全文获取类型
收费全文 | 1383篇 |
免费 | 144篇 |
国内免费 | 107篇 |
专业分类
测绘学 | 101篇 |
大气科学 | 118篇 |
地球物理 | 376篇 |
地质学 | 573篇 |
海洋学 | 62篇 |
天文学 | 64篇 |
综合类 | 193篇 |
自然地理 | 147篇 |
出版年
2024年 | 1篇 |
2023年 | 9篇 |
2022年 | 61篇 |
2021年 | 41篇 |
2020年 | 41篇 |
2019年 | 32篇 |
2018年 | 15篇 |
2017年 | 30篇 |
2016年 | 31篇 |
2015年 | 65篇 |
2014年 | 285篇 |
2013年 | 184篇 |
2012年 | 169篇 |
2011年 | 138篇 |
2010年 | 140篇 |
2009年 | 124篇 |
2008年 | 78篇 |
2007年 | 55篇 |
2006年 | 23篇 |
2005年 | 14篇 |
2004年 | 12篇 |
2003年 | 9篇 |
2002年 | 5篇 |
2001年 | 13篇 |
2000年 | 8篇 |
1999年 | 6篇 |
1998年 | 7篇 |
1997年 | 12篇 |
1996年 | 5篇 |
1995年 | 1篇 |
1994年 | 7篇 |
1993年 | 2篇 |
1991年 | 1篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1979年 | 1篇 |
排序方式: 共有1634条查询结果,搜索用时 15 毫秒
1.
Timothy Pietsch Justine Kemp Colin Pardoe Rainer Grün Jon Olley Rachel Wood 《第四纪科学杂志》2019,34(8):662-673
Kiacatoo Man, a large, rugged Aboriginal adult buried in the Lachlan riverine plains of southeastern Australia, was discovered in 2011. Laser‐ablation uranium series analysis on bone yielded a minimum age for the burial of 27.4 ± 0.4 ka (2σ). Single‐grain, optically stimulated luminescence ages on quartz sediment in which the grave had been dug gave a weighted mean age of 26.4 ± 1.5 ka (1σ). Luminescence samples from the grave infill and from sediment beneath the grave exhibit overdispersed dose distributions consistent with bioturbation or other disturbance, which has obscured the burial signal. The overlap between the minimum (U‐series) and maximum (luminescence) ages places the burial between 27.0 and 29.4 ka (2σ). Luminescence ages obtained from the channel belt of between 28 ± 2 and 25 ± 3 ka indicate that fluvial sedimentation was occurring before the Last Glacial Maximum, which is consistent with the broader geomorphic setting. Together, these results are internally and regionally consistent, and indicate that Kiacatoo Man was one of the more ancient individuals so far identified in Australia. His remains are important to our understanding of patterns of biological variation and other processes that have shaped people in the Murray‐Darling Basin through time. Copyright © 2019 John Wiley & Sons, Ltd. 相似文献
2.
Jan Mangerud Valery I. Astakhov Andrew Murray John Inge Svendsen 《Global and Planetary Change》2001,31(1-4)
Beach and shoreface sediments deposited in the more than 800-km long ice-dammed Lake Komi in northern European Russia have been investigated and dated. The lake flooded the lowland areas between the Barents–Kara Ice Sheet in the north and the continental drainage divide in the south. Shoreline facies have been dated by 18 optical stimulated luminescence (OSL) dates, most of which are closely grouped in the range 80–100 ka, with a mean of 88±3 ka. This implies that that the Barents–Kara Ice Sheet had its Late Pleistocene maximum extension during the Early Weichselian, probably in the cold interval (Rederstall) between the Brørup and Odderade interstadials of western Europe, correlated with marine isotope stage 5b. This is in strong contrast to the Scandinavian and North American ice sheets, which had their maxima in isotope stage 2, about 20 ka. Field and air photo interpretations suggest that Lake Komi was dammed by the ice advance, which formed the Harbei–Harmon–Sopkay Moraines. These has earlier been correlated with the Markhida moraine across the Pechora River Valley and its western extension. However, OSL dates on fluvial sediments below the Markhida moraine have yielded ages as young as 60 ka. This suggests that the Russian mainland was inundated by two major ice sheet advances from the Barents–Kara seas after the last interglacial: one during the Early Weichselian (about 90 ka) that dammed Lake Komi and one during the Middle Weichselian (about 60 ka). Normal fluvial drainage prevailed during the Late Weichselian, when the ice front was located offshore. 相似文献
3.
R. K. Pant N. Basavaiah N. Juyal N. K. Saini M. G. Yadava E. Appel A. K. Singhvi 《第四纪科学杂志》2005,20(5):485-492
The southwest monsoon that dominated Central Himalaya has preserved loessic silt deposits preserved in patches that are proximal to periglacial areas. The occurrence of such silts suggests contemporary prevalence of cold and dry northwesterly winds. Field stratigraphy, geochemistry, mineral magnetism, infrared stimulated luminescence (IRSL) and radiocarbon dating has enabled reconstruction of an event chronology during the past 20 ka. Three events of loess accretion could be identified. The first two events of loess deposition occurred betweem 20 and 9 ka and were separated by a phase of moderate weathering. Pedogenesis at the end of this event gave rise to a well‐developed soil that was bracketed around 9 to > 4 ka. This was followed by the third phase of loess accretion that occurred around 4 to > 1 ka. Episodes of loess deposition and soil formation are interpreted in terms of changes in the strength of the Indian southwest monsoon. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
4.
5.
6.
7.
北达巴特斑岩铜钼矿产于华力西期流纹斑岩中,矿体呈脉状,铜矿体地表为氧化物,钼矿体主要赋存于深部的流纹斑岩中,其矿化作用呈上铜下钼的双层矿化结构模式,矿化为细脉浸染状。矿床的成因类型为斑岩型铜钼矿。 相似文献
8.
9.
10.
三峡库区高切坡致灾因素及防护对策——以重庆市万州区为例 总被引:1,自引:0,他引:1
三峡库区百万移民的搬迁建设导致大量高切坡的形成。未及时治理或治理不当的高切坡,不同程度地发生破坏,影响了人们的正常生活,甚至引发了地质灾害。因此,科学认识及治理高切坡十分必要。重庆市万州区高切坡主要有风化及差异风化、崩塌和土体滑塌等破坏形式。影响破坏的因素主要为工程地质条件、气候及时间效应。针对高切坡不同的破坏形式,以安全、经济及环境和谐的人文理念作为设计指导思想,充分论证了高切坡的防护方案,即:削坡、排水以及格构防护较适合万州区高切坡的防护。这些措施,既能很好地解决高切坡的防护问题,又能兼顾环保、降低造价。研究结果可以作为三峡地区高切坡类地质灾害防护设计的参考。也可为其它流域类似问题借鉴。 相似文献