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71.
Trace-element contents in leucite and its alteration mineral phases from the Quaternary potassic rocks of the Roccamonfina volcano have been determined. The dominant weathering phase of leucite is analcite. In the early stages of the conversion process, it concentrates mainly Rb and Sr with minor amounts of Ba, Ni, V, Zn, La, Ce and Zr. At more advanced stages of the conversion process, only Rb and Y persist, while all other elements (except Cu and Cr that are essentially immobile) are lost, particularly Zn and to a lesser extent La, Ce and Nd. Besides analcite, leucite may also subordinately alter to halloysite. This probably occurs by interaction of waters of low cation/H+ ratio. Halloysite concentrates mainly Sr and, to a lower extent, Ba. Environmental implications are significant only for K, as the release of this element to groundwaters increases greatly the fertility of soils. 相似文献
72.
Massimo Vellante Matthias Förster Michael Pezzopane Norbert Jakowski Tie Long Zhang Umberto Villante Marcello De Lauretis Bruno Zolesi Werner Magnes 《Earth, Moon, and Planets》2009,104(1-4):25-27
Cross-spectral analysis of ULF wave measurements recorded at ground magnetometer stations closely spaced in latitude allows accurate determinations of magnetospheric field line resonance (FLR) frequencies. This is a useful tool for remote sensing temporal and spatial variations of the magnetospheric plasma mass density. The spatial configuration of the South European GeoMagnetic Array (SEGMA, 1.56 < L < 1.89) offers the possibility to perform such studies at low latitudes allowing to monitor the dynamical coupling between the ionosphere and the inner plasmasphere. As an example of this capability we present the results of a cross-correlation analysis between FLR frequencies and solar EUV irradiance (as monitored by the 10.7-cm solar radio flux F10.7) suggesting that changes in the inner plasmasphere density follow the short-term (27-day) variations of the solar irradiance with a time delay of 1–2 days. As an additional example we present the results of a comparative analysis of FLR measurements, ionospheric vertical soundings and vertical TEC measurements during the development of a geomagnetic storm. 相似文献
73.
W.C. Jones P.A.R. Ade J.J. Bock J.R. Bond J. Borrill A. Boscaleri P. Cabella C.R. Contaldi B.P. Crill P. de Bernardis G. De Gasperis A. de Oliveira-Costa G. De Troia G. Di Stefano E. Hivon A.H. Jaffe T.S. Kisner A.E. Lange C.J. MacTavish S. Masi P.D. Mauskopf A. Melchiorri T.E. Montroy P. Natoli C.B. Netterfield E. Pascale F. Piacentini D. Pogosyan G. Polenta S. Prunet S. Ricciardi G. Romeo J.E. Ruhl P. Santini M. Tegmark M. Veneziani N. Vittorio 《New Astronomy Reviews》2006,50(11-12):945
The Boomerang experiment completed its final long duration balloon (LDB) flight over Antarctica in January 2003. The focal plane was upgraded to accommodate four sets of 145 GHz polarization sensitive bolometers (PSBs), identical to those to be flown on the Planck HFI instrument. Approximately, 195 hours of science observations were obtained during this flight, including 75 hours distributed over 1.84% of the sky and an additional 120 hours concentrated on a region covering 0.22% of the sky. We derive the angular power spectra of the cosmic microwave background (cmb) temperature and polarization anisotropies from these data. The temperature anisotropies are detected with high signal to noise on angular scales ranging from several degrees to 10 arcminutes. The curl-free (EE) component is detected at 4.8σ, and a two-sigma upper limit on the curl (BB) component of 8.6 μK2 is obtained on scales corresponding to 0.5°. Both the temperature and polarization anisotropies are found to be consistent with a concordance ΛCDM cosmology that is seeded by adiabatic density perturbations. In addition to the cmb observations, Boomerang03 surveyed a 300 square degree region centered on the Galactic plane. These observations represent the first light for polarization sensitive bolometers, which are currently operational in two South-Pole based polarimeters, as well as Planck HFI, at frequencies ranging from 100 to 350 GHz (3 mm to 850 μm). 相似文献
74.
75.
Antonio Angrisano Salvatore Gaglione Ciro Gioia Marco Massaro Umberto Robustelli 《Acta Geophysica》2013,61(6):1457-1476
The ionosphere is the main error source in GNSS measurements and in extreme cases can degrade the positioning significantly, with errors exceeding 100 m; therefore, modelling and predicting of this type of error is crucial and critical. The ionospheric effect can be reduced using different techniques, such as dual-frequency receiver or suitable augmentation system (DGPS, SBAS); the aforesaid approaches involve the use of expensive devices and/or complex architectures. Single frequency stand-alone receivers are the cheapest and most widespread GNSS devices; they can estimate and partially correct the error due to the ionosphere, through adequate algorithms, which use parameters broadcasted by the navigation message. The aim of this paper is performance assessment of the ionospheric model NeQuick, adopted by the European GNSS Galileo for single frequency receivers. The analysis is performed in measurements domain and the data are collected in different geographical locations and in various geomagnetic conditions. 相似文献
76.
