全文获取类型
收费全文 | 90篇 |
免费 | 5篇 |
国内免费 | 2篇 |
专业分类
测绘学 | 2篇 |
大气科学 | 7篇 |
地球物理 | 34篇 |
地质学 | 22篇 |
海洋学 | 22篇 |
天文学 | 8篇 |
综合类 | 1篇 |
自然地理 | 1篇 |
出版年
2022年 | 1篇 |
2021年 | 1篇 |
2020年 | 1篇 |
2019年 | 2篇 |
2018年 | 3篇 |
2017年 | 2篇 |
2016年 | 3篇 |
2015年 | 2篇 |
2014年 | 2篇 |
2013年 | 6篇 |
2012年 | 10篇 |
2011年 | 4篇 |
2010年 | 8篇 |
2009年 | 4篇 |
2008年 | 9篇 |
2006年 | 4篇 |
2005年 | 1篇 |
2004年 | 4篇 |
2003年 | 2篇 |
2002年 | 2篇 |
2001年 | 3篇 |
1999年 | 3篇 |
1998年 | 6篇 |
1996年 | 1篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1977年 | 1篇 |
排序方式: 共有97条查询结果,搜索用时 15 毫秒
91.
Evidence for abrupt coastal uplifts has been found in emerged sessile assemblages in a sea cave at the southern end of the Izu Peninsula, central Japan. We identified five sessile assemblage zones: Zones I to V, in ascending order. The uppermost zone (Zone I), located at an elevation of 2.7–3.5 m above the present‐day mean sea level (amsl), is a hard massive shellcrust consisting mainly of the barnacles Chthamalus challenger and the tube worm Pomatoleios kraussii. Zone II, at 2.35–2.7 m amsl, is dominated by well‐preserved individuals of C. challenger. Zone III, at 2.0–2.35 m amsl, is strongly eroded and consists mainly of C. challenger and P. kraussii. Zone IV, at 1.6–2.0 m amsl, is characterized by the co‐occurrence of very fresh shells of C. challenger and P. kraussii. Zone V (the lowest zone), at 1.0–1.60 m amsl, is characterized by the co‐occurrence of very fresh shells of Saccostrea kegaki and P. kraussii, and by the absence of C. challenger. Radiocarbon dating by accelerator mass spectrometry (AMS) and the presence of modern taxa in the sessile assemblages suggest that three episodes of coastal uplift have occurred in the area, during AD 570–820, AD 1000–1270, and AD 1430–1660, with magnitudes of 0.9–2.0 m, 0.3–0.8 m, and 1.9–2.2 m, respectively. 相似文献
92.
Masato Saitoh 《地震工程与结构动力学》2012,41(4):623-641
Lumped parameter models with a so called “gyro‐mass” element (GLPMs) have been proposed recently in response to a strong demand for efficiently and accurately representing frequency‐dependent impedance functions of soil–foundation systems. Although GLPMs are considered to be powerful tools for practical applications in earthquake engineering, some problems remain. For instance, although GLPMs show fairly close agreement with the target impedance functions, the accuracy of the transfer functions and the time‐histories of dynamic responses in structural systems comprising GLPMs have never been verified. Furthermore, no assessment has been performed on how much difference appears in the accuracy of dynamic responses obtained from GLPMs and those from conventional Kelvin–Voigt models comprising a spring and a dashpot arranged in parallel with various frequency‐independent constants. Therefore, in this paper, these problems are examined using an example of 2×4 pile groups embedded in a layered soil medium, supporting a single‐degree‐of‐freedom system subjected to ground motions. The results suggest that GLPMs are a new option for highly accurate computations in evaluating the dynamic response of structural systems comprising typical pile groups, rather than conventional Kelvin–Voigt models. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
93.
Characteristics of ChgH–GFP transgenic medaka lines, an in vivo estrogenic compound detection system
We previously reported the characteristics of a ChgH–GFP transgenic medaka line that indicates estrogenic compound pollution in environmental water by the green fluorescence of their liver. Recently, we established four more lines. In this study, the characteristics of the five transgenic medaka lines were investigated. The intensity of reporter gene expression varied among transgenic lines and generally correlated well with the amount of integrated transgene in each line. Line-specific ectopic expression was also observed. However, the sensitivity to 17-β estradiol did not differ among transgenic lines. Three transgenic lines are considered to be suitable as bio-indicators of estrogenic activity, due to the ease of observing green fluorescence in their livers. The transgenic lines can also detect the estrogenic activity of testosterone and 17-β trenbolone at the nominal concentration of 30 and 100 μg/l, respectively. 相似文献
94.
