全文获取类型
收费全文 | 111篇 |
免费 | 19篇 |
国内免费 | 18篇 |
专业分类
地球物理 | 53篇 |
地质学 | 41篇 |
海洋学 | 47篇 |
自然地理 | 7篇 |
出版年
2023年 | 2篇 |
2022年 | 4篇 |
2021年 | 7篇 |
2020年 | 7篇 |
2019年 | 11篇 |
2018年 | 12篇 |
2017年 | 6篇 |
2016年 | 1篇 |
2015年 | 6篇 |
2014年 | 8篇 |
2013年 | 6篇 |
2012年 | 6篇 |
2011年 | 3篇 |
2010年 | 3篇 |
2009年 | 3篇 |
2008年 | 6篇 |
2007年 | 4篇 |
2006年 | 4篇 |
2005年 | 4篇 |
2004年 | 9篇 |
2003年 | 5篇 |
2002年 | 2篇 |
2001年 | 2篇 |
2000年 | 3篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 4篇 |
1994年 | 5篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1984年 | 1篇 |
排序方式: 共有148条查询结果,搜索用时 15 毫秒
21.
PRELIMINARY STUDY OF PALEOEARTHQUAKES ON THE MIDDLE-EASTERN SEGMENT OF JINTA NANSHAN FAULT 下载免费PDF全文
Hexi Corridor is located at the northeastern margin of the Tibetan plateau. Series of late Quaternary active faults are developed in this area. Numerous strong earthquakes occurred in history and nowadays. Jinta Nanshan fault is one of the boundary faults between the Qinghai-Tibet block and the Alxa block. The fault starts from the northwest of Wutongdun in the west, passes through Changshan, Yuanyangchi reservoir, Dakouzi, and ends in the east of Hongdun.
Because the Jinta Nanshan fault is a new active fault in this region, it is important to ascertain its paleoearthquakes since late Pleistocene for the earthquake risk study. Previous studies were carried out on the western part, such as field geomorphic investigation and trench excavation, which shows strong activity in Holocene on the western segment of Jinta Nanshan fault. On the basis of the above research, in this paper, we carried out satellite image interpretation, detailed investigation of faulted landforms and differential GPS survey for the whole fault. Focusing on the middle-eastern part, we studied paleoearthquakes through trench exploration on the Holocene alluvial fan and optical luminescence dating.
The main results are as follows:Early Pleistocene to late Pleistocene alluvial strata are widely developed along the fault and Holocene sediment is only about tens of centimeters thick. The Jinta Nanshan fault shows long-lasting activity since late Quaternary and reveals tens of centimeters of the lowest scarp which illustrates new strong activity on the middle-east segment of this fault. Since late Pleistocene, 4 paleoearthquakes happened respectively before(15.16±1.29) ka, before(9.9±0.5) ka, about 6ka and after(3.5±0.4) ka, revealed by 4 trenches, of which 2 are laid on relatively thicker Holocene alluvial fan. Two events occurred since middle Holocene, and both ruptured the whole fault. 相似文献
22.
GAO Xiang DING Kang REN Yu-gang FU Wen-tao DING Zhong-jun ZHAO Sheng-y LIU Bao-hua 《海洋工程》2017,31(5):618-623
China''s 7000 m manned submersible JIAOLONG carried out an exploration cruise at the Mariana Trench from June to July 2016. The submersible completed nine manned dives on the north and south area of the Mariana Trench from the depth of 5500 to 6700 m, to investigate the geological, biological and chemical characteristics in the hadal area. During the cruise, JIAOLONG deployed a gas-tight serial sampler to collect the water near the sea bottom regularly. Five days later, the sub located the sampler in another dive and retrieved it successfully from the same location, which is the first time that scientists and engineers finished the high accuracy in-situ deployment and retrieval using a manned submersible with Ultra-Short Base Line (USBL) positioning system at the depth more than 6600 m. In this task, we used not only the USBL system of the manned submersible but also a compound strategy, including five position marks, the sea floor terrain, the depth contour, and the heading of the sub. This paper introduces the compound strategy of the target deployment and retrieval with the practical diving experience of JIAOLONG, and provides a promising technique for other underwater vehicles such as manned submersible or Remote Operated Vehicle (ROV) under similar conditions. 相似文献
23.
本文利用有限差分方法,计算了全地幔对流模式和双层地幔对流模式下日本海沟俯冲带热结构、浮力及P波速度异常分布,基于亚稳态橄榄石相变模型推测亚稳态橄榄石的存在范围,同时分析了热传导系数、热膨胀系数和热源对俯冲带热结构的影响,以及俯冲带所受浮力与俯冲带形态的关系.结果表明,双层地幔对流模式下模拟的P波速度异常分布与层析成像结果更为相符,也与深源地震的分布有较好的相关性.板块内部亚稳态橄榄石的存在范围随热传导系数和热膨胀系数的减小而增大,同时忽略相变潜热和剪切生热的影响也会造成模型所预测的亚稳态橄榄石范围偏大.俯冲带所受负浮力在400 km深度附近达到最大值,亚稳态橄榄石的存在使负浮力逐渐减小,甚至在板块内部产生正浮力,不利于俯冲带穿透660 km相变界面. 相似文献
24.
