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61.
Alexander Kurnosov Hauke Marquardt Leonid Dubrovinsky Vasily Potapkin 《Comptes Rendus Geoscience》2019,351(2-3):280-285
Fiber-based laser heating systems offer high flexibility and are increasingly used in high-pressure/high-temperature research. Previous fiber-based laser heating systems were based on lasers delivering radiation with 1-μm wavelength that show unfavorable heating characteristics for many sample materials. We report on the development and first experiments of a waveguide (fiber)-based CO2-laser heating system that can be used in a flexible manner for high-temperature research and for high-pressure/temperature experiments when combined with diamond-anvil cells. The waveguide-based CO2-laser heating system allows convenient heating of optically transparent samples without the need for adding an additional laser absorber. In a pilot experiment, the flexible heating system has been installed on a Brillouin scattering system to measure high-temperature sound-wave velocities in single-crystal MgO. The waveguide-based CO2-laser heating system offers perspectives for a variety of scientific applications, most importantly those that require the use of synchrotron facilities where space is limited and flexible solutions are required. 相似文献
62.
Trace and minor elements in sphalerite: A LA-ICPMS study 总被引:18,自引:0,他引:18
Nigel J. Cook Cristiana L. Ciobanu Allan Pring William Skinner Leonid Danyushevsky Frank Melcher 《Geochimica et cosmochimica acta》2009,73(16):4761-4791
Sphalerite is an important host mineral for a wide range of minor and trace elements. We have used laser-ablation inductively coupled mass spectroscopy (LA-ICPMS) techniques to investigate the distribution of Ag, As, Bi, Cd, Co, Cu, Fe, Ga, Ge, In, Mn, Mo, Ni, Pb, Sb, Se, Sn and Tl in samples from 26 ore deposits, including specimens with wt.% levels of Mn, Cd, In, Sn and Hg. This technique provides accurate trace element data, confirming that Cd, Co, Ga, Ge, In, Mn, Sn, As and Tl are present in solid solution. The concentrations of most elements vary over several orders of magnitude between deposits and in some cases between single samples from a given deposit. Sphalerite is characterized by a specific range of Cd (typically 0.2-1.0 wt.%) in each deposit. Higher Cd concentrations are rare; spot analyses on samples from skarn at Baisoara (Romania) show up to 13.2 wt.% (Cd2+ ↔ Zn2+ substitution). The LA-ICPMS technique also allows for identification of other elements, notably Pb, Sb and Bi, mostly as micro-inclusions of minerals carrying those elements, and not as solid solution. Silver may occur both as solid solution and as micro-inclusions. Sphalerite can also incorporate minor amounts of As and Se, and possibly Au (e.g., Magura epithermal Au, Romania). Manganese enrichment (up to ∼4 wt.%) does not appear to enhance incorporation of other elements. Sphalerite from Toyoha (Japan) features superimposed zoning. Indium-sphalerite (up to 6.7 wt.% In) coexists with Sn-sphalerite (up to 2.3 wt.%). Indium concentration correlates with Cu, corroborating coupled (Cu+In3+) ↔ 2Zn2+ substitution. Tin, however, correlates with Ag, suggesting (2Ag+Sn4+) ↔ 3Zn2+ coupled substitution. Germanium-bearing sphalerite from Tres Marias (Mexico) contains several hundred ppm Ge, correlating with Fe. We see no evidence of coupled substitution for incorporation of Ge. Accordingly, we postulate that Ge may be present as Ge2+ rather than Ge4+. Trace element concentrations in different deposit types vary because fractionation of a given element into sphalerite is influenced by crystallization temperature, metal source and the amount of sphalerite in the ore. Epithermal and some skarn deposits have higher concentrations of most elements in solid solution. The presence of discrete minerals containing In, Ga, Ge, etc. also contribute to the observed variance in measured concentrations within sphalerite. 相似文献
63.
L. Robin M. Cocks Leonid E. Popov 《Proceedings of the Geologists' Association. Geologists' Association》2019,130(6):677-690
The Early Ordovician brachiopods of south-west Wales (Pembrokeshire and Carmarthenshire) are identified, in most cases for the first time. That period is termed the local Arenig Stage in Britain, but it is now correlated with the Floian, Dapingian, and earlier half of the Darriwilian, which are more recently established international stages in the system of stratigraphical nomenclature. The rocks in south-west Wales were laid down as turbidites in a backarc basin which formed part of the margin of the relatively small independent microcontinent of Avalonia at that time. However, since the Rheic Ocean between Avalonia and the immense Gondwana continent was relatively narrow in the Arenig, the brachiopods reviewed here can be established to be part of the Mediterranean Province, which was also extensive in the higher-latitude sectors in and around Gondwana in the Early Ordovician. The 17 brachiopod species identified within the Arenig brachiopod faunas of south-west Wales are described, including the new species Aporthophyla prisca, Tritoechia bolohaulensis, Skenidoides pontyfennensis and Paurorthis? llangynogensis. 相似文献
64.
Vladimir V. Ivanov Igor V. Polyakov Igor A. Dmitrenko Edmond Hansen Irina A. Repina Sergey A. Kirillov Cecillie Mauritzen Harper Simmons Leonid A. Timokhov 《Deep Sea Research Part I: Oceanographic Research Papers》2009,56(1):1-14
A combination of 2-year-long mooring-based measurements and snapshot conductivity–temperature–depth (CTD) observations at the continental slope off Spitsbergen (81°30′N, 31°00′E) is used to demonstrate a significant hydrographic seasonal signal in Atlantic Water (AW) that propagates along the Eurasian continental slope in the Arctic Ocean. At the mooring position this seasonal signal dominates, contributing up to 50% of the total variance. Annual temperature maximum in the upper ocean (above 215 m) is reached in mid-November, when the ocean in the area is normally covered by ice. Distinct division into ‘summer’ (warmer and saltier) and ‘winter’ (colder and fresher) AW types is revealed there. Estimated temperature difference between the ‘summer’ and ‘winter’ waters is 1.2 °C, which implies that the range of seasonal heat content variations is of the same order of magnitude as the mean local AW heat content, suggesting an important role of seasonal changes in the intensity of the upward heat flux from AW. Although the current meter observations are only 1-year long, they hint at a persistent, highly barotropic current with little or no seasonal signal attached. 相似文献
65.