Masato Iguchi Hiroshi Yakiwara Takeshi Tameguri Muhamad Hendrasto Jun-ichi Hirabayashi 《Journal of Volcanology and Geothermal Research》2008
A common sequence of phenomena associated with volcanic explosions is extracted based on seismic and ground deformation observations at 3 active volcanoes in Japan and Indonesia. Macroscopic inflation-related ground deformations are detected prior to individual explosions, while deflations are observed during eruptions. Precursory inflation occurs 5 min to several hours before eruption at the Sakurajima volcano, but just 1–2 min at Suwanosejima and 3–30 min at the Semeru volcano. The sequence commences with minor contraction, which is detected by extensometers 1.5 min before eruption at Sakurajima, as a dilatant first motion of the explosion earthquakes 0.2–0.3 s before surface explosions at Suwanosejima, and as downward tilt 4–5 s prior to eruption at the Semeru volcano. The sequence is detected for explosive eruptions with > 0.1 μrad tilt change at Sakurajima, 90% at Suwanosejima and 75% at Semeru volcanoes. It is inferred that the minor contraction is caused by a volume and pressure decrease due to the release of gas from a pocket at the top of the conduit as the gas pressure exceeds the strength of the confining plug. The subsequent violent expansion may be triggered by sudden outgassing of the water-saturated magma induced by the decrease in confining pressure. 相似文献
95.
In order to clarify the time relation of the expansion of a gas pocket and failure of its overlying plug of lava during Vulcanian
eruptions, infrasound records and video images of the Vulcanian eruption that occurred at Sakurajima volcano on January 2,
2007 were analyzed with respect to their origin times. Weak (≤3 Pa) and slowly increasing air pressure preceded the impulsive
compression phase by 0.25–0.32 s, and a longer-period rarefaction phase of infrasound waves was recognized at all microphone
stations. The velocity of the compression phase was assumed to be supersonic (ca. 400 m/s) up to 850 m above the crater bottom
from other recent explosions. On the other hand, the propagation velocity of the preceding weak signal was regarded to be
similar to the air sound velocity because the lack of impulsiveness is unlikely to be related to the main compression phase.
Therefore, the estimated origin time of the main compression phase was delayed by 0.5–0.7 s from the preceding phase. The
origin time of the preceding phase coincided with the onset of the isotropic expansion process of the pressurized gas pocket,
which was obtained by the waveform inversion of the explosion earthquake. In contrast, the origin time of the main impulsive
phase coincided with the time when the expansion rate reached its peak. This observation suggests that the volumetric increase
of the gas pocket caused swelling of the surface of the crater bottom and its subsequent failure. When the expansion velocity
exceeded a threshold level, the main impulsive compression phase radiated with a high velocity by the sudden releases of the
pressurized gases. The volumetric change at the source was estimated to be 280–560 m3 from the preceding phase of the infrasound. This volume change indicates that the vertical displacement of the swelling ground
was on the order of 1.0 m, assuming the radius of the lava plug was ca. 10 m. 相似文献
96.
97.
Effect of local nonlinearity in cohesionless soil on optimal radius minimizing fixed-head pile bending by inertial and kinematic interactions 总被引:1,自引:1,他引:0
Masato Saitoh 《Acta Geotechnica》2010,5(4):273-286
This study presents the effects of a local nonlinearity in cohesionless soil upon the optimal radius minimizing the bending
strains of a vertical, cylindrical fixed-head pile embedded in a layered soil stratum in a soil–pile–structure system where
the kinematic interaction dominates. The seismic deformation method (SDM) with discretized numerical models is applied since
the SDM is a static numerical method that can easily consider realistic conditions of layered soil strata and the nonlinearity
of the soil. In the numerical models, the local nonlinearity of the soil in the vicinity of the pile is represented by subgrade
springs having bi-linear skeleton curves with a simple hysteretic loop. Various amplitudes of the lateral displacements of
the soil and the lateral forces at the head of the pile are considered as numerical parameters. The results of parametric
analyses reveal the presence of an optimal pile radius that locally minimizes the bending strains of the piles under strong
nonlinearity of the soil, and the optimal pile radius tends to increase as the degree of nonlinearity increases. Criteria
are presented for predicting the increment in the optimal radius of soil–pile–structure systems under strong nonlinearity
in the soil. 相似文献