全文获取类型
收费全文 | 68篇 |
免费 | 0篇 |
国内免费 | 1篇 |
专业分类
大气科学 | 1篇 |
地球物理 | 30篇 |
地质学 | 14篇 |
海洋学 | 5篇 |
天文学 | 18篇 |
自然地理 | 1篇 |
出版年
2024年 | 1篇 |
2019年 | 2篇 |
2017年 | 1篇 |
2015年 | 2篇 |
2011年 | 1篇 |
2010年 | 1篇 |
2009年 | 1篇 |
2008年 | 7篇 |
2007年 | 1篇 |
2006年 | 1篇 |
2005年 | 2篇 |
2004年 | 3篇 |
2003年 | 2篇 |
2002年 | 1篇 |
2001年 | 2篇 |
2000年 | 3篇 |
1999年 | 2篇 |
1998年 | 4篇 |
1997年 | 4篇 |
1996年 | 3篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 4篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1977年 | 2篇 |
1976年 | 1篇 |
排序方式: 共有69条查询结果,搜索用时 31 毫秒
1.
In situ strength measurements on natural upper-mantle minerals 总被引:1,自引:0,他引:1
Junji Yamamoto Jun-ichi Ando Hiroyuki Kagi Toru Inoue Akihiro Yamada Daisuke Yamazaki Tetsuo Irifune 《Physics and Chemistry of Minerals》2008,35(5):249-257
Using in situ strength measurements at pressures up to 10 GPa and at room temperature, 400, 600, and 700°C, we examined rheological
properties of olivine, orthopyroxene, and chromian-spinel contained in a mantle-derived xenolith. Mineral strengths were estimated
using widths of X-ray diffraction peaks as a function of pressure, temperature, and time. Differential stresses of all minerals
increase with increasing pressure, but they decrease with increasing temperature because of elastic strain on compression
and stress relaxation during heating. During compression at room temperature, all minerals deform plastically at differential
stress of 4–6 GPa. During subsequent heating, thermally induced yielding is observed in olivine at 600°C. Neither orthopyroxene
nor spinel shows complete stress relaxation, but both retain some stress even at 700°C. The strength of the minerals decreases
in the order of chromian-spinel ≈ orthopyroxene > olivine for these conditions. This order of strength is consistent with
the residual pressure of fluid inclusions in mantle xenoliths. 相似文献
2.
We present the database of maser sources in H2 O, OH and Si O lines that can be used to identify and study variable stars at evolved stages. Detecting the maser emission in H2 O, OH and Si O molecules toward infrared-excess objects is one of the methods for identifing long-period variables(LPVs, including miras and semiregulars), because these stars exhibit maser activity in their circumstellar shells. Our sample contains 1803 known LPV objects. Forty-six percent of these stars(832 objects) manifest maser emission in the line of at least one molecule: H2 O, OH or Si O. We use the database of circumstellar masers in order to search for LPVs which are not included in the General Catalogue of Variable Stars(GCVS). Our database contains 4806 objects(3866 objects without associations in GCVS) with maser detection in at least one molecule. Therefore it is possible to use the database in order to locate and study the large sample of LPV stars. The database can be accessed at http://maserdb.net. 相似文献
3.
During the dynamic response of multiple partially or fully embedded structures, the subgrade medium at the sides of the structures not only generates the soil-structure interaction forces but also transmits the motions from one structural body to others. With Winkler's hypothesis, these forces and motions are formulated in the time-domain in a simple form utilizing the frequency-domains formulations. The validity of the developed formulations is examined using small-scale-model test results obtained for piles in a synthetic ground. A numerical example is provided to demonstrate the approach proposed and the formulations developed. The simplified time-domain formulations are found to be numerically efficient and yet capable of predicting the behaviour reasonably well. 相似文献
4.
A differential equation is formulated for the dynamic response of ground medium by using a simplified ground model. Applying Galerkin's procedure for weighted residual, this equation leads to a governing equation only at the ground surface. The equation indicates that the ground surface behavior can be computed even further by a simplified model. By solving the governing equation for the boundary conditions along the surface, expressions in simple closed forms are developed for the dynamic response analysis of a massless rigid foundation that rests on the ground surface. Despite their significant simplicity, the developed expressions compute the values very close to those computed by far more complex rigorous solutions. They are found to be capable of capturing the important characteristics of the dynamic ground behavior well. 相似文献
5.
A thin layer element method is formulated to compute the dynamic response of submerged soil. The formulation is based on Biot's equation describing the dynamic behavior of fluid-saturated elasto-porous medium. The dynamic response of submerged soil is computed for various cases by using the developed formulation. The effects of submerged conditions are examined for submerged soil deposits with a water level at and above the ground surface. It is found that both submerged conditions and water body above the ground surface can considerably affect the dynamic response of soil deposits. 相似文献
6.
