全文获取类型
收费全文 | 6062篇 |
免费 | 1798篇 |
国内免费 | 1313篇 |
专业分类
测绘学 | 90篇 |
大气科学 | 90篇 |
地球物理 | 3374篇 |
地质学 | 4446篇 |
海洋学 | 277篇 |
天文学 | 6篇 |
综合类 | 601篇 |
自然地理 | 289篇 |
出版年
2024年 | 54篇 |
2023年 | 133篇 |
2022年 | 219篇 |
2021年 | 280篇 |
2020年 | 228篇 |
2019年 | 347篇 |
2018年 | 276篇 |
2017年 | 281篇 |
2016年 | 330篇 |
2015年 | 317篇 |
2014年 | 363篇 |
2013年 | 391篇 |
2012年 | 374篇 |
2011年 | 334篇 |
2010年 | 329篇 |
2009年 | 435篇 |
2008年 | 429篇 |
2007年 | 375篇 |
2006年 | 414篇 |
2005年 | 317篇 |
2004年 | 362篇 |
2003年 | 284篇 |
2002年 | 252篇 |
2001年 | 261篇 |
2000年 | 260篇 |
1999年 | 171篇 |
1998年 | 195篇 |
1997年 | 172篇 |
1996年 | 171篇 |
1995年 | 163篇 |
1994年 | 158篇 |
1993年 | 130篇 |
1992年 | 105篇 |
1991年 | 50篇 |
1990年 | 42篇 |
1989年 | 48篇 |
1988年 | 37篇 |
1987年 | 30篇 |
1986年 | 8篇 |
1985年 | 10篇 |
1984年 | 4篇 |
1983年 | 2篇 |
1980年 | 1篇 |
1979年 | 21篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1954年 | 8篇 |
排序方式: 共有9173条查询结果,搜索用时 0 毫秒
211.
212.
213.
阿尔金造山带中、新生代的演化 总被引:18,自引:2,他引:18
塔里木盆地东缘的阿尔金造山带中、新生代经历了一个复杂的大地构造演化历程:中生代早期(T)为隆升夷平,中生代中后期(J-K)为裂陷沉积阶段;自古新世-中新世因塔里木盆地向东挤压使得阿尔金造山带东南缘出现了右行走滑仰冲,柴达木壳体向阿尔金造山带之下俯冲,阿尔金造山带隆起.塔里木盆地相对柴达木盆地向北移动,最大距离可达400~500 km,使得原来统一的塔里木-敦煌-柴达木联合盆地裂解.由于逆冲走滑使阿尔金造山带内部发育了一系列小型的走滑盆地,形成了复杂的盆地沉积建造,并伴有动力变质及火山作用;中新世末,东西向挤压转变为不对称的南北向力隅作用,使得阿尔金造山带发生构造反转,右行转变为左行,统一的塔里木-敦煌盆地裂解.塔里木盆地向南漂移,距离达400多公里.塔里木盆地的向东俯冲使阿尔金造山带急骤隆起,同样,在阿尔金造山带内部发育了一系列小型盆地,形成了相应的复杂沉积建造. 相似文献
214.
215.
Agust Gudmundsson 《Comptes Rendus Geoscience》2004,336(1):85-92
Elastic crack models predict a linear relationship between displacement (u) and rupture (trace) length (L) during slip in a fault zone. Attempts to find universal-scaling laws for L/u, however, have generally failed. Here I propose that these attempts have failed because they do not take into account the changes in the mechanical properties, in particular Young's modulus (stiffness), of the fault zone as it evolves. I propose that Young's modulus affects fault displacement both spatially and temporally: spatially when the trace of a fault at a given time dissects host rocks of different stiffnesses, and temporally when the stiffness of the fault zone itself changes. During the evolution of an active fault zone, the effective Young's modulus of its damage zone and fault core normally decreases, and so does the L/u ratio of the fault. By contrast, during inactive periods sealing and healing of the damage zone and core may increase the stiffness, hence the L/u ratio in subsequent slips. This model predicts that not only will the scaling of L/u within a given fault population vary in space and time, but also that of individual faults. To cite this article: A. Gudmundsson, C. R. Geoscience 336 (2004). 相似文献
216.
