全文获取类型
收费全文 | 687篇 |
免费 | 185篇 |
国内免费 | 252篇 |
专业分类
测绘学 | 4篇 |
大气科学 | 4篇 |
地球物理 | 160篇 |
地质学 | 837篇 |
海洋学 | 72篇 |
天文学 | 4篇 |
综合类 | 21篇 |
自然地理 | 22篇 |
出版年
2024年 | 4篇 |
2023年 | 12篇 |
2022年 | 16篇 |
2021年 | 12篇 |
2020年 | 21篇 |
2019年 | 38篇 |
2018年 | 39篇 |
2017年 | 28篇 |
2016年 | 40篇 |
2015年 | 42篇 |
2014年 | 41篇 |
2013年 | 62篇 |
2012年 | 40篇 |
2011年 | 46篇 |
2010年 | 48篇 |
2009年 | 67篇 |
2008年 | 60篇 |
2007年 | 55篇 |
2006年 | 52篇 |
2005年 | 36篇 |
2004年 | 63篇 |
2003年 | 40篇 |
2002年 | 31篇 |
2001年 | 23篇 |
2000年 | 42篇 |
1999年 | 26篇 |
1998年 | 17篇 |
1997年 | 21篇 |
1996年 | 25篇 |
1995年 | 11篇 |
1994年 | 16篇 |
1993年 | 9篇 |
1992年 | 11篇 |
1991年 | 5篇 |
1990年 | 3篇 |
1989年 | 6篇 |
1988年 | 7篇 |
1987年 | 4篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1981年 | 3篇 |
排序方式: 共有1124条查询结果,搜索用时 31 毫秒
31.
北祁连造山带东段白银地区的构造单元划分及韧性变形 总被引:15,自引:0,他引:15
北祁连造山带东段的白银地区可划分出四个构造单元(B1、B2、B3和B4):B1属于中宫变质地块,B2为古祁洋在俯冲过程中形成的增生杂岩,B3属于加里东期的古火山岛弧B4为弧后残余海盆。本区存在两期韧性变形,和线期韧性变形以形成近垂直于造山带的NE-SW向拉伸线理为特征,剪切标志显示其主要为一系列从N-S的逆冲叠覆构造2,与古祁连洋向北的俯冲作用有关,第二期韧性变形形成四条韧性平移剪切带(SZ1、S 相似文献
32.
The Uplift of the Longmenshan Thrust Belt and Subsidence of the West Sichuan Foreland Basin 总被引:8,自引:0,他引:8
Liu Shugen Luo Zhili Dai Sulan Changlu Institute of Technology Chengdu Sichuan ChinaDennis Arne Dalhousie U niversity Canadaand C.J.L. Wilson Melbourne U niversity Australia Jiang M inxi 《《地质学报》英文版》1996,70(1):16-26
Based on fission track dating of apatite, and measurement of vitrinite reflectance of rock samples from the Longmenshan (Longmen Mountain)area and the West Sichuan foreland basin and computer modelling it is concluded that (l)the Songpan-Garze fold belt has uplifted at least by 3-4 km with an uplift rate of no less than 0.3-0.4 mm/a since 10 Ma B.P.; (2) the Longmenshan thrust nappe belt has uplifted at least by 5-6 km with an uplift rate of more than 0.5- 0.6 mm /a since 10 Ma B.P.; (3) the Longmenshan detachment belt has uplifted by 1 - 2 km at a rate of 0.016-0.032 mm/a since 60 Ma B.P.; (4) the West Sichuan foreland basin has uplifted by 1.7-3 km at a rate of 0.028-0.05 mm/a since 60 Ma B.P.; (5) the uplift rate of the area on the west side of the Beichuan-Yingxiu-Xiaoguanzi fault for the last 10 Ma is 40 times as much as that on its east side; (6) the uplifting of the the Songpan - Garze fold belt and the subsidence of the West Sichuan foreland basin 60 Ma ago exhibit a mirro-image correlation, i.e 相似文献
33.
Summary Although wedge and plane sliding stability analyses are well established in the geotechnical literature, certain geologic environments produce blocks which cannot be adequately modelled as either wedges or plane slides. An example is blocks forming in cylindrically folded sedimentary rocks, where the surface of sliding is neither a single plane nor a double plane but is curved. This type of block may be idealized as a prismatic block with multiple sliding planes, all with parallel lines of intersection. If the sliding planes number three or more, the distribution of normal forces, and hence the factor of safety, is indeterminate. A new analytical model for sliding stability analysis is described in which the distribution of normal forces on the contact planes is chosen to minimize the potential energy of the system. The classic wedge and plane solutions are shown to be special cases of this more general model, which allows determination of the safety factor for any shape of prismatic contact surface. An example from Tennessee concerning a block with a curved sliding surface is described and the factor of safety compared with the standard wedge analysis. It is shown that with three or more contact planes, the safety factor may be significantly lower than that calculated from the wedge model, which provides an upper limit on stability. 相似文献
34.