Jun-ichi Ando Kiyoshi Fujino Toru Takeshita 《Physics of the Earth and Planetary Interiors》1993,80(3-4):105-116
Dislocation microstructures of naturally deformed silicate garnets and olivines in garnet-peridotites and silicate garnets in eclogites from four localities have been observed with a transmission electron microscope (TEM) to clarify the dislocation characteristics of silicate garnets. We have obtained the following results: (1) dislocation densities of garnets in all the garnet-peridotites (ρ = 105−107 cm−2) are always nearly an order of magnitude lower than those of co-existing olivines; (2) dislocation densities of garnets in eclogites (ρ = 105−108 cm−2) which are embedded in garnet-peridotites are almost an order of magnitude higher than those of garnets in the surrounding garnet-peridotites; (3) the dominant Burgers vector, b, of mainly edge dislocations in garnet is 100 for specimens with dislocation density ρ = 105−106 cm−2, while b=1/2111 for specimens with ρ = 107−108 cm−2. Result (1) indicates that the observed dislocations in garnets were formed by plastic deformation under the same stresses as for co-existing olivines, and that there is a similar relationship between applied stress and dislocation density for garnets as for olivines. Result (2) suggests that the stress concentration occurred around eclogites embedded in garnet-peridotites, and the resulting differential stress in garnets in eclogites was further elevated by the interlocking of neighboring hard garnet grains. Finally, result (3) indicates that the dominant Burgers vector of mainly edge dislocations in garnet changes from 100 to 1/2111 with increasing applied differential stress. 相似文献
7.
The interaction between a soil layer and an end bearing pile is theoretically investigated. The pile is assumed to be vertical and elastic, the soil is considered as a linear visco-elastic layer with hysteretic type damping. The layer alone is solved first and the wave modes of the layer are used in the analysis of the pile response. The pile response to a harmonic load is obtained in a closed form and used to define stiffness and damping at the level of the pile head. The dimensionless parameters of the problem are identified. A parametric study is conducted to determine the main features of the response and of the equivalent stiffness and damping. The validity of equivalent viscous damping is examined. A comparison is made with the simpler plane strain theory used previously and its accuracy is assessed. 相似文献
8.
Shinsuke Abe Noboru Ebizuka Hideyuki Murayama Katsuhito Ohtsuka Satoru Sugimoto Masa-yuki Yamamoto Hajime Yano Jun-ichi Watanabe Jiří Borovička 《Earth, Moon, and Planets》2004,95(1-4):265-277
Spectra of persistent meteor trains were observed at wavelength between 300 and 930 nm. Two obtained train spectra during
the 1998 and 2001 Leonid meteor showers are reported here. During the 1998 Leonids, one train was detected by a photographic
camera with a spectrograph covering 370–640 nm region. On the other hand, during the 2001 Leonids, video observations were
carried out using image intensified cameras in ultraviolet (UV), visible and near infrared (near-IR) wavelengths. Temperatures
in persistent trains have been measured by atmospheric O2 A(0,1) band at the wavelength near 864.5 nm. From a video spectrum obtained just 7 s after parent fireball’s flare, a rotational
temperature of 250 K at altitude of 88.0±0.5 km was estimated. We can say that the cooling time scale of train strongly depends
on the initial mass of its fireball at least for Leonids. Based on cooling constant calculated from our results, we estimated
a temperature of ∼
∼130 K as a final exothermic temperature at early stage of persistent trains. 相似文献
9.
Daisaku Nogami † Taichi Kato Hajime Baba Rudolf Novák J. J. Lockley M. Somers 《Monthly notices of the Royal Astronomical Society》2001,322(1):79-84
We report on time-resolved photometry carried out during the 1995 short outburst and the 1997 long outburst in the eclipsing dwarf nova DV UMa. The revised orbital period is 0.0858526172 (67) d. We detected gigantic superhumps with an amplitude of ∼0.6 mag in the mid-phase of the 1997 outburst, revealing the SU UMa nature of DV UMa. The superhump period is 0.0887 (4) d. The superhumps became less clear during the late phase of the superoutburst, and we found two possible periods of 0.0885 (15) and 0.0764 (15). During both outbursts, the eclipse was wide and shallow near the maximum, and then became narrower and deeper, which is qualitatively well explained by the current disc instability theory. 相似文献
10.
S. Takechi T. Onishi T. Miyachi N. Hasebe K. Nogami S. Sasaki T. Iwai R. Srama 《Planetary and Space Science》2008,56(9):1309-1313
A cosmic dust detector for use onboard a satellite is currently being constructed from piezoelectric lead zirconate titanate (PZT). The characteristics of the PZT detector were studied by bombarding it with hypervelocity iron particles, which were supplied by a Van de Graaff accelerator. There was a linear relationship between the rise time of the signal observed from the detector and the particle's velocity, which was above 10 km/s on impact. It was also found that the rise time was almost independent of the collisional angle between the particles and the PZT surface within the limits of the particle's parameters used in this experiment. 相似文献