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41.
During the recent United States foreclosure crisis, investors purchased and leased thousands of homes nationwide, opening up formerly owner-occupied neighborhoods to renters. Yet, little is known about how this process affected regional patterns of residential segregation and inequality. In this study, we combine property-level data on real estate transactions and subsidized housing vouchers from 2004 to 2014 to assess whether the conversion of foreclosures to rentals enabled low-income renters to live in more advantaged neighborhoods in Phoenix, Arizona. Renters with vouchers living in investor-purchased foreclosures were in lower-poverty neighborhoods compared with those not living in investor-purchased foreclosures. This suggests that foreclosure sales may have widened the geography of opportunity for low-income renters with subsidized housing. 相似文献
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A previous authors' non-Boussinesq model of solar differential rotation (BPCM) is used to determine the angular velocity distribution within the convection zone, when the momentum and energy equations are solved with boundary conditions expressing the homogeneity of flux and temperature at the Sun's surface. 相似文献
44.
Lucio Lirer Paola Petrosino Ines Alberico 《Journal of Volcanology and Geothermal Research》2001,112(1-4)
Volcanological analysis of the 10 000 yr
–1538
explosive activity at Campi Flegrei shows that the most common explosive eruptions are characterized by the emplacement of flow or surge deposits, originating from the interaction between magma and shallow and/or sea water. The minimum volumes of pyroclastic products range between 0.04 and 0.7 km3; the proximal areas covered by these products range from 3–4 to 40–50 km2. The pyroclastic flow and surge deposits occurring inside the caldera have been strongly controlled by pre-existent morphology; because of this, the area of present Napoli city was blanketed by approximately 5 m of pyroclastic deposits, during the last 5000 yr.Previous analysis suggests that the presence of even very low topographic obstacles may influence pyroclastic density current run out such that future eruptive deposits would mainly be confined inside the caldera rim. We suggest that a future eruption at Campi Flegrei would not seriously involve the urbanized area of Napoli city located on the hills. On the contrary, the plains located on the eastern side of the caldera (Fuorigrotta, Bagnoli) would be the most damaged area. 相似文献
45.
Fitting the results of linear normal-mode analysis of the solar five-minute oscillations to the observed k - ω diagram selects a class of models of the Sun's envelope. It is a property of all the models in this class that their convection zones are too deep to permit substantial transmission of internal g modes of degree 20 or more. This is in apparent conflict with Hill and Caudell's (1979) claim to have detected such modes in the photosphere. A proposal to resolve the conflict was made by Rosenwald and Hill (1980). They pointed out that despite the impressive agreement between linearized theory and observation, nonlinear phenomena in the solar atmosphere might influence the eigenfrequencies considerably. In particular, they suggested that a correct nonlinear analysis could predict a shallow convection zone. This paper is an enquiry into whether their hypothesis is plausible. We construct k - ω diagrams assuming that the modes suffer local nonlinear distortions in the atmosphere that are insensitive to the amplitude of oscillation over the range of amplitudes that are observed. The effect of the nonlinearities on the eigenfrequencies is parameterized in a simple way. Taking a class of simple analytical models of the Sun's envelope, we compute the linear eigenfrequencies of one model and show that no other model can be found whose nonlinear eigenfrequencies agree with them. We show also that the nonlinear eigenfrequencies of a particular solar model with a shallow convective zone, computed with more realistic physics, cannot be made to agree with observation. We conclude, therefore, that the hypothesis of Rosenwald and Hill is unlikely to be correct. 相似文献
46.
Piero Bareschino Teresita Gravina Lucio Lirer Antonio Marzocchella Paola Petrosino Piero Salatino 《Journal of Volcanology and Geothermal Research》2007
Fluidization of pyroclastic solids has long been indicated as one key to explain the enhanced mobility of dense pyroclastic gravity currents and their associated hazard. However there is a lack of characterization of the actual pattern and extent of fluidization establishing in real pyroclastic flows and some authors still raise arguments about the relevance of fluidization to the mobility of dense pyroclastic gravity currents. The present paper addresses the fluidization of pyroclastic granular solids with a specific focus on the analysis of factors that may promote homogeneous fluidization and retard solids de-aeration and consolidation. These factors include fines content, particle polydispersity and the establishment of shear flow. 相似文献
47.
Lucio Mayer Fabio Governato Monica Colpi Ben Moore Thomas R. Quinn Carlton M. Baugh 《Astrophysics and Space Science》2001,276(2-4):375-382
We study the evolution of galaxy satellites with high resolutionN-body simulations. Satellites are modelled as replicas of typical low and high surface brightness galaxies (LSBs and HSBs).
Encounters on high eccentricity orbits (as typical in hierarchical models of galaxy formation) strip LSBs of most of their
stars and tend to decrease their surface brightness. In contrast, bar instability in HSBs leads to substantial loss of angular
momentum of the stellar component and to an increase in central surface brightness. In both cases the remnant resembles a
spheroidal galaxy with an exponential surface brightness profile. A simple modelling of colour evolution and interaction-driven
star formation gives M/L ratios for the remnants that are roughly consistent with observations. These results suggest an evolutionary scenario for
the dwarf galaxies in our Local Group, faint dSphs being the descendants of LSBs and brighter dSphs/dEs being the final state
of HSB satellites.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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Luca Pietranera Stefan A. Buehler Paolo G. Calisse Claudia Emde Darren Hayton Viju Oommen John Bruno Maffei Lucio Piccirillo Giampaolo Pisano Giorgio Savini T. R. Sreerekha 《Monthly notices of the Royal Astronomical Society》2007,376(2):645-650
Ice crystal clouds in the upper troposphere can generate polarization signals at the μK level. This signal can seriously affect very sensitive ground-based searches for E and B modes of cosmic microwave background polarization. In this paper, we estimate this effect within the Cℓ OVER experiment observing bands (97, 150 and 220 GHz) for the selected observing site (Llano de Chajnantor, Atacama desert, Chile). The results show that the polarization signal from the clouds can be of the order of or even bigger than the cosmic microwave background expected polarization. Climatological data suggest that this signal is fairly constant over the whole year in Antarctica. On the other hand, the stronger seasonal variability in Atacama allows for a 50 per cent of clean observations during the dry season. 相似文献