全文获取类型
收费全文 | 9382篇 |
免费 | 2188篇 |
国内免费 | 753篇 |
学科分类
地球科学 | 12323篇 |
出版年
2024年 | 29篇 |
2023年 | 123篇 |
2022年 | 247篇 |
2021年 | 307篇 |
2020年 | 397篇 |
2019年 | 428篇 |
2018年 | 342篇 |
2017年 | 326篇 |
2016年 | 296篇 |
2015年 | 362篇 |
2014年 | 442篇 |
2013年 | 473篇 |
2012年 | 523篇 |
2011年 | 539篇 |
2010年 | 444篇 |
2009年 | 505篇 |
2008年 | 521篇 |
2007年 | 643篇 |
2006年 | 681篇 |
2005年 | 550篇 |
2004年 | 562篇 |
2003年 | 484篇 |
2002年 | 415篇 |
2001年 | 298篇 |
2000年 | 338篇 |
1999年 | 283篇 |
1998年 | 275篇 |
1997年 | 228篇 |
1996年 | 266篇 |
1995年 | 205篇 |
1994年 | 199篇 |
1993年 | 174篇 |
1992年 | 110篇 |
1991年 | 68篇 |
1990年 | 49篇 |
1989年 | 52篇 |
1988年 | 43篇 |
1987年 | 34篇 |
1986年 | 24篇 |
1985年 | 7篇 |
1984年 | 1篇 |
1981年 | 4篇 |
1980年 | 2篇 |
1979年 | 16篇 |
1954年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
2.
3.
4.
5.
Robert P. Dziak Christopher G. Fox Robert W. Embley 《Marine Geophysical Researches》1991,13(3):203-208
Morphologic studies of an oceanic transform, the Blanco Transform Fault Zone (BTFZ), have shown it to consist of a series of extensional basins that offset the major strike-slip faults. The largest of the extensional basins, the Cascadia Depression, effectively divides the transform into a northwest segment, composed of several relatively short strike-slip faults, and a southeast segment dominated by fewer, longer faults. The regional seismicity distribution (m
b
4.0) and frequency-magnitude relationships (b-values) of the BTFZ show that the largest magnitude events are located on the southeast segment. Furthermore, estimates of the cumulative seismic moment release and seismic moment release rate along the southeast segment are significantly greater than that of the northwest segment. These observations suggest that slip along the southeast segment is accommodated by a greater number of large magnitude earthquakes. Comparison of the seismic moment rate, derived from empirical estimates, with the seismic moment rate determined from plate motion constraints suggests a difference in the seismic coupling strength between the segments. This difference in coupling may partially explain the disparity in earthquake size distribution. However, the results appear to confirm the relation between earthquake size and fault length, observed along continental strike-slip faults, for this oceanic transform. 相似文献
6.
Using an idealized ocean general circulation model, we examine the effect of “mixing hotspots” (localized regions of intense
diapycnal mixing) predicted based on internal wave-wave interaction theory (Hibiya et al., 2006) on the meridional overturning circulation of the Pacific Ocean. Although the assumed diapycnal diffusivity in the
mixing hotspots is a little larger than the predicted value, the upwelling in the mixing hotspots is not sufficient to balance
the deep-water production; out of 17 Sv of the downwelled water along the southern boundary, only 9.2 Sv is found to upwell
in the mixing hotspots. The imbalance as much as 7.8 Sv is compensated by entrainment into the surface mixed layer in the
vicinity of the downwelling region. As a result, the northward transport of the deep water crossing the equator is limited
to 5.5 Sv, much less than estimated from previous current meter moorings and hydrographic surveys. One plausible explanation
for this is that the magnitude of the meridional overturning circulation of the Pacific Ocean has been overestimated by these
observations. We raise doubts about the validity of the previous ocean general circulation models where diapycnal diffusivity
is assigned ad hoc to attain the current magnitude suggested from current meter moorings and hydrographic surveys. 相似文献
7.
R. E. Kirk K. Robertson R. B. Whitmarsh P. R. Miles 《Marine Geophysical Researches》1991,13(2):153-160
A technique has been devised for firing arrays of bottom shots on the ocean bed in depths upto 4000 m or more. Ten kilogram explosive charges are dropped from the surface while the shooting ship is navigated acoustically. They are detonated at preset times by an electronic timer which initiates an electrical detonator, detonating cord and cast PETN/TNT explosive. Ranges to ocean bottom seismographs, and the shot instants, can be calculated from the arrival-time differences of the direct and surface-reflected water waves. The accuracy, which is dependent on water-depth and range, was better than 22 m in range and 14 msec in shot instant for our experiments. 相似文献
8.
9.
以国家重大产业技术开发专项“西部煤炭资源高精度三维地震勘探技术”项目的由来、意义和总体研究目标为引,概括的介绍了项目依托工程中各个专项技术研究完成情况,并对非均匀介质成像技术、高精度三维地震静校正技术、高密度采集技术、特观技术、岩性反演技术、属性体解释技术等六项重大关键技术取得的突破性进展进行了重点说明。指出随着我国煤炭生产重点的逐步西移,应加强诸如叠前、叠后深度偏移技术的研究,以解决复杂山区三维地震面元内地震反射波散射问题,提高其三维地震勘探精度,为西部煤炭工业做出新贡献! 相似文献
10.
依托“西部煤炭资源高精度三维地震勘探技术”工程,对晋城矿区进行了旨在提高小断层,小陷落柱探测能力的高密度三维地震勘探。根据面元选择因素及该区地质任务,采用5m×5m网格进行野外数据采集;考虑炮检距、方位角、覆盖次数、排列片横纵比及煤层埋深(350~500m)等因素,采用中点放炮、60道接收,24次覆盖(横向4次,纵向6次)的8线16炮束状观测系统,基岩中激发。原始资料经同一处理流程后,获得5m×5m×1ms、5m×10m×1ms、10m×10m×1ms及2.5m×2.5m×1ms不同单元的三维数据体多个,通过对比可以发现小断层,小陷落柱在其小面元叠加时间剖面、顺层切片及相干切片都有清晰的反映。实例说明,小面元采集技术可以提高对小构造的纵、横向分辨能力,满足山区对三维地震精确勘探的要求。 相似文献