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41.
Lucia Pappalardo Luisa Ottolini Giuseppe Mastrolorenzo 《Contributions to Mineralogy and Petrology》2008,156(1):1-26
More than ca 100 km3 of nearly homogeneous crystal-poor phonolite and ca 100 km3 of slightly zoned trachyte were erupted 39 ka during the Campanian Ignimbrite super eruption, the most powerful in the Neapolitan
area. Partition coefficient calculations, equilibrium mineral assemblages, glass compositions and texture were used to reconstruct
compositional, thermal and pressure gradients in the pre-eruptive reservoir as well as timing and mechanisms of evolution
towards magma chamber overpressure and eruption. Our petrologic data indicate that a wide sill-like trachytic magma chamber
was active under the Campanian Plain at 2.5 kbar before CI eruption. Thermal exchange between high liquidus (1199°C) trachytic
sill and cool country rocks caused intense undercooling, driving a catastrophic and fast (102 years) in situ fractional crystallization and crustal assimilation that produced a water oversaturated phonolitic cap and
an overpressure in the chamber that triggered the super eruption. This process culminated in an abrupt reservoir opening and
in a fast single-step high decompression. Sanidine phenocrysts crystal size distributions reveal high differentiation rate,
thus suggesting that such a sill-like magmatic system is capable of evolving in a very short time and erupting suddenly with
only short-term warning. 相似文献
42.
Fernando Scordari Emanuela Schingaro Gennaro Ventruti Maria Lacalamita Luisa Ottolini 《Physics and Chemistry of Minerals》2008,35(3):163-174
The crystal chemistry of red phlogopites from Mt. Vulture (Italy) ignimbrites has been studied by electron microprobe, secondary
ion mass spectrometry (SIMS), single crystal structural investigation and Fourier transform infrared (FTIR) spectroscopy.
The analysed phlogopite has Fe/(Fe + Mg) ∼ 0.35, TiO2 (wt%): 2.8–5.0 and H2O (wt%): 1.24–3.37. Infrared spectra revealed the presence of bands due to the NH4+ and H2O stretching and bending vibrations. The samples belong to the 1M polytype. The bimodal behaviour of several structural parameters allows red micas to be clustered into two distinct groups:
K+ ↔ NH4+, H2O and M3+-vacancy substitutions dominate in the first group; M3+,4+-oxy, in the second group. It has to be pointed out that quantitative analysis of hydrogen (via SIMS) together with the characterization
of the local environment of the anionic site (via FTIR) are fundamental in assessing the correct structural formula and the
substitution mechanisms in micas.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
43.
M. C. Lima e Cunha V. P. Pereira E. Menegotto A. C. Bastos Neto L. D. Oliveira M. L. L. Formoso 《Environmental Geology》2008,55(6):1355-1362
The vegetal species Ampelozizyphus amazonicus Ducke (Rhamnaceae Family) was chosen as a sampling medium for the lateritic surfaces of the Pitinga Mine in the Amazon region,
in order to study the biogeochemical behavior of this species and compare it with the chemical composition of a reference
plant. The Pitinga mining district is one of the largest producers of tin in the world. This district contains unique deposits
of cryolite and rare metals such as Zr, Nb, Ta, Y and REEs related to granitic bodies that intrude into the volcanic and acid
pyroclastic rocks. The results showed that the species A. amazonicus predominantly concentrates significant levels of Zr, Nb, Ta, Th, Be, Sc over U, Hf, Ga and In. These elements are characteristic
of the mineral paragenesis for the region, suggesting that this plant can provide a representative sampling medium future
geochemical exploration programs in the region. 相似文献
44.
Fast error analysis of continuous GPS observations 总被引:4,自引:1,他引:3
It has been generally accepted that the noise in continuous GPS observations can be well described by a power-law plus white
noise model. Using maximum likelihood estimation (MLE) the numerical values of the noise model can be estimated. Current methods
require calculating the data covariance matrix and inverting it, which is a significant computational burden. Analysing 10 years
of daily GPS solutions of a single station can take around 2 h on a regular computer such as a PC with an AMD AthlonTM 64 X2 dual core processor. When one analyses large networks with hundreds of stations or when one analyses hourly instead
of daily solutions, the long computation times becomes a problem. In case the signal only contains power-law noise, the MLE
computations can be simplified to a process where N is the number of observations. For the general case of power-law plus white noise, we present a modification of the MLE equations
that allows us to reduce the number of computations within the algorithm from a cubic to a quadratic function of the number
of observations when there are no data gaps. For time-series of three and eight years, this means in practise a reduction
factor of around 35 and 84 in computation time without loss of accuracy. In addition, this modification removes the implicit
assumption that there is no environment noise before the first observation. Finally, we present an analytical expression for
the uncertainty of the estimated trend if the data only contains power-law noise.
