全文获取类型
收费全文 | 146篇 |
免费 | 6篇 |
专业分类
测绘学 | 1篇 |
大气科学 | 6篇 |
地球物理 | 42篇 |
地质学 | 29篇 |
海洋学 | 17篇 |
天文学 | 40篇 |
综合类 | 1篇 |
自然地理 | 16篇 |
出版年
2022年 | 1篇 |
2021年 | 2篇 |
2019年 | 6篇 |
2018年 | 2篇 |
2017年 | 2篇 |
2016年 | 4篇 |
2014年 | 3篇 |
2013年 | 5篇 |
2012年 | 7篇 |
2011年 | 9篇 |
2010年 | 14篇 |
2009年 | 16篇 |
2008年 | 7篇 |
2007年 | 3篇 |
2006年 | 2篇 |
2005年 | 2篇 |
2004年 | 2篇 |
2003年 | 4篇 |
2002年 | 3篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1998年 | 4篇 |
1997年 | 5篇 |
1996年 | 4篇 |
1995年 | 5篇 |
1994年 | 5篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1989年 | 2篇 |
1987年 | 2篇 |
1986年 | 5篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1978年 | 4篇 |
1976年 | 1篇 |
1971年 | 1篇 |
1969年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有152条查询结果,搜索用时 15 毫秒
101.
A double-planed structure of deep seismic zone has been found over a wide area more then 300 km × 200 km in the Tohoku District, the northeastern part of Honshu, Japan. This prominent feature of the configuration of the deep seismic zone has been ascertained through a precise determination of the microearthquake hypocenters by using the data from the seismic network of Tohoku University. The two planes are nearly parallel to each other, the distance between the two planes being from 30 to 40 km.Composite focal mechanism solutions are derived from the superposition of the distribution of first motions of P waves, and the different fault types are obtained for the two groups of earthquakes; the earthquakes which occurred in the upper plane are characterized by reverse faulting, some of them by down-dip compressional stresses, and those in the lower plane by down-dip extensional stresses. The evidence obtained here provides valuable information for the definition of the type of mechanism producing the plate motion beneath the island arc. 相似文献
102.
Induced seismicity in mines in Canada—An overview 总被引:1,自引:0,他引:1
Henry S. Hasegawa Robert J. Wetmiller Don J. Gendzwill 《Pure and Applied Geophysics》1989,129(3-4):423-453
Monitoring of mine-induced seismicity in Canada has improved with the expansion of regional seismograph networks into areas of active mining. However, the severity, and in some cases the frequency, of mine-induced tremors has increased as mining extends to greater depths and at accelerated rates of extraction. Because of the complex design and large areal extent of many mines (potash, coal and metalliferous), the most feasible and practical way to monitor these tremors at the present time is to deploy a network of seismometers in and on the surface above mines experiencing microearthquake activity. A few of these mines already have a network of seismometers deployed around them and plans are under way to deploy seismograph networks around other mines that have experienced some rather severe tremors in recent times. Six possible mechanisms for mine-induced tremors are described and the associatedP- andS-wave radiation patterns presented. A comparison of actual seismic radiation patterns with theoretical predictions is a quick way to diagnose the potential source mechanisms. In addition, recognizing the pattern of microearthquake activity preceding larger tremors can be used to mitigate the potential effects of severe tremors. 相似文献
103.
104.
Omodaka Toshihiro Hayashi Masahiko Suzuki Saeko Hasegawa Tetsuo Miyawaki Ryosuke 《Astrophysics and Space Science》1986,118(1-2):401-404
High resolution strip maps of CS (J=1–0) and H51 line emission across the Orion bright bar are presented. They reveal the existence of a high density molecular layer (molecular sheet) plane parallel to the ionization front. This molecular sheet is redshifted relative to the ambient molecular cloud by about 2 km s–1. The rapid decrease of the CS emission at about 50 arc sec from the bar suggests that a shock front exists here and the sheet is a post shock layer.Paper presented at the IAU Third Asian-Pacific Regional Meeting, held in Kyoto, Japan, between 30 September–6 October, 1984.This work was carried out under the common use observation program at the Nobeyama Radio Observatory (NRO). NRO, a branch of the Tokyo Astronomical Observatory, University of Tokyo, Japan, is a cosmic radio observing facility open to outside users. 相似文献
105.
106.
107.
