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31.
Saradee Sengupta Dhurjati Prasad Sengupta Saswati Bandyopadhyay 《Journal of the Geological Society of India》2016,87(5):503-519
The present work provides a detailed lithological map of the western part of the Satpura basin around Sohagpur and reports the presence of new archosauromorph fossil bones from that region. The study area is dominated by the Bagra Formation along with a narrow patch of the underlying upper part of the Denwa Formation. The lower Denwa and the underlying Pachmarhi formations are absent here. The presence of the Pachmarhi Formation, as a tongue shaped area, as mapped by Crookshank (1936) is discarded in this study on the basis of lithology and petrographic analyses, instead the presence of the Bagra Formation is suggested in this area. A comparison of the lithologies and the vertebrate faunas of the upper Gondwana formations between eastern and western part of the basin has been carried out for the first time. The comparison indicates that the Denwa Formation present in the western sector represents only the topmost part of the formation while the complete succession of Denwa is preserved in the eastern sector. The Bagra Formation in the western sector documents the presence of sheet-like sandstone bodies unlike the eastern part. The vertebrate fauna of the eastern part is dominated by temnospondyl amphibians while that of the western part is dominated by archosauromorph. The vertebrate fossils of upper part of Denwa Formation, found from similar lithologies in west and east though, have differences in the amount of transportation before their burial. 相似文献
32.
Sitiraju Srinivasa Rao Dinesh Kumar Sahadevan Milind R. Wadodkar M/ S. S. Nagaraju Sudipta Chattaraj William Joseph Prasanth Rajankar Titu Sengupta M. V. Venugopalan Subrata N. Das Asok Kumar Joshi Jaswanth Raj Sharma Eadara Amminedu 《Journal of the Indian Society of Remote Sensing》2016,44(2):277-285
33.
This paper deals with the computation of the depth to the magnetic interface from the total magnetic field intensity values obtained along profiles in the offshore area between Vengurla and Rajapur bay off the West Coast of India, by the application of one dimensional spectral analysis method.From the response characteristics of the total field magnetic values it is surmised that the magnetic interface may be identified with the Deccan trap series of rocks which are likely to form the magnetic basement rocks in this area.The plot of depths to the basement rocks as obtained from spectral analysis indicates that the basement is sloping towards outer edge of the Continental Shelf though not uniformly. 相似文献
34.
Diptansu Sengupta Basab Mukhopadhyay Om Prakash Mishra 《Journal of the Geological Society of India》2018,92(6):661-670
The annual b-value fluctuation patterns in Burmese subduction zone and Andaman–Sumatra subduction zone are evaluated from earthquake data (January 1990 to June 2016; Mw ³ 4.3) to identify seismic cycles with sequential dynamic phases as described in the ‘elastic failure model’ of Main et al. (1989). Two seismic cycles have been identified in Andaman–Sumatra subduction zone, one started in 1990 and ended on 2004 with occurrence of great Sumatra earthquake (Mw 9.0) and the other started in 2005 and continuing till date with the phase of crack coalescence and fluid diffusion (3A&B). Similarly, the subduction zone of Burma shows evidence of one incomplete seismic cycle within 1990–2016 and presently undergoing the crack coalescence and fluid diffusion (3A&B) phase. The analysis has prompted to subdivide the area into thirteen smaller seismic blocks (A to M) to analyse area specific seismic trend and vulnerability analysis employing Hurst Statistics. Hurst plots with the dynamic phases of ‘elastic failure model’ of earthquake generation is compared to assess the blocks with high seismic vulnerability. The analysis suggest that north Andaman zone (block G) and north Burma fold belt (block M) are seismically most vulnerable. Moreover, the seismic vulnerability of Tripura fold belt and Bangladesh plain (block K) is equally high. 相似文献
35.
In Korea most of the old mine workings were worked with room and pillar method or sublevel caving method and today they possess
great possibility of surface subsidence especially for shallow depth mines. In most of the cases, mine roadways, rooms and
pillars are irregular in shape and information about the local geology is uncertain. For these reasons, it is difficult to
standardize the estimating method of subsidence especially sinkhole type over abandoned mine area. This paper describes the
application procedure for the fuzzy reasoning techniques to analyze the possibility of sinkhole occurrences over abandoned
mines. This technique is implemented in software which can simplify the analysis procedure and present the possibility of
sinkhole subsidence without having precise information about local geological/mining conditions. This technique has been applied
to forecast sinkhole possibilities at Bonghwa site where a massive sinkhole has already been occurred. 相似文献
36.
