全文获取类型
收费全文 | 343篇 |
免费 | 4篇 |
国内免费 | 6篇 |
专业分类
测绘学 | 23篇 |
大气科学 | 27篇 |
地球物理 | 39篇 |
地质学 | 161篇 |
海洋学 | 16篇 |
天文学 | 79篇 |
自然地理 | 8篇 |
出版年
2022年 | 10篇 |
2021年 | 6篇 |
2020年 | 5篇 |
2019年 | 3篇 |
2018年 | 14篇 |
2017年 | 13篇 |
2016年 | 16篇 |
2015年 | 12篇 |
2014年 | 17篇 |
2013年 | 24篇 |
2012年 | 15篇 |
2011年 | 15篇 |
2010年 | 14篇 |
2009年 | 15篇 |
2008年 | 15篇 |
2007年 | 10篇 |
2006年 | 12篇 |
2005年 | 9篇 |
2004年 | 7篇 |
2003年 | 14篇 |
2002年 | 6篇 |
2001年 | 10篇 |
2000年 | 11篇 |
1999年 | 3篇 |
1998年 | 4篇 |
1997年 | 8篇 |
1996年 | 8篇 |
1995年 | 4篇 |
1994年 | 5篇 |
1993年 | 2篇 |
1992年 | 4篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1987年 | 2篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1982年 | 5篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1977年 | 2篇 |
1974年 | 1篇 |
1973年 | 2篇 |
1972年 | 1篇 |
1969年 | 2篇 |
1967年 | 1篇 |
1965年 | 1篇 |
1961年 | 1篇 |
1958年 | 1篇 |
1956年 | 3篇 |
排序方式: 共有353条查询结果,搜索用时 15 毫秒
341.
Vasundhara R. Chakraborty Pavan Hänel Andreas Heiser Erwin 《Earth, Moon, and Planets》1997,78(1-3):321-328
Persistent jet and shell structures from comet Hale-Bopp showing gradual changes in the shapes and orientations with aspect
angle and solar illumination geometry indicate long lived active sources. A model to simulate the dust features has been applied
to the series of observations from September 1996 to May 1997. Most of the structures can be explained as arising due to ejections
from persistent active regions at comet-o-centric latitudes near +65°, +55°, −5° to −15°, −35° and −65°. The best fitting
pole positions vary between 255° ±10° and 275° ± 10° in right ascension and −45° ± 10° to −75° ± 10° in declination. Lower
limits on the dust and gas production rates at various epochs are presented.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
342.
We shall study homogeneous and isotropic clouds formed of String membranes. These membranes are considered in extra dimensions of a higher dimensional Bianchi-I space-time. Some solutions are found for the field equations of the system. 相似文献
343.
In this paper we obtain similarity solutions for the propagation of plane relativistic shock waves in the presence of a transverse magnetic field for the medium, where the nucleon number density obeys a power law of distance from the plane of explosion. The shock surface moves with constant velocity and the total energy of the disturbance is dependent on time. The solutions are applicable only to an isothermal medium or a cold gas. 相似文献
344.
Nibir Mandal Atin Kumar Mitra Santanu Misra Chandan Chakraborty 《Journal of Earth System Science》2006,115(6):643-660
In the Precambrian Singhbhum Craton of eastern India, newer dolerite dikes occur profusely with varying outcrop lengths. We
have analysed the nature of their length-size and orientation distributions in relation to the theory of fractals. Two orientational
sets of dikes (NW-SE and NE-SW) are present. Both the sets show strongly non-power-law size distributions, as reflected in
non-linear variations in logarithmic space. We analyzed thousands of data, revealing that polynomial functions with a degree
of 3 to 4 are the best representatives of the non-linear variations. Orientation analysis shows that the degree of dispersions
from the mean trend tends to decrease with increasing dike length. The length-size distributions were studied by simulating
fractures in physical models. Experimental fractures also show a non-power-law distribution, which grossly conforms to those
of the dolerite dikes. This type of complex size distributions results from the combined effects of nucleation, propagation
and coalescence of fractures. 相似文献
345.
Sudipta Sengupta 《Journal of Structural Geology》1983,5(2):197-210
The boudinage structure in the Väddö area in Sweden developed during an early isoclinal folding. During a second deformation which deformed the axial surfaces and the limbs of the isoclinal folds, the shapes of boudins were variously modified. The resulting structures include folding of the individual boudins into half-waves, a tile-like piling up of straight or gently folded boudins and arrangement of straight boudins in a herring-bone pattern. Similar structures have been produced experimentally in soft models containing ‘boudins’ of different competencies. The relative importance of the different physical parameters which contribute towards the development of the various structures is examined. In particular, the experiments showed that when the competence contrast between the boudin and the host material was rather small, the shape of the boudins was modified by a second deformation into trapezoidal forms often with flame-shaped projections at the edges. From an analysis of the experimental and natural structures, a set of criteria has been formulated which can be used to identify structures formed by superposed deformations and to give an approximate idea of the competence contrast between the boudin and the host rock during the second deformation. 相似文献
346.
