全文获取类型
收费全文 | 3385篇 |
免费 | 153篇 |
国内免费 | 46篇 |
专业分类
测绘学 | 86篇 |
大气科学 | 271篇 |
地球物理 | 719篇 |
地质学 | 1310篇 |
海洋学 | 241篇 |
天文学 | 623篇 |
综合类 | 12篇 |
自然地理 | 322篇 |
出版年
2023年 | 14篇 |
2021年 | 40篇 |
2020年 | 61篇 |
2019年 | 82篇 |
2018年 | 87篇 |
2017年 | 99篇 |
2016年 | 117篇 |
2015年 | 100篇 |
2014年 | 119篇 |
2013年 | 175篇 |
2012年 | 114篇 |
2011年 | 168篇 |
2010年 | 151篇 |
2009年 | 200篇 |
2008年 | 174篇 |
2007年 | 172篇 |
2006年 | 156篇 |
2005年 | 137篇 |
2004年 | 135篇 |
2003年 | 98篇 |
2002年 | 93篇 |
2001年 | 67篇 |
2000年 | 66篇 |
1999年 | 59篇 |
1998年 | 56篇 |
1997年 | 61篇 |
1996年 | 54篇 |
1995年 | 42篇 |
1994年 | 29篇 |
1993年 | 30篇 |
1992年 | 27篇 |
1991年 | 40篇 |
1990年 | 22篇 |
1989年 | 26篇 |
1988年 | 31篇 |
1987年 | 37篇 |
1986年 | 23篇 |
1985年 | 30篇 |
1984年 | 27篇 |
1983年 | 18篇 |
1982年 | 27篇 |
1981年 | 31篇 |
1980年 | 28篇 |
1979年 | 17篇 |
1978年 | 15篇 |
1977年 | 20篇 |
1976年 | 17篇 |
1974年 | 26篇 |
1973年 | 21篇 |
1971年 | 14篇 |
排序方式: 共有3584条查询结果,搜索用时 31 毫秒
111.
112.
On the minimization of correlated residuals 总被引:1,自引:0,他引:1
Martin Füllekrug 《Geophysical Journal International》1996,126(1):63-68
113.
114.
Martin Connors Alan R. Hildebrand Mark Pilkington Carlos Ortiz-Aleman Rene E. Chavez Jaime Urrutia-Fucugauchi Eduardo Graniel-Castro Alfredo Camara-Zi Juan Vasquez John F. Halpenny 《Geophysical Journal International》1996,127(3):F11-F14
The buried Chicxulub impact structure is marked by a dramatic ring of sinkholes (called cenotes if containing water), and adjacent less prominent partial rings, which have been shown to coincide with maxima in horizontal gravity gradients and a topographic depression. These observations, along with the discreteness and spacing of the features, suggest a formation mechanism involving faulting in the outer slump zone of the crater, which would thus have a diameter of approximately 180 km.
An opposing view, based primarily on the interpretation of gravity data, is that (he crater is much larger than the cenote ring implies. Given the association of the known cenote ring with faults, we here examine northern Yucatan for similar rings in gravity, surface features and elevation, which we might expect to be associated with outer concentric faults in the case of a larger, possibly multiring, structure.
No such outer rings have been found, although definite patterns are seen in the distribution of karst features outside the crater rim. We explain these patterns as resulting mainly from deformation related to the block fault zone that parallels tbe shelf edge of eastern Yucatan. 相似文献
An opposing view, based primarily on the interpretation of gravity data, is that (he crater is much larger than the cenote ring implies. Given the association of the known cenote ring with faults, we here examine northern Yucatan for similar rings in gravity, surface features and elevation, which we might expect to be associated with outer concentric faults in the case of a larger, possibly multiring, structure.
No such outer rings have been found, although definite patterns are seen in the distribution of karst features outside the crater rim. We explain these patterns as resulting mainly from deformation related to the block fault zone that parallels tbe shelf edge of eastern Yucatan. 相似文献
115.
Nuclear power plant siting provided the first significant public opportunity to examine nuclear safety and to affect nuclear policy. These discussions were prompted and fueled by perceptions of nuclear risk. Now, as we begin the process of nuclear decommissioning, we are finding that power plant removal—unsiting–is also likely to attract public interest. This paper presents a preliminary survey of how we are likely to react to this emerging theme, applying these findings within a land use context to see if it is likely to produce issues salient to the public. In so doing it also examines how these issues could affect decommissioning timing and type. It suggests that the most likely prospect is that power plants will remain on the landscape long after they are closed. 相似文献
116.
117.
118.
119.
Summary A combination of low frequency sodar, radar wind profiler and in-situ balloon-borne measurements of temperature and water vapor have been used to investigate the structure of elevated stratified layers within the transition layer above the nocturnal boundary layer during the Vertical Transport and Mixing Field Campaign in Salt Lake City Utah, during October, 2000. Elevated layers determined from sodar and radar vertical time sections were penetrated with a balloon-born instrument package to determine the fine scale temperature and moisture structure of the layers. As expected a potential temperature increase was found in the upper half of the layers; however the magnitude was considerably smaller than found above the daytime well-mixed layer and the vertical distance of the increase was quite variable. Mixing ratio, in the mean was found to have a relative maximum in the lower portion of the layers. It was found that the potential temperature within the layers decreased with time relative to background values, regardless of whether the layer descended or ascended. 相似文献
120.
Radiative Exchange in an Urban Street Canyon 总被引:1,自引:4,他引:1
The influence of building geometry on the radiation terms ofthe surface energy balance is a principal reason for surfacetemperature differences between rural and urban areas.Methods exist to calculate the radiation balance in an urban area,but their validity across the range of urban geometries andmaterials has not been carefully considered.Here the exchange of diffuse radiation in an urban street canyon isinvestigated using a method incorporating all reflections of radiation.This exact solution is compared to two commonly used approximationsthat retain either no reflections, or just one reflection of radiation.The area-averaged net radiative flux density from the facets of the canyondecreases in magnitude monotonically as the canyon aspect ratio increases.The two approximate solutions possess unphysical differences from thismonotonic decrease for high canyon aspect ratios or low materialemissivities/high material albedos.The errors of the two approximate solutions are small for near blackbodymaterials and small canyon aspect ratios but can be an order ofmagnitude for intermediate material properties and deep street canyons.Urban street canyon models need to consider at least one reflectionof radiation and multiple reflections are desirable for full applicability. 相似文献