全文获取类型
收费全文 | 146篇 |
免费 | 3篇 |
国内免费 | 7篇 |
专业分类
测绘学 | 3篇 |
大气科学 | 25篇 |
地球物理 | 52篇 |
地质学 | 43篇 |
海洋学 | 15篇 |
天文学 | 16篇 |
自然地理 | 2篇 |
出版年
2022年 | 1篇 |
2021年 | 2篇 |
2020年 | 1篇 |
2019年 | 3篇 |
2018年 | 5篇 |
2017年 | 3篇 |
2016年 | 6篇 |
2015年 | 1篇 |
2014年 | 7篇 |
2013年 | 13篇 |
2012年 | 4篇 |
2011年 | 9篇 |
2010年 | 6篇 |
2009年 | 6篇 |
2008年 | 9篇 |
2007年 | 6篇 |
2006年 | 17篇 |
2005年 | 5篇 |
2004年 | 3篇 |
2003年 | 5篇 |
2002年 | 8篇 |
2001年 | 6篇 |
2000年 | 1篇 |
1999年 | 3篇 |
1998年 | 2篇 |
1997年 | 3篇 |
1996年 | 5篇 |
1995年 | 2篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1984年 | 2篇 |
1982年 | 1篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1933年 | 2篇 |
排序方式: 共有156条查询结果,搜索用时 31 毫秒
111.
A.J. Coates R.A. Frahm D.O. Kataria G. Collinson J.D. Winningham S. Barabash R. Lundin Y. Futaana A. Grigoriev H. Gunell J.-J. Thocaven W. Baumjohann H. Koskinen J.U. Kozyra Y. Ma A. Galli P. Bochsler E.C. Roelof N. Krupp M. Fraenz S. McKenna-Lawlor R. Cerulli-Irelli A. Milillo C.C. Curtis K.C. Hsieh A. Asamura 《Planetary and Space Science》2008,56(6):802-806
We report the detection of electrons due to photo-ionization of atomic oxygen and carbon dioxide in the Venus atmosphere by solar helium 30.4 nm photons. The detection was by the Analyzer of Space Plasma and Energetic Atoms (ASPERA-4) Electron Spectrometer (ELS) on the Venus Express (VEx) European Space Agency (ESA) mission. Characteristic peaks in energy for such photoelectrons have been predicted by Venus atmosphere/ionosphere models. The ELS energy resolution (ΔE/E∼7%) means that these are the first detailed measurements of such electrons. Considerations of ion production and transport in the atmosphere of Venus suggest that the observed photoelectron peaks are due primarily to ionization of atomic oxygen. 相似文献
112.
Slope failure is a widely observed phenomenon in the mountainous areas in Taiwan due to rainy climatic and fragile geological conditions. Landslides easily occur after intense rainfall, especially from typhoons, and, accordingly, cause a great loss of human life and property. At the northern end of the Western Foothill belt in northern Taiwan, Huafan University is founded on a dip-slope about 20° toward the southwest composed of early Miocene alternations of sandstone and shale. Data from continuous monitoring using inclinometers and groundwater gauges reveal that 6–10 mm/month of slope creeping occurs, and a potential sliding surface is then detected about 10–40 m beneath the slope surface. To understand the potential runout process of the dip-slope failure at the campus, particle flow code 3D models based on a discrete element method are applied in this study. Results of the simulation reveal a critical value of the friction coefficient to be 0.13 and that more than 90% of the campus buildings will slide down in 100 s when the friction coefficient is reduced to half the critical value. The weakening of the shear zone due to the rise of groundwater during rainstorms is assumed to be the main factor. Some suggestions for preventing landslide disasters are to construct catchpits to drain runoff and lower the groundwater table and to install a sufficient number of ground anchors and retaining walls to stabilize the slope. 相似文献
113.