Electronic supplementary material The online version of this article (doi: ) contains supplementary material, which is available to authorized users. 相似文献
45.
Claudio Bastos Pereira 《Astrophysics and Space Science》1996,240(1):1-11
EG And is a S-type symbiotic star. Presented are UV observations made by IUE from 1978 to 1991. From these observations the electron density and the electron temperature were obtained. The size of the Heii emitting region was estimated as 7.3R. Line and continuum variations confirm the binary nature of EG And. 相似文献
46.
47.
María Luisa Crawford 《Contributions to Mineralogy and Petrology》1966,13(3):269-294
Two suites of regionally metamorphosed semi-pelitic schists were studied in order to investigate the paragenesis of low temperature plagioclase, from which something may be inferred as to the nature of the peristerite solvus at the temperatures and pressures of formation of these rocks: one from the Gile Mountain Formation in the Hanover and Mt. Cube quadrangles, eastern Vermont, U.S.A.; the other from the Alpine schists along the Haast River, South Westland, New Zealand. Plagioclase, muscovite, biotite, chlorite, carbonate, and garnet compositions were determined with an ARL EMX electron probe microanalyzer. The variation in plagioclase composition with increasing grade in the Vermont schists suggests that the peristerite solvus is asymmetrical with a near vertical albite-rich side and a sloping oligoclase-rich side. The top of the solvus appears to lie slightly above the temperature expressed by the almandine isograd in these schists. The compositions of the coexisting albite and oligoclase in the New Zealand rocks suggest a lower geothermal gradient than in Vermont, creating a different pattern of variation in plagioclase composition. Distribution diagrams of Mg, Ti, and AlIV for muscovite-biotite and chlorite-biotite pairs in both suites of rocks support the hypothesis that the plagioclase relations observed represent equilibrium. 相似文献
48.
Oliveira MM Silva Filho MV Cunha Bastos VL Fernandes FC Cunha Bastos J 《Marine environmental research》2007,63(4):303-312
Brain acetylcholinesterase (AChE) of some fishes from the coast of Rio de Janeiro State was studied as a possible pesticide biomarker in marine environmental monitoring. AChE specific activity in brain varied from 145 to 530 U/g of proteins and the Michaelis-Menten constant (K(M)) for acetylthiocholine varied from 104 to 291 microM among the 20 species studied. The enzyme sensitivity to methyl paraoxon, evaluated by the inhibition kinetic constants, shows that some species (Paralonchurus brasiliensis and Genidens genidens) are more sensitive (IC50-30 min=455 and 468 nM, respectively). The less sensitive Merluccius hubbsi and Percophis brasiliensis (IC50-30 min=3339 and 3259 nM, respectively) belong to the super-order Paracanthopterygii, which includes the more ancient species. On the other hand, more susceptible species belong to the super-order Acanthopterygii, which includes more recent species. These results suggest a possible evolutionary linkage for AChE sensitivity to methyl paraoxon. The application of inhibition kinetic constants for fish brain AChE in phylogenetic studies is still being investigated. The results have shown that a fish sentinel species should have the highest brain AChE level among the more sensitive ones. 相似文献
49.
