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141.
Gianfranco Brambilla Stefania Paola De Filippis Vittorio Esposito Gaetano Settimo 《洁净——土壤、空气、水》2013,41(2):113-118
Dioxin‐like compounds from regular, occasional or fugitive airborne sources of emission may fall out on fodders close to be harvested for silage and hay production. In this way, a prolonged long‐term intake of contaminated forages in dairy animals may be envisaged, able to determine a rise of the background contamination in milk. We simulated different risk scenarios taking into account the inventoried bulk dry depositions in rural areas of the aforesaid contaminants, silage and hay biomass production per hectare, forages regimen in dairy animals, and the congeners carry‐over rate (COR) from forages to milk. Considering atmospheric depositions >10 pg I‐TE m?2 day?1 and accounting for a 30% COR, dairy milk could rise up to the PCDD/F level of 3 pg WHO1998‐TE g?1 fat. The modelling indicates that in rural areas bulk emissions should be selectively minimised, accounting for the calendar of the different agricultural practices, because of their potential impact on the fodders. Since environmental factors play a non‐negligible role in food production, a stronger harmonisation between I‐TE and WHO1998–2005‐TE scales with respect to dioxin‐like polychlorobiphenyl congeners inclusion is envisaged. This will allow the prevention of the human indirect exposure to such contaminants when released in the air. 相似文献
142.
P. Rebusco E. Churazov H. Böhringer W. Forman 《Monthly notices of the Royal Astronomical Society》2005,359(3):1041-1048
The impact of stochastic gas motions on the metal distribution in cluster cores is evaluated. Peaked abundance profiles are a characteristic feature of clusters with cool cores, and abundance peaks are probably associated with the brightest cluster galaxies (BCGs), which dwell in cluster cores. However, the width of the abundance peaks is significantly broader than the BCG light distribution, suggesting that some gas motions are transporting metals originating from within the BCG. Assuming that this process can be treated as diffusive, and using the brightest X-ray cluster A426 (Perseus) as an example, we estimate that a diffusion coefficient of the order of 2 × 1029 cm2 s−1 is needed to explain the width of the observed abundance profiles. Much lower (higher) diffusion coefficients would result in too peaked (too shallow) profiles. Such diffusion could be produced by stochastic gas motions, and our analysis provides constraints on the product of their characteristic velocity and their spatial coherence scale. We speculate that the activity of the supermassive black hole of the BCG is driving the stochastic gas motions in cluster cores. When combined with the assumption that the dissipation of the same motions is a key gas heating mechanism, one can estimate both the velocity and the spatial scale of such diffusive processes. 相似文献
143.
Mayra Osorio Guillem Anglada Susana Lizano Paola D'Alessio 《Astrophysics and Space Science》2004,292(1-4):369-374
We investigate the physical conditions of the material around massive protostars by modelling the so-called hot molecular cores. We present a model for the spectral energy distribution (SED) as well as the ammonia line emission of the G31.41+0.31 hot core. We find that the best fit to the SED is achieved by assuming a density distribution corresponding to the collapse of a magnetized logatropic sphere. On the other hand, the line emission is reproduced by adopting a gas phase ammonia abundance increasing towards the center of the core, as a result of the release of the ammonia molecules trapped in ice grain mantles. 相似文献
144.
Since the eighteenth century, pioneer seismologists have used information from the periodical press to compile their lists of European earthquakes. A systematic reading of three eighteenth century periodicals –Gaceta de Madrid (1701–1750), Gazeta de Lisboa (1715–1751) and Mercure de France (1732–1763) – has been carried out in the frame of the EC project ‘Review of Historical Seismicity in Europe (RHISE)’. The retrieval of earthquake records provides data on European and Mediterranean earthquakes. Sources and records are here analysed to verify their reliability and to understand the significance of the earthquake information they supply. Special attention has been paid to earthquakes that affected Italian territory, by means of a comparison between records and space-time, intensity parameters of the Italian seismic catalogue: this comparison shows that about 45% of the earthquakes mentioned by the periodicals are unknown in the Italian catalogue, and that 30% of them are damaging earthquakes. 相似文献
145.
Claudio Codella Rafael Bachiller Milena Benedettini Paola Caselli 《Astrophysics and Space Science》2003,287(1-4):171-174
The preliminary results from a multiline mm-wave survey of H2S and SO2 emission towards the Cepheus A star forming region are presented. Large scale maps (? 5'×4') and high-resolution line profiles which clearly indicate the occurrence of multiple H2S and SO2 outflows are reported. In particular, a 0.6 pc long outflow flowing towards South from the CepA-East position has been discovered. In addition, besides the well known regions CepA-East and CepA-West other four clumps of shocked gas have been detected. These clumps exhibit distinct H2S/SO2 ratios, suggesting different chemical compositions for different regions and show that in Cepheus A the mass loss has strongly modified the chemistry of the quiescent gas. 相似文献
146.
Cesare Barbieri Carlo Blanco Beatrice Bucciarelli Regina Coluzzi Andrea Di Paola Luciano Lanteri Gian Luca Li Causi Ettore Marilli Piero Massimino Vincenzo Mezzalira Stefano Mottola Roberto Nesci Alessandro Omizzolo Fernando Pedichini Francesca Rampazzi Corinne Rossi Ruggero Stagni Milcho Tsvetkov Roberto Viotti 《Experimental Astronomy》2003,15(1):29-43
There is a widespread interest to digitize the precious information contained in the astronomical plate archives, both for
the preservation of their content and for its fast distribution to all interested researchers in order to achieve their better
scientific exploitation. This paper presents the first results of our large-scale project to digitize the archive of plates
of the Italian Astronomical Observatories and of the Specola Vaticana. Similar systems, composed by commercial flat-bed retro-illuminated
scanners plus dedicated personal computers and acquisition and analysis software, have been installed in all participating
Institutes. Ad-hoc codes have been developed to acquire the data, to test the suitability of the machines to our scientific needs, and to reduce
the digital data in order to extract the astrometric, photometric and spectroscopic content. Two more elements complete the
overall project: the provision of high quality BVRI CCD sequences in selected fields with the Campo Imperatore telescopes,
and the distribution of the digitized information to all interested researchers via the Web. The methods we have derived in
the course of this project have been already applied successfully to plates taken by other Observatories, for instance at
Byurakan and at Hamburg. 相似文献
147.
