全文获取类型
收费全文 | 625篇 |
免费 | 21篇 |
国内免费 | 7篇 |
专业分类
测绘学 | 38篇 |
大气科学 | 84篇 |
地球物理 | 104篇 |
地质学 | 246篇 |
海洋学 | 46篇 |
天文学 | 103篇 |
综合类 | 4篇 |
自然地理 | 28篇 |
出版年
2021年 | 7篇 |
2020年 | 5篇 |
2018年 | 25篇 |
2017年 | 20篇 |
2016年 | 22篇 |
2015年 | 16篇 |
2014年 | 19篇 |
2013年 | 38篇 |
2012年 | 22篇 |
2011年 | 35篇 |
2010年 | 20篇 |
2009年 | 43篇 |
2008年 | 27篇 |
2007年 | 30篇 |
2006年 | 32篇 |
2005年 | 27篇 |
2004年 | 17篇 |
2003年 | 25篇 |
2002年 | 23篇 |
2001年 | 23篇 |
2000年 | 17篇 |
1999年 | 14篇 |
1998年 | 10篇 |
1997年 | 16篇 |
1996年 | 2篇 |
1995年 | 6篇 |
1994年 | 8篇 |
1993年 | 4篇 |
1992年 | 5篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 7篇 |
1987年 | 12篇 |
1986年 | 4篇 |
1985年 | 7篇 |
1984年 | 6篇 |
1983年 | 5篇 |
1982年 | 6篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1975年 | 4篇 |
1974年 | 2篇 |
1973年 | 3篇 |
1972年 | 2篇 |
1971年 | 2篇 |
1969年 | 2篇 |
1950年 | 1篇 |
1948年 | 2篇 |
1925年 | 1篇 |
排序方式: 共有653条查询结果,搜索用时 93 毫秒
11.
Hege Fonneland-Jorgensen Harald Furnes Karlis Muehlenbachs Yildirim Dilek 《Island Arc》2005,14(4):517-541
Abstract The Solund‐Stavfjord ophiolite complex (SSOC) in western Norway represents a remnant of the Late Ordovician oceanic lithosphere, which developed in an intermediate‐ to fast‐spreading Caledonian back‐arc basin. The internal architecture and magmatic features of its crustal component suggest that the SSOC has a complex, multistage sea floor spreading history in a supra‐subduction zone environment. The youngest crustal section associated with the propagating rift tectonics consists of a relatively complete ophiolite pseudostratigraphy, including basaltic volcanic rocks, a transition zone between the sheeted dyke complex and the extrusive sequence, sheeted dykes, and high‐level isotropic gabbros. Large‐scale variations in major and trace element distributions indicate significant remobilization far beyond that which would result from magmatic processes, as a result of the hydrothermal alteration of crustal rocks. Whereas K2O is strongly enriched in volcanic rocks of the extrusive sequence, Cu and Zn show the largest enrichment in the dyke complex near the dyke–volcanic transition zone or within this transition zone. The δ18O values of the whole‐rock samples show a general depletion structurally downwards in the ophiolite, with the largest and smallest variations observed in volcanic rocks and the transition zone, respectively. δ18O values of epidote–quartz mineral pairs indicate 260–290°C for volcanic rocks, 420°C for the transition zone, 280–345°C for the sheeted dyke complex and 290–475°C for the gabbros. The 87Sr/86Sr isotope ratios show the widest range and highest values in the extrusive rocks (0.70316–0.70495), and generally the lowest values and the narrowest range in the sheeted dyke complex (0.70338–0.70377). The minimum water/rock ratios calculated show the largest variations in volcanic rocks and gabbros (approximately 0–14), and generally the lowest values and range in the sheeted dyke complex (approximately 1–3). The δD values of epidote (?1 to ?12‰), together with the δ18O calculated for Ordovician seawater, are similar to those of present‐day seawater. Volcanic rocks experienced both cold and warm water circulation, resulting in the observed K2O‐enrichment and the largest scatter in the δ18O values. As a result of metal leaching in the hot reaction zone above a magma chamber, Zn is strongly depleted in the gabbros but enriched in the sheeted dyke complex because of precipitation from upwelling of discharged hydrothermal fluids. The present study demonstrates that the near intact effect of ocean floor hydrothermal activity is preserved in the upper part of the SSOC crust, despite the influence of regional lower greenschist facies metamorphism. 相似文献
12.
With the acceleration of industrialization, coal- burning atmospheric pollution is getting more and more serious in many regions in China. However, there are only about ten odd years literature records about pollution in some large and mid-sized cities, where the atmosphere has perhaps been polluted for several decades, and therefore it is difficult to know the process and characteristic of pollution, and diffi-cult to evaluate its damage to environment. Lacustrine sediment, a natural record w… 相似文献
13.
14.
15.
16.
17.
18.
19.
Höhn Stefan Koglin Nikola Klopf Lisa Schüssler Ulrich Tragelehn Harald Frimmel Hartwig E. Zeh Armin Brätz Helene 《International Journal of Earth Sciences》2018,107(1):359-377
International Journal of Earth Sciences - Stratigraphically well-defined volcanic rocks in Palaeozoic volcano-sedimentary units of the Frankenwald area (Saxothuringian Zone, Variscan Orogen) were... 相似文献
20.