全文获取类型
收费全文 | 5890篇 |
免费 | 1812篇 |
国内免费 | 1202篇 |
专业分类
测绘学 | 87篇 |
大气科学 | 92篇 |
地球物理 | 3335篇 |
地质学 | 4274篇 |
海洋学 | 200篇 |
天文学 | 6篇 |
综合类 | 613篇 |
自然地理 | 297篇 |
出版年
2024年 | 18篇 |
2023年 | 62篇 |
2022年 | 177篇 |
2021年 | 259篇 |
2020年 | 189篇 |
2019年 | 330篇 |
2018年 | 267篇 |
2017年 | 274篇 |
2016年 | 316篇 |
2015年 | 301篇 |
2014年 | 354篇 |
2013年 | 383篇 |
2012年 | 355篇 |
2011年 | 341篇 |
2010年 | 314篇 |
2009年 | 435篇 |
2008年 | 429篇 |
2007年 | 378篇 |
2006年 | 416篇 |
2005年 | 322篇 |
2004年 | 373篇 |
2003年 | 289篇 |
2002年 | 257篇 |
2001年 | 260篇 |
2000年 | 263篇 |
1999年 | 172篇 |
1998年 | 198篇 |
1997年 | 173篇 |
1996年 | 172篇 |
1995年 | 163篇 |
1994年 | 159篇 |
1993年 | 133篇 |
1992年 | 106篇 |
1991年 | 50篇 |
1990年 | 42篇 |
1989年 | 47篇 |
1988年 | 41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8904条查询结果,搜索用时 15 毫秒
421.
韩凤财 《华北地质矿产杂志》1994,9(4):365-368
经勘察评价和国家级评审鉴定,天镇县城关T_(67)井属锂-锶-偏硅酸三项达标的复合型优质饮用天然矿泉水。矿泉水产于近东西向挽近断裂带上,马圈痒地热田边部,地势平坦,环境无污染,交通便利,水质独特,水量丰富,具有综合开发优势,适宜建厂开发。 相似文献
422.
I. Lerche 《Pure and Applied Geophysics》1994,143(4):537-562
Equations have been presented previously which predict that reflector curvature can affect significantly seismic reflection amplitudes at both zero and nonzero source-receiver offsets. Here the fact that faults are generally concave-upward is used to examine the curvature effect for compaction-driven faults which the sediments have both exponential and logarithmic porosity decreases with increasing depth.The curvature effect is generally larger over upwardly concave reflectors where amplitudes can either increase with offset (exposed focus) or decrease with offset (buried focus). The magnitude of the effect depends on the ratio between the depth to the structure and the radius of curvature of the structure. A phase change of 90° also occurs at a critical offset in the case of an exposed focus concave-upward reflector, with decreasing amplitude at offsets larger than the critical value. Dip move-out (DMO) dominantly removes the amplitude variation with offset due to curvature. These results suggest that when looking for amplitude variations with offset in a fault prospect, DMO should be applied as a preprocessing step. Compaction-driven faults have an exposed focus and, for an exponential variation of porosity with depth, there is a maximum curvature effect at a depth roughly the same as the scaling depth for the porosity. Logarithmic porosity with depth variations suggest a continued increase in the curvature effect of faults with increasing depth, to a maximum amplitude increase of about 35% relative to a plane interface. 相似文献
423.
The frictional behavior of lizardite and antigorite serpentinites: Experiments,constitutive models,and implications for natural faults 总被引:2,自引:0,他引:2
Laboratory studies of the frictional behavior of rocks can provide important information about the strength and sliding stability of natural faults. We have conducted friction experiments on antigorite and lizardite serpentinites, rocks common to both continental and oceanic crustal faults. We conducted both velocity-step tests and timed-hold tests on bare surfaces and gouge layers of serpentinite at room temperature. We find that the coefficient of friction of lizardite serpentinite is quite low (0.15–0.35) and could explain the apparent low stresses observed on crustal transform faults, while that of antigorite serpentinite is comparable to other crustal rocks (0.50–0.85). The frictional behavior of both types of serpentinite is well described by a two-mechanism model combining state-variable-dominated behavior at high slip velocities and flow-dominated behavior at low velocities. The two-mechanism model is supported by data from velocity-step tests and timed-hold tests. The low velocity behavior of serpentinite is strongly rate strengthening and should result in stable fault creep on natural faults containing either antigorite or lizardite serpentinite. 相似文献
424.
425.
426.
427.
Evaluation of the Importance of Model Features For Cyclic Deformation Due to Dip-Slip Faulting 总被引:1,自引:0,他引:1
Steven C. Cohen 《Geophysical Journal International》1994,119(3):831-841
428.
本文在系统的有限应变测量的基础上,对闽东南长乐—南澳断裂带东山段剪切变形特征进行了分析:利用变形石英显微亚结构。(动态重结晶颗粒)估算了剪切带内古应力并(σ—σ_3):通过对剪切变形能密度分布W(x)格离散化计算,采用有限差分数值近方法,获得了剪切热数值解:最后总结了研究地区剪切变形,剪切加热与动热成岩成矿作用的相对时空关系以及长乐—南澳断裂域构造意义 相似文献
429.
沂沭活断层分段特征及地震趋势的预测 总被引:2,自引:0,他引:2
沂沭活断层以莒南—汤头一线为界可分成南北两大段。其中,北段以蠕滑为主,南段则表现为强烈的粘滑错动。另外,在南段内还存在着一个次一级的段落。文中详细分析了各段的断层滑动方式及地震活动的特点,并对沂沭断裂带今后的地震趋势作了预测。 相似文献
430.