全文获取类型
收费全文 | 146篇 |
免费 | 11篇 |
国内免费 | 5篇 |
专业分类
测绘学 | 3篇 |
大气科学 | 1篇 |
地球物理 | 65篇 |
地质学 | 19篇 |
海洋学 | 24篇 |
天文学 | 44篇 |
综合类 | 1篇 |
自然地理 | 5篇 |
出版年
2021年 | 1篇 |
2019年 | 4篇 |
2018年 | 3篇 |
2017年 | 5篇 |
2016年 | 4篇 |
2015年 | 3篇 |
2014年 | 9篇 |
2013年 | 8篇 |
2012年 | 6篇 |
2011年 | 10篇 |
2010年 | 7篇 |
2009年 | 13篇 |
2008年 | 2篇 |
2007年 | 2篇 |
2006年 | 3篇 |
2005年 | 5篇 |
2004年 | 4篇 |
2003年 | 4篇 |
2002年 | 6篇 |
2001年 | 9篇 |
2000年 | 1篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 3篇 |
1995年 | 1篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1986年 | 5篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1973年 | 2篇 |
1972年 | 4篇 |
1971年 | 1篇 |
1969年 | 4篇 |
1968年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有162条查询结果,搜索用时 20 毫秒
21.
Horizontal bidirectional loading tests are conducted for real-sized high-damping rubber (HDR) bearings with diameters of 700 mm (HDR700) and 1300 mm (HDR1300). The hysteresis loops of these bearings under bidirectional horizontal loadings are compared with those under unidirectional loadings. The results show that the bearing force measurement in the primary direction of loading increases when there is displacement in the orthogonal direction. Unusually, the maximum restoring force in the orthogonal direction to the primary loading direction occurs near zero displacement. On the basis of the observations of the restoring forces, a rate-independent model is proposed. This model simulates well the test results under both bidirectional loading and unidirectional loading. It can reproduce the irregular restoring forces characteristics around zero displacement as described above. Bidirectional loading induced twist deformation in the HDR bearings that increased local shear strains. This phenomenon results in an early failure as observed in HDR700. The additional shear strain is estimated based on the twist deformation measured by video image analysis. The comparison of the nominal total shear stress demonstrates that the increase of shear stress because of bidirectional loading occurs when the average shear strain is larger than about 200%. The larger the shear strain, the greater the bidirectional effect. It is shown that the nominal total shear stress of average strain of 350% under bidirectional circular loading pattern is approximately the same as the average shear strain of 400% under unidirectional loading. This means that the average shear strain of 350% under a bidirectional circular loading corresponds to a local shear strain of 400%. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
22.
Anton Varlamov Natalia Smirnova Masashi Hayakawa Kiyohumi Yumoto 《Acta Geophysica》2012,60(3):928-941
Fractal analysis of magnetic records (1 Hz sampling rate) of 5 stations (Guam, Moshiri, Paratunka, Magadan, and Chokurdakh)
located along the 210 magnetic meridian (210 MM) has been performed using the Higuchi method. The period of 22 months (October
1992 to July 1994) that embodies the date of the strong Guam earthquake of 8 August1993 has been considered. A comparison
of the ULF emissions scaling parameters (spectral exponents β and fractal dimensions D) obtained at different latitudes has been made. Dependence of β and D on the Kp index of geomagnetic activity has been analyzed for each of the 24 local time intervals. It is revealed that D decreases ( β increases) with increasing geomagnetic activity at all stations, but the rates of decrease (increase) are different at different
stations and in different time intervals. It is shown that the evening, night and early morning hours are preferable to study
magnetospheric effects, whereas the noon hours are the most suitable for the analysis of lithospheric effects. A possibility
of using the data of the 210 MM stations as reference materials for the Guam seismically active area is discussed. 相似文献
23.
Irina G. Kudintseva Alexander P. Nickolaenko Masashi Hayakawa 《Surveys in Geophysics》2010,31(4):427-448
We describe the space–time distribution of the pulsed electric field in the middle atmosphere above a positive Γ-shaped lightning
stroke. The channel of such a discharge contains a vertical and a horizontal section. The current wave moves initially vertically
and then turns horizontally so that radiation appears from the vertical electric dipole followed by that from the horizontal
dipole. Combined with reflection from the perfectly conducting ground, the source provides three subsequent pulses in the
atmosphere, with the lag being determined by the finite velocity of the current wave in the Γ-shaped stroke. The pulses are
reproduced by reflections from the air-ground and the air-ionosphere interfaces and the waveform resembles the M-component,
which is often noted in the negative strokes (e.g. Yashunin et al., J Geophys Res 112:D10109, 2007). The non-stationary fine structure appears in the spatial distribution of electric field, which persists for 2 ms or even
more and exceeds the runaway electron threshold. Estimates support the idea of free electron bunching in the mesosphere by
the pulsed electric field. Focusing may occur about 10 km away from the point of electron- field interaction; it is delayed
by a few ms from the moment of interaction. The data presented might be helpful in realistic modeling of the red sprite formation. 相似文献
24.
