全文获取类型
收费全文 | 523篇 |
免费 | 43篇 |
国内免费 | 80篇 |
专业分类
测绘学 | 19篇 |
大气科学 | 67篇 |
地球物理 | 105篇 |
地质学 | 272篇 |
海洋学 | 48篇 |
天文学 | 70篇 |
综合类 | 9篇 |
自然地理 | 56篇 |
出版年
2023年 | 11篇 |
2022年 | 10篇 |
2021年 | 22篇 |
2020年 | 18篇 |
2019年 | 22篇 |
2018年 | 29篇 |
2017年 | 15篇 |
2016年 | 23篇 |
2015年 | 20篇 |
2014年 | 27篇 |
2013年 | 32篇 |
2012年 | 22篇 |
2011年 | 45篇 |
2010年 | 19篇 |
2009年 | 29篇 |
2008年 | 28篇 |
2007年 | 22篇 |
2006年 | 28篇 |
2005年 | 21篇 |
2004年 | 18篇 |
2003年 | 11篇 |
2002年 | 13篇 |
2001年 | 10篇 |
2000年 | 11篇 |
1999年 | 8篇 |
1998年 | 4篇 |
1997年 | 9篇 |
1996年 | 8篇 |
1995年 | 10篇 |
1994年 | 6篇 |
1993年 | 5篇 |
1991年 | 5篇 |
1990年 | 5篇 |
1989年 | 7篇 |
1987年 | 3篇 |
1984年 | 4篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 8篇 |
1980年 | 5篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 4篇 |
1975年 | 5篇 |
1974年 | 6篇 |
1973年 | 2篇 |
1972年 | 3篇 |
1970年 | 2篇 |
1966年 | 3篇 |
1914年 | 2篇 |
排序方式: 共有646条查询结果,搜索用时 0 毫秒
1.
2.
Urban land transformation for pro-poor economies 总被引:1,自引:0,他引:1
Solomon Benjamin 《Geoforum》2004,35(2):177-187
The transformation of land into a setting for clustering local economies can become an important cornerstone of poverty policy. This transformation has several functional aspects, which in turn have important institutional and political aspects. Underlying both the functional and institutional factors is the role of local government and local democracy. Such a conceptualization puts to center stage several paradoxes: A terrain that seems “slum-like” turns out to be highly productive and employment generating. Complex tenure forms and mixed land use seen as “unplanned” turn out to be pre-requisites for economic development. There are institutional paradoxes that contrast efforts at “transparency” and managerial “best practices”. Here, the messiness of local bureaucracies in municipal government turns out to be critical for poor groups to influence interventions in their favor. Influencing the public process may be more effective in stealth-like ways rather taking a more visible approach. Most fundamentally these issues remind us that the potential of cities to reinforce or reduce poverty moved far beyond projects and programs and the normative frameworks used by planners and administrators. Instead, it is the transformative process of turning land into economic settings that might be at the center stage. This is a stage where poor groups are the central actors who stealth-like draw on complex alliances across ethnic and class lines to shapes cities in their interests. 相似文献
3.
Simangele Dlamini Solomon G.Tesfamichael Gregory D.Breetzke Tholang Mokhele 《地球空间信息科学学报》2021,24(4):666-677
In this study, we employed a number of geospatial techniques to examine the spatio-temporal patterns and changes of environmental attitudes and place attachment... 相似文献
4.
