全文获取类型
收费全文 | 1112篇 |
免费 | 54篇 |
国内免费 | 22篇 |
专业分类
测绘学 | 25篇 |
大气科学 | 132篇 |
地球物理 | 280篇 |
地质学 | 360篇 |
海洋学 | 107篇 |
天文学 | 174篇 |
综合类 | 9篇 |
自然地理 | 101篇 |
出版年
2024年 | 4篇 |
2023年 | 8篇 |
2022年 | 8篇 |
2021年 | 17篇 |
2020年 | 26篇 |
2019年 | 30篇 |
2018年 | 34篇 |
2017年 | 49篇 |
2016年 | 36篇 |
2015年 | 37篇 |
2014年 | 47篇 |
2013年 | 73篇 |
2012年 | 38篇 |
2011年 | 69篇 |
2010年 | 56篇 |
2009年 | 79篇 |
2008年 | 68篇 |
2007年 | 61篇 |
2006年 | 56篇 |
2005年 | 39篇 |
2004年 | 43篇 |
2003年 | 34篇 |
2002年 | 24篇 |
2001年 | 19篇 |
2000年 | 24篇 |
1999年 | 18篇 |
1998年 | 15篇 |
1997年 | 19篇 |
1996年 | 17篇 |
1995年 | 18篇 |
1994年 | 9篇 |
1993年 | 10篇 |
1992年 | 7篇 |
1991年 | 9篇 |
1990年 | 8篇 |
1989年 | 5篇 |
1988年 | 6篇 |
1987年 | 7篇 |
1986年 | 4篇 |
1985年 | 7篇 |
1984年 | 6篇 |
1983年 | 9篇 |
1982年 | 5篇 |
1981年 | 5篇 |
1980年 | 3篇 |
1979年 | 4篇 |
1978年 | 5篇 |
1977年 | 2篇 |
1976年 | 5篇 |
1967年 | 1篇 |
排序方式: 共有1188条查询结果,搜索用时 312 毫秒
981.
The evolution of the Oued es Seffaia alluvial fan during the last 50,000 years is analyzed in the light of chronometric data derived from AMS radiocarbon and optical dating techniques. These ages have enabled the temporal constraint of the distalward progression of the intersection point (the upper limit of the locus of deposition) which has resulted in the telescopic segmentation of the fan. Comparison of these data with the Late Quaternary climatic history of the Maghreb highlights several problems of interpretation; due both to our limited knowledge of regional palaeoclimates and of the response of dryland fluvial systems to climate changes. However, our data provide some evidence to suggest that fan incision and formation of telescopic segments occurs in response to changes from arid to less arid conditions, supporting the conclusions of some of the work from other areas. 相似文献
982.
Kevin Hall 《地球表面变化过程与地形》1993,18(2):121-129
An indication of the extent of weathering on different aspects of rock outcrops on Livingston Island, Antarctica, was obtained by means of a Schmidt hammer, a cone indenter and measurement of weathering rind thickness. Results show that weathering, particularly chemical weathering, is enhanced on the lee side of outcrops where snow accumulates as a result of prolonged wetting by the melting snow. Rock moisture and temperature data indicate that the south-facing, snow-accumulation side of obstacles have high rock moisture levels and maintain relatively high temperatures. Whilst chemical weathering is greater on the leeward side of outcrops, mechanical processes are greater on the windward side. The presence of late-lying snow thus appears to exert a strong influence on weathering. 相似文献
983.
984.
AbstractAs interest in outdoor activities in remote areas is increasing, there is a strong need for improved avalanche forecasting at the regional scale. Due to important logistical and safety matters, avalanche terrain measurements (avalanche observations, snowpack profiles, and stability tests) are not always possible for practitioners/forecasters. An interesting alternative would be to analyze the snowpack without these challenges by using snow model outputs. The SNOWPACK model is currently used operationally for avalanche forecasting and research in the Swiss Alps. Thus, this paper presents a summary of analyses that have been conducted to assess the potential of using the SNOWPACK model driven with both in-situ and forecasted meteorological data in three different Canadian climate and geomorphological contexts. A comparison of meteorological data from in-situ and predicted datasets for two winters shows that the GEMLAM weather model is the most accurate for the three climatic contexts of this project, but also showed a bias proportional to precipitation intensity/rate. Snow simulations forced with GEMLAM are the closest to field measurements. Finally, predictions of persistent weak layers have been validated using the InfoEx platform from Avalanche Canada. Crust and surface hoar formation dates agree with the information reported in InfoEx. 相似文献
985.
Silica diagenesis in Cenozoic mudstones of the North Viking Graben: physical properties and basin modelling
下载免费PDF全文
![点击此处可从《Basin Research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Thilo Wrona Christopher A.‐L. Jackson Mads Huuse Kevin G. Taylor 《Basin Research》2017,29(Z1):556-575
Silica diagenesis can significantly change physical properties of the host strata and release large volumes of water. Predicting these changes and their timing is essential to understanding compaction, fluid flow and rock deformation in sedimentary basins. In this paper, the influence of silica diagenesis (opal‐A/CT transformation) on physical properties is determined, the sediment volume affected by these changes is mapped, and a new technique to model silica diagenesis is introduced. A petrophysical analysis of 16 exploration wells shows that the opal‐A/CT transformation leads to a porosity reduction of c.20% (from 49 to 29%) in Cenozoic mudstones of the North Viking Graben. Using three‐dimensional seismic reflection data, it is shown that the c.50 m thick opal‐A/CT transformation zone covers an area of >1500 km2, equating to a minimum volume of 75 km3. The spatial and temporal evolution of opal‐A/CT transformation is simulated using an innovative basin modelling approach, the results of which indicate that the transformation started around Middle‐to‐Late Eocene times and then migrated upwards until it gradually fossilised between the Miocene and present. These findings are important, as they help understanding how these sediments compact and when fluids are released by diagenesis. 相似文献
986.
Horsburgh Kevin Haigh Ivan D. Williams Jane De Dominicis Michela Wolf Judith Inayatillah Addina Byrne David 《Ocean Dynamics》2021,71(6-7):715-730
Ocean Dynamics - In this paper, we show that over the next few decades, the natural variability of mid-latitude storm systems is likely to be a more important driver of coastal extreme sea levels... 相似文献
987.
988.
989.
990.
Kevin D. McKeegan 《Meteoritics & planetary science》2007,42(7-8):1045-1054