全文获取类型
收费全文 | 406篇 |
免费 | 15篇 |
国内免费 | 1篇 |
专业分类
测绘学 | 7篇 |
大气科学 | 31篇 |
地球物理 | 92篇 |
地质学 | 165篇 |
海洋学 | 41篇 |
天文学 | 43篇 |
自然地理 | 43篇 |
出版年
2024年 | 1篇 |
2023年 | 3篇 |
2022年 | 2篇 |
2021年 | 3篇 |
2020年 | 6篇 |
2019年 | 10篇 |
2018年 | 8篇 |
2017年 | 5篇 |
2016年 | 12篇 |
2015年 | 13篇 |
2014年 | 17篇 |
2013年 | 32篇 |
2012年 | 18篇 |
2011年 | 21篇 |
2010年 | 18篇 |
2009年 | 26篇 |
2008年 | 18篇 |
2007年 | 26篇 |
2006年 | 23篇 |
2005年 | 19篇 |
2004年 | 25篇 |
2003年 | 14篇 |
2002年 | 17篇 |
2001年 | 8篇 |
2000年 | 4篇 |
1999年 | 7篇 |
1998年 | 8篇 |
1997年 | 5篇 |
1996年 | 6篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 6篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1979年 | 2篇 |
1977年 | 4篇 |
1976年 | 1篇 |
1974年 | 2篇 |
1971年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有422条查询结果,搜索用时 15 毫秒
41.
Harold Clénet Georges Ceuleneer Patrick Pinet Bénédicte Abily Yves Daydou Esther Harris Isma Amri Céline Dantas 《Lithos》2010,114(3-4):265-281
Using the HyMap instrument, we have acquired visible and near infrared hyperspectral data over the Maqsad area of the Oman ophiolite (~ 15 × 60 km). This survey allowed us to identify and map the distribution of clinopyroxene-rich cumulates (inter-layered clinopyroxenites and wehrlites) whose occurrence was previously undocumented in this area. The cumulates reach several hundred meters in thickness and crop out at distances exceeding 15 km on both sides of the Maqsad former spreading centre. They occur either in mantle harzburgites, as km-sized layered intrusions surrounded by fields of pegmatitic dykes consisting of orthopyroxene-rich pyroxenite and gabbronorites, or at the base of the crustal section where they are conformably overlain by cumulate gabbros. These ultramafic cumulates crystallized from silica- and Mg-rich melts derived from a refractory mantle source (e.g. high Cr#, low [Al2O3], low [TiO2]). These melts are close to high-Ca boninites, although, strictly speaking, not perfect equivalents of present-day, supra-subduction zone, boninites. Chemical stratigraphy reveals cycles of replenishment, mixing and fractional crystallization from primitive (high Mg#) melts, typical of open magma chambers and migration of inter-cumulus melts. The TiO2 content of clinopyroxene is always low (≤ 0.2 wt.%) but quite variable compared to the associated pegmatites that are all derived from a source ultra-depleted in high field strength elements (HFSE). This variability is not caused by fractional crystallization alone, and is best explained by hybridization between the ultra-depleted melts (parent melts of the pegmatites) and the less depleted mid-ocean ridge basalts (MORB) parent of the dunitic–troctolitic–gabbroic cumulates making up the crustal section above the Maqsad diapir.We propose that, following a period of magma-starved spreading, the Maqsad mantle diapir, impregnated with tholeiitic melts of MORB affinity, reached shallow depths beneath the ocean ridge. This diapir induced melting of the formerly accreted and hydrothermally altered lithosphere. At this stage, these boninitic-like lithospheric melts crystallized as pegmatitic dykes. As the diapir continued to rise, the amount of MORB reaching shallow depths increased, together with the surrounding temperature, leading to the formation of magma chambers where the crystallization of layered cumulates became possible. These cumulates remained rich in pyroxene and devoid of plagioclase as long as the contribution of MORB-derived melts was moderate relative to the lithospheric-derived melts. As the contribution of MORB to the refilling of the magma chamber increased, gabbroic cumulates started to crystallize. 相似文献
42.