Improved Representation of Land-surface Heterogeneity in a Non-hydrostatic Numerical Weather Prediction Model 总被引:2,自引:1,他引:2
This study focuses on the relevance of accurate surface parameters, in particular soil moisture, and of parameterizations for heterogeneous land surfaces, for the prediction of sensible and latent heat fluxes by a mesoscale weather forecast model with horizontal grid resolution of 7 km. The analysis is based on model integrations for a 30-day period, which are compared both to flux measurements obtained from the LITFASS-2003 field experiment and to high-resolution-model (1-km grid spacing) results. At first, the relevance of improved parameter sets and input data compared to usual operational practice for an accurate prediction of near-surface fluxes is shown and discussed. It is demonstrated that an observation-based land-surface assimilation scheme leads to an improved soil moisture analysis, which is shown to be essential for the realistic simulation of surface fluxes. Secondly, the implementation of two efficient parameterization strategies for subgrid-scale variability of the surface, the mosaic and the tile approach, is presented. Using these methods, the simulations are in better agreement with measurements than simulations with simple aggregation methods that use effective surface parameters. Integrations with the mosaic approach reproduce high resolution simulations very well and more accurately than simulations with the tile method. Finally, the high resolution simulations are analyzed to justify and discuss the approximations underlying both methods. 相似文献
5.
Volker Rachold Mikhail N. Grigoriev Felix E. Are Steve Solomon Erk Reimnitz Heidemarie Kassens Martin Antonow 《International Journal of Earth Sciences》2000,89(3):450-460
This article presents a comparison of sediment input by rivers and by coastal erosion into both the Laptev Sea and the Canadian Beaufort Sea (CBS). New data on coastal erosion in the Laptev Sea, which are based on field measurements and remote sensing information, and existing data on coastal erosion in the CBS as well as riverine sediment discharge into both the Laptev Sea and the CBS are included. Strong regional differences in the percentages of coastal erosion and riverine sediment supply are observed. The CBS is dominated by the riverine sediment discharge (64.45᎒6 t a-1) mainly of the Mackenzie River, which is the largest single source of sediments in the Arctic. Riverine sediment discharge into the Laptev Sea amounts to 24.10᎒6 t a-1, more than 70% of which are related to the Lena River. In comparison with the CBS, the Laptev Sea coast on average delivers approximately twice as much sediment mass per kilometer, a result of higher erosion rates due to higher cliffs and seasonal ice melting. In the Laptev Sea sediment input by coastal erosion (58.4᎒6 t a-1) is therefore more important than in the CBS and the ratio between riverine and coastal sediment input amounts to 0.4. Coastal erosion supplying 5.6᎒6 t a-1 is less significant for the sediment budget of the CBS where riverine sediment discharge exceeds coastal sediment input by a factor of ca. 10. 相似文献
6.
F. Felix Hahn 《International Journal of Earth Sciences》1914,5(2):112-145
Ohne Zusammenfassung 相似文献
7.
S. E. Agarry M.Eng. T. O. K. Audu M.Sc. Ph.D. B. O. Solomon M.Sc. Ph.D. 《International Journal of Environmental Science and Technology》2009,6(3):443-450
The present study investigated the phenol utilization kinetics of a pure culture of an indigenous Pseudomonas fluorescence under steady state and non-steady state (washout) conditions. Steady states of a continuous culture with an inhibitory substrate was used to estimate kinetic parameters under substrate limitation (chemo stat operation) Pure cultures of an indigenous Pseudomonas fluorescence were grown in continuous culture on phenol as the sole source of carbon and energy at dilution rates of 0.010 - 0.20/h. Using different dilution rates, several steady states were investigated and the specific phenol consumption rates were calculated. In addition, phenol degradation was investigated by increasing the dilution rate above the critical dilution rate (washout cultivation). The results showed that the specific phenol consumption rate increased with increased dilution rate at steady state and phenol degradation by Pseudomonas fluorescence can be described by simple substrate inhibition kinetics under substrate limitation but cannot be described by simple substrate inhibition kinetics under washout cultivation. Fitting of the steady state data from continuous cultivation to various inhibition models resulted in the best fit for Haldane, Yano and Koga (2), Aiba and Teissier kinetic inhibition models. The rsmax value of 0.229 mg/mg/h obtained from the inhibition model equations was comparable to the experimentally calculated rsmax value of 0.246 mg/mg/h obtained under washout cultivation. Therefore, the biokinetic constants evaluated using these models showed good tolerance and growth of the indigenous organism. 相似文献
8.
9.
10.