全文获取类型
收费全文 | 379篇 |
免费 | 18篇 |
国内免费 | 4篇 |
专业分类
测绘学 | 5篇 |
大气科学 | 41篇 |
地球物理 | 130篇 |
地质学 | 140篇 |
海洋学 | 18篇 |
天文学 | 56篇 |
综合类 | 2篇 |
自然地理 | 9篇 |
出版年
2024年 | 2篇 |
2021年 | 7篇 |
2020年 | 6篇 |
2019年 | 9篇 |
2018年 | 13篇 |
2017年 | 21篇 |
2016年 | 24篇 |
2015年 | 20篇 |
2014年 | 19篇 |
2013年 | 28篇 |
2012年 | 28篇 |
2011年 | 17篇 |
2010年 | 9篇 |
2009年 | 17篇 |
2008年 | 15篇 |
2007年 | 4篇 |
2006年 | 8篇 |
2005年 | 11篇 |
2004年 | 9篇 |
2003年 | 4篇 |
2002年 | 16篇 |
2001年 | 7篇 |
1999年 | 2篇 |
1998年 | 3篇 |
1997年 | 7篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1994年 | 6篇 |
1992年 | 5篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1977年 | 2篇 |
1975年 | 2篇 |
1968年 | 2篇 |
1967年 | 5篇 |
1966年 | 4篇 |
1965年 | 6篇 |
1964年 | 4篇 |
1962年 | 2篇 |
1961年 | 4篇 |
1960年 | 5篇 |
1959年 | 5篇 |
1958年 | 3篇 |
1957年 | 2篇 |
1956年 | 3篇 |
1955年 | 3篇 |
1927年 | 1篇 |
1926年 | 2篇 |
1915年 | 1篇 |
排序方式: 共有401条查询结果,搜索用时 15 毫秒
1.
In South Africa attempts are being made to address the socio-spatial distortions of the apartheid era through a more equitable
distribution of resources, and the re-drawing of municipal geographical boundaries. However, boundaries are not neutral geographic
lines. Boundary changes are often associated with a redistribution of political power and resources. The aim of this paper
is to analyse the effects of the contemporary territorial and administrative restructuring on urban dynamics in South Africa.
More specifically, the focus is on how the process of territorial restructuring impacted on metropolitan areas as well as
on secondary cities and their hinterlands. Examining and elucidating the manner in which various social, economic and political
forces have manifested themselves in the process of boundary delimitation in a major metropolitan centre as well as adjacent
rural areas is a central theme of this paper. There were considerable contestations over the delimitation of new local government
boundaries. Affluent metro authorities like that in Durban were opposed to the spatial extension of their boundaries because
of the costs of the providing services and infrastructure in the deprived margins. Similarly, there was concern that incorporation
of rural areas will result in increased municipal service charges being imposed on these communities. Tensions were heightened
between urban and rural regions because traditional leaders believed that their territorial jurisdiction and authority were
being undermined. In other parts of the country, the merger of traditionally white and black fragments of secondary cities
often resulted in many black locations continuing to be marginalized. There appears to be neither the political will nor the
economic capacity to upgrade these zones of marginalized urban communities. While the Municipal Demarcation Board was largely
successful in eliminating the political geography of apartheid at a macro- scale, this paper suggests that the greater challenge
for government and policy makers is to reduce the socio-spatial and economic inequalities which appears to be still very high
and perhaps increasing.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
2.
Delphine Yeghicheyan Cécile Bossy Martine Bouhnik Le Coz Chantal Douchet Guy Granier Alexie Heimburger Francois Lacan Aurélie Lanzanova Tristan C. C. Rousseau Jean‐Luc Seidel Mickaël Tharaud Frédéric Candaudap Jérôme Chmeleff Christophe Cloquet Sophie Delpoux Marie Labatut Rémi Losno Catherine Pradoux Yann Sivry Jeroen E. Sonke 《Geostandards and Geoanalytical Research》2013,37(4):449-467
The natural river water certified reference material SLRS‐5 (NRC‐CNRC) was routinely analysed in this study for major and trace elements by ten French laboratories. Most of the measurements were made using ICP‐MS. Because no certified values are assigned by NRC‐CNRC for silicon and 35 trace element concentrations (rare earth elements, Ag, B, Bi, Cs, Ga, Ge, Li, Nb, P, Rb, Rh, Re, S, Sc, Sn, Th, Ti, Tl, W, Y and Zr), or for isotopic ratios, we provide a compilation of the concentrations and related uncertainties obtained by the participating laboratories. Strontium isotopic ratios are also given. 相似文献
3.
