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61.
Carlota M. Grossi Alessandra Bonazza Peter Brimblecombe Ian Harris Cristina Sabbioni 《Environmental Geology》2008,56(3-4):455-461
Cities of the twenty-first century will expose buildings to environments that are quite different from those experienced over preceding periods. The recent reduction in sulfur dioxide in cities and continued pressure to lower the emissions of combustion generated pollutants creates a potential for climate induced deterioration, by contrast, to be more important. Given that climate will likely change over the next hundred years, recession rates of calcareous stones have been predicted for Oviedo (Spain), Paris and Prague over the period 1981–2099. This can give guidance as to the likely change in balance of future threat. The Lipfert, ICP, and MULTI-ASSESS functions were used to calculate recession from estimates of climate and air quality. It is likely that under a continued decline or stable levels of pollution, recession rates having reached low values will remain largely unchanged over the coming century, despite likely changes in climate. Although the functions adopted disagree in a quantitative sense, there is evidence that they were reasonably concordant in the last decades of the twentieth century. In a cleaner future their different underlying assumptions lead to poorer agreement. 相似文献
62.
Suspended‐sediment concentration data are a missing link in reconstructions of the River Waal in the early 1800s. These reconstructions serve as a basis for assessing the long‐term effects of major interventions carried out between 1850 AD and the early 20th century. We used a 2D physics‐based morphodynamic model accounting for the influence of floodplain vegetation to fill in this gap. Historical discharge hydrographs were derived from a correlation between flow discharge records at Cologne and water level measurements of the Rhine branches in the Netherlands, taking into account the discharge distribution between the branches. Historical floodplain sedimentation rates were estimated using old cartographic information and recent geomorphologic field work. The computed historical sedimentation rates are found to be within the range of measured data, which suggests that fine suspended sediment concentrations in the early 1800s were comparable to contemporary ones. The computations show also how vegetation enhances the formation of natural levees close to the main channel and at the same time decreases the sedimentation rates in farther areas of the floodplain. A sensitivity analysis shows suspended sediment composition to have a strong influence on the resulting quantities and patterns of floodplain deposition. The reconstruction has also provided validation of the modelling tools to reproduce the effects of vegetation on sediment dynamics, enabling their implementation to study other cases. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
63.
Alessandra Ascione Alessandro Iannace Pamela Imbriale Nicoletta Santangelo Antonio Santo 《地学学报》2014,26(1):1-13
Continental carbonates of Quaternary age in southern Italy commonly exhibit the facies of calcareous tufa, often reported as related to shallow aquifers fed by meteoric waters and to organic processes. A close spatial relationship exists between the mappable tufa deposits and major Quaternary extensional faults. With respect to the Ca‐Mg‐HCO3 composition of limestone aquifers’ springs, tufa‐depositing springs exhibit higher salinity and alkalinity, are slightly warmer, have lower pH and are enriched in SO4 and CO2. Their δ13C values are systematically positive and compatible with a deep‐seated carbon source. A clear input of soil‐derived organic carbon is indicated only for small, non‐mappable tufas deposited by perched springs. The dataset indicates that the large tufa deposits owe their origin to a supplementary source of CO2 advected by degassing through active faults, as a necessary prerequisite for inducing a rise of total dissolved salts and alkalinity. Meteoric waters that have come from a shallow aquifer are able to precipitate only limited amount of carbonates. 相似文献
64.
65.
Claudio Tomasi Stefano Marani Vito Vitale Frank Wagner Alessandra Cacciari Angelo Lupi 《Tellus. Series B, Chemical and physical meteorology》2000,52(2):734-749
Measurements of direct solar irradiance were taken employing 4 different sun‐photometers at near infrared wavelengths, suitable for use in atmospheric hygrometry. This technique utilising a set of spectral ratios, in and out of selected water vapour absorption bands, was applied to the measurements to obtain accurate evaluations of precipitable water. For all the hygrometric ratios given by the 4 sun‐photometers used at the 3 stations of Sagres, Monchique and Mt. Foia, during the CLEARCOLUMN experiment, we determined the calibration curves by correcting them for the Rayleigh scattering effects and, then, plotting the natural logarithms of such corrected ratios versus the square root of the water vapour mass present along the atmospheric slant path. The regression lines drawn for the various scatter diagrams were estimated to give evaluations of precipitable water with an uncertainty of less than 5%, 3% and 10% at the 3 stations, respectively. The calibration curves of the sun‐photometer located at the Sagres station were determined using the precipitable water evaluations obtained from the local radiosounding measurements taken on 5 clear‐sky days. Those of the sun‐photometers used at the Monchique and Mt. Foia stations were instead determined through intercomparison between subsets of measurements simultaneously taken with various instruments at Sagres and Mt. Foia. Using these calibration curves, we examined all the field measurements determining the time‐patterns of precipitable water at the 3 stations. During the period from 16 June to 25 July 1997, precipitable water was found to vary between 1.1 and 3.7 g cm−2 at the Sagres station (with an accuracy within ±13%), between 1.0 and 2.8 g cm−2 at Monchique (±11%) and between 0.8 and 3.0 g cm−2 at the top of Mt. Foia (±26%). 相似文献
66.
