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41.
Anisotropic spatially homogeneous Bianchi type-I cosmological model in bimetric theory of gravitation (Rosen, 1973) is considered.
It is shown that the Bianchi type-I cosmological model does not exist in case of both meson field and mesonic perfect fluid
(with or without mass parameter). Hence only vacuum models can be obtained (Reddy and Venkateswarlu, 1989).
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
42.
In recent major earthquakes, the researchers have found the need for consideration of vertical seismic acceleration for the stability analysis of the man-made and natural slopes. However, in most past studies, the performance of slopes has been assessed by accounting only the horizontal seismic component of the ground motion, without giving due weightage to the effect of vertical component. In the present study, analytical expressions are derived to determine the factor of safety, yield seismic coefficient and consequently the seismic displacement of cohesionless soil slope under combined horizontal and vertical components of the ground motion. The derivation uses the Newmark’s sliding block approach, in which the soil slope with a planar failure surface within the framework of conventional pseudo-static analysis is assumed to follow the Mohr-Coulomb failure criterion. The effects of vertical seismic coefficient on the stability of cohesionless slope have been studied through a set of graphical presentations for a specific range of soil parameters. It is observed that overlooking the effect of the vertical component of the ground motion on factor of safety and the displacement while designing the slope may be detrimental, resulting in the slope failure. The general expressions presented in this paper may be highly useful in the field of earthquake geotechnical engineering practice for designing the cohesionless soil slopes under combined horizontal and vertical seismic loads. 相似文献
43.
The lowest unit of the Talchir Formation of Talchir Basin, Orissa, was described by pioneer workers as the ‘basal boulder
bed’. In an attempt to explain the co-existence of gravel and clay, materials of contrasting hydraulic properties, a probable
situation resembling the effects of the action of ground-ice enabled boulders to be carried down by sluggish currents resulting
in an intermixture of large boulders and fine mud was conceived. Misinterpretation of this conclusion led to a general tendency
to describe the ‘basal boulder bed’ as ‘glacial tillite’. However, the unit described as ‘basal boulder bed’ is actually represented
by a matrix rich conglomerate with pockets of normally graded silty clay. The present study reveals that the depositional
imprints preserved in this part of the sedimentary succession indicate emplacement of successive debris flows generated through
remobilization of pre-existing unconsolidated sediments. Small pockets of fine-grained turbidites presumably deposited from
the entrained turbidity currents associated with the debris flows suggest the composite character of the debris flow deposit. 相似文献
44.
In this paper, we have constructed mesonic stiff fluid cosmological models in five dimensional LRS Bianchi type-I and Bianchi
type-VI0 space times in general theory of relativity. Some physical and geometrical properties of the models are discussed. 相似文献
45.
46.
S. Pradhan K. K. Bandyopadhyay R. N. Sahoo V. K. Sehgal R. Singh V. K. Gupta D. K. Joshi 《Journal of the Indian Society of Remote Sensing》2014,42(4):711-718
Field experiment was conducted in a sandy loam soil of Indian Agricultural Research Institute, New Delhi during the year 2011–13 to see the effect of irrigation, mulch and nitrogen on canopy spectral reflectance indices and their use in predicting the grain and biomass yield of wheat. The canopy reflectances were measured using a hand held ASD FieldSpec Spectroradiometer at booting stage of wheat. Four spectral reflectance indices (SRIs) viz. RNDVI (Red Normalized Difference Vegetation Index), GNDVI (Green Normalized Difference Vegetation Index), SR (Simple Ratio) and WI (Water Index) were computed using the spectral reflectance data. Out of these four indices, RNDVI, GNDVI and SR were significantly and positively related with the grain and biomass yield of wheat whereas WI was significantly and negatively related with the grain and biomass yield of wheat. Calibration with the second year data showed that among the SRIs, WI could account for respectively, 85 % and 86 % variation in grain and biomass yield of wheat with least RMSE (395 kg ha?1 (15 %) for grain yield and 1609 kg ha?1 (20 %) for biomass yield) and highest d index (0.95 for grain yield and 0.91 for biomass yield). Therefore it can be concluded that WI measured at booting stage can be successfully used for prediction of grain and biomass yield of wheat. 相似文献
47.
48.
In this paper, we have investigated Bianchi type VI h cosmological model filled with perfect fluid in the framework of f(R,T) gravity, where R is the Ricci scalar and T is the trace of the energy-momentum tensor proposed by Harko et al. (Phys. Rev. D 84:024020, 2011). We have obtained the cosmological models by solving the field equations. Some physical behaviors of the model are also studied. 相似文献
49.
Effects of climate change on thermal properties of lakes and reservoirs, and possible implications 总被引:1,自引:2,他引:1
G. B. Sahoo S. G. Schladow J. E. Reuter R. Coats 《Stochastic Environmental Research and Risk Assessment (SERRA)》2011,25(4):445-456
Meteorologic-driven processes exert large and diverse impacts on lakes’ internal heating, cooling, and mixing. Thus, continued
global warming and climate change will affect lakes’ thermal properties, dynamics, and ecosystem. The impact of climate change
on Lake Tahoe (in the states of California and Nevada in the United States) is investigated here, as a case study of climate
change effects on the physical processes occurring within a lake. In the Tahoe basin, air temperature data show upward trends
and streamflow trends indicate earlier snowmelt. Precipitation in the basin is shifting from snow to rain, and the frequency
of intense rainfall events is increasing. In-lake water temperature records of the past 38 years (1970–2007) show that Lake
Tahoe is warming at an average rate of 0.013°C/year. The future trends of weather variables, such as air temperature, precipitation,
longwave radiation, downward shortwave radiation, and wind speed are estimated from predictions of three General Circulation
Models (GCMs) for the period 2001–2100. Future trends of weather variables of each GCM are found to be different to those
of the other GCMs. A series of simulation years into the future (2000–2040) is established using streamflows and associated
loadings, and meteorologic data sets for the period 1994–2004. Future simulation years and trends of weather variables are
selected so that: (1) future simulated warming trend would be consistent with the observed warming trend (0.013°C/year); and
(2) future mixing pattern frequency would closely match with the historical mixing pattern frequency. Results of 40-year simulations
show that the lake continues to become warmer and more stable, and mixing is reduced. Continued warming in the Tahoe has important
implications for efforts towards managing biodiversity and maintaining clarity of the lake. 相似文献