全文获取类型
收费全文 | 319篇 |
免费 | 20篇 |
专业分类
测绘学 | 8篇 |
大气科学 | 39篇 |
地球物理 | 68篇 |
地质学 | 139篇 |
海洋学 | 69篇 |
天文学 | 8篇 |
自然地理 | 8篇 |
出版年
2024年 | 2篇 |
2023年 | 2篇 |
2022年 | 7篇 |
2021年 | 13篇 |
2020年 | 8篇 |
2019年 | 9篇 |
2018年 | 13篇 |
2017年 | 14篇 |
2016年 | 21篇 |
2015年 | 12篇 |
2014年 | 15篇 |
2013年 | 13篇 |
2012年 | 23篇 |
2011年 | 20篇 |
2010年 | 11篇 |
2009年 | 19篇 |
2008年 | 18篇 |
2007年 | 16篇 |
2006年 | 13篇 |
2005年 | 10篇 |
2004年 | 12篇 |
2003年 | 9篇 |
2002年 | 8篇 |
2001年 | 4篇 |
2000年 | 7篇 |
1999年 | 10篇 |
1998年 | 3篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1995年 | 3篇 |
1992年 | 5篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1988年 | 3篇 |
1986年 | 2篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有339条查询结果,搜索用时 15 毫秒
71.
The aim of this study is to separate various fractions of phosphorus in surface sediments of the Amazon continental shelf and compare them with other areas of the Brazilian shelf. Surface sediments were collected from the river-mouth transect (RMT) and open-self transect (OST). The extraction techniques available in the literature have been used to separate the following forms: Fe-PO4, Al-PO4, Ca-PO4, and associated organic matter. The results indicate that the concentrations of phosphorus are uniform in the study area and may be compared with many other nonpolluted environments. Among the inorganic forms, Ca-PO4 is dominant in all the samples, and Fe-PO4 is present in lower concentrations. Al-PO4 is more significant on the Amazon continental shelf than other parts of the Brazilian coast and other coastal environments of the world. 相似文献
72.
M. A. Allison C. A. Nittrouer L. E. C. Faria Jr. O. M. Silveira A. C. Mendes 《Geo-Marine Letters》1996,16(1):36-40
Modern and Holocene muddy strata were studied along the shoreline adjacent to the Amazon river mouth using sedimentological, radiochemical, physical, and seismic methods. The present paper is a synthesis of the results, collected during the AmasSeds project, that is used to outline a regional shoreline sediment budget. Erosion of relict Amazon muds in southern Amapa supplies 106 tons yr–1 to the Amazon advective mud stream. Local rivers are sediment-poor (total suspended discharge ~ 1 × 106 tons yr–1), but form depositional sandflats on the shoreface downdrift of the river mouths. Mudflat accumulation in northern Amapa sequesters 106–107 tons yr–1 by tidal-flat aggradation, alongshore mudcape accretion, and sediment trapping by mangroves. The processes temporarily store 1.5 × 108 tons of Amazon mud in January–June. 相似文献
73.
74.
Pétrick Anderson Soares Guilherme Faht Adilson Pinheiro Marcos Rivail da Silva Evelyn Zucco 《水文研究》2013,27(19):2710-2720
The modified tracer gas technique is used to determine the reaeration coefficient in six different water bodies of the Itajaí River basin, three with rural land use and three in urban areas. Propane was used as the tracer gas and Rhodamine WT as the conservative tracer, providing information on dilution, mixing and dispersion. Liquefied petroleum gas was used instead of high purity propane, aimed at reducing the costs associated with the field trials. Reaeration‐rate coefficients observed in the field ranged from 25.8 to 367.7 d?1. Two data sets could be observed where smaller streams had substantially larger coefficients of between 133.1 and 367.7 d?1, while the larger streams had values ??ranging from 25.8 to 54.5 d?1. Five empirical equations were evaluated by comparing the values ??obtained in the field. The equations proposed by Tsivolgou and Wallace and Tsivoglou and Neal showed greater adherence to the values ??determined in the tests. Reaeration‐rate coefficients obtained in the field were correlated with the hydrodynamic characteristics of the watercourses, thus establishing a mathematical function through which to obtain estimates for future evaluations. The R2 value obtained using this equation was 0.959, indicating a high correlation between the calculated values ??and those estimated in the field. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
75.
76.
Modelling of coupled fluid‐mechanical problems in fractured geological media using enriched finite elements
下载免费PDF全文
![点击此处可从《国际地质力学数值与分析法杂志》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Jose Roberto Silvestre Euripedes do Amaral Vargas Jr. Luiz Eloy Vaz Antonio Claudio Soares 《国际地质力学数值与分析法杂志》2015,39(10):1104-1140
Geological environments, such as petroleum reservoirs, normally exhibit physical discontinuities, for example, fractures and faults. Because of the reduced thickness of these discontinuities, finite element formulations with strong discontinuity have been applied to the numerical modelling of geological environments. Until now, two relevant characteristics of petroleum reservoirs have not been addressed by these formulations. The first is the pore pressure jump in the direction normal to a discontinuity in a fluid‐mechanical coupling condition, which is present primarily in sealing faults owing to the contrast of permeability with the porous medium. The absence of this jump can affect the prediction of the deformability of a physical discontinuity. Furthermore, reservoir models frequently use coarse meshes. Thus, the method used to evaluate the pore pressure in the discontinuity may exhibit a strong dependence relative to the mesh refinement. Based on these characteristics, in this study, a formulation of an enriched finite element for application to coupled fluid‐mechanical problems with pre‐existing physical discontinuities saturated by a single fluid is presented. The formulation employs discontinuous interpolation functions and enables the reproduction of jumps of displacement and pore pressure associated with a discontinuity inside the element without the need to discretise it. An approximation to estimate the pore pressure in the discontinuity was developed, one which seeks to minimise the influence of refinement. The element's response is verified by comparison with a one‐dimensional analytical solution and simple examples that are simulated using commercial software. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
77.
78.
Meena Sansar Raj Soares Lucas Pedrosa Grohmann Carlos H. van Westen Cees Bhuyan Kushanav Singh Ramesh P. Floris Mario Catani Filippo 《Landslides》2022,19(5):1209-1229
Landslides - Event-based landslide inventories are essential sources to broaden our understanding of the causal relationship between triggering events and the occurring landslides. Moreover,... 相似文献
79.
Peixoto Filho Flávio Tito Vargas Junior Euripedes do Amaral Santos Erick Slis Raggio Ferreira Francisco Henriques 《Geotechnical and Geological Engineering》2021,39(6):4127-4142
Geotechnical and Geological Engineering - In coring operations, core jamming is a permanent concern, taking place when the rock core sample becomes stuck within the inner core barrel, thus... 相似文献
80.
Soares Wilson Cartaxo Coutinho Roberto Quental da Cunha Renato Pinto 《Geotechnical and Geological Engineering》2021,39(8):5599-5618
Geotechnical and Geological Engineering - Hollow auger piles are a new solution technique being used more often in recent years as a foundation for buildings of 15 floors or less in the coastal... 相似文献