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61.
62.
We have analyzed the July 15,2009,Fiordland earthquake(M_w 7.8),which occurred in the southwestern part of the South Island of New Zealand.This thrust-related earthquake in the southern Fiordland subduction zone is the largest New Zealand earthquake in the past 80 years.We have constrained a rupture model for this earthquake using coseismic offsets derived from the continuous geodetic network(Global Positioning System) of the New Zealand Institute of Geological and Nuclear Sciences (GNS Science).Our anal... 相似文献
63.
Bhaskar Kundu 《地学前缘(英文版)》2011,2(4):539-549
Higher Himalayan Crystalline (HHC) complex of the Sikkim Himalaya predominantly
consists of high-grade pelitic migmatites. In this study, reaction textures, mineral/bulk rare earth elements
(REE), trace element partition coefficients and trace element zoning profiles in garnet are used to demonstrate
a complex petrogenetic process during crustal anatexis. With the help of equilibrium REE and trace
element partitioning model, it is shown that strong enrichment of Effective Bulk Composition (EBC) is
responsible for the zoning in garnet in these rocks. The data strongly support disequilibrium element partitioning
and suggest that the anatectic melts associated with mafic selvedges are likely produced by
disequilibrium melting because of fast melt segregation process. 相似文献
64.
N. Udaya Shankar K. Golap S. Sachdev R. Dodson M. Katwaroo Ch.V. Sastry 《Astrophysics and Space Science》2002,282(1):15-28
The Mauritius Radio Telescope (MRT) has been built with the main objective of surveying the southern sky at meter wavelengths.
MRT is a Fourier synthesis, T-shaped non-coplanar array. It consists of a2048 m long East-West arm with 1024 fixed helices
and a 880 m long South arm with 15 trolleys. Each trolley has four helices. A 512 channel, 2-bit 3-level complex correlation
receiver is used to process the data from the EW and S group outputs. At least 60 days of observing are required for obtaining
the Fourier components of the brightness distribution of the sky required to complete the survey. The MRT survey will be one
of the most extensive survey at low frequencies providing a moderately deep radio catalog reaching a source density of about
2 × 104 sr-1 over most of the sky south of δ=-10°with an angular resolution of 4' × 4.6' sec (δ) and a limiting flux density of 200 mJy (3 σ level) at 151 MHz. This paper
will describe the telescope, the observations carried out so far, challenges of imaging with the data acquired over a period
exceeding four years with a non-coplanar array, and summarises the results obtained so far.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
65.
Necking, tearing, slab detachment and subsequently slab loss complicate the subduction zone processes and slab architecture.
Based on evidences which include patterns of seismicity, seismic tomography and geochemistry of arc volcanoes, we have identified
a horizontal slab tear in the subducted Indo-Australian slab beneath the Sunda arc. It strongly reflects on trench migration,
and causes along-strike variations in vertical motion and geochemically distinct subduction-related arc magmatism. We also
propose a model for the geodynamic evolution of slab detachment. 相似文献
66.
67.
Bhaskar J. Choudhury 《Surveys in Geophysics》1991,12(1-3):63-84
Physical principles governing passive microwave remote sensing of hydrological variables are outlined and illustrated by actual observations by ground-based, air-borne and space-borne microwave radiometers operating at different frequencies. Specific hydrological variables addressed in this paper are soil moisture, seasonal inundation of rivers and swamps, vegetation, snow, and rainfall. Passive remote sensing provides measurements of electromagnetic radiation emitted by the land-atmosphere system, which can be related more directly to the radiative characteristics of the system than to physical or physiological characteristics. Estimation of hydrological variables from microwave observations necessarily involves models relating the radiative to the physical characteristics, and in general more than one physical characteristics determine the microwave observations. This non-uniqueness in the relationship between microwave observations to a particular hydrological variable leads to uncertainties in the estimation of the variable. Notwithstanding this limitation, the principles and the examples given in this paper illustrate the value of passive microwave observations to regional and global hydrology at a temporal resolution of days aggregated to a decade. 相似文献
68.
Electro-flotation tests were conducted on chalcopyrite particles with a modified Hallimond tube designed for electro-flotation, using platinum anode—copper cathode and graphite anode—copper cathode systems. Flotation tests were carried out for fines of chalcopyrite of size below 20 microns with potassium ethylxanthate as collector. Studies were done on flotation with hydrogen and oxygen separately with the usual variables. Dissolution of chalcopyrite at various current densities, with reagent at optimum conditions and without reagent was also studied. It is observed that electro-flotation particularly with oxygen, is effective in the flotation of fine particles of chalcopyrite. 相似文献
69.
Summary Assuming a zero regional, Parasnis presented a linear relationship between the relative gravity and the average surface rock density. If a certain amount of regional variation in the relative gravity exists this method cannot be relied upon. In the present article an extension of Parasnis' method is suggested for the case when linear regional exists. A field example from the Godavari Valley is described. 相似文献
70.
R Srinivasan K Naha Y J Bhaskar Rao A B Vrevsky S I Rybakov A I Golubev M Efimov 《Journal of Earth System Science》1993,102(4):567-585
The middle to late Archaean rocks of Kola and Karelia in the eastern Baltic shield consist of the Infracomplex overlain by the Saamian complex, and the Lopian greenstone belts. The Infracomplex which forms the basement is a polymigmatite, parts of which are at least 3100 Ma old. The Saamian in the central Belomorian region comprises granite gneiss, amphibolite, garnet-kyanite gneiss and high alumina gneisses which belong to the Keret, Hetolombina and Chupa suites. The Lopian greenstone belts ranging in age from 3000 to 2700 Ma are composed of peridotitic, pyroxenitic and basaltic komatiites, tholeiitic basalts, andesites, dacites and rhyolites, together with tuffs, graywackes and iron formations. Whereas there is a dominance of volcanic over sedimentary rocks in the greenstone belts of the Baltic shield, a significant proportion of detrital and chemogenic sedimentary rocks characterizes the Dharwar succession of approximately the same time span in the southern Indian shield. Association of mature and immature detrital sedimentary rocks with bimodal volcanic assemblages points to a back-arc setting for the Dharwar belts. This contrasts with the association of immature sediments with calc-alkaline volcanic rocks in the greenstone belts of the eastern Baltic shield, suggesting an island arc environment there. 相似文献