全文获取类型
收费全文 | 86篇 |
免费 | 3篇 |
专业分类
大气科学 | 2篇 |
地球物理 | 35篇 |
地质学 | 24篇 |
海洋学 | 3篇 |
天文学 | 22篇 |
自然地理 | 3篇 |
出版年
2022年 | 3篇 |
2020年 | 1篇 |
2017年 | 4篇 |
2016年 | 5篇 |
2015年 | 1篇 |
2014年 | 5篇 |
2013年 | 3篇 |
2012年 | 5篇 |
2011年 | 3篇 |
2010年 | 2篇 |
2009年 | 2篇 |
2008年 | 8篇 |
2007年 | 5篇 |
2006年 | 10篇 |
2005年 | 2篇 |
2004年 | 1篇 |
2003年 | 1篇 |
2002年 | 2篇 |
2000年 | 3篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 3篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1987年 | 1篇 |
1986年 | 3篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1979年 | 2篇 |
1977年 | 1篇 |
排序方式: 共有89条查询结果,搜索用时 171 毫秒
31.
Physically based dynamic run-out modelling for quantitative debris flow risk assessment: a case study in Tresenda,northern Italy 总被引:1,自引:1,他引:0
Byron Quan Luna Jan Blahut Corrado Camera Cees van Westen Tiziana Apuani Victor Jetten Simone Sterlacchini 《Environmental Earth Sciences》2014,72(3):645-661
Quantitative landslide risk assessment requires information about the temporal, spatial and intensity probability of hazardous processes both regarding their initiation as well as their run-out. This is followed by an estimation of the physical consequences inflicted by the hazard, preferentially quantified in monetary values. For that purpose, deterministic hazard modelling has to be coupled with information about the value of the elements at risk and their vulnerability. Dynamic run-out models for debris flows are able to determine physical outputs (extension, depths, velocities, impact pressures) and to determine the zones where the elements at risk can suffer an impact. These results can then be applied for vulnerability and risk calculations. Debris flow risk has been assessed in the area of Tresenda in the Valtellina Valley (Lombardy Region, northern Italy). Three quantitative hazard scenarios for different return periods were prepared using available rainfall and geotechnical data. The numerical model FLO-2D was applied for the simulation of the debris flow propagation. The modelled hazard scenarios were consequently overlaid with the elements at risk, represented as building footprints. The expected physical damage to the buildings was estimated using vulnerability functions based on flow depth and impact pressure. A qualitative correlation between physical vulnerability and human losses was also proposed. To assess the uncertainties inherent in the analysis, six risk curves were obtained based on the maximum, average and minimum values and direct economic losses to the buildings were estimated, in the range of 0.25–7.7 million €, depending on the hazard scenario and vulnerability curve used. 相似文献
32.
Minority ethnic populations in England and Wales have been increasing steadily as a share of the total population since the 1991 Census. In this paper, we are interested in how internal migration has changed as a possible consequence. Our analysis focuses on the movements between 12 area groups, as defined by the Office for National Statistics, and addresses the following three research questions: (1) how has internal migration in England and Wales evolved from 1991 to 2004; (2) what are the main differences in the movements between the White (majority) population and the ethnic minority population; and (3) how do migration patterns differ when ethnicity, education and employment statuses are considered together? The data come from the 1991 to 2004 National Health Service Central Registers, the 1999–2004 patient registers and the 2001 Census. We find strong stability in the migration patterns of the total population over time. However, large differences appear when the flows are disaggregated by ethnicity and further by education and employment. Education level is an important factor influencing the migration patterns for the White population, whereas employment status is a much more important factor for the ethnic minority population. 相似文献
33.
Corrado Massa 《Astrophysics and Space Science》2008,314(1-3):23-24
If gravity is a mixture of the ordinary attractive force carried by the massless graviton, and of a repulsive force carried
by a particle with nonzero mass, an evaporating black hole might leave a stable remnant. 相似文献
34.