Alessandra Celletti Gabriella Pinzari 《Celestial Mechanics and Dynamical Astronomy》2005,93(1-4):1-52
The discovery of the asteroid Ceres by Piazzi in 1801 motivated the development of a mathematical technique proposed by Gauss,
(Theory of the Motion of the Heavenly Bodies Moving about the Sun in Conic Sections, 1963) which allows to recover the orbit
of a celestial body starting from a minimum of three observations. Here we compare the method proposed by Gauss (Theory of
the Motion of the Heavenly Bodies Moving about the Sun in Conic Sections, New York, 1963) with the techniques (based on three
observations) developed by Laplace (Collected Works 10, 93–146, 1780) and by Mossotti (Memoria Postuma, 1866). We also consider
another method developed by Mossotti (Nuova analisi del problema di determinare le orbite dei corpi celesti, 1816–1818), based
on four observations. We provide a theoretical and numerical comparison among the different procedures. As an application,
we consider the computation of the orbit of the asteroid Juno. 相似文献
67.
Alessandra Celletti Gabriella Della Penna Claude Froeschlé 《Celestial Mechanics and Dynamical Astronomy》2002,83(1-4):257-274
We investigate the break-down threshold of librational invariant curves. As a model problem, we consider a variant of a mapping introduced by M. Hénon, which well describes the dynamics of librational motions surrounding a stable invariant point. We verify in concrete examples the applicability of Greene's method, by computing the instability transition values of a sequence of periodic orbits approaching an invariant curve with fixed noble frequency. However, this method requires the knowledge of the location of the periodic orbits within a very good approximation. This task appears to be difficult to realize for a libration regime, due to the different topology of the phase space. To compute the break-down threshold, we tried an alternative method very easy to implement, based on the computation of the fast Lyapunov indicators and frequency analysis. Such technique does not require the knowledge of the periodic orbits, but again, it appears very difficult to have a precision better than Greene's method for the computation of the critical parameter. 相似文献
68.
Gomiero A Da Ros L Nasci C Meneghetti F Spagnolo A Fabi G 《Marine pollution bulletin》2011,62(11):2483-2495
Despite a large number of gas platforms existing in the Adriatic Sea, which is a semi-enclosed basin characterized by a slow turnover rate and increasing industrial as well as other anthropogenic activities, the effects of these structures on the aquatic ecosystem require further investigation. Since 1998, multidisciplinary studies have been performed by CNR-ISMAR to comply with legislation and to support the development of protocols for the monitoring of offshore activities in the Adriatic Sea. The present study was developed to implement a biomonitoring plan to assess the ecotoxicological effects of the extraction activities of an off-shore gas platform. Biomarkers were evaluated in mussels collected from the platform in relation to physiological stress, DNA damage, cellular damage, oxidative stress and exposure effects. Organic contaminants and trace element bioaccumulation were also assessed in the soft body of the mussels to correlate bioaccumulation of pollutants with biomarker responses. The results indicate an absence of platform-related environmental stress. 相似文献
69.
Macro‐ and meso‐scale structural criteria for identifying pre‐thrusting normal faults within foreland fold‐and‐thrust belts: Insights from the Central‐Northern Apennines (Italy) 下载免费PDF全文
Reliable macro‐ and meso‐scale structural criteria for identifying pre‐thrusting normal faults within inversion‐dominated foreland thrust belts are here reappraised by showing field cases from the Central‐Northern Apennines of Italy. Field‐based analyses of relative chronologies among the structures allow determination of the timing of pre‐thrusting normal faulting, the positive inversion of the faults and their post‐thrusting reactivation when absolute chronostratigraphic constraints are lacking. The correct identification of pre‐thrusting normal faults allows recognition of shortcut and reactivation anticlines, and these have important implications for the definition of the thrust‐belt structural style and for the estimation of post‐orogenic extension. 相似文献
70.
High‐P tectono‐metamorphic evolution of mylonites from the Variscan basement of the Northern Apennines,Italy 下载免费PDF全文
Deborah Lo Pò Roberto Braga Hans‐Joachim Massonne Giancarlo Molli Alessandra Montanini Giuseppe M. Bargossi 《Journal of Metamorphic Geology》2018,36(1):23-39
Strain localization within shear zones may partially erase the rock fabric and the metamorphic assemblage(s) that had developed before the mylonitic event. In poly‐deformed basements, the loss of information on pre‐kinematic phases of mylonites hinders large‐scale correlations based on tectono‐metamorphic data. In this study, devoted to a relict unit of Variscan basement reworked within the nappe stack of the Northern Apennines (Italy), we investigate the possibility to reconstruct a complete pressure (P)–temperature (T)–deformation (D) path of mylonitic micaschist and amphibolite by integrating microstructural analysis, mineral chemistry and thermodynamic modelling. The micaschist is characterized by a mylonitic fabric with fine‐grained K‐white mica and chlorite enveloping mica‐fishes, quartz, and garnet pseudomorphs. Potassic white mica shows Mg‐rich cores and Mg‐poor rims. The amphibolite contains green amphibole+plagioclase+garnet+quartz+ilmenite defining S1 with a superposed mylonitic fabric localized in decimetre‐ to centimetre‐scale shear zones. Garnet is surrounded by an amphibole+plagioclase corona. Phase diagram calculations provide P–T constraints that are linked to the reconstructed metamorphic‐deformational stages. For the first time an early high‐P stage at >11 kbar and 510°C was constrained, followed by a temperature peak at 550–590°C and 9–10 kbar and a retrograde stage (<475°C, <7 kbar), during which ductile shear zones developed. The inferred clockwise P–T–D path was most likely related to crustal thickening by continent‐continent collision during the Variscan orogeny. A comparison of this P–T–D path with those of other Variscan basement occurrences in the Northern Apennines revealed significant differences. Conversely, a correlation between the tectono‐metamorphic evolution of the Variscan basement at Cerreto pass, NE Sardinia and Ligurian Alps was established. 相似文献