全文获取类型
收费全文 | 102篇 |
免费 | 6篇 |
国内免费 | 1篇 |
专业分类
测绘学 | 1篇 |
大气科学 | 10篇 |
地球物理 | 32篇 |
地质学 | 12篇 |
海洋学 | 7篇 |
天文学 | 34篇 |
自然地理 | 13篇 |
出版年
2024年 | 1篇 |
2021年 | 1篇 |
2019年 | 2篇 |
2018年 | 6篇 |
2017年 | 3篇 |
2016年 | 4篇 |
2015年 | 1篇 |
2014年 | 6篇 |
2013年 | 3篇 |
2012年 | 3篇 |
2011年 | 5篇 |
2010年 | 3篇 |
2009年 | 8篇 |
2008年 | 2篇 |
2007年 | 7篇 |
2006年 | 5篇 |
2005年 | 4篇 |
2004年 | 3篇 |
2003年 | 3篇 |
2002年 | 3篇 |
2001年 | 6篇 |
2000年 | 1篇 |
1999年 | 6篇 |
1998年 | 4篇 |
1997年 | 1篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1990年 | 1篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有109条查询结果,搜索用时 687 毫秒
1.
2.
Propagation of electromagnetic (EM) waves from an earthquake focus in the conductive Earth has been investigated using 1/1,000,000 scaling models taking earth-ionosphere and ocean-Moho plane parallel-plate waveguides into account. Microwaves at a frequency, ωm, a million times higher than that of seismic EM signal (SEMS), ω, were generated at the model focus. They are propagated in a salt solution modeling the earth's crust and reflected by ocean, fault planes, ionosphere and Moho plane all made by aluminum. Distribution of EM power was mapped by scanning a detector antenna over the model Earth's surface. The skin depth, δ, calculated by the exact skin depth equation, 1/δ=ω(μ/2)1/2 [(1+(1/ωρ)2)1/2 −1]1/2 where dielectric constant, and permeability, μ are the same but resistivity, ρ, 10−6 times smaller than that of Earth, gave 10−6 times small skin depth validating the model scaling index. Images for evanescent and wave-ripple standing waves disturbed by normal, strike-slip and dip-slip conductive fault planes have been obtained using an aluminum plate. The co-circular contour map above the epicenter due to evanescence was pushed to the north east direction from the epicenter by the presence of ocean for the Loma Prieta earthquake, while to north direction for the Kobe earthquake. The intensity of EM ULF emissions for the Loma Prieta earthquake is discussed quantitatively. 相似文献
3.
Yoshiki Fukutomi Chihiro Kodama Yohei Yamada Akira T. Noda Masaki Satoh 《Theoretical and Applied Climatology》2016,124(3-4):737-755
Lower-tropospheric tropical synoptic-scale disturbances (TSDs) are associated with severe weather systems in the Asian Monsoon region. Therefore, exact prediction of the development and behavior of TSDs using atmospheric general circulation models is expected to improve weather forecasting for this region. Recent state-of-the art global cloud-system resolving modeling approaches using a Nonhydrostatic Icosahedral Atmospheric Model (NICAM) may improve representation of TSDs. This study evaluates TSDs over the western Pacific in output from an Atmospheric Model Intercomparison Project (AMIP)-like control experiment using NICAM. Data analysis compared the simulated and observed fields. NICAM successfully simulates the average activity, three-dimensional structures, and characteristics of the TSDs during the Northern summer. The variance statistics and spectral analysis showed that the average activity of the simulated TSDs over the western Pacific during Northern summer broadly captures that of observations. The composite analysis revealed that the structures of the simulated TSDs resemble the observed TSDs to a large degree. The simulated TSDs exhibited a typical southeast- to northwest-oriented wave-train pattern that propagates northwestward from near the equator around 150 ° E toward the southern coast of China. However, the location of the simulated wave train and wave activity center was displaced northward by approximately a few degrees of latitude from that in the observation. This displacement can be attributed to the structure and strength of the background basic flow in the simulated fields. Better representation of the background basic states is required for more successful simulation of TSDs. 相似文献
4.
