全文获取类型
收费全文 | 87篇 |
免费 | 3篇 |
国内免费 | 2篇 |
专业分类
测绘学 | 1篇 |
大气科学 | 2篇 |
地球物理 | 17篇 |
地质学 | 47篇 |
海洋学 | 3篇 |
天文学 | 10篇 |
综合类 | 1篇 |
自然地理 | 11篇 |
出版年
2022年 | 1篇 |
2019年 | 3篇 |
2018年 | 4篇 |
2017年 | 5篇 |
2016年 | 5篇 |
2015年 | 4篇 |
2014年 | 5篇 |
2013年 | 9篇 |
2012年 | 12篇 |
2011年 | 6篇 |
2010年 | 9篇 |
2009年 | 6篇 |
2008年 | 4篇 |
2007年 | 4篇 |
2006年 | 2篇 |
2005年 | 1篇 |
2004年 | 1篇 |
2003年 | 2篇 |
2002年 | 1篇 |
1998年 | 3篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1990年 | 2篇 |
1973年 | 1篇 |
排序方式: 共有92条查询结果,搜索用时 250 毫秒
1.
Application of X-ray computed tomography for analyzing cleat spacing and cleat aperture in coal samples 总被引:2,自引:2,他引:2
S. Mazumder K.-H.A.A. Wolf K. Elewaut R. Ephraim 《International Journal of Coal Geology》2006,68(3-4):205-222
New techniques to determine distributions of cleat aperture, cleat orientation and cleat spacing from CT scans have been developed. For cleat orientation and spacing distributions, two different coal blocks were scanned. The CT scans have been analyzed for the three orthogonal directions. Histograms of the cleat orientations are bimodal, expressing the typical cleat texture of face and butt cleats and bedding perpendicular relaxation fractures. Deviations up to 20° from the peak values in the cleat orientation distributions were used as input for automated image analysis of cleat spacing. Distributions of the cleat spacing measurements are related to the face and butt cleat directions. The term “relevant cleat length” is introduced as a measure to extract the amount of cleat length involved with the cleat spacing measurements. The ratio ranges from 0.03 to 0.38 and expresses the difference in cleat texture in both samples. Cleat spacing versus relevant cleat length shows sample specific patterns for face cleat, butt cleat and bedding. To describe cleat aperture quantitatively, peak height and missing attenuation have been used. The image of a cleat was seen as a convolution of a rectangular fracture profile with a Gaussian point spread function. 相似文献
2.
3.
Dhruba Mukhopadhyay Tapas Bhattacharya Tapan Chakraborty Arun Kanti Dey 《Journal of Earth System Science》1990,99(2):249-268
In the western part of the North Singhbhum fold belt near Lotapahar and Sonua the remobilized basement block of Chakradharpur
Gneiss is overlain by a metasedimentary assemblage consisting of quartz arenite, conglomerate, slate-phyllite, greywacke with
volcanogenic material, volcaniclastic rocks and chert. The rock assemblage suggests an association of volcanism, turbidite
deposition and debris flow in the basin. The grade of metamorphism is very low, the common metamorphic minerals being muscovite,
chlorite, biotite and stilpnomelane. Three phases of deformation have affected the rocks. The principal D1 structure is a
penetrative planar fabric, parallel to or at low angle to bedding. No D1 major fold is observed and the regional importance
of this deformation is uncertain. The D2 deformation has given rise to a number of northerly plunging major folds on E-W axial
planes. These have nearly reclined geometry and theL
2lineation is mostly downdip on theS
2surface, though some variation in pitch is observed. The morphology of D2 planar fabric varies from slaty cleavage/schistosity
to crenulation cleavage and solution cleavage. D3 deformation is weak and has given rise to puckers and broad warps on schistosity
and bedding. The D2 major folds south of Lotapahar are second order folds in the core of the Ongarbira syncline whose easterly
closure is exposed east of the mapped area. Photogeological study suggests that the easterly and westerly closing folds together
form a large synclinal sheath fold. There is a continuity of structures from north to south and no mylonite belt is present,
though there is attenuation and disruption along the fold limbs. Therefore, the Singhbhum shear zone cannot be extended westwards
in the present area. There is no evidence that in this area a discontinuity surface separates two orogenic belts of Archaean
and Proterozoic age. 相似文献
4.
Champa Mazumder 《Pure and Applied Geophysics》1973,105(1):810-815
Summary In this paper the displacement due to an impulsive twist produced by impulsive shearing stresses acting on a finite circular area on the plane surface of a semi-infinite solid of homogeneous anisotropic material has been found.Paper presented by Dr. A. K. Mitra of Jadavpur University. 相似文献
5.
