全文获取类型
收费全文 | 982篇 |
免费 | 71篇 |
国内免费 | 64篇 |
专业分类
测绘学 | 56篇 |
大气科学 | 122篇 |
地球物理 | 235篇 |
地质学 | 429篇 |
海洋学 | 92篇 |
天文学 | 123篇 |
综合类 | 11篇 |
自然地理 | 49篇 |
出版年
2022年 | 18篇 |
2021年 | 17篇 |
2020年 | 26篇 |
2019年 | 19篇 |
2018年 | 30篇 |
2017年 | 22篇 |
2016年 | 34篇 |
2015年 | 28篇 |
2014年 | 36篇 |
2013年 | 49篇 |
2012年 | 19篇 |
2011年 | 54篇 |
2010年 | 45篇 |
2009年 | 40篇 |
2008年 | 36篇 |
2007年 | 45篇 |
2006年 | 35篇 |
2005年 | 35篇 |
2004年 | 27篇 |
2003年 | 27篇 |
2002年 | 30篇 |
2001年 | 30篇 |
2000年 | 16篇 |
1999年 | 29篇 |
1998年 | 14篇 |
1997年 | 14篇 |
1996年 | 7篇 |
1995年 | 15篇 |
1994年 | 14篇 |
1993年 | 12篇 |
1992年 | 9篇 |
1991年 | 21篇 |
1990年 | 14篇 |
1989年 | 11篇 |
1987年 | 9篇 |
1986年 | 10篇 |
1985年 | 8篇 |
1983年 | 15篇 |
1981年 | 10篇 |
1980年 | 9篇 |
1979年 | 8篇 |
1977年 | 11篇 |
1976年 | 8篇 |
1975年 | 6篇 |
1974年 | 6篇 |
1971年 | 7篇 |
1966年 | 7篇 |
1964年 | 6篇 |
1962年 | 6篇 |
1960年 | 6篇 |
排序方式: 共有1117条查询结果,搜索用时 62 毫秒
21.
鄂尔多斯盆地中部奥陶系方解石脉中包裹体流体势研究 总被引:5,自引:2,他引:5
结合前人研究成果,归纳出了一种利用盐水包裹体均一温度与盐度确定流体势的方法,并对鄂尔多斯盆地中部气田奥陶系方解石脉中包裹体进行了流体势计算,推算出了古流体运移方向。 相似文献
22.
Michel Mbina Mounguengui François Baudin Jacques Lang Olivier Jocktane 《Comptes Rendus Geoscience》2003,335(3):327-334
The Interior Basin of Gabon, created during the break-up between South America and Africa, displays thick Neoproterozoic to Aptian p.p. fluvio-lacustrine deposits overlain by Aptian to Albian marine facies. Rock–Eval analyses from outcrop and drillhole samples show high content in organic matter (up to 25%) related to types I and II. These intervals are encountered within Permian, Neocomian–Barremian as well as Aptian siliciclastic succession. They constitute fairly good to excellent potential petroleum source rocks, which are most probably at the origin of oil indices recognized both in drillholes and in surface. 相似文献
23.
1,4—二溴苯,4,4’—二溴联苯、4,4’—二溴三联和亚磷酸三乙酯在催化剂无氯化镍催化下,干燥氮气保护.反应得到相应的有机二磷酸四乙酯。 相似文献
24.
25.
26.
27.
28.
Howard J. Falcon‐Lang 《Geology Today》2011,27(4):154-158
Plants have been making wood (secondary xylem) for more than 370 million years. This familiar material is one of the keys to their massive success. Wood allows plants to attain breathtaking heights and maximize the capture of sunlight for growth. By creating complex, multi‐layered forests, the evolution of wood, has done more to shape life on land than almost any other innovation. Wood is one of the most common terrestrial fossils encountered in the geological record. Whether preserved as huge petrified logs or as minute chunks of charcoal, fossil wood is abundant in rocks of Late Devonian age and younger. It is of enormous scientific importance, shedding light on the identity and stature of ancient trees. As a record of growth over a sustained period, it also tells us much about the climates and environments in which those trees lived. In this article, I explain some aspects of the origin, evolution, preservation, and identification of fossil wood, and emphasise its great significance for geology. 相似文献
29.
Marieke Ahlborn Torsten Haberzettl Junbo Wang Karoline Henkel Thomas Kasper Gerhard Daut Liping Zhu Roland Mäusbacher 《Boreas: An International Journal of Quaternary Research》2017,46(2):229-241
A possible asynchronicity of the spatial and temporal moisture availability on the Tibetan Plateau has been a controversial subject of discussion in recent years. Here we present the first attempt to systematically investigate possible spatial and temporal variations in moisture availability by examining two lakes, Tangra Yumco and Nam Co, on an east–west transect on the southern Tibetan Plateau using identical proxies for palaeoenvironmental reconstruction. In this study, an independent record from Tangra Yumco was analysed applying a multi‐proxy approach to reconstruct variations in moisture availability since the Lateglacial. Results were subsequently compared with previously published records from Nam Co and additional records from Tso Moriri (northwestern Himalaya) and Naleng Co (southeastern Tibetan Plateau). Our results show that Tangra Yumco was at least partially ice covered prior to 17.1 cal. ka BP. A temperature rise after 17.1 cal. ka BP probably resulted in thawing of the permafrost. At 16.0 cal. ka BP moisture availability increased, representing an initial monsoonal intensification. Warmer conditions between 13.0 and 12.4 cal. ka BP and cooler conditions between 12.4 cal. ka BP and the onset of the Holocene reflect the Bølling‐Allerød and Younger Dryas. At the onset of the Holocene moisture availability rapidly increased, with moisture highest prior to 8.5 cal. ka BP when temperatures were also highest. After 8.5 cal. ka BP the moisture availability gradually decreased and showed only minor amplitude variations. These findings are consistent with the records from large lakes like Nam Co, Tso Moriri, and Naleng Co, revealing a synchronous pattern of moisture availability on the southern Tibetan Plateau. 相似文献
30.