Fung-Chun Li Jacques Angelier Rou-Fei Chen Hui-Ming Hsieh Benoît Deffontaines Ching-Ruey Luo Tso-Tchang Wu Ming-Chao Lin 《Comptes Rendus Geoscience》2005,337(13):1131-1139
We discuss the present-day sediment transport by rivers, and hence the erosion rate in upstream basins, based on the example of Taiwan Rivers where large datasets are available. After data correction, the values of the suspended sediment load in the lower Kaoping River are nearly three times smaller than those from the literature. On the other hand, we add the bed load evaluated from numerical modelling, despite limitations from data and models. Whereas the contribution of the chemical denudation rate in Taiwan is minor, the bed load is significant and must be evaluated. We point out that biases in data collection may favour high values of suspended load data, and that large series of datasets are needed to reduce uncertainties and smooth the time variability effect. To cite this article: F.-C. Li et al., C. R. Geoscience 337 (2005). 相似文献
114.
115.
Without any omen, massive landslides induced by the Chi-Chi earthquake blocked up gorges of Ching-Shui creek, and produced a new landslide lake.Although emergency spillways have been constructed to prevent dam failures,overtopping and possible breaching may still occur due to excessive inflows in raining seasons. As a result, the downstream valleys will have serious inundation and the safety of people and properties will be in immediate danger. The purpose of this work is to simulate and to analyze the inundation potentials downstream of Tsao-Ling landslide lake using a hydrologic/hydraulic approach and GIS (Geographic Information System) technology. Hydrologic analysis is employed to describe regional rainfall-runoff characteristics andto design rainfall/runoff scenarios. One-dimensional dam break flood routings are performed with different return periods of rainfall events and dam failure durations for downstream creeks. The depletion hydrographs of dam break routings are applied into two-dimensional overland flow simulations for downstream lowlands. The results of hydraulic computations are evaluated with GIS maps for inundation potentials analysis, which can be usedto assist the planning of emergency response measures. 相似文献
116.
Paul A. Hsieh 《Ground water》1996,34(6):1082-1089
117.
Results from a direct numerical simulation (DNS) of the neutral and unstable turbulent Ekman layer at a Reynolds number of 1000 were used to evaluate turbulence closure models. For the neutrally stratified Ekman layer, the higher-order moments of velocity were examined and the accuracy of a kurtosis model was assessed. For the unstable Ekman layer, the analysis of higher-order moments was extended to temperature-velocity correlations. Model coefficients were optimised using DNS data and it was shown that the optimised models accurately captured the distributions of all fourth-order moments. These low-Reynolds number results can be extrapolated to higher Reynolds numbers to parameterise turbulence in other flow fields with rotational effects such as the atmospheric boundary layer. 相似文献
118.
A real time kinematic (RTK), GPS-based, track-keeping control of a small boat is discussed in this paper. The internal model control (IMC) method is adopted in the autopilot design and the controller is recast in the PID controller format that is characterized by its simple structure and relative ease of implementation. The track-keeping mission is achieved through a sequence of course-changing maneuvers and the reference heading is computed with the line-of-sight (LOS) guidance law. Path planning based on Bezier curves to achieve obstacle avoidance is investigated. First, computer simulations are carried out to find the feasible controller design parameter that achieves satisfactory simulation results. Then the feasible controller design parameter is applied in the small-boat-based experiments to demonstrate the practical use of the proposed autopilot design method. 相似文献
119.
Nonlinear interdecadal changes in the El Niño-Southern Oscillation (ENSO) phenomenon are investigated using several tools: a nonlinear canonical correlation analysis (NLCCA) method based on neural networks, a hybrid coupled model, and the delayed oscillator theory. The leading NLCCA mode between the tropical Pacific wind stress (WS) and sea surface temperature (SST) reveals notable interdecadal changes of ENSO behaviour before and after the mid 1970s climate regime shift, with greater nonlinearity found during 1981–99 than during 1961–75. Spatial asymmetry (for both SST and WS anomalies) between warm El Niño and cool La Niña events was significantly enhanced in the later period. During 1981–99, the location of the equatorial easterly anomalies was unchanged from the earlier period, but in the opposite ENSO phase, the westerly anomalies were shifted eastward by up to 25°. According to the delayed oscillator theory, such an eastward shift would lengthen the duration of the warm events by up to 45%, but leave the duration of the cool events unchanged. Supporting evidence was found from a hybrid coupled model built with the Lamont dynamical ocean model coupled to a statistical atmospheric model consisting of either the leading NLCCA or CCA mode. 相似文献
120.