Domenico Ridente Umberto Fracassi Daniela Di Bucci Fabio Trincardi Gianluca Valensise 《Tectonophysics》2008,453(1-4):110
Recent seismicity in and around the Gargano Promontory, an uplifted portion of the Southern Adriatic Foreland domain, indicates active E–W strike-slip faulting in a region that has also been struck by large historical earthquakes, particularly along the Mattinata Fault. Seismic profiles published in the past two decades show that the pattern of tectonic deformation along the E–W-trending segment of the Gondola Fault Zone, the offshore counterpart of the Mattinata Fault, is strikingly similar to that observed onshore during the Eocene–Pliocene interval. Based on the lack of instrumental seismicity in the south Adriatic offshore, however, and on standard seismic reflection data showing an undisturbed Quaternary succession above the Gondola Fault Zone, this fault zone has been interpreted as essentially inactive since the Pliocene. Nevertheless, many investigators emphasised the genetic relationships and physical continuity between the Mattinata Fault, a positively active tectonic feature, and the Gondola Fault Zone. The seismotectonic potential of the system formed by these two faults has never been investigated in detail. Recent investigations of Quaternary sedimentary successions on the Adriatic shelf, by means of very high-resolution seismic–stratigraphic data, have led to the identification of fold growth and fault propagation in Middle–Upper Pleistocene and Holocene units. The inferred pattern of gentle folding and shallow faulting indicates that sediments deposited during the past ca. 450 ka were recurrently deformed along the E–W branch of the Gondola Fault Zone.We performed a detailed reconstruction and kinematic interpretation of the most recent deformation observed along the Gondola Fault Zone and interpret it in the broader context of the seismotectonic setting of the Southern Apennines-foreland region. We hypothesise that the entire 180 km-long Molise–Gondola Shear Zone is presently active and speculate that also its offshore portion, the Gondola Fault Zone, has a seismogenic behaviour. 相似文献
77.
Solute transport in rivers and streams with hyporheic zone exchange and/or in-stream storage is typically affected by the prevailing flow rate. The research reported here focuses on stream tracer experiments repeated many times along the same Austrian (Mödlingbach) and Italian (Torrente Lura) channel reaches to characterize parameter dependency on flow rate. Both groups of data sets showed an increase of storage zone area and main stream area with discharge. In either case, a strong negative correlation was obtained between storage zone residence time and flow rate. From the Mödlingbach data, no clear relationship with Q emerged for the dispersion coefficient and the dead zone ratio, whereas Torrente Lura showed a clear positive correlation of the dispersion coefficient with the flow rate and a slightly negative Q-dependency for the dead zone ratio. Mödlingbach and Torrente Lura results are presented against the background of other repeat experiments reported in literature. 相似文献
78.
Umberto Rizza Massimo Cassiani Umberto Giostra Cristina Mangia 《Boundary-Layer Meteorology》2000,95(2):319-339
An advanced model aimed at describing the problem of dispersion in theconvective boundary layer is proposed. The pollutant particles are groupedin clusters and modelled as Gaussian puffs. The expansion of each puff ismodelled according to the concept of relative dispersion and expressed interms of the spectral properties of the energy containing eddies of the turbulent field. The centre of mass of each puff is moved along a stochastic trajectory, obtained using a Lagrangian stochastic model and filtering the velocity with a recursive Kalman filter. At any instant, a filtering procedure, depending both on travel time and on puff size, acts to select spectral components involved in the expansion and in the meandering of the puff. Such an approach requires only a moderate number of puff releases, so that the proposed model is faster to run than a standard Lagrangian model. On the other hand, unlike the traditional puff model, it allows us to simulate both expansion and meandering of the puff. Therefore, it is well suited to simulate dispersion when the turbulent structures are larger thanthe plume dimensions, as for example in convective conditions. Being based onspectral formulations in both Eulerian and Lagrangian parts, the model is consistent in all the turbulent parameterizations utilised. Comparisons with a standard Lagrangian particle model as well as with a classical convective experimental dataset show good performance of the proposed model. 相似文献
79.
Leonardo Chiauzzi Angelo Masi Marco Mucciarelli Marco Vona Francesca Pacor Giovanna Cultrera Frantisek Gallovič Antonio Emolo 《Bulletin of Earthquake Engineering》2012,10(2):517-545
In this paper earthquake damage scenarios for residential buildings (about 4200 units) in Potenza (Southern Italy) have been
estimated adopting a novel probabilistic approach that involves complex source models, site effects, building vulnerability
assessment and damage estimation through Damage Probability Matrices. Several causative faults of single seismic events, with
magnitude up to 7, are known to be close to the town. A seismic hazard approach based on finite faults ground motion simulation
techniques has been used to identify the sources producing the maximum expected ground motion at Potenza and to generate a
set of ground motion time histories to be adopted for building damage scenarios. Additionally, site effects, evaluated in
a previous work through amplification factors of Housner intensity, have been combined with the bedrock values provided by
hazard assessment. Furthermore, a new relationship between Housner and EMS-98 macroseismic intensity has been developed. This
relationship has been used to convert the probability mass functions of Housner intensity obtained from synthetic seismograms
amplified by the site effects coefficients into probability mass function of EMS-98 intensity. Finally, the Damage Probability
Matrices have been applied to estimate the damage levels of the residential buildings located in the urban area of Potenza.
The proposed methodology returns the full probabilistic distribution of expected damage, thus avoiding average damage index
or uncertainties expressed in term of dispersion indexes. 相似文献
80.
Slope stability assessment is a geotechnical problem characterized by many sources of uncertainty. Some of them, e.g., are connected to the variability of soil parameters involved in the analysis. Beginning from a correct geotechnical characterization of the examined site, only a complete approach to uncertainty matter can lead to a significant result. The purpose of this paper is to demonstrate how to model data uncertainty in order to perform slope stability analysis with a good degree of significance.
Once the input data have been determined, a probabilistic stability assessment (first-order second moment and Monte Carlo analysis) is performed to obtain the variation of failure probability vs. correlation coefficient between soil parameters. A first result is the demonstration of the stability of first-order second moment (FOSM) (both with normal and lognormal distribution assumption) and Monte Carlo (MC) solutions, coming from a correct uncertainty modelling. The paper presents a simple algorithm (Fuzzy First Order Second Moment, FFOSM), which uses a fuzzy-based analysis applied to data processing. 相似文献