全文获取类型
收费全文 | 441篇 |
免费 | 43篇 |
国内免费 | 35篇 |
专业分类
测绘学 | 17篇 |
大气科学 | 29篇 |
地球物理 | 124篇 |
地质学 | 133篇 |
海洋学 | 42篇 |
天文学 | 59篇 |
综合类 | 27篇 |
自然地理 | 88篇 |
出版年
2024年 | 1篇 |
2022年 | 10篇 |
2021年 | 8篇 |
2020年 | 12篇 |
2019年 | 7篇 |
2018年 | 11篇 |
2017年 | 13篇 |
2016年 | 15篇 |
2015年 | 10篇 |
2014年 | 17篇 |
2013年 | 20篇 |
2012年 | 14篇 |
2011年 | 16篇 |
2010年 | 18篇 |
2009年 | 25篇 |
2008年 | 51篇 |
2007年 | 27篇 |
2006年 | 38篇 |
2005年 | 20篇 |
2004年 | 21篇 |
2003年 | 14篇 |
2002年 | 18篇 |
2001年 | 16篇 |
2000年 | 10篇 |
1999年 | 14篇 |
1998年 | 12篇 |
1997年 | 10篇 |
1996年 | 13篇 |
1995年 | 7篇 |
1994年 | 3篇 |
1993年 | 6篇 |
1992年 | 4篇 |
1991年 | 8篇 |
1990年 | 10篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1984年 | 1篇 |
1983年 | 3篇 |
1981年 | 1篇 |
1978年 | 2篇 |
1977年 | 2篇 |
排序方式: 共有519条查询结果,搜索用时 15 毫秒
471.
Simplified algorithms for calculating double-couple rotation 总被引:3,自引:0,他引:3
Yan Y. Kagan 《Geophysical Journal International》2007,171(1):411-418
We derive new, simplified formulae for evaluating the 3-D angle of earthquake double-couple (DC) rotation. The complexity of the derived equations depends on both accuracy requirements for angle evaluation and the completeness of desired solutions. The solutions are simpler than my previously proposed algorithm based on the quaternion representation designed in 1991. We discuss advantages and disadvantages of both approaches. These new expressions can be written in a few lines of computer code and used to compare both DC solutions obtained by different methods and variations of earthquake focal mechanisms in space and time. 相似文献
472.
EARTHQUAKE FOCAL MECHANISM AND ITS TECTONIC SIGNIFICANCE ALONG THE TWO SIDES OF THE RED RIVER FAULT ZONE 总被引:1,自引:0,他引:1
The Red River Fault Zone is a gigantic slide-slip fault zone extending up to 1000km from Tibet to South China Sea. It has been divided into the north, central and south segments according to the difference of the geometry, kinetics, and seismicity on the land, but according to the contacted relationship between the old pre-Cenozoic block in Indochina Peninsula and the South China block, the Red River Fault Zone was divided into two parts extending from land to ocean, the north and south segments. Since the Tertiary, the Red River Fault Zone suffered first the sinistral movement and then the dextral movement. The activities of the north and the south segments were different. Based on the analysis of earthquakes and focal mechanism solutions, earthquakes with the focus depths of 0-33km are distributed over the whole region and more deep earthquakes are distributed on the northeastern sides of the Red River fault. Types of faulting activities are the thrust in the northwest, the normal in the north and the 相似文献
473.
474.
475.
476.
Jesús Carrera Xavier Sánchez-Vila Inmaculada Benet Agustín Medina Germán Galarza Jordi Guimerà 《Hydrogeology Journal》1998,6(1):178-190
Matrix diffusion has become widely recognized as an important transport mechanism. Unfortunately, accounting for matrix diffusion
complicates solute-transport simulations. This problem has led to simplified formulations, partly motivated by the solution
method. As a result, some confusion has been generated about how to properly pose the problem. One of the objectives of this
work is to find some unity among existing formulations and solution methods. In doing so, some asymptotic properties of matrix
diffusion are derived. Specifically, early-time behavior (short tests) depends only on φ
m
2
R
m
D
m
/ L
m
2, whereas late-time behavior (long tracer tests) depends only on φ
m
R
m
, and not on matrix diffusion coefficient or block size and shape. The latter is always true for mean arrival time. These
properties help in: (a) analyzing the qualitative behavior of matrix diffusion; (b) explaining one paradox of solute transport
through fractured rocks (the apparent dependence of porosity on travel time); (c) discriminating between matrix diffusion
and other problems (such as kinetic sorption or heterogeneity); and (d) describing identifiability problems and ways to overcome
them.
Received, October 1997 · Revised, November 1997 · Accepted, December 1997 相似文献
477.
478.
Earthquake swarms in California are often localized to areas within dextral offsets in the linear trend in active fault strands, suggesting a relation between earthquake swarms and local crustal spreading. Local crustal spereading is required by the geometry of dextral offsets when, as in the San Andreas system, faults have dominantly strike-slip motion with right-lateral displacement. Three clear examples of this relation occur in the Imperial Valley, Coso Hot Springs, and the Danville region, all in California. The first two of these areas are known for their Holocene volcanism and geothermal potential, which is consistent with crustal spreading and magmatic intrusion. The third example, however, shows no evidence for volcanism or geothermal activity at the surface. 相似文献
479.
Summary Focal mechanisms of 74 shallow and 16 intermediate earthquakes (1964–1970) in the Kamchatka-Commander region are discussed. Regional stress systems and the nature of faulting are analyzed. Complex stress fields in the Kamchatka-Commander region and variable aftershock processes of strong Kamchatka earthquakes show the existence of heterogeneities of the active seismic zone in the Region. 相似文献
480.
Mashael M. Al-Saud 《Arabian Journal of Geosciences》2008,1(1):49-61
Makkah and central Red Sea regions have been re-evaluated from recent earthquake data analysis. Epicenters of recent seismic
activity are concentrated in three local seismic zones. These are Ad Damm fault (NE), Nu’man–Makkah–Fatima (NW), and Jeddah-Red
Sea (NW) seismic zones. Moreover, an extended seismic zone along the central part of Red Sea is observed. Most of these epicenters
are distributed along tectonic faults, as indicated from the subsurface structure analysis of the aeromagnetic anomaly map.
Some epicenters of small magnitudes are inaccurately located. The study indicates the existence of large active structural
basin south of Makkah region, which traverse Ad Damm fault zone with the Red Sea transform faults. Slip vector analyses were
carried out for 50 available earthquake focal mechanisms around Makkah region. In Nu’man, Makkah, and Fatima structural zones,
the slip vectors generally trend NW and NNW. However, in the southern part at the Ad Dam structure zone, the slip vector trends
NE–SW. These may result from the current complicated drifting motion of Arabian plate away from African plate combined with
the opening of the Red Sea rift. 相似文献