《International Geology Review》2012,54(1):49-57
AbstractThe Antarctic Bottom Water (AABW) current plays a crucial role in storing and transporting heat, water, and nutrients around the world. However, it is impossible to monitor AABW in the Plio-Pleistocene by direct measurement. Hence, abyssal erosion was usually chosen as an effective indicator of the presence of the AABW in the Indian and Eastern Pacific Oceans during that period. Here, we report a high-resolution magnetostratigraphy of a gravity core, the JL7KGC-01A from the south of the Mariana Trench, northwest Pacific Ocean. The main results are as follows: (1) polarity data suggest that the sequence recorded the late Gauss chron to the early Brunhes chron, including the Jaramillo, Cobb Mountain, and Olduvai normal subchrons; (2) the sedimentary processes in the study area since 2.9 Ma show three stages of sedimentation: 83 cm/Ma during 2.9–1.2 Ma, 183 cm/Ma during 1.2–0.7 Ma, and no sedimentation since ~0.7 Ma; (3) the area south of the Mariana Trench experienced a significant change in the deposition rate at 1.2 Ma, which could be correlated with the intensified desertification in inland Asia, and experienced a prominent depositional hiatus since the early middle Pleistocene, which likely resulted from the enhanced/expanded AABW. Based on these new polarity data and comparisons with previous studies around the Pacific Ocean, we therefore propose that the AABW experienced a notable change during the early–mid Pleistocene transition. 相似文献
25.
26.
Hernando Tavera Isabel Bernal Fleur O. Strasser Maria C. Arango-Gaviria John E. Alarcón Julian J. Bommer 《Bulletin of Earthquake Engineering》2009,7(1):71-111
A Mw 7.9 earthquake event occurred on 15 August 2007 off the coast of central Peru, 60 km west of the city of Pisco. This event
is associated with subduction processes at the interface of the Nazca and South American plates, and was characterised by
a complex source mechanism involving rupture on two main asperities, with unilateral rupture propagation to the southeast.
The rupture process is clearly reflected in the ground motions recorded during this event, which include two separate episodes
of strong shaking. The event triggered 18 accelerographic stations; the recordings are examined in terms of their characteristics
and compared to the predictions of ground-motion prediction equations for subduction environments, using the maximum-likelihood-based
method of Scherbaum et al. (Bull Seismol Soc Am 94(6):2164–2185, 2004). Additionally, macroseismic observations and damage
patterns are examined and discussed in the light of local construction practices, drawing on field observations gathered during
the post-earthquake reconnaissance missions. 相似文献
27.
Shear partitioning in the Philippines: Constraints from Philippine Fault and global positioning system data 总被引:4,自引:0,他引:4
Mario A. Aurelio 《Island Arc》2000,9(4):584-597
Abstract The Philippine Fault is a major left-lateral structure formed in an island arc setting. It accommodates a component of the oblique convergence between the Philippine Sea Plate and the Philippine archipelago. This observation is quantified through a series of global positioning satellite experiments between 1991 and 1996. The formation of the Fault marks the onset of a new geodynamic regime in the Philippine region. In the central Philippines, this event corresponds to the creation of a new tectonic boundary separating the Philippine Mobile Belt and the Philippine Sea Plate, following the latter's kinematic reorganization that occurred around 4 Ma ago. During this event, the Philippine Sea Plate changed its relative movement with respect to Eurasia from a northward to a north-westward motion, favoring the formation of a Philippine Fault–Philippine Trench system under a shear partitioning mechanism. 相似文献
28.
29.
蛟龙号载人潜水器在位于雅普海沟北部6 745 m深处的底栖沉积环境中采集到两只石鳖样本,这是石鳖物种分布于此的新记录。形态学和DNA分子标记均支持两只石鳖为鳞侧石鳖属(Leptochiton)同一物种。该种在形态上与L.vanbellei和L.deforgesi接近;在系统发生方面,与L.vanbellei,L.deforgesi和L.boucheti的亲缘关系密切。这是截至目前世界石鳖分布报道的第三深度记录。 相似文献
30.
Keisuke Taira 《Journal of Oceanography》2006,62(5):753-758
CTD (Conductivity-Temperature-Depth) data at five stations across the Izu-Ogasawara Trench at 34°N were examined. Geostrophic
velocity was in accordance with the directly measured currents. Above the trench floor, potential temperature increased at
a rate of 0.6 m°C/1000 db from 8000 db to 9417 db, and salinity increased from 8300 db to the bottom. Potential density was
almost constant at 7100–8700 db, and it increased to the bottom. Above the eastern and western flanks, inversion of potential
density was indicated in the bottom layers with an increase of potential temperature and a decrease of salinity, suggesting
geothermal heating and outflow of ground water. 相似文献