全文获取类型
收费全文 | 106篇 |
免费 | 7篇 |
专业分类
测绘学 | 3篇 |
大气科学 | 2篇 |
地球物理 | 42篇 |
地质学 | 44篇 |
海洋学 | 9篇 |
天文学 | 8篇 |
自然地理 | 5篇 |
出版年
2022年 | 2篇 |
2021年 | 2篇 |
2020年 | 1篇 |
2019年 | 2篇 |
2018年 | 9篇 |
2017年 | 2篇 |
2016年 | 3篇 |
2015年 | 20篇 |
2014年 | 9篇 |
2013年 | 7篇 |
2012年 | 3篇 |
2011年 | 8篇 |
2010年 | 2篇 |
2009年 | 8篇 |
2008年 | 10篇 |
2007年 | 3篇 |
2006年 | 3篇 |
2005年 | 1篇 |
2004年 | 3篇 |
2003年 | 3篇 |
2002年 | 2篇 |
2000年 | 2篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1993年 | 1篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1979年 | 2篇 |
1977年 | 1篇 |
排序方式: 共有113条查询结果,搜索用时 15 毫秒
1.
The Bayesian detection of discontinuities in a polynomial regression and its application to the cycle-slip problem 总被引:4,自引:1,他引:3
Maria Clara de Lacy Mirko Reguzzoni Fernando Sansò Giovanna Venuti 《Journal of Geodesy》2008,82(9):527-542
This paper deals with the problem of detecting and correcting cycle-slips in Global Navigation Satellite System (GNSS) phase
data by exploiting the Bayesian theory. The method is here applied to undifferenced observations, because repairing cycle-slips
already at this stage could be a useful pre-processing tool, especially for a network of permanent GNSS stations. If a dual
frequency receiver is available, the cycle-slips can be easily detected by combining two phase observations or phase and range
observations from a single satellite to a single receiver. These combinations, expressed in a distance unit form, are completely
free from the geometry and depend only on the ionospheric effect, on the electronic biases and on the initial integer ambiguities;
since these terms are expected to be smooth in time, at least in a short period, a cycle-slip in one or both the two carriers
can be modelled as a discontinuity in a polynomial regression. The proposed method consists in applying the Bayesian theory
to compute the marginal posterior distribution of the discontinuity epoch and to detect it as a maximum a posteriori (MAP)
in a very accurate way. Concerning the cycle-slip correction, a couple of simultaneous integer slips in the two carriers is
chosen by maximazing the conditional posterior distribution of the discontinuity amplitude given the detected epoch. Numerical
experiments on simulated and real data show that the discontinuities with an amplitude 2 or 3 times larger than the noise
standard deviation are successfully identified. This means that the Bayesian approach is able to detect and correct cycle-slips
using undifferenced GNSS observations even if the slip occurs by one cycle. A comparison with the scientific software BERNESE
5.0 confirms the good performance of the proposed method, especially when data sampled at high frequency (e.g. every 1 s or
every 5 s) are available. 相似文献
2.
Pennsylvanian carbonate platforms adjacent to deltaic systems in an active marine foreland basin (Escalada Fm., Cantabrian Zone,NW Spain) 下载免费PDF全文
Juan Ramón Bahamonde Oscar Merino‐Tomé Giovanna Della Porta Elisa Villa 《Basin Research》2015,27(2):208-229
The Pennsylvanian marine foreland basin of the Cantabrian Zone (NW Spain) is characterized by the unique development of kilometre‐size and hundred‐metre‐thick carbonate platforms adjacent to deltaic systems. During Moscovian time, progradational clastic wedges fed by the orogen comprised proximal alluvial conglomerates and coal‐bearing deltaic sequences to distal shelfal marine deposits associated with carbonate platforms (Escalada Fm.) and distal clay‐rich submarine slopes. A first phase of carbonate platform development (Escalada I, upper Kashirian‐lower Podolskian) reached a thickness of 400 m, nearly 50 km in width and developed a distal high‐relief margin facing a starved basin, nearly 1000‐m deep. Carbonate slope clinoforms dipped up to 30° and consisted of in situ microbial boundstone, pinching out downslope into calciturbidites, argillaceous spiculites and breccias. The second carbonate platform (Escalada II, upper Podolskian‐lower Myachkovian) developed beyond the previous platform margin, following the basinward progradation of siliciclastic deposits. Both carbonate platforms include: (1) a lower part composed of siliciclastic‐carbonate cyclothems characterized by coated‐grain and ooid grainstones; and (2) a carbonate‐dominated upper part, composed of tabular and mound‐shaped wackestone and algal‐microbial boundstone strata alternating at the decametre scale with skeletal and coated‐grain grainstone beds. Carbonate platforms initiated in distal sectors of the foreland marine shelf during transgressions, when terrigenous sediments were stored in the proximal part, and developed further during highstands of 3rd‐order sequences in a high‐subsidence context. During the falling stage and lowstand systems tracts, deltaic systems prograded across the shelf burying the carbonate platforms. Key factors involved in the development of these unique carbonate platforms in an active foreland basin are: (1) the large size of the marine shelf (approaching 200 km in width); (2) the subsidence distribution pattern across the marine shelf, decreasing from proximal shoreline to distal sectors; (3) Pennsylvanian glacio‐eustacy affecting carbonate lithofacies architecture; and (4) the environmental conditions optimal for fostering microbial and algal carbonate factories. 相似文献
3.
4.