Rivalenti Giorgio Mazzucchelli Maurizio Vannucci Riccardo Hofmann Albrecht W. Ottolini Luisa Bottazzi Piero Obermiller Walter 《Contributions to Mineralogy and Petrology》1995,122(3):275-288
Field, mineralogical and petrological data are presented on a newly found carbonatite occurrence associated with “kamafugite”
lava at Cupaello, central Italy. This carbonatite occurrence is part of the Late Pleistocene Umbria-Latium ultra-alkaline
district (ULUD) which extends southwards within the Apennines to Mount Vulture, delineating an important magmatic province
along the most peripheral belt of the Tyrrhenian extensional tectonic system. This province is distinct, but probably related
genetically with the more abundant and common leucite-bearing assemblages of the Roman Comagmatic Region and represents the
first reported occurrence of carbonatite assemblages in the Mediterranean Basin. The Cupaello suite indicates that primary
or near-primary mantle silicate melts of “kamafugitic” composition are transitional with Ca-carbonatite liquid and provides
direct evidence of immiscibility of carbonatite from “kamafugite” magma. It is inferred that a primary mantle origin of Ca-carbonatites
is conditional upon a potential silicate magma that may be coupled with the carbonatite, but may not have reached the surface.
The data indicate a strong genetic link between ULUD Ca-carbonatites and some African analogues, supporting the view that
their genesis depends on similar source and associated tectonic conditions.
Received: 17 January 1995 / Accepted: 14 June 1995 相似文献
50.
The effect of halogens on Zr diffusion and zircon dissolution in hydrous metaluminous granitic melts 总被引:1,自引:0,他引:1
Don R. Baker Aida Conte Carmela Freda Luisa Ottolini 《Contributions to Mineralogy and Petrology》2002,142(6):666-678
Diffusion of Zr and zircon solubility in hydrous, containing approximately 4.5 wt% H2O, metaluminous granitic melts with halogens, either 0.35 wt% Cl (LCl) or 1.2 wt% F (MRF), and in a halogen-free melt (LCO) were measured at 1.0 GPa and temperatures between 1,050 and 1,400 °C in a piston-cylinder apparatus using the zircon dissolution technique. Arrhenius equations for Zr diffusion in each hydrous melt composition are, for LCO with 4.4ǂ.4 wt% H2O: % MathType!MTEF!2!1!+- % feaaeaart1ev0aaatCvAUfKttLearuavP1wzZbItLDhis9wBH5garm % Wu51MyVXgaruWqVvNCPvMCG4uz3bqee0evGueE0jxyaibaieYlf9ir % Veeu0dXdh9vqqj-hEeeu0xXdbba9ev6pc9fs0-rqaqpepmKs4qpepe % I8kaL8kuc9pgc9q8qqaq-dhH6hb9hs0dXdHu6deP0u0-vr0-vr0db8 % meaabaqaciGacaGaaeaabaWaaeaaeaaakeaacqWGebarcqGH9aqpcq % aIYaGmcqGGUaGlcqaI4aaocqaI4aaocqGHXcqScqaIWaamcqGGUaGl % cqaIWaamcqaIZaWmcqWG4baEcqaIXaqmcqaIWaamdaahaaWcbeqaai % abgkHiTiabiIda4aaakiGbcwgaLjabcIha4jabcchaWnaabmaabaWa % aSaaaeaacqGHsislcqaIXaqmcqaI0aancqaIWaamcqGGUaGlcqaIXa % qmcqGHXcqScqaIZaWmcqaIZaWmcqGGUaGlcqaI5aqoaeaacqWGsbGu % cqWGubavaaaacaGLOaGaayzkaaaaaa!571F! D = 2.88 ±0.03x10 - 8 exp( [( - 140.1 ±33.9)/(RT)] )D = 2.88 \pm 0.03x10^{ - 8} \exp \left( {{{ - 140.1 \pm 33.9} \over {RT}}} \right) , for LCl with 4.5ǂ.5 wt% H2O: % MathType!MTEF!2!1!