Yves Feisel Richard W. White Richard M. Palin Tim E. Johnson 《Journal of Metamorphic Geology》2018,36(6):799-819
In this study, we investigate the metamorphic history of the Assynt and Gruinard blocks of the Archean Lewisian Complex, northwest Scotland, which are considered by some to represent discrete crustal terranes. For samples of mafic and intermediate rocks, phase diagrams were constructed in the Na2O–CaO–K2O–FeO–MgO–Al2O3–SiO2–H2O–TiO2–O2 (NCKFMASHTO) system using whole‐rock compositions. Our results indicate that all samples equilibrated at similar peak metamorphic conditions of ~8–10 kbar and ~900–1,000°C, consistent with field evidence for in situ partial melting and the classic interpretation of the central region of the Lewisian Complex as representing a single crustal block. Melt‐reintegration modelling was employed in order to estimate probable protolith compositions. Phase equilibria calculated for these modelled undepleted precursors match well with those determined for a subsolidus amphibolite from Gairloch in the southern region of the Lewisian Complex. Both subsolidus lithologies exhibit similar phase relations and potential melt fertility, with both expected to produce orthopyroxene‐bearing hornblende granulites, with or without garnet, at the conditions inferred for the Badcallian metamorphic peak. For fully hydrated protoliths, prograde melting is predicted to first occur at ~620°C and ~9.5 kbar, with up to 45% partial melt predicted to form at peak conditions in a closed‐system environment. Partial melts calculated for both compositions between 610 and 1,050°C are mostly trondhjemitic. Although the melt‐reintegrated granulite is predicted to produce more potassic (granitic) melts at ~700–900°C, the modelled melts are consistent with the measured compositions of felsic sheets from the central region Lewisian Complex. 相似文献
43.
44.
Isabelle Coutand Michael Walsh Bertha Louis Frank Chanier Jacky Ferrière Jean‐Yves Reynaud 《地学学报》2014,26(4):287-297
The North Anatolian Fault Zone (NAFZ) is one of the most hazardous active faults on Earth, yet its Pliocene space‐time propagation across the north Aegean domain remains poorly constrained. We use low‐temperature multi‐thermochronology and inverse thermal modelling to quantify the cooling history of the upper crust across the Olympus range. This range is located in the footwall of a system of normal faults traditionally interpreted as resulting from superposed Middle–Late Miocene N–S stretching, related to the back‐arc extension of the Hellenic subduction zone, and a Pliocene‐Quaternary transtensional field, attributed to the south‐westward propagation of the NAFZ. We find that accelerated exhumational cooling occurred between 12 and 6 Ma at rates of 15–35 °C Ma?1 and decreased to <3 °C Ma?1 by 8–6 Ma. The absence of significant Plio‐Pleistocene cooling across Olympus suggests that crustal exhumation there is driven by late Miocene back‐arc extension, while the impact of the NAFZ remains limited. 相似文献
45.
In the Aspe Valley (western Pyrenees), the Europe/Iberia boundary corresponds to a complex fracturing zone, called the ‘Bielle–Accous Wrench-Faulting Corridor’, which represents the classical ‘North-Pyrenean Fault’. Located between the High Primary Range and the North-Pyrenean Zone, the BAWC shows different south-verging sheets mainly composed of Triassic materials. The Bedous ophite, associated with Muschelkalk and Keuper sediments, is also Triassic in age and involved in the same Pyrenean thrusting structures. So, contrary to a recent interpretation, this magmatic rock cannot be related to a supposed Danian plutonism inducing metamorphic processes in the surrounding Mesozoic formations. To cite this article: J. Canérot et al., C. R. Geoscience 336 (2004). 相似文献
46.