Seiichi Sakamoto Glenn J. White Kentarou Kawaguchi Masatoshi Ohishi Kumiko S. Usuda & Tetsuo Hasegawa 《Monthly notices of the Royal Astronomical Society》1998,301(3):872-880
Absorption lines of MgH and CaH N = 1 − 0 transitions were searched for in foreground molecular clouds towards the continuum sources associated with Sgr B2 (M) and W49A (N). None of these lines was detected with our sensitivity level of ∼20 mK. Millimetric absorption lines of MgO, MgOH, CaO and CaOH were also searched for towards Sgr B2 (M) without success. The fractional abundances relative to molecular hydrogen are ≲ 1.0 × 10−11 for MgH, ≲ 7.9 × 10−13 for MgO, ≲ 1.6 × 10−10 for MgOH, ≲ 1.6 × 10−9 for CaH, ≲ 2.0 × 10−12 for CaO, and ≲ 2.5 × 10−10 for CaOH, respectively. The low abundances measured in absorption indicate that a significant fraction of interstellar magnesium and calcium cannot be tied up in their monohydrides, monoxides and monohydroxides. The low abundance of MgH also implies that grain-surface chemistry involving magnesium is not efficient and that magnesium is depleted on to grains to a factor of ≳ 102.5 in well-shielded molecular clouds. 相似文献
108.
N. Hirano T. Hasegawa M. Hayashi M. Tamura N. Ohashi 《Astrophysics and Space Science》1995,224(1-2):113-116
We have searched for CO outflows in eight embedded IRAS sources located in the Taurus molecular cloud using the 45m telescope of Nobeyama Radio Observatory. We have detected CO wing emission in four of these sources. CO outflow associated with TMC1A (04365+2535) is strong and spatially compact (radius 0.04 pc). The dynamical timescale of 2.5 × 103 yr suggests this outflow is the youngest one in Taurus.We have combined our data with previously published survey data and have analyzed the physical properties of the outflow sources. We found that 12 out of 16 embedded sources ( 75 %) have CO outflows associated with them; this indicates that almost all stars experience a phase of molecular outflow in their embedded stage. The IRAS color of the outflow sources suggests that the outflows appear in considerably early phase of the evolution of YSOs, that is, as early as YSOs became observable with IRAS and that visible outflow sources are in a transient phase of evolution between embedded sources and visible T Tauri stars without outflow. Visible outflow sources are systematically more luminous than visible no-outflow sources, while embedded outflow sources have comparable luminosities with visible no-outflow sources. Such luminosity function suggests that the YSOs with outflow undergo mass accretion and increase their stellar mass as they progress from embedded sources to visible outflow sources. Typical mass accretion rate derived from the bolometric luminosity is 2 ×10–6
M
yr
–1. The timescale for mass accretion to acquire typical stellar mass, 0.5 – 0.8M
, is 2.5 – 4 × 105 yr. 相似文献
109.
We estimated three-dimensional P- (Vp) and S-wave velocity (Vs) and Vp/Vs structures in and around the Onikobe volcanic area, northeastern Japan, by local travel time tomography. We used travel time data from source and receiver pairs located within and outside the study area, which plays an important role in obtaining the optimum ray coverage and in elucidating the deeper structure more accurately. Detailed information on deeper structures is essential for imaging the complete volcanic system from the magmatic source zone through areas of shallow hydrothermal circulation. More than 50 000 travel time data for the P-waves and 35 000 for the S-waves were used to image the velocity structure. Our results show the following dominant features: (1) two conduits in the upper crust with low Vp and low Vs indicative of H2O-rich fluid pathways: one lying beneath Naruko volcano, the other beneath the focal area of the 1962 Northern Miyagi earthquake (M6.5); (2) an underlying broad region in the lower crust with low Vp, low Vs and high Vp/Vs, suggestive of a zone of partial melt, from which the fluids in (1) are derived; and (3) low Vp/Vs areas near the surface of the Sanzugawa and Onikobe calderas, suggesting a diffuse vapor-saturated cap. 相似文献
110.
Numerical simulations using a full-nonlinear BIM (Boundary Integral Method) potential-theory wave model are carried out to study the internal velocity and acceleration fields of an solitary wave overturning on a reef with vertical face (submerged breakwater) and their relation to breaker type. The simulations make it clear that the jet size normalized by the incident wave height is uniquely governed by the crown height of the reef, while the jet shape is similar and independent of the size. Further, they reveal that the overall internal kinematics of overturning waves is clearly related to the jet size. As the jet size increases and the breaker type changes from spilling to plunging, the kinematics thus become increasingly different from those of steady waves. Water particles with the greatest velocities or accelerations within the wave converge towards the jet. After the breaking, both of the velocities and accelerations almost simultaneously reach extreme values near locations beneath the jet. Some of the extreme values are closely related to the breaker type and can be uniquely determined by substituting the breaker type index into the regression equations suggested here. 相似文献