Methods reported in the literature for rock fracture simulations include approaches based on stochastic geometry, multiple-point
statistics and a combination of geostatistics for fracture density and object-based modelling for fracture geometries. The
advantages and disadvantages of each of these approaches are discussed with examples. By way of review, the authors begin
with the geostatistical indicator simulation method, based on the truncated–Gaussian algorithm; this is followed by multiple-point
statistical simulation and then the stochastic geometry approach, which is based on marked point process simulation. A new
approach, based on pluriGaussian structural simulation, is then introduced. The new approach incorporates in the simulation
the spatial correlation between different sets of fractures, which in general, is very difficult, if not impossible, to accomplish
in the three methods reviewed. Each simulation method is summarised together with detailed simulation procedures for each.
A published two-dimensional fracture dataset is used as a means of assessing the performance of each simulation method and
of demonstrating the concepts discussed in the text. 相似文献
6.
Layers with high magnetic susceptibility contain heavy minerals that are the most likely to preserve signatures of impact in metamorphosed Precambrian rocks. The following impact indicators are resistant to alteration and metamorphism and are likely to be found in heavy mineral layers: impact diamond, SiC, shocked zircon, high-pressure TiO2 phases, reidite, and high-pressure chromite. Coesite and stishovite could also be present but are not likely to be preserved in rocks metamorphosed above the greenschist facies. Looking for layers with high magnetic susceptibility will also identify layers that might contain concentrations of zircon for dating. 相似文献
7.
Bimal Kanti Paul 《The Professional geographer》1998,50(3):287-301
On May 13, 1996, a disastrous tornado hit the Tangail district of Bangladesh, killing more than 700 people and causing extensive damage to homes, crops, and livestock. This paper explores and analyzes how tornado victims adjusted to this destruction. Data collected from two study sites show that victims received emergency assistance from people both in neighboring areas and from more distant areas, as well as from government agencies and non-governmental organizations (NGOs). At both sites, NGOs played the leading role in minimizing the hardships of victims through extraordinary disaster relief and rehabilitation efforts. Because of the extensive support received, the tornado victims were able to return to their “normal” lives very quickly. This study concludes with several recommendations to help cope with future tornado disasters. 相似文献
8.
Onkari Prasad Sant Prasad Kanti Prasad R. R. Kelkar 《Journal of Earth System Science》1998,107(1):5-18
Moisture profiles have been estimated over the region bounded by the latitudes 40°N and 40°S and longitudes 30°E to 130°E
using INSAT digital infra red cloud imagery data. The representativeness of these profiles in representing moisture field
associated with the development and movement of synoptic scale systems during the period September 15th, 1996 to March 31st,
1997 has been examined. It has been shown that the changes in the moisture field associated with the withdrawal of the southwest
and northeast monsoons from the Indian sub-continent, development and movement of synoptic scale sytems (depressions, tropical
cyclones and waves in easterlies) and equatorial troughs in the Indian Ocean could be clearly seen in humidity profiles. The
initial development of tropical systems is first seen in the humidity field in the upper troposphere. These profiles could
be used in monitoring the initial development and subsequent movement of tropical systems. Further the data on moisture distribution
from the data gap regions of the Indian Ocean could be used as an additional source of moisture in numerical analysis and
prognosis. 相似文献
9.
Recently, a field theoretic model for a UV complete theory of gravity has been proposed by Hor̃ava. This theory is a non-relativistic
renormalizable gravity theory which coincides with Einstein’s general relativity at large distances. Subsequently Lü et al.
have formulated the modified Friedmann equations and have presented a solution in vacuum. In the present work, we rewrite
the modified FRW equations in the form of usual FRW equations in Einstein gravity and consequences have been analyzed. Also
the thermodynamics of the FRW universe has been studied. 相似文献
10.
Bimal Kanti Paul 《Natural Hazards》2010,54(2):483-495
The objectives of this paper are to examine the extent of human injuries caused by Cyclone Sidr, which made landfall in Bangladesh
coast on November 15, 2007, and report on the circumstances, type and causes of injuries, along with selected risk factors
associated with such injuries. Relevant data was collected through a questionnaire survey administered among the cyclone victims.
Semi-structured interviews with key personnel were also conducted to obtain information regarding the circumstances causing
injuries and public response to care for the injured. The questionnaire survey data reveals that among the respondent families,
132 persons sustained various types of injuries. Since the respondent families comprised of 1,443 members, the injury rate
was 9.15%. All injured victims were treated either onsite or in local hospitals. The most common types of injuries were soft-tissue
injuries (cuts, bruises, and scrapes) and fracture/dislocations. The most common causes of injuries for survivors were associated
with falling trees. Analysis of risk factors reveals that age is significantly correlated with injuries. Both formal and informal
interviews suggest that injured persons and their family members were in general pleased with medical response they received
from various sources. Several recommendations have been suggested to reduce future cyclone-related injuries in Bangladesh. 相似文献