+- % feaaeaart1ev0aaatCvAUfKttLearuavP1wzZbItLDhis9wBH5garm % Wu51MyVXgaruWqVvNCPvMCG4uz3bqee0evGueE0jxyaibaieYlf9ir % Veeu0dXdh9vqqj-hEeeu0xXdbba9ev6pc9fs0-rqaqpepmKs4qpepe % I8kaL8kuc9pgc9q8qqaq-dhH6hb9hs0dXdHu6deP0u0-vr0-vr0db8 % meaabaqaciGacaGaaeaabaWaaeaaeaaakeaacqWGebarcqGH9aqpcq % aIYaGmcqGGUaGlcqaIZaWmcqaIZaWmcqGHXcqScqaIWaamcqGGUaGl % cqaIWaamcqaI1aqncqWG4baEcqaIXaqmcqaIWaamdaahaaWcbeqaai % abgkHiTiabisda0aaakiGbcwgaLjabcIha4jabcchaWnaabmaabaWa % aSaaaeaacqGHsislcqaIYaGmcqaI1aqncqaI0aancqGGUaGlcqaI4a % aocqGHXcqScqaI2aGncqaI0aancqGGUaGlcqaIXaqmaeaacqWGsbGu % cqWGubavaaaacaGLOaGaayzkaaaaaa!5719! D = 2.33 ±0.05x10 - 4 exp( [( - 254.8 ±64.1)/(RT)] )D = 2.33 \pm 0.05x10^{ - 4} \exp \left( {{{ - 254.8 \pm 64.1} \over {RT}}} \right) and for MRF with 4.9ǂ.3 wt% H2O: % MathType!MTEF!2!1!+- % feaaeaart1ev0aaatCvAUfKttLearuavP1wzZbItLDhis9wBH5garm % Wu51MyVXgaruWqVvNCPvMCG4uz3bqee0evGueE0jxyaibaieYlf9ir % Veeu0dXdh9vqqj-hEeeu0xXdbba9ev6pc9fs0-rqaqpepmKs4qpepe % I8kaL8kuc9pgc9q8qqaq-dhH6hb9hs0dXdHu6deP0u0-vr0-vr0db8 % meaabaqaciGacaGaaeaabaWaaeaaeaaakeaacqWGebarcqGH9aqpcq % aIYaGmcqGGUaGlcqaI1aqncqaI0aancqGHXcqScqaIWaamcqGGUaGl % cqaIWaamcqaIZaWmcqWG4baEcqaIXaqmcqaIWaamdaahaaWcbeqaai % abgkHiTiabiwda1aaakiGbcwgaLjabcIha4jabcchaWnaabmaabaWa % aSaaaeaacqGHsislcqaIYaGmcqaIYaGmcqaIZaWmcqGGUaGlcqaI4a % aocqGHXcqScqaIXaqmcqaI1aqncqGGUaGlcqaI1aqnaeaacqWGsbGu % cqWGubavaaaacaGLOaGaayzkaaaaaa!5715! D = 2.54 ±0.03x10 - 5 exp( [( - 223.8 ±15.5)/(RT)] )D = 2.54 \pm 0.03x10^{ - 5} \exp \left( {{{ - 223.8 \pm 15.5} \over {RT}}} \right) . Solubilities determined by the dissolution technique were reversed for LCO +4.5ǂ.5 wt% H2O by crystallization of a Zr-enriched glass of LCO composition at 1,200 and 1,050 °C at 1.0 GPa. The solubility data were used to calculate partition coefficients of Zr between zircon and hydrous melt, which are given by the following expressions: for LCO % MathType!MTEF!2!1!+- % feaaeaart1ev0aaatCvAUfKttLearuavP1wzZbItLDhis9wBH5garm % Wu51MyVXgaruWqVvNCPvMCG4uz3bqee0evGueE0jxyaibaieYlf9ir % Veeu0dXdh9vqqj-hEeeu0xXdbba9ev6pc9fs0-rqaqpepmKs4qpepe % I8kaL8kuc9pgc9q8qqaq-dhH6hb9hs0dXdHu6deP0u0-vr0-vr0db8 % meaabaqaciGacaGaaeaabaWaaeaaeaaakeaacyGGSbaBcqGGUbGBcq % WGebardaqhaaWcbaGaemOwaOLaemOCaihabaGaemOEaONaemyAaKMa % emOCaiNaem4yamMaem4Ba8MaemOBa4Maei4la8IaemyBa0Maemyzau % MaemiBaWMaemiDaqhaaOGaeyypa0JaeGymaeJaeiOla4IaeGOnayJa % eG4mamZaaeWaaeaadaWcaaqaaiabigdaXiabicdaWiabicdaWiabic % daWiabicdaWaqaaiabdsfaubaaaiaawIcacaGLPaaacqGHsislcqaI % 1aqncqGGUaGlcqaI4aaocqaI3aWnaaa!5924! lnDZrzircon/melt = 1.63( [10000/(T)] ) - 5.87\ln D_{Zr}^{zircon/melt} = 1.63\left( {{{10000} \over T}} \right) - 5.87 , for LCl % MathType!MTEF!2!1!