Mr. S. K. Chakraborty M. Sc. 《Pure and Applied Geophysics》1958,40(1):15-18
Summary The problem of disturbances in an elastic medium produced by a twist on the surface of a spheroidal cavity has been solved using spheroidal functions. 相似文献
347.
Vibration of buried pipelines induced by moving axial and radial loads has been studied in this paper. A thin shell model has been used for the pipeline, which is assumed to be lying in an infinite isotropic homogeneous elastic medium. In order to allow for the possible motion of the pipe out of phase with the surrounding ground a very thin layer of viscoelastic material is assumed to separate the pipe from the ground. Calculations indicate the presence of the interfacial viscoelastic layer does not influence the pipe response in a significant manner. So all the numerical results presented here are for the case when the pipe is assumed to be perfectly bonded. These show that the maximum pipewall displacements and stresses occur in a soft soil at long wavelengths. 相似文献
348.
Assimilation of satellite-derived surface datasets has been explored in the study. Three types of surface data, namely sea level anomaly, sea surface temperature and sea surface salinity, have been used in various data assimilation experiments. The emphasis has been on the extra benefit arising out of the additional sea level assimilation and hence there are two parallel runs, in one of which sea level assimilation has been withheld. The model used is a state-of-the art ocean general circulation model (OGCM) and the assimilation method is the widely used singular evolutive extended Kalman filter (SEEK). Evaluation of the assimilation skill has been carried out by comparing the simulated depth of the 20°C isotherm with the same quantity measured by buoys and Argo floats. Simulated subsurface temperature and salinity profiles have also been compared with the same profiles measured by Argo floats. Finally, surface currents in the assimilation runs have been compared with currents measured by several off-equatorial buoys. Addition of sea level has been found to substantially improve the quality of simulation. An important feature that has been effectively simulated by the addition of sea level in the assimilation scheme is the near-surface temperature inversion (2-3°C) in the northern Bay of Bengal. 相似文献
349.
Deepesh Kumar Jain Arindam Chakraborty Ravi S. Nanjundiah 《Meteorology and Atmospheric Physics》2013,122(3-4):159-173
The simulation of precipitation in a general circulation model relying on relaxed mass flux cumulus parameterization scheme is sensitive to cloud adjustment time scale (CATS). In this study, the frequency of the dominant intra-seasonal mode and interannual variability of Indian summer monsoon rainfall (ISMR) simulated by an atmospheric general circulation model is shown to be sensitive to the CATS. It has been shown that a longer CATS of about 5 h simulates the spatial distribution of the ISMR better. El Niño Southern Oscillation–ISMR relationship is also sensitive to CATS. The equatorial Indian Ocean rainfall and ISMR coupling is sensitive to CATS. Our study suggests that a careful choice of CATS is necessary for adequate simulation of spatial pattern as well as interannual variation of Indian summer monsoon precipitation. 相似文献
350.
Arindam Chakraborty Amit K. Ghosh Abhijit Mazumder 《Journal of the Geological Society of India》2017,90(4):428-436
Petrographic thin section analysis of the samples collected from the type section of Neil West Coast Formation, situated in the west coast of Neil Island yielded moderately preserved coralline red algae, benthic and planktic foraminifers, coral fragments, echinoid spines and gastropod shells. The coralline red algae are represented by both non-geniculate and geniculate forms. The non-geniculate forms belong to melobesids, lithophylloids and mastophoroides. The geniculate forms are represented by species of Amphiroa, Corallina, and Jania. However, the diversity and abundance of coralline algal forms are less in comparison to the benthic foraminifers those are represented by Amphistegina, Neorotalia, Ammonia, Elphidium, Operculina, Assilina, Amphisorus and texularids. Planktic foraminifers like Globigerinoides and other biogenic components viz., gastropod shells, echinoid spines and coral fragments are also common. A foraminiferal-algal grainstone facies has been recognized as observed in the field as well as in thin section analysis. The overall assemblage of the biogenic components and facies analysis indicate intertidal to near shore environment of deposition with high energy condition and increased hydrodynamic activity. 相似文献