Landfill leachates are not adequately treated in traditional wastewater treatment plants, on account of their problematic peculiarities: i.e., dark colour, high concentration of recalcitrant pollutants and COD, and high toxicity. In this work, 19 biomasses (15 autochthonous and 4 allochthonous) were exploited in biosorption treatment for the remediation of a leachate (influent) and the effluent coming from the biological oxidation with activated sludge and nitrification–denitrification treatment. The effects of the initial pH, the biomass amount, and the medium for the biomass pre-culture were considered. The best configuration was: pH 5, 5 g L??1 biomass cultivated on STY medium. Eventually, the two most effective biomasses, Cunninghamella bertholletiae MUT 2861 and Aspergillus fumigatus MUT 4050, were used in consecutive 2 h cycles in a batch biosorption experiment. The effectiveness of the treatment decreased in subsequent cycles in terms of decolourisation (31–15%). COD, Cl?, SO42?, total N, and toxicity were removed mainly in the second cycle of treatment (up to ??36, ??12, ??15, ??17 and ??49%, respectively). The results suggest that the effluent toxicity was basically due to uncoloured substances, which were mainly removed after coloured molecules. 相似文献
5.
Acta Geochimica - To quantify water erosion rates and annual soil loss in mountainous areas, two different empirical models were used to estimate the effects of soil erosion in a small mountain... 相似文献
6.
Maiorano Luigi; Bartolino Valerio; Colloca Francesco; Abella Alvaro; Belluscio Andrea; Carpentieri Paolo; Criscoli Alessandro; Jona Lasinio Giovanna; Mannini Alessandro; Pranovi Fabio; Reale Bruno; Relini Giulio; Viva Claudio; Ardizzone Gian Domenico 《ICES Journal of Marine Science》2009,66(1):137-146
7.
Giovanni?BesioEmail author Paolo?Blondeaux Maurifio?Brocchini Giovanna?Vittori 《Ocean Dynamics》2003,53(3):232-238
A simple mathematical model is described, which reproduces the major features of sand waves' appearance and growth and in particular predicts their migration speed. The model is based on the linear stability analysis of the flat configuration of the sea bottom subject to tidal currents.
Attention is focused on the prediction of the complex growth rate that bottom perturbations undergo because of both oscillatory fluid motions and residual currents. While the real part r of controls the amplification or decay of the amplitude of the bedforms, the imaginary part i is related to their migration speed.
Previous works on the migration of the sand waves (Németh etal. 2002) consider a forcing tide made up by the M2 constituent (oscillatory period equal to 12 h) plus the residual current Z0 and predict always a downcurrent migration of the bedforms. However, field cases exist of upcurrent-migrating sand waves (downcurrent/upcurrent-migrating sand waves mean bedforms moving in the direction of the steady residual tidal current or in the opposite direction, respectively).
The inclusion of a tide constituent characterized by a period of 6 h (M4) is the main novelty of the present work, which allows for the prediction of the migration of sand waves against the residual current Z0. Indeed, the M4 tide constituent, as does also the residual current Z0, breaks the symmetry of the problem forced only by the M2 tide constituent, and induces sand-wave migration.
The model proposed by Besio etal. (2003a) forms the basis for the present analysis. Previous works on the subject (Gerkema 2000; Hulscher 1996a,b; Komarova and Hulscher 2000) are thus improved by using a new solution procedure (Besio etal. 2003a) which allows for a more accurate evaluation of the growth rate for arbitrary values of the parameter r, which is the ratio between the horizontal tidal excursion and the perturbation wavelength.
Responsible Editor: Jens Kappenberg 相似文献
8.
Vincenzo Amico Giuseppe Impellizzeri Giovanna Oriente Mario Piattelli Sebastiano Sciuto Corrado Tringali 《Marine pollution bulletin》1979,10(10):282-284
Concentrations of chlorinated hydrocarbons (DDT and metabolites, PCBs, aldrin, dieldrin, HCB and BHCs) have been determined in the tissues of five species of marine animals sampled in selected areas of the central Mediterranean. 相似文献
9.
The island of Pantelleria is an active volcano located in the Sicily Channel (southern Italy), occurring in the middle of a continental rift system.Since the 1980's the island has been periodically surveyed by means of geodetic and geophysical methods to monitor the regional and local volcanic dynamics. Also, high-precision gravity measurements were started in 1990.The present paper is an analysis of the time-space gravity changes. Gravity measurements were carried out on a network presently formed by twenty stations. The gravity network was fully surveyed in June 1990 and June 1995 and partially surveyed in September 1993. Two absolute gravity stations were established in 1993 to provide a reference system and to check for long-term variations.The areal distribution of the gravity changes during the 1990–1995 time interval, obtained in the thirteen stations of the 1990 network, is strongly similar to the Bouguer anomaly field and to the large-scale features of the basement of the island. Otherwise, gravity changes are directly correlated with the Bouguer anomaly and inversely correlated with the altimetric variations. Comparison with the geological setting suggests that the present activity may be ascribed to the influence of the geodynamics of the Sicily Channel. 相似文献
10.
Vincenzo Amico Giovanna Oriente Mario Piattelli Corrado Tringali 《Marine pollution bulletin》1979,10(6):177-179
The levels of PCBs, DDT and BHC residues have been determined in thalli of 12 species of marine algae harvested along the east coast of Sicily. The results are discussed in comparison with those obtained earlier with animal species sampled in the same area. 相似文献