H. Albert Gilg Yves Krüger Heinrich Taubald Alfons M. van den Kerkhof Martin Frenz Giulio Morteani 《Mineralium Deposita》2014,49(7):861-877
Fluid inclusion studies in combination with hydrogen, oxygen and sulphur isotope data provide novel insights into the genesis of giant amethyst-bearing geodes in Early Cretaceous Paraná continental flood basalts at Amestita do Sul, Brazil. Monophase liquid inclusions in colourless quartz, amethyst, calcite, barite and gypsum were analysed by microthermometry after stimulating bubble nucleation using single femtosecond laser pulses. The salinity of the fluid inclusions was determined from ice-melting temperatures and a combination of prograde and retrograde homogenisation temperatures via the density maximum of the aqueous solutions. Four mineralisation stages are distinguished. In stage I, celadonite, chalcedony and pyrite formed under reducing conditions in a thermally stable environment. Low δ34SV-CDT values of pyrite (?25 to ?32?‰) suggest biogenic sulphate reduction by organotrophic bacteria. During the subsequent stages II (amethyst, goethite and anhydrite), III (early subhedral calcite) and IV (barite, late subhedral calcite and gypsum), the oxidation state of the fluid changed towards more oxidising conditions and microbial sulphate reduction ceased. Three distinct modes of fluid salinities around 5.3, 3.4 and 0.3 wt% NaCl-equivalent characterise the mineralisation stages II, III and IV, respectively. The salinity of the stage I fluid is unknown due to lack of fluid inclusions. Variation in homogenisation temperatures and in δ18O values of amethyst show evidence of repeated pulses of ascending hydrothermal fluids of up to 80–90 °C infiltrating a basaltic host rock of less than 45 °C. Colourless quartz and amethyst formed at temperatures between 40 and 80 °C, while the different calcite generations and late gypsum precipitated at temperatures below 45 °C. Calculated oxygen isotope composition of the amethyst-precipitating fluid in combination with δD values of amethyst-hosted fluid inclusions (?59 to ?51?‰) show a significant 18O-shift from the meteoric water line. This 18O-shift, high salinities of the fluid inclusions with chloride-sulphate composition, and high δ34S values of anhydrite and barite (7.5 to 9.9?‰) suggest that sedimentary brines from deeper parts of the Guaraní aquifer system must have been responsible for the amethyst mineralisation. 相似文献
47.
Fault zone geometry of a mature active normal fault: A potential high permeability channel (Pirgaki fault, Corinth rift, Greece) 总被引:2,自引:1,他引:2
We present results from petrophysical analysis of a normal fault zone with the aim of defining the flow pathways and their behavior during seismic and interseismic periods. Data are obtained on porosity geometry, strain structure and mineralogy of different domains of a normal fault zone in the Corinth rift. Data point out a close relationship between mineralogy of the clayey minerals, porosity network and strain structures and allow definition of a macroscopic anisotropy of the flow parameters with a strong control by microscopic ultracataclasite structures. The Pirgaki fault zone, developed within pelagic limestone, has a sharp asymmetric porosity profile, with a high porosity volume in the fault core and in the damage zone of the hanging wall. From porosity volumes and threshold measurements, a matrix permeability variation of 6 orders of magnitude could be expected between the protolith and the fault core. Modifications of this pathway during seismic and interseismic phases are depicted. Healing of cracks formed during seismic slip events occurred in the fault core zone and the porous network in the damage zone is sealed in a second step. The lens geometry of the fault core zone is associated with dissolution surfaces and open conduits where dissolved matter could move out of the fault core zone. These elementary processes are developed in particular along Riedel's structures and depend on the orientation of the strain surfaces relative to the local stress and depend also on the roughness of each surface type. P-surfaces are smooth and control shearing process. R-surfaces are rough and present two wavelengths of roughness. The long one controls localization of dissolution surfaces and conduits; the short one is characteristic of dissolution surfaces. The dissolved matter can precipitate in the open structures of the hanging wall damage zone, decreasing the connectivity of the macroscopic conduit developed within this part of the fault zone. 相似文献
48.