Indian peninsular shield, which was once considered to be seismically stable, is experiencing many earthquakes recently. As
part of the national level microzonation programme, Department of Science and Technology, Govt. of India has initiated microzonation
of greater Bangalore region. The seismic hazard analysis of Bangalore region is carried out as part of this project. The paper
presents the determination of maximum credible earthquake (MCE) and generation of synthetic acceleration time history plot
for the Bangalore region. MCE has been determined by considering the regional seismotectonic activity in about 350 km radius
around Bangalore city. The seismotectonic map has been prepared by considering the faults, lineaments, shear zones in the
area and historic earthquake events of more than 150 events. Shortest distance from the Bangalore to the different sources
is measured and then peak ground acceleration (PGA) is calculated for the different source and moment magnitude. Maximum credible
earthquake found in terms of moment magnitude is 5.1 with PGA value of 0.146 g at city centre with assuming the hypo central
distance of 15.88 km from the focal point. Also, correlations for the fault length with historic earthquake in terms of moment
magnitude, yields (taking the rupture fault length as 5% of the total fault length) a PGA value of 0.159 g. Acceleration time
history (ground motion) and a response acceleration spectrum for the corresponding magnitude has been generated using synthetic
earthquake model considering the regional seismotectonic parameters. The maximum spectral acceleration obtained is 0.332 g
for predominant period of 0.06 s. The PGA value and synthetic earthquake ground motion data from the identified vulnerable
source using seismotectonic map will be useful for the PGA mapping and microzonation of the area. 相似文献
217.
Deep-large faults in the central continental margin of eastern China are well developed. Based on the regularity of spatial
and temporal distribution of the faults, four fault systems were divided: the Yanshan orogenic belt fault system, the Qinling-Dabie-Sulu
orogenic belt fault system, the Tanlu fault system and the East China Sea shelf basin-Okinawa trough fault system. The four
fault systems exhibit different migration behaviors. The Yanshan orogenic belt fault system deflected from an EW to a NE direction,
then to a NNE direction during the Indo-Chinese epoch-Yanshanian epoch. The thrust-nappe strength of the Qinling-Dabie orogenic
belt fault system showed the tendency that the strength was greater in the south and east, but weaker in the north and west.
This fault system faulted in the east and folded in the west from the Indo-Chinese epoch to the early Yanshanian epoch. At
the same time, the faults also had a diachronous migration from east to west from the Indo-Chinese epoch to the early Yanshanian
epoch. On the contrary, the thrust-nappe strength was greater in the north and west, weaker in the south and east during the
late Yanshanian epoch-early Himalayan epoch. The Tanlu fault system caused the basin to migrate from west to east and south
to north. The migration regularity of the East China Sea shelf basin-Okinawa trough fault system shows that the formation
age became younger in the west. The four fault systems and their migration regularities were respectively the results of four
different geodynamic backgrounds. The Yanshan orogenic belt fault system derived from the intracontinental orogeny. The Qinling-Dabie-Sulu
orogenic belt fault system derived from the collision of plates and intracontinental subduction. The Tanlu fault system derived
from the strike-slip movement and the East China Sea shelf basin-Okinawa trough fault system derived from plate subduction
and retreat of the subduction belt.
Translated from Journal of Jilin University (Earth Science Edition), 2005, 35(5): 554–563 [译自: 吉林大学学报 (地球科学版)] 相似文献
218.
岷山隆起西以岷江断裂为界,东为虎牙断裂。该地区构造活动强烈,地震活动频繁,是重要活动区。岷山隆起是岷江断裂和虎牙断裂由西向东的推覆逆掩运动差异运动导致的。GPS及地质研究表明岷江断裂、虎牙断裂现今仍在活动。岷江断裂为左右旋走滑断裂,运动速度大于2mm/a;虎牙断裂整体速度2.55mm/a,断裂性质为右旋走滑断裂,而震源机制解为左旋走滑断裂。这一结果,可能与GPS观测时段、位置及断裂面结构、几何特征有关。 相似文献
219.
东吉庄矿泉水是1989年由地质矿产部环境管理司会同卫生部、轻工业部等有关单位的国家饮用天然矿泉水技术评审组鉴定通过,符合GB8537-87的国家标准要求,属含锶重碳酸镁·钙·钠型低矿化度中性饮用天然矿泉水,已于同年建立了奥玉饮料厂,生产瓶装矿泉水及奥玉饮料。为了保护矿泉水资源免遭环境污染,对该矿泉水水源地进行了水源地保护规划。 相似文献
220.