Dilip K Mukhopadhyay Bidyut K Bhadra Tamal K Ghosh Deepak C Srivastava 《Journal of Earth System Science》1996,105(2):157-171
Numerous peraluminous and porphyritic granitic bodies and augen gneisses of granitic compositions occur in the nappe sequences
of the Lower Himalaya. They are Proterozoic-to-lower Paleozoic in age and have been grouped into the ‘Lesser Himalaya granite
belt’. The mode of emplacement and tectonic significance of these granites are as yet uncertain but they are generally considered
to be sheet-like intrusions into the surrounding rocks. The small and isolated granite body (the Chur granite) that crops
out around the Chur peak in the Himachal Himalaya is one of the more famous of these granites. Several lines of evidence have
been adduced to show that the Chur granite has a thrust (the Chur thrust) contact with the underlying metasedimentary sequence
(locally called the Jutogh Group). The Chur granite with restricted occurrence at the highest topographic and structural levels
represents an erosional remnant of a much larger sub-horizontal thrust sheet. The contact relations between the country rocks
and many of the other granite and granitic augen gneisses in the Lesser Himalaya belt are apparently similar to that of the
Chur granite suggesting that at least some of them may also represent thrust sheets. 相似文献
35.
大陆层控构造论盆-山系与造山带成因及演化新模式 总被引:1,自引:0,他引:1
大陆构造以受中地壳塑性层控制的盆-山系和冲叠造山带厚皮构造为主要构造类型,而与中生代以来才出现的受软流层控制的大洋岩石圈板块构造截然不同。由上地壳正断层上盘断陷盆地和下盘断隆山所组成的盆-山系,与地球自转速度逐渐变慢派生不同性质水平力和重力的共同作用有关。当地球自转速度突然变化时,将派生强烈的侧压力,使升降幅度较大、具有侧向应变空间的断陷盆地与断隆山之间的上地壳发生冲叠运动,盆-山系由此演变成冲叠造山带。后者对前者存在着严格的继承关系,服从于“升降-冲叠律”。中生代以来的盆-山系和冲叠造山带有的是板块活动产物 相似文献
36.
研究区构造格局的基本特征是上地壳多层次自北而南的逆冲—拆离,柳林、洪清、大洪山3条逆掩断层与深部拆离面一起组成了尖端指向南的楔形薄皮构造。逆冲系统以背驮式扩展演化。多层次推覆构造格局因后期高角度断裂的切割破坏而复杂化,构造格局定型时代为燕山期 相似文献
37.
Depositional sequence architecture and filling response model of the Cretaceous in the Kuqa depression, the Tarim basin 总被引:1,自引:0,他引:1
The Cretaceous system of the Kuqa depression is a regional scale (second order) depositional sequence defined by parallel unconformities or minor angular unconformities. It can be divided into four third-order sequence sets, eleven third-order sequences and tens of fourth- and fifth-order sequences. It consists generally of a regional depositional cycle from transgression to regression and is composed of three sets of facies associations: alluvial-fluvial, braided river-deltaic and lacustrine-deltaic facies associations. They represent the lowstand, transgressive and highstand facies tracts within the second-order sequence. The tectonic subsidence curve reconstructed by backstripping technique revealed that the Cretaceous Kuqa depression underwent a subsidence history from early accelerated subsidence, middle rapid subsidence and final slower subsidence phases during the Cretaceous time, with the correspondent tectonic subsidence rates being 30-35 m/Ma, 40-45 m/Ma and 5-10 m/Ma obtained from northern foredeep. This is likely attributed to the foreland dynamic process from early thrust flexural subsidence to late stress relaxation and erosion rebound uplift. The entire sedimentary history and the development of the three facies tracts are a response to the basin subsidence process. The slower subsidence foreland gentle slope was a favorable setting for the formation of braided fluvial deltaic systems during the late period of the Cretaceous, which comprise the important sandstone reservoirs in the depression. Sediment records of impermanent marine transgression were discovered in the Cretaceous and the major marine horizons are correctable to the highstands of the global sea level during the period. 相似文献
38.
内蒙古大青山地区构造特征与成矿关系 总被引:10,自引:1,他引:10
内蒙古大青山地区的临河-集宁断裂带是华北板块北缘的一条重要断裂带,它主要由韧性剪切带、韧脆性剪切带和推覆构造等构成.推覆构造自南向北可分为叠瓦逆冲推覆构造带、紧闭褶皱一逆冲断层变形带、宽缓褶皱-断层转折褶皱带、滑脱褶皱-断层传播褶皱带等4个变形带.断裂带从韧性到脆性表示了其出露深度不同,并有由南到北活动强度逐渐减弱的趋势.该区主要分布有以金为主的多金属矿床和以煤、大理岩为主的非金属矿床.区内金多金属矿床多与韧性剪切带有关,断裂构造为金属矿床的形成提供了空间,也是成矿物质的通道.研究指出了该地区的找矿前景与方向. 相似文献
39.
山西五台地区系舟山逆冲推覆构造地质特征 总被引:4,自引:0,他引:4
系舟山逆冲推覆构造带位于中生代燕山造山带的西南端,分布于系舟山掀斜向斜的北西翼,形成于晚侏罗世晚期,空间上由一系列近平行排列的逆冲断裂组成,剖面上表现为侧幕展布的犁式逆冲断裂所构成的前陡、后缓的单冲式叠瓦状构造。主体由北西向南东方向逆冲.逆冲扩展方式为前展式,运移距离大于5.8km。推覆构造中应力状态在横、纵向上呈现有规律的变化,根带以挤压为主的高角度逆冲断裂及复杂多级褶皱为主;中带以单剪为主,形成叠瓦状构造;锋带挤压作用增强,发育反冲断层和不对称褶皱。随着挤压应力的松弛减弱,山前形成规模较大的正断层。 相似文献
40.