The geological model about volcanism of the Green Tuff geosyncline deduced from the field observations consists of the following processes:
- Dome-shaped uplift with a mean diameter of 30 km.
- Collapse of the central part of the domes forming basins with a mean diameter of 10 km.
- Volcanic activity inside the collapse basins. It is considered that these consecutive processes resulted from the magmatic uplift from a deep part of the crust.
5.
6.
7.
—Uniaxial compression, triaxial compression and Brazialian tests were conducted on several kinds of rock, with particular attention directed to the principal tensile strain. In this paper we aim to clarify the effects of the experimental environment—such as confining pressure, loading rate, water content and anisotropy—on the critical tensile strain, i.e., the measured principal tensile strain at peak load.¶It was determined that the chain-type extensometer is a most suitable method for measuring the critical tensile strain in uniaxial compression tests. It is also shown that the paper-based strain gage, whose effective length is less than or equal to a tenth of the specimen’s diameter and glued on with a rubber-type adhesive, can be effectively used in the Brazilian tests.¶The effect of confining pressure P C on the critical tensile strain ? TC in the brittle failure region was between ?0.02 × 10?10 Pa?1 and 0.77 × 10?10 Pa?1. This pressure sensitivity is small compared to the critical tensile strain values of around ?0.5 × 10?2. The strain rate sensitivities ?? TC /?{log(d|?|/dt)} were observed in the same way as the strength constants in other failure criteria. They were found to be from ?0.10 × 10?3 to ?0.52 × 10?3 per order of magnitude in strain rate in the triaxial tests. The average magnitude of the critical tensile strain ? TC increased due to the presence of water by 4% to 20% for some rocks, and decreased by 22% for sandstone. It can at least be said that the critical tensile strain is less sensitive to water content than the uniaxial compressive strength under the experimental conditions reported here. An obvious anisotropy was observed in the P-wave velocity and in the uniaxial compressive strength of Pombetsu sandstone. It was not observed, however, in the critical tensile strain, although the data do show some variation.¶A "tensile strain criterion" was proposed, based on the above experimental results. This criterion signifies that stress begins to drop when the principal tensile strain reaches the critical tensile strain. The criterion is limited to use within the brittle failure region. The critical tensile strain contains an inelastic strain component as well as an elastic one. It is affected by the strain rate, however, it is relatively insensitive to the confining pressure, the presence of water and anisotropy. 相似文献
8.
9.
Sanae Koizumi Takehiko Hiraga Chihiro Tachibana Miki Tasaka Tomonori Miyazaki Tamio Kobayashi Asako Takamasa Naoki Ohashi Satoru Sano 《Physics and Chemistry of Minerals》2010,37(8):505-518
Synthesized mineral powders with particle size of <100 nm are vacuum sintered to obtain highly dense and fine-grained polycrystalline
mantle composites: single phase aggregates of forsterite (iron-free), olivine (iron containing), enstatite and diopside; two-phase
composites of forsterite + spinel and forsterite + periclase; and, three-phase composites of forsterite + enstatite + diopside.
Nano-sized powders of colloidal SiO2 and highly dispersed Mg(OH)2 with particle size of ≤50 nm are used as chemical sources for MgO and SiO2, which are common components for all of the aggregates. These powders are mixed with powders of CaCO3, MgAl2O4, and Fe(CO2CH3)2 to introduce mineral phases of diopside, spinel, and olivine to the aggregates, respectively. To synthesize highly dense
composites through pressureless sintering, we find that calcined powders should be composed of particles that have: (1) fully
or partially reacted to the desired minerals, (2) a size of <100 nm and (3) less propensity to coalesce. Such calcined powders
are cold isostatically pressed and then vacuum sintered. The temperature and duration of the sintering process are tuned to
achieve a balance between high density and fine grain size. Highly dense (i.e., porosity ≤1 vol%) polycrystalline mantle mineral
composites with grain size of 0.3–1.1 μm are successfully synthesized with this method. 相似文献
10.