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101.
The Piqiang Fault is a prominent strike-slip (tear) fault that laterally partitions the Keping Shan Thrust Belt in the NW Tarim Basin, China. In satellite images, the Piqiang Fault appears as a sharp, NW-trending lineament that can be traced for more than 70 km. It is oblique to the general structural trend of the thrust belt and subparallel to the thrust transport direction. This paper presents a structural analysis of the Piqiang Fault, based on satellite image interpretation and field data. A net loss of Late Paleozoic sediment across the fault zone implies that it was initiated as a major normal fault during the Early Permian, and corresponds to widespread extension and magmatism during this period. Differential erosion across the fault resulted in the subsequent removal of sediment from the east relative to the west. During the Middle to Late Cenozoic, contraction of the NW Tarim Basin and the formation of the Keping Shan Thrust Belt resulted in reactivation of the Piqiang Fault as a strike-slip (tear) fault. The fault has accommodated lateral differences in thrust density and spacing which have arisen due to the abrupt, pre-existing change in stratigraphic thickness across it. The Piqiang Fault provides an insight into the formation of oblique, strike-slip (tear) faults in contractional belts and demonstrates the importance of inherited basement structures in such settings.  相似文献   
102.
Performance of constitutive models in predicting behavior of remolded clay   总被引:2,自引:2,他引:0  
The performance of several soil constitutive models was evaluated by comparing experimental results and simulated behavior of a medium plasticity clay. Input parameters for the soil constitutive models were obtained from triaxial compression and extension tests on normally and overconsolidated medium plasticity clay. The soil models employed for this study were the Cam Clay, Modified Cam Clay, 3-SKH, and S-CLAY1 models. In order to investigate the influence of some of the input parameters on the performance of the models, sensitivity analyses were also performed. The comparisons demonstrate that the Cam Clay model was able to predict the normally consolidated compressive behavior of medium plasticity clay. Both 3-SKH and Cam Clay models were able to produce acceptable predictions for stress?Cstrain and stress path behavior for overconsolidated compression of the soil. The 3-SKH model did not perform satisfactorily for predicting pore pressure variations, while the Cam Clay model demonstrated fairly acceptable predictions. For the normally consolidated reduced extension test, the Modified Cam Clay and S-CLAY1 models performed better than the Cam Clay and 3-SKH models in predicting the stress?Cstrain curve, pore pressure variations, and stress path.  相似文献   
103.
We present here preliminary results of our wide-field study of NGC 3109: a low luminosity galaxy in the outskirts of the Local Group. Its edge-on orientation (which simplifies the study of a possible halo) and the possibility that it could, in fact, be a small spiral (the smallest in the Local Group) makes its deep analysis of major relevance to understand the properties of dwarf galaxies and the transition from dwarf irregulars to spirals. This revised version was published online in September 2006 with corrections to the Cover Date.  相似文献   
104.
105.
In 1996, after 150 years of relative calm, Turrialba Volcano was reawakening. A visible plume and serious damage to surrounding vegetation due to acid rain are the most obvious signals. As part of the Network for Observation of Volcanic and Atmospheric Change project, four gas-monitoring stations were initially installed on the west flank of the volcano with the purpose of measuring sulphur dioxide emissions during this period of increased activity using the scanning-differential optical absorption spectroscopy technique. We present here the results of semicontinuous gas flux measurements over a period of 5 years (from 2008 to 2012), providing a novel data set that documents a relatively rapid increase in SO2 fluxes from around 350 t day?1 to around 4,000 t day?1 leading up to an eruptive period, followed by a gradual return to the former baseline values. Gas flux data were also compared with seismic data for selected periods of interest, providing insights into the link between degassing and seismicity. The most important result from this comparison is the identification of an inflexion point in the gas emissions followed by a clearly increasing trend in seismic activity, distinguishable 6 months prior to a phreatic eruptive event that occurred on 5 January 2010. This signal can be interpreted as a possible indicator of future eruptive events. Monitoring of SO2 thus complements seismic monitoring as a forecasting tool for eruptive events. Such monitoring is critical considering the proximity of Turrialba to the Central Valley, an area inhabited by more than 50 % of Costa Rica’s population.  相似文献   
106.
Scientific visualization is an integral part of the modeling workflow, enabling researchers to understand complex or large data sets and simulation results. A high-resolution stereoscopic virtual reality (VR) environment further enhances the possibilities of visualization. Such an environment also allows collaboration in work groups including people of different backgrounds and to present results of research projects to stakeholders or the public. The requirements for the computing equipment driving the VR environment demand specialized software applications which can be run in a parallel fashion on a set of interconnected machines. Another challenge is to devise a useful data workflow from source data sets onto the display system. Therefore, we develop software applications like the OpenGeoSys Data Explorer, custom data conversion tools for established visualization packages such as ParaView and Visualization Toolkit as well as presentation and interaction techniques for 3D applications like Unity. We demonstrate our workflow by presenting visualization results for case studies from a broad range of applications. An outlook on how visualization techniques can be deeply integrated into the simulation process is given and future technical improvements such as a simplified hardware setup are outlined.  相似文献   
107.
Boundary-Layer Meteorology - The goal of this work is to summarize synoptic meteorological conditions during the Coastal Fog (C-FOG) field project that took place onshore and offshore of the Avalon...  相似文献   
108.
109.
An electromagnetic inversion model has been applied to echoes from the subsurface sounding Shallow Radar (SHARAD) to retrieve the dielectric properties of the uppermost Basal Unit (BU) beneath the North Polar Layered Deposits of Mars. SHARAD data have been carefully selected to satisfy the assumption of the inversion model which requires a stratigraphy consisting of mostly plane parallel layers. The resulting values of the dielectric constant have been interpreted in terms of a variable percentage of dust in an ice–dust mixture through the use of a mixing model for dielectric properties. The resulting dust content exceeds 65%, reaching perhaps 95%, depending on the permittivity values assumed for the dust. Such a concentration is higher than that obtained by Selvans et al. (Selvans, M.M., Plaut, J.J., Aharonson, O. [2010]. J. Geophys. Res, 115, E09003). This discrepancy could be justified considering that our observations refer to the uppermost BU layer, whereas Selvans et al. (Selvans, M.M., Plaut, J.J., Aharonson, O. [2010]. J. Geophys. Res, 115, E09003) probed the BU full thickness. Moreover, if the BU is considered spatially inhomogeneous, with very different dust content and thickness (Tanaka, K.L., Skinner, J.A., Fortezzo, C.M., Herkenhoff, K.E., Rodriguez, J.A.P., Bourke, M.C., Kolb, E.J., Okubo, C.H. [2008]. Icarus, 196, 318–358), the discrepancy could be furtherly reconciled.  相似文献   
110.
A classification of watercourses proposed by Hasholt 1999 has been tested in Denmark using data from detailed field investigations from 42 watercourses and their surrounding area. Three types of landscapes are included: the moraine landscape from the Weichselian glaciation, the moraine landscape from the Saalian glaciation and the outwash plains. The performance of the classification in separating types of watercourses is discussed and modifications are suggested.  相似文献   
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