Debasis Sen Gupta 《Journal of Earth System Science》1995,104(3):407-417
Recrystallized grain size was measured from quartzite mylonite specimens collected from parts of Singhbhum shear zone in eastern
India. The specimens were collected along five traverses (Mushabani, Pathargora, Surda, Rakha and Jadugoda) across the elongation
of the shear zone. The sheared quartzites range from protomylonite through mylonite to ultramylonite. The microstructural
studies of the specimens reflect that dynamic recrystallization was the main deformation process. Estimation of flow stresses
were derived from these specimens using empirical equations relating to flow stress and recrystallized grain size. The calculated
stresses range from 12–28 MPa (Mercieret al 1977), 23–49 MPa (Twiss 1977), 20–68 MPa (Christie and Ord 1980), considering all the traverses. The results show that these
values can only be used semiquantitatively. 相似文献
37.
A three-dimensional kinematic limit analysis approach based on the radial point interpolation method (RPIM) has been used to compute collapse loads for rectangular foundations. The analysis is based on the Mohr-Coulomb yield criterion and the associated flow rule. It is understood that the internal plastic power dissipation function and flow rule constraints can be expressed entirely in terms of plastic strain rates without involving stresses. The optimization problem has been solved on basis of the semidefinite programming (SDP) by using highly efficient primal-dual interior point solver MOSEK in MATLAB. The results have been presented in terms of the variation of the shape factors with changes in the aspect ratio (L/B) of the footing for different values of soil internal friction angle (ϕ). Computations have revealed that the shape factors, sc and sq, due to effects of cohesion and surcharge increase continuously with (1) decrease in L/B and (2) increase in ϕ. On the other hand, the shape factor sγ, due to the effect of soil unit weight, increases very marginally with an increase in L/B up to (1) ϕ = 25° for a rough footing and (2) ϕ = 35° for a smooth footing. Thereafter, for greater values of ϕ, the variation of sγ with L/B has been found to be quite similar to that of the factors sc and sq. The variations of (1) nodal velocity patterns, (2) plastic power dissipation, and (3) maximum plastic shear strain rates have also been examined to interpret the associated failure mechanism. 相似文献
38.
When individuals of a species utilize an environment, they generate movement patterns at a variety of spatial and temporal scales. Field observations coupled with location technologies (e.g. GPS tags) enable the capture of detailed spatio‐temporal data regarding these movement patterns. These patterns contain information about species‐specific preferences regarding individual decision‐making, locational choices and the characteristics of the habitat in which the animal resides. Spatial Data Mining approaches can be used to extract repeated spatio‐temporal patterns and additional habitat preferences hidden within large spatially explicit movement datasets. We describe a method to determine the periodicity and directionality in movement exhibited by a migratory bird species. Results using a High Arctic‐nesting Svalbard Barnacle Goose movement data yielded undetected patterns that were secondarily corroborated with expert field knowledge. Individual revisits by the geese to specific locations in the breeding and wintering grounds of Svalbard, Norway and Solway, Scotland, occurred with a periodicity of 334 days . Further, the orientation of this movement was detected to be mostly north‐south. During long‐range migration the geese use the north‐south oriented Norwegian islands as “stepping stones”, Short‐range movement between mudbank roosts to feeding fields in Solway also retained a north‐south orientation. 相似文献
39.
Chandreyee Sengupta K. S. Dwarakanath D. J. Saikia 《Monthly notices of the Royal Astronomical Society》2009,397(1):548-557
We present the results of Giant Metrewave Radio Telescope (GMRT) observations of the interacting system Arp86 in both neutral atomic hydrogen, H i , and in radio continuum at 240 606 and 1394 MHz. In addition to H i emission from the two dominant galaxies, NGC 7752 and NGC 7753, these observations show a complex distribution of H i tails and bridges due to tidal interactions. The regions of highest column density appear related to the recent sites of intense star formation. H i column densities ∼1–1.5 × 1021 cm−2 have been detected in the tidal bridge which is bright in Spitzer image as well. We also detect H i emission from the galaxy 2MASX J23470758+2926531, which is shown to be a part of this system. We discuss the possibility that this could be a tidal dwarf galaxy. The radio continuum observations show evidence of a non-thermal bridge between NGC 7752 and NGC 7753, and a radio source in the nuclear region of NGC 7753 consistent with it having a low-ionization nuclear emission region nucleus. 相似文献
40.
By measuring the ratio of wavelength to arclength of folds in closely associated disharmonically folded competent layers,
it is possible to determine which layer has undergone a greater layer-parallel strain and has a smaller competence. This method
may lead to a paradoxical situation. For example when foliated quartzite and mica schist layers are folded together, the mica
schist laminae show a much larger buckle shortening than the quartzite layers. On the other hand, the geometry of folds in
quartzite indicates that quartzite was more competent than the mica schist. The structure can be explained by different modes
of buckling, general buckling in quartzite layers and internal buckling in strongly anisotropic mica schists. 相似文献