全文获取类型
收费全文 | 113篇 |
免费 | 3篇 |
国内免费 | 12篇 |
专业分类
测绘学 | 3篇 |
大气科学 | 2篇 |
地球物理 | 9篇 |
地质学 | 63篇 |
海洋学 | 7篇 |
天文学 | 35篇 |
综合类 | 4篇 |
自然地理 | 5篇 |
出版年
2023年 | 3篇 |
2020年 | 1篇 |
2019年 | 6篇 |
2018年 | 5篇 |
2017年 | 5篇 |
2016年 | 4篇 |
2015年 | 3篇 |
2014年 | 10篇 |
2013年 | 3篇 |
2012年 | 6篇 |
2011年 | 7篇 |
2010年 | 5篇 |
2009年 | 8篇 |
2008年 | 9篇 |
2007年 | 9篇 |
2006年 | 7篇 |
2005年 | 1篇 |
2004年 | 7篇 |
2003年 | 6篇 |
2002年 | 5篇 |
2001年 | 1篇 |
2000年 | 3篇 |
1999年 | 1篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1995年 | 2篇 |
1993年 | 1篇 |
1991年 | 4篇 |
1990年 | 1篇 |
1981年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有128条查询结果,搜索用时 24 毫秒
31.
Innokenty Kantor Leonid Dubrovinsky Catherine McCammon Anastasia Kantor Sakura Pascarelli Giuliana Aquilanti Wilson Crichton Maurizio Mattesini Rajeev Ahuja Jailton Almeida Vadim Urusov 《Physics and Chemistry of Minerals》2006,33(1):35-44
Combined X-ray powder diffraction, Mössbauer, and XANES spectroscopy in situ experiments revealed the transformation of cubic (Mg0.8Fe0.2)O ferropericlase to a rhombohedrally distorted phase at 35(1) GPa and room temperature. The Mössbauer spectroscopy results show that the rhombohedral distortion does not involve magnetic ordering. Combined with data from the literature, our results imply that the cubic to rhombodedral transition occurs in (Mg,Fe)O under conditions of non-hydrostatic stress over a wide range of composition (0.2≤x Fe≤1). 相似文献
32.
Immiscible silicate liquid partition coefficients: implications for crystal-melt element partitioning and basalt petrogenesis 总被引:2,自引:1,他引:2
Ilya V. Veksler Alexander M. Dorfman Leonid V. Danyushevsky Jakob K. Jakobsen Donald B. Dingwell 《Contributions to Mineralogy and Petrology》2006,152(6):685-702
This study investigates partitioning of elements between immiscible aluminosilicate and borosilicate liquids using three synthetic mixtures doped with 32 trace elements. In order to get a good spatial separation of immiscible liquids, we employed a high-temperature centrifuge. Experiments were performed at 1,050–1,150°C, 1 atm, in sealed Fe and Pt containers. Quenched products were analysed by electron microprobe and LA ICP-MS. Nernst partition coefficients (D’s) between the Fe-rich and Si-rich aluminosilicate immiscible liquids are the highest for Zn (3.3) and Fe (2.6) and the lowest for Rb and K (0.4–0.5). The plots of D values against ionic potential Z/r in all the compositions show a convex upward trend, which is typical also for element partitioning between immiscible silicate and salt melts. The results bear upon the speciation and structural position of elements in multicomponent silicate liquids. The ferrobasalt–rhyolite liquid immiscibility is observed in evolved basaltic magmas, and may play an important role in large gabbroic intrusions, such as Skaergaard, and during the generation of unusual lavas, such as ferropicrites. 相似文献
33.
34.
岩浆镍-铜-铂族元素(PGE)硫化物矿床是峨眉火成岩省地幔柱活动形成的两个重要的成矿系列之一[1~3].目前已发现的与峨眉火成岩省相关的40余个镍-铜-铂族元素硫化物矿床(或矿点)中,多数分布在内带[3,4].它们可分为:1)富Ni、Cu而贫PGE的Ni-Cu型(如力马河和清水河);2)富Ni,Cu且PGE中等的Ni-Cu-PGE型(如清矿山和黄草坪);3)贫Ni、Cu富PGE的PGE型(如金宝山和杨合武). 相似文献
35.
Tetsuya Komabayashi Kei Hirose Nagayoshi Sata Yasuo Ohishi Leonid S. Dubrovinsky 《Earth and Planetary Science Letters》2007,260(3-4):564-569
A phase transition in pure CaSiO3 perovskite was investigated at 27 to 72 GPa and 300 to 819 K by in-situ X-ray diffraction experiments in an externally-heated diamond-anvil cell. The results show that CaSiO3 perovskite takes a tetragonal form at 300 K and undergoes phase transition to a cubic structure above 490–580 K in a pressure range studied here. The transition boundary is strongly temperature-dependent with a slightly positive dT / dP slope of 1.1 (± 1.3) K/GPa. It is known that the transition temperature depends on Al2O3 content dissolved in CaSiO3 perovskite [Kurashina et al., Phys. Earth Planet. Inter. 145 (2004) 67–74]. The phase transition in CaSiO3(+ 3 wt.% Al2O3) perovskite therefore could occur in a cold subducted mid-oceanic ridge basalt (MORB) crust at about 1200 K in the upper- to mid-lower mantle. This phase transition is possibly ferroelastic-type and may cause large seismic anomalies in a wide depth range. 相似文献
36.
