首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   5942篇
  免费   1784篇
  国内免费   1208篇
测绘学   200篇
大气科学   104篇
地球物理   3281篇
地质学   4215篇
海洋学   197篇
天文学   8篇
综合类   617篇
自然地理   312篇
  2024年   18篇
  2023年   65篇
  2022年   175篇
  2021年   257篇
  2020年   184篇
  2019年   330篇
  2018年   262篇
  2017年   277篇
  2016年   318篇
  2015年   308篇
  2014年   350篇
  2013年   392篇
  2012年   358篇
  2011年   343篇
  2010年   319篇
  2009年   436篇
  2008年   433篇
  2007年   384篇
  2006年   422篇
  2005年   327篇
  2004年   373篇
  2003年   290篇
  2002年   251篇
  2001年   262篇
  2000年   264篇
  1999年   174篇
  1998年   196篇
  1997年   173篇
  1996年   170篇
  1995年   161篇
  1994年   158篇
  1993年   130篇
  1992年   107篇
  1991年   50篇
  1990年   41篇
  1989年   51篇
  1988年   38篇
  1987年   31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8934条查询结果,搜索用时 453 毫秒
351.
��³������ִ��������о�   总被引:3,自引:3,他引:0  
????????1956??1999??????????????????????????顢?????顢?????????????????????????????б??????е??????Щ???????????????4??????У?1956??1978????????????????????????????????ε????Ms7.4?????????????й??1978??1985???1990??1995?????????????????????????鶫??????Ms6.2 ??Ms6.1?????й??  相似文献   
352.
??????????32??????λ?????????????????20??????????????????????????????????????????????????????????????20????80??????????????????????????????????????????????2006???????????????2?????????????????????????Ρ??????????????????????????????????????????á?  相似文献   
353.
�봨8.0������ǰ��ؿǴ�ֱ�α����   总被引:5,自引:0,他引:5  
??????8.0?????????????????????????????????????Ms8.0?????????????α????????:???????????α???????????????????????????????????仯???????????????????????????????????????????????????????????????????????????????α???????  相似文献   
354.
???ò??GPS????8????????????????????????????????????????????????????????:?????????-?????????γ?????200 km???????????????????????-????????????γ?????75 km??????????????????????????????????????????????????????????????????????????????????????????????  相似文献   
355.
在总结分析现有复杂断层及倒转褶皱3维建模方法的基础上,提出一种基于广义三棱柱(GTP)的3维交互建模方法(岩柱体分区RPBP建模法)。文中定义了岩柱体、界限三角形两个重要概念,RPBP法可以通过构建断层界限三角形,将复杂断层系转化为多个简单断层系,然后采用构建简单断层系模型的方法来实现复杂断层系的3维建模;而对于倒转褶皱,RPBP法则通过构建褶皱轴界限三角形避免数据局部重复和冲突,使GTP建模过程得以顺利进行。实验表明,该方法能便捷可靠地实现含多断层相互切割、倒转褶皱等复杂地质体的真3维建模。  相似文献   
356.
裂陷盆地中的构造变换带及其石油地质意义   总被引:16,自引:0,他引:16  
构造变换带是裂陷盆地中的重要构造变形。讨论了构造变换带的含义、类型及对油气聚集的意义。裂陷盆地主干正断层之间的几何关系可以分为同向倾斜、背向倾斜和相向倾斜共3种组合方式;正断层之间的构造变换方式可以分为缓冲式、接力式、消长式、传递式和消减式等5种形式,构成15种类型的构造变换带。不同方式的断裂组合所形成的不同构造变换带类型会随着主干正断层位移的渐进增大发生相应的转变。构造变换带是有利的油气聚集区带:(1)它常常是主边界断裂带上地形高差变化较小的部位,是主要碎屑物源注入裂陷盆地的入口处,有利于发育储集层;(2)长期处于盆地内部相对高的构造部位,而且近邻生油凹陷,是油气运移指向区带;(3)它是裂陷盆地构造变形相对复杂的区带,有利于发育多种样式的油气圈闭。  相似文献   
357.
Based on new multibeam bathymetric data and about 300 km long single seismic profiles, three topographic units were identified:the canyons, fractural valley and submarine terrace on the north of Chiwei Island where is a structural transition zone between the southern trough and the middle trough. The Chiwei Canyon and the North Chiwei Canyon are two of the largest canyons in the East China Sea (ECS) slope. Topographic features and architectures of them are described. The study shows that both of them are originated along faults. The evolution and spatial distribution of topographic units in the study area are controlled mainly by three groups of faults which were formed and reactive in the recent extensional phase of Okinawa Trough. The Chiwei Canyon was initiated during the middle Pleistocene and guided by F4 that is a N-S trending fault on the slope and F1, a large NW-SE trending fault on the trough. The pathway migration from the remnant channel to the present one of Chiwei Canyon is the result of uplift of tilted fault block that is coupled to the recent extension movements of the southern trough. The submarine terrace is detached from the ECS slope by the NEE-trending fault. The North Chiwei Canyon, developing during the late Pleistocene, is guided by F5, a N-S trending fault, diverted and blocked by the submarine terrace.  相似文献   
358.