Segmentation and kinematics of the North America‐Caribbean plate boundary offshore Hispaniola 下载免费PDF全文
Sylvie Leroy Nadine Ellouz‐Zimmermann Jordane Corbeau Frédérique Rolandone Bernard Mercier de Lépinay Bertrand Meyer Roberte Momplaisir José‐Luis Granja Bruña Anne Battani Céline Baurion Evgueni Burov Valérie Clouard Rémy Deschamps Christian Gorini Youri Hamon Manfred Lafosse Jottin Leonel Laetitia Le Pourhiet Pilar Llanes Estrada Nicolas Loget Francis Lucazeau Daniel Pillot Jeffrey Poort Kevin R. Tankoo José‐Luis Cuevas José‐Fernando Alcaide Claude Jean Poix Alfonso Muñoz‐Martin Serge Mitton Yamil Rodriguez Julien Schmitz Leonardo Seeber Andres Carbo‐Gorosabel Santiago Muñoz 《地学学报》2015,27(6):467-478
We explored the submarine portions of the Enriquillo–Plantain Garden Fault zone (EPGFZ) and the Septentrional–Oriente Fault zone (SOFZ) along the Northern Caribbean plate boundary using high‐resolution multibeam echo‐sounding and shallow seismic reflection. The bathymetric data shed light on poorly documented or previously unknown submarine fault zones running over 200 km between Haiti and Jamaica (EPGFZ) and 300 km between the Dominican Republic and Cuba (SOFZ). The primary plate‐boundary structures are a series of strike‐slip fault segments associated with pressure ridges, restraining bends, step overs and dogleg offsets indicating very active tectonics. Several distinct segments 50–100 km long cut across pre‐existing structures inherited from former tectonic regimes or bypass recent morphologies formed under the current strike‐slip regime. Along the most recent trace of the SOFZ, we measured a strike‐slip offset of 16.5 km, which indicates steady activity for the past ~1.8 Ma if its current GPS‐derived motion of 9.8 ± 2 mm a?1 has remained stable during the entire Quaternary. 相似文献
4.
5.
Sara Teitelbaum Annie Montpetit Jean-François Bissonnette Clément Chion Guy Chiasson Frédérik Doyon 《社会与自然资源》2019,32(1):93-112
This article explores the suitability of Ostrom and colleagues' social-ecological systems framework (SESF) for the study of resource-dependent communities in Canada. Through a broad literature about resource-dependent communities in Canada, three main approaches are identified, named staples research, rural development, and sustainability studies. Each of these research traditions is analyzed with regards to a common set of criteria – focus, scale, methods, treatment of institutions, and treatment of environmental dimensions. Research in each category is compared and contrasted with the SESF approach, to identify areas of overlap and divergence. Results indicate that the SESF is unlikely to provide additional benefit in terms of in-depth of social analysis, however, it does provide a unique contribution in terms of its coupled approach to conceiving social and ecological systems and its ability to operationalize these relationships through structured variables. 相似文献
6.
Airborne laser scanning (ALS) is an active remote sensing technique providing range data as 3D point clouds. This paper aims at presenting a survey of the literature related to such techniques, with emphasis on the new sensors called full-waveform lidar systems. Indeed, an emitted laser pulse interacts with complex natural and man-made objects leading to a temporal distortion of the returned energy profile. The new technology of full-waveform laser scanning systems permits one to digitize the complete waveform of each backscattered pulse. Full-waveform lidar data give more control to an end user in the interpretation process of the physical measurement and provide additional information about the structure and the physical backscattering characteristics of the illuminated surfaces. In this paper, the theoretical principles of full-waveform airborne laser scanning are first described. Afterwards, a review of the main sensors as well as signal processing techniques are presented. We then discuss the interpretation of full-waveform measures with special interest on vegetated and urban areas. 相似文献
7.
Frédéric Gueydan Yves M. Leroy Laurent Jolivet 《International Journal of Earth Sciences》2001,90(1):181-196
Localized shear zones along low-angle normal faults have been identified in regions of extension at the brittle-ductile transition of the continental crust. The possibility of the strain localizing at a depth of 10 km is interpreted here as a consequence of an increase in the equivalent shear stress applied to the flow of the lower crust. This enhancement of the flow stress is seen as a prerequisite for the triggering of brittle deformation mechanisms leading to strain localization. The lower crust rheology used to examine this stress increase is strain-rate, temperature and grain-size dependent, due to the coupling of dislocation and diffusion creep. The model structure proposed consists of a top layer, the upper crust, gliding rigidly above a bottom layer, the lower crust, which deforms in simple shear. During a short time interval (1400 years), the equivalent shear stress is found to increase by a factor of up to 3 (67 MPa for anorthite and 17 MPa for quartz). For anorthite, this stress could explain the activation of a Mohr-Coulomb failure with a friction coefficient of 0.2, which is reasonable at the depth of 10 km. Dislocation creep is activated during a rapid change in the prescribed velocity, whereas diffusion creep dominates if the velocity is held constant, highlighting the importance of grain-size sensitivity for lower crustal rheology. 相似文献
8.
9.
Ohne Zusammenfassung 相似文献
10.