Changes in cloudiness over the Amazon rainforests during the last two decades: diagnostic and potential causes 总被引:1,自引:1,他引:0
Paola A. Arias Rong Fu Carlos D. Hoyos Wenhong Li Liming Zhou 《Climate Dynamics》2011,37(5-6):1151-1164
This study shows a decrease of seasonal mean convection, cloudiness and an increase of surface shortwave down-welling radiation during 1984?C2007 over the Amazon rainforests based on the analysis of satellite-retrieved clouds and surface radiative flux data. These changes are consistent with an increase in surface temperature, increased atmospheric stability, and reduction of moisture transport to the Amazon based on in situ surface and upper air meteorological data and reanalysis data. These changes appear to link to the expansion of the western Pacific warm pool during the December?CFebruary season, to the positive phase of the Atlantic Multidecadal Oscillation and increase of SST over the eastern Pacific SST during the March?CMay season, and to an increase of the tropical Atlantic meridional SST gradient and an expansion of the western Pacific warm pool during September?CNovember season. The resultant increase of surface solar radiation during all but the dry season in the Amazon could contribute to the observed increases in rainforest growth during recent decades. 相似文献
148.
A large landslide occurred at Maierato (Vibo Valencia District), Southern Italy, on 15 February 2010, when rapid failure was produced after several days of preliminary movements. The landslide can be classified as a rotational slide with flowing of the mass. It occurred within a larger deep-seated gravitational movement area and was preconditioned for failure by the intrinsic geological weakness of the area. Actually, the in situ survey showed the presence of several ancient movement surfaces all around the urban area. The landslide-triggering factor was the increase in the groundwater flow, consequent to a period of heavy and prolonged rainfall. The aim of the paper is to explain the mechanism of occurrence of the February 2010 composite landslide, in order to assess the landslide hydrogeological susceptibility in the whole urban area of Maierato. For this reason, the present paper deals with: (1) identification of the landslide mechanism and triggering factors (2) slope stability back-analysis using a finite-difference-based shear strength reduction method, and (3) 3D groundwater flow modelling extended to the whole urban area both in pre- and post-failure conditions. The results show that the February 2010 composite landslide was triggered by a water table increase of about 15 m uphill the landslide scarp. This hydrogeological condition could be reached after the period of heavy and prolonged rainfall preceding the landslide event. Finally, based on the groundwater modelling in post-failure condition, a landslide hydrogeological susceptibility map was drawn for the all urban area of Maierato, showing the presence of extended areas exposed to hazard. 相似文献
149.
Paola de Capoa Angelida Di Staso Francesco Guerrera Vincenzo Perrone Mario Tramontana Mohamed Najib Zaghloul 《Geodinamica Acta》2013,26(2):141-157
Abstract Volcaniclastic debris-rich formations, characterising the Troina-Tusa Unit in the Sicilian Maghrebian Chain, are examined. The Troina-Tusa Unit terrains sedimented in the Maghrebian Flysch Basin, which, from Jurassic to Early Miocene, constituted the southernmost branch of the Western Tethys, located between Africa and the Mesomediterranean Terrane margins. New field, biostratigraphic and pétrographie data enable a reconstruction of the palaeogeographic and structural evolution of the Flysch Basin immediately before its deformation. All the studied formations transpired to be Burdigalian in age. The sandstone compositions, showing different source areas (magmatic arc, recycled orogen and continental block), indicate a provenance for the clastic material from a crystalline basement with an active volcanic arc, replaced by a remnant volcanic arc, which was rapidly completely eroded. The source area that has been considered is Sardinia, where Upper Oligocene -Aquitanian calc-alkaline volcanites are widespread, but the sedimentological characteristics and the Burdigalian age do not fit with this provenance. The Burdigalian calc-alkaline arc should be located on the internal side of the Troina-Tusa Basin, above the already stacked Peloritanian units. A migration of the volcanic activity, connected with the subduction plain roll-back, can be envisaged from the Sardinia Block to the Peloritanian Chain, this latter still docked to the Sardinia-Corsica massif. © 2002 Editions scientifiques et médicales Elsevier SAS. All rights reserved. 相似文献
150.
The linkage between physical and biological processes, particularly the effect of the circulation field on the distribution of phytoplankton, is studied by applying a two-dimensional model and an adjoint data assimilation approach to the Gulf of Maine-Georges Bank region. The model results, comparing well with observation data, reveal seasonal and geographic variations of phytoplankton concentration and verify that the seasonal cycles of phytoplankton are controlled by both biological sources and ad-vection processes which are functions of space and time and counterbalance each other. Although advective flux divergences have greater magnitudes on Georges Bank than in the coastal region of the western Gulf of Maine, advection control over phytoplankton concentration is more significant in the coastal region of the western Gulf of Maine. The model results also suggest that the two separated populations in the coastal regions of the western Gulf of Maine and on Georges Bank are self-sustaining. 相似文献