Francesco Brardinoni Reto Grischott Florian Kober Corrado Morelli Marcus Christl 《地球表面变化过程与地形》2020,45(15):3955-3974
We examine the sensitivity of 10Be concentrations (and derived denudation rates), to debris-flow and anthropogenic perturbations in steep settings of the Eastern Alps, and explore possible relations with structural geomorphic connectivity. Using cosmogenic 10Be as a tracer for functional geomorphic connectivity, we conduct sampling replications across four seasons in Gadria, Strimm and Allitz Creek. Sampling sites encompass a range of structural connectivity configurations, including the conditioning of a sackung, all assessed through a geomorphometric index (IC). By combining information on contemporary depth of erosion and sediment yield, disturbance history and post-LGM (Last Glacial Maximum) sedimentation rates, we constrain the effects of debris-flow disturbance on 10Be concentrations at the Gadria sites. Here, we argue that bedrock weakening imparted by the sackung promotes high depth of erosion. Consequently, debris flows recruit sediment beyond the critical depth of spallogenic production (e.g., >3 m), which in turn, episodically, due to predominantly muogenic production pathways, lowers 10Be concentration by a factor of 4, for at least 2 years. In contrast, steady erosion in Strimm Creek yields very stable 10Be concentrations through time. In Allitz Creek, we observe two- to fourfold seasonal fluctuations in 10Be concentrations, which we explain as the combined effects of water diversion and hydraulic structures on sediment mixing. We further show that 10Be concentration correlates inversely with the IC index, where sub-basins characterized by high concentrations (long residence times) exhibit low IC values (structurally disconnected) and vice versa, implying that, over millennial time scales a direct relation exists between functional and structural connectivity, and that the IC index performed as a suitable metric for structural connectivity. The index performs comparably better than other metrics (i.e., mean slope and mean normalized channel steepness index) previously used to assess topographic controls on denudation rates in active unglaciated ranges. In terms of landscape evolution, we argue that the sackung, by favouring intense debris-flow activity across the Holocene, has aided rapid postglacial reshaping of the Gadria basin, which currently exhibits a topographic signature characteristic of unglaciated debris-flow systems. © 2020 John Wiley & Sons, Ltd. 相似文献
35.
Corrado Massa 《Astrophysics and Space Science》1993,209(2):307-308
The time variation of the gravitational constantG is discussed in the light of the gravity modified form of quantum electrodynamics. From the experimental upper limit |a/| < 5 × 10–15 yr–1 on the time variation of the electromagnetic fine structure constant one finds |/G| < 5 × 10–13 yr–1. 相似文献
36.
Andrea Bollati Sveva Corrado Maurizio Marino 《International Journal of Earth Sciences》2012,101(4):1011-1031
The western Lucretili Mts. in the central Apennines (Latium, Italy) have been recently re-mapped in great detail and are the subject of combined stratigraphic, sedimentological and structural investigations. In this paper, we present a new stratigraphic interpretation of the Jurassic paleogeography of western Lucretili Mts., where a rift-derived intrabasinal paleo-high of the Alpine Tethys has been identified for the first time by means of facies analysis and biostratigraphic dating. Recognised facies associations, combined with dated stratigraphic sections, allow to define the morphology of the structural paleo-high and to identify the associated gravity-driven deposits (olistoliths) accumulated in the surrounding basin. Furthermore, we investigated the modes of interaction between Jurassic extensional structures and the subsequent contractional patterns developed during the Tertiary mountain building. In detail, the role played during Apennines tectonics by the paleo-escarpments bounding the paleo-high and by the surrounding olistoliths has been analysed. The paleo-escarpments either acted as focussing features for ENE-directed frontal thrust ramp localisation and were offset with small shortening amounts or reactivated as NNE striking high angle transpressional faults or preserved the original geometries as a result of variable orientation of paleo-escarpments with respect to the Neogene compressive stress field (with ENE oriented sigma1). Newly formed ENE striking tear faults connect these either inherited or neo-formed discontinuities. This complex stratigraphic and structural pattern is substantially different from the previous interpretations of this portion of the central Apennines based on a hypothesised layer-cake stratigraphy deformed by neo-formed Neogene thrusts. This contribution strengthens the importance of integrating facies analyses and structural investigations to detect the influence of pre-orogenic structures on compressive structural patterns, in an area where commercial seismic lines are not available and cannot help in reconstructing the subsurface geometries. 相似文献
37.
