全文获取类型
| 收费全文 | 316篇 |
| 免费 | 23篇 |
| 国内免费 | 4篇 |
专业分类
| 测绘学 | 19篇 |
| 大气科学 | 15篇 |
| 地球物理 | 113篇 |
| 地质学 | 90篇 |
| 海洋学 | 31篇 |
| 天文学 | 54篇 |
| 综合类 | 2篇 |
| 自然地理 | 19篇 |
出版年
| 2024年 | 1篇 |
| 2021年 | 11篇 |
| 2020年 | 9篇 |
| 2019年 | 7篇 |
| 2018年 | 11篇 |
| 2017年 | 17篇 |
| 2016年 | 26篇 |
| 2015年 | 14篇 |
| 2014年 | 17篇 |
| 2013年 | 21篇 |
| 2012年 | 25篇 |
| 2011年 | 23篇 |
| 2010年 | 22篇 |
| 2009年 | 26篇 |
| 2008年 | 15篇 |
| 2007年 | 14篇 |
| 2006年 | 11篇 |
| 2005年 | 18篇 |
| 2004年 | 11篇 |
| 2003年 | 10篇 |
| 2002年 | 6篇 |
| 2001年 | 5篇 |
| 2000年 | 7篇 |
| 1999年 | 3篇 |
| 1998年 | 2篇 |
| 1997年 | 3篇 |
| 1996年 | 2篇 |
| 1995年 | 1篇 |
| 1994年 | 2篇 |
| 1988年 | 2篇 |
| 1983年 | 1篇 |
排序方式： 共有343条查询结果，搜索用时 906 毫秒
91.
Antonio Pusceddu Silvia Bianchelli Miquel Canals Anna Sanchez-Vidal Xavier Durrieu De Madron Serge Heussner Vasilios Lykousis Henko de Stigter Fabio Trincardi Roberto Danovaro 《Deep Sea Research Part I: Oceanographic Research Papers》2010,57(3):441-457
We describe the quantitative and compositional (phytopigment, protein, carbohydrate and lipid) patterns of sedimentary organic matter along bathymetric gradients in seven submarine canyons and adjacent open slopes located at four European regions: one along the NE Atlantic and three along the Mediterranean continental margins. The investigated areas are distributed along a putative longitudinal gradient of decreasing primary production from the Portuguese (northeastern Atlantic Ocean), to the Catalan (western Mediterranean Sea), Southern Adriatic (central Mediterranean Sea) and Southern Cretan (eastern Mediterranean Sea) margins. Sediment concentrations of organic matter differed significantly between the Portuguese margin and the Mediterranean regions and also from one study area to the other within the Mediterranean Sea. Differences in quantity and composition of sediment organic matter between canyons and open slopes were limited and significant only in the eutrophic Portuguese margin, where the differences were as large as those observed between regions (i.e. at the mesoscale). These results suggest that the overall trophic status of deep margin sediments is controlled mostly by the primary productivity of the overlying waters rather than by the local topography. Moreover, we also report that the quantity and nutritional quality of sediment organic matter in canyons and adjacent open slopes do not show any consistent depth-related pattern. Only the Nazaré and Cascais canyons in the Portuguese margin, at depths deeper than 500 m, displayed a significant accumulation of labile organic matter. The results of our study underline the need of further investigations of deep margins through sampling strategies accounting for adequate temporal and spatial scales of variability. 相似文献
92.
93.
94.
We invert 2D surface gravity data constrained both by geological and seismic information. We use a number of pre-processing tools in order to reduce the general multi-body inversion into several single-body inversions, whereby we can reduce the overall complexity of the inversion task. This is done with as few assumptions as possible. Furthermore, for a single-body inversion we uncouple the determination of the shape of the causative sources from the determination of their mass density contrast to the surroundings. The inversion for the geometrical shape of the source body is done in steps. Firstly, a rough 3D shape of the source is modelled—a model consisting of the vertical mass columns of equal height. The horizontal extension is implied by the surface gravity signal. Subsequently, the shape of each source body is modified to obtain a better fit to the surface gravity data. In each modification step, the overall change of the shape of the source body is followed by an update of the mass density contrast to the surroundings. The technique was applied to a set of gravity data from the Eastern Goldfield area in Western Australia. The area has been widely studied in the past. In 1999, two seismic profiles that cross-sect the area were measured. Furthermore, an extensive geological modelling for the area has been conducted. The practical goal of this work was to verify the geological interpretation using the potential field data (mainly the gravity data although magnetic data were also available) and only weakly constrained by the seismic information. The result was the reconstruction of the ‘rough’ 3D geometry of the source bodies and the estimation of a constant mass density contrast to the surroundings. A possible extension of this technique for detailed studies of the geological model is briefly discussed. 相似文献
95.
Federico Murrone Fabio Rossi Pierluigi Claps 《Stochastic Hydrology and Hydraulics》1997,11(6):483-510
A conceptual-stochastic approach to short time runoff data modelling is proposed, according to the aim of reproducing the
hydrological aspects of the streamflow process and of preserving as much as possible the dynamics of the process itself. This
latter task implies preservation of streamflow characteristics at higher scales of aggregation and, within a conceptual framework,
involves compatibility with models proposed for the runoff process at those scales. At a daily time scale the watershed response
to the effective rainfall is considered as deriving from the response of three linear reservoirs, respectively representing
contributions to streamflows of large deep aquifers, with over-year response lag, of aquifers which run dry by the end of
the dry season and of subsurface runoff. The surface runoff component is regarded as an uncorrelated point process. Considering
the occurrences of effective rainfall events as generated by an independent Poisson process, the output of the linear system
represents a conceptually-based multiple shot noise process. Model identification and parameter estimation are supported by
information related to the aggregated runoff process, in agreement to the conceptual framework proposed, and this allows parameter
parsimony, efficient estimation and effectiveness of the streamflow reproduction. Good performances emerged from the model
application and testing made with reference to some daily runoff series from Italian basins. 相似文献
96.
The non‐stationary cross‐correlation coefficients in the seismic analysis of MDOF structural systems
A method concerning the evaluation, in a very compact form, of the non‐stationary modal cross‐correlation coefficients of MDOF structural systems subjected to seismic excitations is presented. It is available both in the case when the excitation is considered as a white‐noise process and when it is considered as a filtered process. The evaluation of these coefficients is required when a transient seismic analysis is performed by the use of the modal response spectrum approach. This is necessary when the strong‐motion phase of the earthquake is significantly short with respect to the fundamental period of the structure. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
97.
98.
99.
We investigate the properties of intermittency of magnetic turbulence by using magnetic field data collected by the Helios spacecraft in the inner heliosphere. Clear scaling laws for magnetic structure functions are visible in periods where the velocity of the bulk plasma is low. Within these periods we found that intermittency of magnetic turbulence is high with respect to velocity field. A comparison with fluid flows where passive scalars are more intermittent than velocity, yields to consider the magnetic field like a “passive vector”. 相似文献