全文获取类型
收费全文 | 4459篇 |
免费 | 521篇 |
国内免费 | 761篇 |
专业分类
测绘学 | 703篇 |
大气科学 | 564篇 |
地球物理 | 735篇 |
地质学 | 1990篇 |
海洋学 | 340篇 |
天文学 | 65篇 |
综合类 | 307篇 |
自然地理 | 1037篇 |
出版年
2024年 | 13篇 |
2023年 | 52篇 |
2022年 | 129篇 |
2021年 | 173篇 |
2020年 | 184篇 |
2019年 | 215篇 |
2018年 | 144篇 |
2017年 | 196篇 |
2016年 | 180篇 |
2015年 | 179篇 |
2014年 | 236篇 |
2013年 | 362篇 |
2012年 | 255篇 |
2011年 | 203篇 |
2010年 | 156篇 |
2009年 | 215篇 |
2008年 | 263篇 |
2007年 | 270篇 |
2006年 | 290篇 |
2005年 | 228篇 |
2004年 | 249篇 |
2003年 | 184篇 |
2002年 | 189篇 |
2001年 | 145篇 |
2000年 | 134篇 |
1999年 | 124篇 |
1998年 | 124篇 |
1997年 | 127篇 |
1996年 | 93篇 |
1995年 | 103篇 |
1994年 | 78篇 |
1993年 | 50篇 |
1992年 | 43篇 |
1991年 | 23篇 |
1990年 | 34篇 |
1989年 | 18篇 |
1988年 | 16篇 |
1987年 | 15篇 |
1986年 | 12篇 |
1985年 | 12篇 |
1984年 | 6篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1977年 | 2篇 |
1973年 | 1篇 |
排序方式: 共有5741条查询结果,搜索用时 46 毫秒
81.
82.
Jorge Dinis Jacques Rey Pierre-Charles de Graciansky 《Comptes Rendus Geoscience》2002,334(10):757-764
. Three transgressive–regressive 2nd-order cycles were identified in the Upper Aptian–Albian fluvial and marine deposits of the Lusitanian Basin. Its widespread nature, probably including eustatic origin, allows correlation between the southern package, with precise stratigraphic positioning, and the northern series with a poorly constrained age. The main unconformities can be related to the onset of an oceanic crust, in the western margin of Galicia during the Late Aptian, in the bay of Biscay during the Early Albian, and, to the northwest of the Galicia triple point, during the Middle to Late Albian transition, and, at the Albian–Cenomanian boundary, to a probable compressive event with Africa due to the rotation of Iberia. To cite this article: J. Dinis et al., C. R. Geoscience 334 (2002) 757–764. 相似文献
83.
A structural transect in the Lower Dolpo highlights that the deformation and metamorphism of the Tibetan Zone (TZ) increase toward the bottom of the sequence. The contact with the underlying HHC is marked by a metamorphic jump from amphibolite facies in the carbonatic rocks of the upper part of the HHC to greenschist facies marbles in the TZ. Moreover, the HHC and the TZ show different metamorphic histories. The contact zone shows a strain increase accompanied by asymmetric folds with a top-to-the-northeast vergence, connected to a down-to-the-northeast tectonic transport. The contact is interpreted as an extensional shear zone, connected to the South Tibetan Detachment System. To cite this article: R. Carosi et al., C. R. Geoscience 334 (2002) 933–940. 相似文献
84.
We analyse longitudinal river profiles in southwestern Taiwan. As all necessary data are not available, a physical modelling of river erosion would be subject to large uncertainties. We thus shortcut this modelling and adopt simple empirical exponential equations giving riverbed elevation as a function of downstream distance. We identify a positive altimetric anomaly, which reveals active uplift of an anticline at the front of the fold-and-thrust belt. To cite this article: J. Angelier, R.-F. Chen, C. R. Geoscience 334 (2002) 1103–1111. 相似文献
85.
Global heat budget, plate tectonics and climatic change 总被引:1,自引:0,他引:1
For the past 2000 Ma, the temperature of the Earth's surface has fluctuated around a mean similar to that of today, although individual locations have undergone long-term changes of ∼30°C at different times in different places. Water bodies absorb at least five times as much solar radiation as land surfaces, and ocean currents transport the excess heat absorbed in the tropics towards the poles. Changes in the distribution of land and sea due to plate tectonics explain the major temperature fluctuations (>25°C) around the globe in the last 350 Ma, and are first-order controls. Large-scale changes in ocean currents and thermohaline circulations are probably second-order controls (15–25°C). The Milankovitch orbital cycles are third-order controls producing variations in air temperature of the order of 10°C, while massive volcanic eruptions and changes in carbon dioxide are amongst the fourth-order controls producing minor perturbations (<5°C). The major climatic fluctuations are continuous but regional in effect and not global. Extraterrestrial factors may not cause major changes in climate when viewed from a geological perspective. 相似文献
86.
87.
88.
89.
90.
我国制造业集群分布现状及其发展特征 总被引:28,自引:0,他引:28
目前,在我国很多地区,例如长江三角洲和珠江三角洲,以个别市、县、镇或村为范围,集中某种产品的生产所形成的制造业集群表现出极强的活力和竞争力。集群中的很多企业根据不同技术能力,纷纷进入了全球价值链,已经使中国成为跨国公司控制之下的“世界工厂”。文章从目前局限性的资料出发,将这一现象的分布现状进行了分析,并对其发展特征进行了描述。认为,在新型工业化道路中,企业只有在本地舍作和结网,加强创新,才能有效地插入全球价值链,参与国际竞争。为此,需要通过政策的支持,鼓励合作的信用环境,使价值链上的各级企业以及利益相关者进行合作。 相似文献