莱州湾地区郯庐断裂带的构造特征及其新生代演化   总被引:22,自引:0,他引:22  
郯庐断裂带中段分东西两支从莱州湾进入渤海,在莱州湾地区的构造特征与演化历史一直鲜为人知。通过对横穿研究区的两条地震测线的解释和分析,揭示了该区郯庐断裂带中段在研究区的构造差异,研究表明郯庐断裂带东西两支在该研究区表现出不同的断裂性质,西支断裂表现为正断层,东支断裂表现为走滑断层。郯庐断裂是本研究区的主控断裂,通过对本地区地层形态及其组合、断层的剖面形态和空间展布规律的深入研究,揭示了郯庐断裂带在莱州湾地区新生代以来的构造演化历史:古新世—始新世的伸展阶段、渐新世—中新世早期的挤压和右行走滑阶段、中新世中晚期至今的稳定发展阶段,这几个不同时期的演化阶段主要受太平洋板块运动的方向和速度变化的控制。  相似文献   
359.
Cap-rock seals can be divided genetically into those that fail by capillary leakage (membrane seals) and those whose capillary entry pressures are so high that seal failure preferentially occurs by fracturing and/or wedging open of faults (hydraulic seals). A given membrane seal can trap a larger oil column than gas column at shallow depths, but below a critical depth (interval), gas is more easily sealed than oil. This critical depth increases with lower API gravity, lower oil GOR and overpressured conditions (for the gas phase). These observations arise from a series of modelling studies of membrane sealing and can be conveniently represented using pressure/ depth (P/D) profiles through sealed hydrocarbon columns. P/D diagrams have been applied to the more complex situation of the membrane sealing of a gas cap underlain by an oil rim; at seal capacity, such a two-phase column will be always greater than if only oil or gas occurs below the seal.These conclusions contrast with those for hydraulic seals where the seal capacity to oil always exceeds that for gas. Moreover, a trapped two-phase column, at hydraulic seal capacity will be less than the maximum-allowed oil-only column, but more than the maximum gas-only column. Unlike membrane seals, hydraulic seal capacity should be directly related to cap-rock thickness, in addition to the magnitude of the minimum effective stress in the sealing layer and the degree of overpressure development in the sequence as a whole.Fault-related seals are effectively analogous to membrane cap-rocks which have been tilted to the angle of the fault plane. Consequently, all of the above conclusions derived for membrane cap-rocks apply to both sealing faults sensu stricto (fault plane itself seals) and juxtaposition faults (hydrocarbon trapped laterally against a juxtaposed sealing unit). The maximum-allowed two-phase column trapped by a sealing fault is greater than for equivalent oil-only and gas-only columns, but less than that predicted for a horizontal membrane cap-rock under similar conditions. Where a two-phase column is present on both sides of a sealing fault (which is at two-phase seal capacity), a deeper oil/water contact (OWC) in one fault block is associated with a deeper gas/oil contact (GOC) compared with the adjacent fault block. If the fault seal is discontinuous in the gas leg, however, the deeper OWC is accompanied by a shallower GOC, whereas a break in the fault seal in the oil leg results in a common OWC in both fault blocks, even though separate GOC's exist. Schematic P/D profiles are provided for each of the above situations from which a series of fundamental equations governing single- and two-phase cap-rock and fault seal capacities can be derived. These relationships may have significant implications for exploration prospect appraisal exercises where more meaningful estimates of differential seal capacities can be made.The membrane sealing theory developed herein assumes that all reservoirs and seals are water-wet and no hydrodynamic flow exists. The conclusions on membrane seal capacity place constraints on the migration efficiency of gas along low-permeabiligy paths at depth where fracturing, wedging open of faults and/or diffusion process may be more important. Contrary to previous assertions, it is speculated that leakage of hydrocarbons through membrane seals occurs in distinct pulses such that the seal is at or near the theoretically calculated seal capacity, once this has been initially attained.Finally, the developed seal theory and P/D profile concepts are applied to a series of development geological problems including the effects of differential depletion, and degree of aquifer support, on sealing fault leakage, and the evaluation of barriers to vertical cross-flow using RFT profiles through depleted reservoirs. It is shown that imbibition processes and dynamic effects related to active cross-flow across such barriers often preclude quantitative analysis and solution of these problems for which simulation studies are usually required.  相似文献   
360.
本文主要根据二维地震剖面并结合野外露头的分析认为,十万大山盆地东南缘的基底断裂是钦防海槽向北西冲断-推覆的前锋断层,断裂两侧的中、古生界在地层层位与厚度上存在明显差异。钦防海西-印支海槽的西界不应是灵山断裂,而应是十万大山盆地东南缘的基底断裂,其范围远大于现今博(白)—罗(定)—广(宁)断裂与灵山断裂之间的范围。基底断裂为一无根的推覆构造带,其下掩覆了十万大山盆地东南缘的许多区域,是下一步油气勘探的重要领域。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号