Yanjun Shen Taikan Oki Shinjiro Kanae Naota Hanasaki Nobuyuki Utsumi Masashi Kiguchi 《水文科学杂志》2013,58(10):1775-1793
AbstractChanges in water resources availability, as affected by global climate warming, together with changes in water withdrawal, could influence the world water resources stress situation. In this study, we investigate how the world water resources situation will likely change under the Special Report on Emissions Scenarios (SRES) by integrating water withdrawal projections. First, the potential changes in water resources availability are investigated by a multi-model analysis of the ensemble outputs of six general circulation models (GCMs) from organizations worldwide. The analysis suggests that, while climate warming might increase water resources availability to human society, there is a large discrepancy in the size of the water resource depending on the GCM used. Secondly, the changes in water-stressed basins and the number of people living in them are evaluated by two indices at the basin scale. The numbers were projected to increase in the future and possibly to be doubled in the 2050s for the three SRES scenarios A1b, A2 and B1. Finally, the relative impacts of population growth, water use change and climate warming on world water resources are investigated using the global highly water-stressed population as an overall indicator. The results suggest that population and socio-economic development are the major drivers of growing world water resources stress. Even though water availability was projected to increase under different warming scenarios, the reduction of world water stress is very limited. The principal alternative to sustainable governance of world water resources is to improve water-use efficiency globally by effectively reducing net water withdrawal.
Editor Z.W. Kundzewicz; Associate editor D. Gerten 相似文献
25.
Nobuyuki Morikawa Shigeki Senna Yuzuru Hayakawa Hiroyuki Fujiwara 《Pure and Applied Geophysics》2011,168(3-4):645-657
The strong ground motion prediction method ??Recipe?? was published by the Headquarters for Earthquake Research Promotion (HERP) of Japan. HERP has applied this method to prepare shaking maps for scenario earthquakes in specific active faults. Recently, Recipe was updated following its verification by simulations of strong ground motions associated with the Mw?=?6.6 off-shore earthquake west of Fukuoka prefecture in 2005, which occurred in the northwest part of the Kego fault zone located in northern Kyushu, Japan. One of the prominent changes in the upgraded version of Recipe is the inclusion of a procedure to evaluate seismic intensities on the ground surface from waveforms of S-wave velocity of 400?m/s on the engineering bedrock. By applying the upgraded version of Recipe, we have made shaking-maps for earthquakes in the southeast part of the Kego fault zone, which is located directly below the mega-city of Fukuoka. We assume four source models for scenario earthquakes; the locations of the asperities and the hypocenters vary between the models. The results show that in all cases, disastrous seismic intensities can strike a wide area of Fukuoka city. Differences in the distributions of seismic intensities among the four cases can be clearly observed in the area located on the extension of the source fault. Furthermore, we construct a velocity-layer structure model on the engineering bedrock for the central area of Fukuoka city. We assess not only the distribution of seismic intensities but also waveforms on the ground by using an equivalent linear method for the central area of Fukuoka city. 相似文献
26.
K. Myokei Y. Matsudo T. Asano T. Suzuki Y. Hobara K. Michimoto M. Hayakawa 《Journal of Atmospheric and Solar》2009,71(5):597-602
Continuous observations of sprites in the Hokuriku area of Japan were performed from two optical sites during the three winter periods. The purpose of this observation is to study the major effect in the appearance of sprites and in determining the morphology of sprites (columns or carrots). Detailed analysis is performed based on the estimation of the height of ?10 °C at the time of sprite occurrence. When the height of ?10 °C is lower than 1800 m, the occurrence of sprites is infrequent, and the dominant shape is column. Then when it is increased (1800–3000 m), a new situation takes place, namely the occurrence of sprites is very enhanced and more spectacular shapes like carrots tend to be frequently observed in addition to column sprites. These sprite characteristics are first compared with those of parent lightning in the Hokuriku area and with our latest computer simulations on sprite initiation. 相似文献
27.
Three-dimensional EM computer simulation on sprite initiation above a horizontal lightning discharge
The purpose of this paper is to study the three-dimensional (3D) effects of the source current and the electromagnetic (EM) pulse on the distribution of upper atmospheric electric field and ionization created. A new lightning model has been employed; i.e., we have included a horizontal channel in addition to the conventional vertical channel. The effects of the horizontal lightning channel are summarized as follows: (1) the effect of a vertical channel plays a fundamental role in the whole view of sprite initiation; (2) the position of a sprite is shifted from the position of its parent vertical channel in response to the length of a horizontal channel; and (3) we observe very fine structures with local maxima and minima in the “reduced” electric field (the electric field divided by the neutral gas density). These theoretical inferences are discussed and compared with the observational facts so far reported (such as lateral shift of sprites, morphological difference of sprites, etc.). 相似文献
28.
29.
This study presents the dynamic behaviour of a rigid block which rests on a footing supported by a spring and a dashpot on a rigid base. The response of the rigid body is examined carefully when the base is excited by a harmonic force. It is found that a periodic motion appears in three different modes: stick-stick, stick-slip and slip-slip. The conditions that initiate the stick-stick and slip-slip modes are derived in explicit forms and the maximum sliding displacement is also obtained analytically. Useful dimensionless parameters are proposed for the presentation of the dynamic behaviour. The accuracy of results is confirmed by the response history computed by the Nigam-Jennings method. 相似文献
30.
The correlation of whistler occurrence rate at a low latitude with thunderstorm activity at its conjugate region and with solar activity 总被引:1,自引:0,他引:1
The correlations of occurrence rate of whistlers in January during one solar cycle (1977–1987) at a low latitude station (Yamaoka, geomag. lat. 25°, L=1.26) with thunderstorm activity near its conjugate region and also with solar activity have been investigated, and it is found that the occurrence rate has no correlation with the lightning flashes near the conjugate point, while it is negatively correlated with solar activity. On the basis of these findings it is suggested that the ionospheric absorption is of major importance in the long-term variation of whistler occurrence rate, with the duct formation being of secondary effect, while the lightning activity is only a necessary condition for whistler occurrence. 相似文献