+- % feaaeaart1ev0aaatCvAUfKttLearuavP1wzZbItLDhis9wBH5garm % Wu51MyVXgaruWqVvNCPvMCG4uz3bqee0evGueE0jxyaibaieYlf9ir % Veeu0dXdh9vqqj-hEeeu0xXdbba9ev6pc9fs0-rqaqpepmKs4qpepe % I8kaL8kuc9pgc9q8qqaq-dhH6hb9hs0dXdHu6deP0u0-vr0-vr0db8 % meaabaqaciGacaGaaeaabaWaaeaaeaaakeaacyGGSbaBcqGGUbGBcq % WGebardaqhaaWcbaGaemOwaOLaemOCaihabaGaemOEaONaemyAaKMa % emOCaiNaem4yamMaem4Ba8MaemOBa4Maei4la8IaemyBa0Maemyzau % MaemiBaWMaemiDaqhaaOGaeyypa0JaeGymaeJaeiOla4IaeGinaqJa % eG4naCZaaeWaaeaadaWcaaqaaiabigdaXiabicdaWiabicdaWiabic % daWiabicdaWaqaaiabdsfaubaaaiaawIcacaGLPaaacqGHsislcqaI % 0aancqGGUaGlcqaI3aWncqaI1aqnaaa!5920! lnDZrzircon/melt = 1.47( [10000/(T)] ) - 4.75\ln D_{Zr}^{zircon/melt} = 1.47\left( {{{10000} \over T}} \right) - 4.75 and, for MRF by % MathType!MTEF!2!1!+- % feaaeaart1ev0aaatCvAUfKttLearuavP1wzZbItLDhis9wBH5garm % Wu51MyVXgaruWqVvNCPvMCG4uz3bqee0evGueE0jxyaibaieYlf9ir % Veeu0dXdh9vqqj-hEeeu0xXdbba9ev6pc9fs0-rqaqpepmKs4qpepe % I8kaL8kuc9pgc9q8qqaq-dhH6hb9hs0dXdHu6deP0u0-vr0-vr0db8 % meaabaqaciGacaGaaeaabaWaaeaaeaaakeaacyGGSbaBcqGGUbGBcq % WGebardaqhaaWcbaGaemOwaOLaemOCaihabaGaemOEaONaemyAaKMa % emOCaiNaem4yamMaem4Ba8MaemOBa4Maei4la8IaemyBa0Maemyzau % MaemiBaWMaemiDaqhaaOGaeyypa0JaeGymaeJaeiOla4IaeGinaqJa % eG4naCZaaeWaaeaadaWcaaqaaiabigdaXiabicdaWiabicdaWiabic % daWiabicdaWaqaaiabdsfaubaaaiaawIcacaGLPaaacqGHsislcqaI % 0aancqGGUaGlcqaI5aqocqaIXaqmaaa!591C! lnDZrzircon/melt = 1.47( [10000/(T)] ) - 4.91\ln D_{Zr}^{zircon/melt} = 1.47\left( {{{10000} \over T}} \right) - 4.91 . Experiments on the same compositions, but with water contents down to 0.5 wt%, demonstrated reductions in both the diffusion coefficient of Zr and zircon solubility in the melt. The addition of halogens at the concentration levels studied to metaluminous melts has a small effect on either the diffusion of Zr in the melt, or the solubility of zircon at all water concentrations and temperatures investigated. At 800 °C, the calculated diffusion coefficient of Zr is lowest in LCl, 9᎒-17 m2 s-1, and is highest in LCO, 4᎒-15 m2 s-1. Extrapolation of the halogen-free solubility data to a magmatic temperature of 800 °C yields solubilities of approximately one-third of those directly measured in similar compositions, predicted by earlier studies of zircon dissolution and based upon analyses of natural rocks. This discrepancy is attributed to the higher oxygen fugacity of the experiments of this study compared with previous studies and nature, and the effect of oxygen fugacity on the structural role of iron in the melt, which, in turn, affects zircon solubility, but does not significantly affect Zr diffusion. 相似文献