311-323
The paper presents the results of laboratory model tests and theoretical analysis on the behavior of a strip footing supported
on sheet pile wall-stabilized sandy slope and loaded vertically to failure. The parameters varied in the study include the
height, stiffness and location of the sheet pile wall, the location of the footing relative to the slope crest and the relative
density of sand. Two-dimensional plane strain finite element analyses was used to analyze a prototype strip footing on sandy
slope with same conditions. The results indicate that the inclusion of sheet pile wall has significant effect in improving
the response of the strip footing and the slope itself. The theoretical results confirm the experimental results of the model
footing tests and show reasonable agreement. Based on the numerical and experimental results, critical values of the sheet
pile wall parameters for maximum stabilizing effect are established. 相似文献
200.
Corey A Cohn Shawn C Fisher Bruce J Brownawell Martin AA Schoonen 《Geochemical transactions》2010,11(1):2
Cellular exposure to particulate matter with concomitant formation of reactive oxygen species (ROS) and oxidization of biomolecules
may lead to negative health outcomes. Evaluating the particle-induced formation of ROS and the oxidation products from reaction
of ROS with biomolecules is useful for gaining a mechanistic understanding of particle-induced oxidative stress. Aqueous suspensions
of pyrite particles have been shown to form hydroxyl radicals and degrade nucleic acids. Reactions between pyrite-induced
hydroxyl radicals and nucleic acid bases, however, remain to be determined. Here, we compared the oxidation of adenine by
Fenton-generated (i.e., ferrous iron and hydrogen peroxide) hydroxyl radicals to adenine oxidation by hydroxyl radicals generated
in pyrite aqueous suspensions. Results show that adenine oxidizes in the presence of pyrite (without the addition of hydrogen
peroxide) and that the rate of oxidation is dependent on the pyrite loading. Adenine oxidation was prevented by addition of
either catalase or ethanol to the pyrite/adenine suspensions, which implies that hydrogen peroxide and hydroxyl radicals are
causing the adenine oxidation. The adenine oxidation products, 8-oxoadenine and 2-hydroxyadenine, were the same whether hydroxyl
radicals were generated by Fenton or pyrite-initiated reactions. Although nucleic acid bases are unlikely to be directly exposed
to pyrite particles, the formation of ROS in the vicinity of cells may lead to oxidative stress. 相似文献