38.
This study first explores the role of spatial heterogeneity, in both the saturated hydraulic conductivity Ks and rainfall intensity r, on the integrated hydrological response of a natural slope. On this basis, a mathematical model for estimating the expected areal‐average infiltration is then formulated. Both Ks and r are considered as random variables with assessed probability density functions. The model relies upon a semi‐analytical component, which describes the directly infiltrated rainfall, and an empirical component, which accounts further for the infiltration of surface water running downslope into pervious soils (the run‐on effect). Monte Carlo simulations over a clay loam soil and a sandy loam soil were performed for constructing the ensemble averages of field‐scale infiltration used for model validation. The model produced very accurate estimates of the expected field‐scale infiltration rate, as well as of the outflow generated by significant rainfall events. Furthermore, the two model components were found to interact appropriately for different weights of the two infiltration mechanisms involved. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
39.
Corrado Massa 《Astrophysics and Space Science》1997,253(2):285-289
The possibility that the deceleration parameter q might be a null constant is discussed; such possibilitiy is interesting
because solves the horizon problem and the flatness problem with no need of inflation. A simple way to get q = const = 0 is
explored: the way assumes Einstein's field equations without cosmological term and introduces a massless scalar field V with
negative energy density. Both in the early and in the present universe one finds the Whitrow-Randall relation Gut2 = const 1 G gravitational coupling, u mass-energy density, t cosmic time). The interaction between the V-field and the ordinary
matter is briefly discussed; as possible consequence of this interaction the true value of the Hubble parameter might be one
half the observed value.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
40.
Corrado Cigolini 《Bulletin of Volcanology》2010,72(6):693-704
Data collected at Somma-Vesuvius during the 1998–1999 radon surveys have been revisited and reinterpreted in light of recent
geophysical and geochemical information. The duration of selected radon anomalies, together with the decay properties of radon,
have been used to estimate the permeability and porosity of rocks of the deep hydrothermal system. The current local cyclic
seismicity is explained by means of a double convective-cell model. Convective cells are separated by a low-permeability horizon
located at about 2–2.5 km below sea level. Fluids convecting within the upper cells show temperatures ranging 300–350°C. Rock
permeabilities in this sector are estimated on the order of 10−12 m2, for porosities (ϕ) of about 10−5 typical of a brittle environment where fluid velocities may reach ∼800 m/day. Fluid temperatures within the lower cells may
be as high as 400–450°C, consistent with supercritical regimes. The hydrodynamic parameters for these cells are lower, with
permeability k ∼ 10−15 m2, and porosity ranging from 10−6 to 10−7. Here, fluid motion toward the surface is controlled by the fracture network within a porous medium approaching brittle–ductile
behaviour, and fluid velocities may reach ∼1,800 m/day. The low-permeability horizon is a layer where upper and lower convecting
cells converge. In this region, fluids (convecting both at upper and lower levels) percolate through the wallrock and release
their brines. Due to self-sealing processes, permeability within this horizon reaches critical values to keep the fluid pressure
near lithostatic pressure (for k ∼ 10−18 m2). Deep fluid pressure buildups precede the onset of hydrothermally induced earthquakes. Permeability distribution and rock
strength do not exclude that the next eruption at Somma-Vesuvius could be preceded by a seismic crisis, eventually leading
to a precursory phreatic explosion. The coupling of these mechanisms has the potential of inducing pervasive failure within
rocks of the hydrothermal shell, and may be a prelude to a magmatic eruption. It is finally emphasised that the integrated
analysis of seismic and geochemical data, including radon emissions, could be successfully used in testing temperature distributions
and variations of porosity and permeability in active geothermal reservoirs. 相似文献