Yves Noel Raffaella Demichelis Fabien Pascale Piero Ugliengo Roberto Orlando Roberto Dovesi 《Physics and Chemistry of Minerals》2009,36(1):47-59
The structure and vibrational spectrum of boehmite have been investigated at the quantum-mechanical level with the CRYSTAL
code, using a Gaussian-type basis set and the B3LYP Hamiltonian. Three space groups are considered in this study: Cmcm, Cmc21, P21/c. Cmcm turns out to correspond to a transition state, whereas Cmc21 and P21/c are minimum energy structures. The difference among them is the position of H atoms only, the Al-O frame being essentially
the same. Harmonic frequencies at the Γ point have been computed. The comparison between calculated and experimental frequencies
shows a good agreement for the Al-O part of the spectrum (under 790 cm−1). For the Al-OH bending modes (800–1,300 cm−1) an absolute differences of 50–100 cm−1 is observed; for the OH stretching modes (3,200–3,500 cm−1) it increases to 120–200 cm−1: anharmonicity is large because OH groups are involved in strong hydrogen bonds. 相似文献
49.
Holger Frey Christian Huggel Yves Bühler Daniel Buis Maria Dulce Burga Walter Choquevilca Felipe Fernandez Javier García Hernández Claudia Giráldez Edwin Loarte Paul Masias Cesar Portocarrero Luis Vicuña Marco Walser 《Landslides》2016,13(6):1493-1507
The town of Santa Teresa (Cusco Region, Peru) has been affected by several large debris-flow events in the recent past, which destroyed parts of the town and resulted in a resettlement of the municipality. Here, we present a risk analysis and a risk management strategy for debris-flows and glacier lake outbursts in the Sacsara catchment. Data scarcity and limited understanding of both physical and social processes impede a full quantitative risk assessment. Therefore, a bottom-up approach is chosen in order to establish an integrated risk management strategy that is robust against uncertainties in the risk analysis. With the Rapid Mass Movement Simulation (RAMMS) model, a reconstruction of a major event from 1998 in the Sacsara catchment is calculated, including a sensitivity analysis for various model parameters. Based on the simulation results, potential future debris-flows scenarios of different magnitudes, including outbursts of two glacier lakes, are modeled for assessing the hazard. For the local communities in the catchment, the hazard assessment is complemented by the analysis of high-resolution satellite imagery and fieldwork. Physical, social, economic, and institutional vulnerability are considered for the vulnerability assessment, and risk is eventually evaluated by crossing the local hazard maps with the vulnerability. Based on this risk analysis, a risk management strategy is developed, consisting of three complementing elements: (i) standardized risk sheets for the communities; (ii) activities with the local population and authorities to increase social and institutional preparedness; and (iii) a simple Early Warning System. By combining scientific, technical, and social aspects, this work is an example of a framework for an integrated risk management strategy in a data scarce, remote mountain catchment in a developing country. 相似文献
50.
Yves Goddéris Louis M. François Jacques Schott David Labat 《Geochimica et cosmochimica acta》2006,70(5):1128-1147
A numerical model of chemical weathering in soil horizons and underlying bedrock (WITCH) has been coupled to a numerical model of water and carbon cycles in forest ecosystems (ASPECTS) to simulate the concentration of major species within the soil horizons and the stream of the Strengbach granitic watershed, located in the Vosges Mountains (France). For the first time, simulations of solute concentrations in soil layers and in the catchment river have been performed on a seasonal basis. The model is able to reproduce the concentrations of most major species within the soil horizons, as well as catching the first-order seasonal fluctuations of aqueous calcium, magnesium and silica concentrations. However, the WITCH model underestimates concentrations of Mg2+ and silica at the spring of the catchment stream, and significantly underestimates Ca2+ concentration. The deficit in calculated calcium can be compensated for by dissolution of trace apatite disseminated in the bedrock. However, the resulting increased Ca2+ release yields important smectite precipitation in the deepest model layer (in contact with the bedrock) and subsequent removal of large amount of silica and magnesium from solution. In contrast, the model accurately accounts for the concentrations of major species (Ca, Mg and silica) measured in the catchment stream when precipitation of clay minerals is not allowed. The model underestimation of Mg2+ and H4SiO4 concentrations when precipitation of well crystallized smectites is allowed strongly suggests that precipitation of well crystallized clay minerals is overestimated and that more soluble poorly crystallized and amorphous materials may be forming. In agreement with observations on other watersheds draining granitic rocks, this study indicates that highly soluble trace calcic phases control the aqueous calcium budget in the Strengbach watershed. 相似文献