全文获取类型
收费全文 | 632篇 |
免费 | 37篇 |
国内免费 | 11篇 |
专业分类
测绘学 | 41篇 |
大气科学 | 62篇 |
地球物理 | 124篇 |
地质学 | 224篇 |
海洋学 | 55篇 |
天文学 | 131篇 |
综合类 | 1篇 |
自然地理 | 42篇 |
出版年
2024年 | 2篇 |
2023年 | 5篇 |
2022年 | 6篇 |
2021年 | 10篇 |
2020年 | 10篇 |
2019年 | 15篇 |
2018年 | 19篇 |
2017年 | 26篇 |
2016年 | 31篇 |
2015年 | 22篇 |
2014年 | 21篇 |
2013年 | 34篇 |
2012年 | 36篇 |
2011年 | 41篇 |
2010年 | 37篇 |
2009年 | 52篇 |
2008年 | 28篇 |
2007年 | 27篇 |
2006年 | 25篇 |
2005年 | 27篇 |
2004年 | 21篇 |
2003年 | 12篇 |
2002年 | 13篇 |
2001年 | 17篇 |
2000年 | 6篇 |
1999年 | 11篇 |
1998年 | 5篇 |
1997年 | 5篇 |
1996年 | 5篇 |
1995年 | 8篇 |
1994年 | 12篇 |
1993年 | 13篇 |
1992年 | 10篇 |
1991年 | 8篇 |
1990年 | 7篇 |
1989年 | 4篇 |
1988年 | 7篇 |
1986年 | 6篇 |
1985年 | 3篇 |
1984年 | 8篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 7篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1973年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有680条查询结果,搜索用时 31 毫秒
41.
42.
43.
44.
45.
Jean Servant Robert Delmas Jacques Rancher Marcel Rodriguez 《Journal of Atmospheric Chemistry》1984,1(4):391-401
A partial balance of mineral N is given for the basins of two coastal rivers in a forest zone in the Ivory Coast. The dry and wet depositions on the basin surfaces is given for particulate matter (NO3
–, NH4
+). The quantity of mineral N washed away in the rivers is evaluated. The losses from leaching of the soils by rainwater are about 0.33 to 1.0% of the atmospheric depositions for NH4
+–N and 2.2 to 5.8% for NO3
––N. The yearly atmospheric input of N compounds to the ecosystem, about 1.4 g N m–2 y–1, is at least 14% of mineral N formed in the soils and is therefore quite significant. 相似文献
46.
Pascal Richet 《Geochimica et cosmochimica acta》1984,48(3):471-483
With the configurational entropy theory of relaxation processes of Adam and Gibbs (1965), one predicts that the viscosity depends on temperature according to log , where Sconf is the configurational entropy of the liquid. Thermochemical calculations of Sconf performed for some mineral compositions show the importance of non-configurational contributions to the entropy differences between amorphous and crystalline phases. Except for the case of SiO2, the available thermodynamic data indicate that the above equation for viscosity accounts quantitatively for the experimentally determined temperature dependence of the viscosity of silicate melts. The Adam and Gibbs theory also provides a simple rationale for the non linear variation of the logarithmic viscosity with composition in mixed alkali silicate liquids at low temperatures, the minimum of viscosity resulting from the contribution of the entropy of mixing to Sconf. 相似文献
47.
The spatial organization of decadal and bidecadal components (fluctuations) of annual rainfall is identified in this research for two regions: (1) southern South America, and (2) southern North America (conterminous USA, southeastern Canada and northern and central Mexico). Findings indicate that these decadal and bidecadal components have highly coherent wave-like spatial organization. Two types of organization of decadal and bidecadal components of annual rainfall were identified: a train of propagating fluctuations and quasi-standing fluctuations. For decadal components, such patterns alternate in time. A widespread change in the spatial organization of decadal component of annual rainfall took place simultaneously in both continents in 1932. The bidecadal component is organized as standing fluctuations in southern North America and as travelling fluctuations in southern South America, The spatial pattern of decadal fluctuations of annual rainfall has 12- and 13-year cycles, and the spatial pattern of bidecadal fluctuations has predominantly 21- and 22-year cycles. 相似文献
48.
Vincent Jomelli & Pascal Bertran 《Geografiska Annaler: Series A, Physical Geography》2001,83(1-2):15-28
We analyse the morphology and sedimentology of 25 dirty snow avalanche deposits in the French Alps. The deposits typically have either a snow-ball structure or a massive structure with sliding planes. The snow balls show a longitudinal and a vertical sorting that reflects a sieve effect, similar to that observed in other rapid inertial granular flows. The massive type results from snow compaction when the avalanche is channelled by a gully or when it reaches the distal part of the scree. Velocity decrease and compaction limit the deformation to a zone at the base of the snow mass and cause the formation of distinctive sliding planes. These appear as smooth recrystallised surfaces due to local melt from frictional heating. The flow can be assimilated to a frictional granular flow. No systematic variation of size and shape of the rock debris has been observed along the profiles in both types of deposit. The distribution of rock debris and its fabric suggest that the clasts are transported passively and do not undergo any sorting during displacement. Snow melt after avalanching causes a redistribution of rock debris particularly when the snow thickness is important. This redistribution does not generate new sedimentological characteristics such as enhanced sorting or fabric. 相似文献
49.
50.