Stratigraphic constraints on late Pleistocene glacial erosion and deglaciation of the Chukchi margin, Arctic Ocean 总被引:2,自引:0,他引:2
At least two episodes of glacial erosion of the Chukchi margin at water depths to ∼ 450 m and 750 m have been indicated by geophysical seafloor data. We examine sediment stratigraphy in these areas to verify the inferred erosion and to understand its nature and timing. Our data within the eroded areas show the presence of glaciogenic diamictons composed mostly of reworked local bedrock. The diamictons are estimated to form during the last glacial maximum (LGM) and an earlier glacial event, possibly between OIS 4 to 5d. Both erosional events were presumably caused by the grounding of ice shelves originating from the Laurentide ice sheet. Broader glaciological settings differed between these events as indicated by different orientations of flutes on eroded seafloor. Postglacial sedimentation evolved from iceberg-dominated environments to those controlled by sea-ice rafting and marine processes in the Holocene. A prominent minimum in planktonic foraminiferal δ18O is identified in deglacial sediments at an estimated age near 13,000 cal yr BP. This δ18O minimum, also reported elsewhere in the Amerasia Basin, is probably related to a major Laurentide meltwater pulse at the Younger Dryas onset. The Bering Strait opening is also marked in the composition of late deglacial Chukchi sediments. 相似文献
37.
On stochastic stability of regional ocean models to finite-amplitude perturbations of initial conditions 总被引:1,自引:0,他引:1
We consider error propagation near an unstable equilibrium state (classified as an unstable focus) for spatially uncorrelated and correlated finite-amplitude initial perturbations using short- (up to several weeks) and intermediate (up to 2 months) range forecast ensembles produced by a barotropic regional ocean model. An ensemble of initial perturbations is generated by the Latin Hypercube design strategy, and its optimal size is estimated through the Kullback–Liebler distance (the relative entropy). Although the ocean model is simple, the prediction error (PE) demonstrates non-trivial behavior similar to that existing in 3D ocean circulation models. In particular, in the limit of zero horizontal viscosity, the PE at first decays with time for all scales due to dissipation caused by non-linear bottom friction, and then grows faster than (quasi)-exponentially. Statistics of a prediction time scale (the irreversible predictability time (IPT)) quickly depart from Gaussian (the linear predictability regime) and becomes Weibullian (the non-linear predictability regime) as amplitude of initial perturbations grows. A transition from linear to non-linear predictability is clearly detected by the specific behavior of IPT variance. A new analytical formula for the model predictability horizon is introduced and applied to estimate the limit of predictability for the ocean model. 相似文献
38.
Vsevolod M. Gavshin Leonid V. Miroshnichenko 《Geostandards and Geoanalytical Research》2000,24(2):241-246
West Siberian brown coals from the Kansk-Achinsk basin and their combustion products are generally characterized by a low uranium content. In some places where brown coal has been altered (losing density, becoming cracked or friable), the uranium content has increased by concentrations ranging from 1001000 μg g−1 . At these locations distinct signs of underground fires are visible. The uranium distribution patterns suggest that the burnt organic matter was a source of uranium and altered varieties of coal serve as a geochemical barrier to uranium transport. 相似文献
39.
Leonid M. Baskin 《Polar research》2000,19(1):23-29
The dynamic state of reindeer husbandry in northern Russia during the 20th century was studied as a basis for predicting the consequences of the current drastic changes taking place there. Similar forms and methods of reindeer husbandry were used with different frequencies and effectiveness throughout the century. In the future reindeer husbandry will conform to market requirements, landscape features and national traditions. In some areas, the more sophisticated methods of management developed in conjunction with large-scale, highly productive reindeer husbanry, could be lost and a subsistence economy, including hunting, could predominate. 相似文献
40.
Varghese Swamy Leonid S. Dubrovinsky Masanori Matsui 《Physics and Chemistry of Minerals》1997,24(6):440-446
We investigated the lattice vibrational properties and lattice dynamical behaviour of diopside by combining laser micro-Raman spectroscopic measurements with quasi-harmonic lattice dynamic simulation using a transferable interatomic potential. We obtained polarized Raman spectra from a Fe-poor natural diopside and the temperature dependencies of the Raman modes to 1125?K from high-temperature Raman spectra of a Fe-poor and a Fe-rich natural diopside. The various modes display different temperature dependencies: from ?0.021?cm?1/K to ?0.004?cm?1/K. The temperature shift of low frequency modes is generally higher. A comparison of experimentally determined frequencies and symmetries of vibrational modes of the optical type (Raman and infrared) obtained in this and earlier studies with those calculated by us suggests that a consistent characterization of the vibrational properties was achieved. The good agreement between the experimental and simulated data on the temperature-dpendencies of the Raman modes (within 5%), crystal structure (2%), bulk modulus (5%), volume thermal expansivity (6%), and constant volume heat capacity (0.2%) testifies to the applicability of the transferable interatomic potential and the lattice dynamic model to predicting the vibrational, physical, and thermodynamic properties. The simulated properties from the lattice dynamic calculations are very similar to those obtained by molecular dynamic calculations with the same potential model. 相似文献