Anna Spivak Natalia Solopova Valerio Cerantola Elena Bykova Egor Zakharchenko Leonid Dubrovinsky Yuriy Litvin 《Physics and Chemistry of Minerals》2014,41(8):633-638
Magnesite, siderite and ferromagnesites Mg1?x Fe x CO3 (x = 0.05, 0.09, 0.2, 0.4) were characterized using in situ Raman spectroscopy at high pressures up to 55 GPa. For the Mg–Fe-carbonates, the Raman peak positions of six modes (T, L, ν4, ν1, ν3 and 2ν2) in the dependence of iron content in the carbonates at ambient conditions are presented. High-pressure Raman spectroscopy shows that siderite undergoes a spin transition at ~40 GPa. The examination of the solid solutions with compositions Mg0.6Fe0.4CO3, Mg0.8Fe0.2CO3, Mg0.91Fe0.09CO3 and Mg0.95Fe0.05CO3 indicates that with increase in the amount of the Fe spin transition pressure increases up to ~45 GPa. 相似文献
66.
Vitaly ISUPOV SODOV Ariunbileg Svetlana SHATSKAYA Marina KOLPAKOVA Ljudmila RAZVOROTNEVA Alexander VLADIMIROV Stepan SHVARTSEV Leonid KUIBIDA Sergey KRIVONOGOV Ekaterina MOROZ 《《地质学报》英文版》2014,88(Z1):137-138
正1 Introduction Increasing demand for uranium raw materials for the nuclear industry has stimulated interest in non-traditional sources,including hydromineral ones[Qin,2009].Those are saline lakes located in the uranium ore districts.Accumulation of uranium in such lakes results from the leaching of uranium from the rocks by surface and ground 相似文献
67.
We review petrologic observations of reaction textures from high-grade rocks that suggest the passage of fluids with variable alkali activities. Development of these reaction textures is accompanied by regular compositional variations in plagioclase, pyroxenes, biotite, amphibole and garnet. The textures are interpreted in terms of exchange and net-transfer reactions controlled by the K and Na activities in the fluids. On the regional scale, these reactions operate in granitized, charnockitized, syenitized etc. shear zones within high-grade complexes. Thermodynamic calculations in simple chemical systems show that changes in mineral assemblages, including the transition from the hydrous to the anhydrous ones, may occur at constant pressure and temperature due only to variations in the H2O and the alkali activities. A simple procedure for estimating the activity of the two major alkali oxides, K2O and Na2O, is imple- mented in the TWQ software. Examples of calculations are presented for well-documented dehydration zones from South Africa, southern India, and Sri Lanka. The calculations have revealed two end-member regimes of alkalis during specific metamorphic processes: rock buffered, which is characteristic for the precursor rocks containing two feldspars, and fluid-buffered for the precursor rocks without K-feldspar. The observed reaction textures and the results of thermodynamic modeling are compared with the results of available experimental studies on the interaction of the alkali chloride and carbonate-bearing fluids with metamorphic rocks at mid-crustal conditions. The experiments show the complex effect of alkali activities in the fluid phase on the mineral assemblages. Both thermodynamic calculations and experiments closely reproduce paragenetic relations theoretically predicted by D.S. Korzhinskii in the 1940s. 相似文献
68.
69.
L. V. Zamana A. B. Ptitsyn G. Chu S. A. Reshetova A. V. Dar’in I. A. Kalugin 《Doklady Earth Sciences》2011,437(1):335-339
On the basis of bottom sediment core dating performed by the technogenic isotope 137Cs, the rate of sedimentation in periodically drying Zun-Torei Lake (water area is up to 300 km2) is estimated at 2.88 mm per year over the last 59 years. This value is in agreement with the data of palinological determinations
(3.44 mm per year). High sedimentation rates are attributed to intensive evaporite sedimentation and probable eolian addition
of terrigenous material. 相似文献
70.
Jan Paav Ilja Knésl Anna Vymazalová Ivan Vavín Ludmila Ivanovna Gurskay Leonid Ruslanovich Kolbantsev 《地学前缘(英文版)》2011,2(1):81-85
The Polar Urals region of northern Russia is well known for large chromium (Cr)-bearing massifs with major chromite orebodies, including the Centralnoye I deposit in the Ray-Iz ultramafic massif of the Ural ophiolite belt. New data on platinum (Pt)-group elements (PGE), geochemistry and mineralogy of the host dunite shows that the deposit has anomalous iridium (Ir) values. These values indicate the predominance of ruthenium–osmium–iridium (Ru–Os–Ir)-bearing phases among the platinum-group mineral (PGM) assemblage that is typical of mantle-hosted chromite ores. Low Pt values in chromites and increased Pt values in host dunites might reflect the presence of cumulus PGM grains. The most abundant PGM found in the chromite is erlichmanite (up to 15 μm). Less common are cuproiridsite (up to 5 μm), irarsite (up to 4–5 μm), and laurite (up to 4 μm). The predominant sulfide is heazlewoodite, in intergrowth with Ni–Fe alloys, sporadically with pentlandite, and rarely with pure nickel. Based on the average PGE values and estimated Cr-ore resources, the Centralnoye I deposit can be considered as an important resource of PGE. 相似文献