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71.
An exact solution of the vacuum Brans-Dicke field equations is obtained for the metric tensor of a spatially-homogeneous and anisotropic Bianchi type I configuration. The solution has no analogy in Einstein's theory for the layer values of the BD parameter. Some properties of the solution are discussed. 相似文献
72.
73.
Algorithms are derived for constructing five dimensional Kaluza-Klein cosmological space-times in the presence of a perfect fluid source in the framework of f(R,T) gravity theory proposed by Harko et al. (Phys. Rev. D 84:024020, 2011). Starting from the solution of Reddy et al. (Int. J. Theor. Phys 51:3222-3227, 2012b) some classes of new solutions are generated which correspond to accelerating models of the Universe. The physical and kinematical behaviors of the models are studied. 相似文献
74.
Abstract— We conducted Mössbauer spectroscopic studies on the Ghubara meteorite which had been described as at least two‐generation regolith breccia on the macro scale. The isomer shift and quadrupole splitting of the Fe‐Ni part are quite different from those obtained in ordinary chondrites, reflecting shock effects. We observed a large amount of magnetite that may have come from weathering of, primarily, the silicate fraction. We found very similar iron mineralogy in the Densmore meteorite. 相似文献
75.
Kant S 《Population geography : a journal of the Association of Population Geographers of India》1995,17(1-2):49-64
"The paper examines urbanisation in Himachal Pradesh [India] in terms of size, growth, evolution, site and functional characteristics of urban centres for [the] 1901-91 period. In addition, the role played by the changing political and administrative geography has also been considered." 相似文献
76.
77.
Yogesh Kant B. D. Bharath Javed Mallick Clement Atzberger Norman Kerle 《Journal of the Indian Society of Remote Sensing》2009,37(2):201-214
The knowledge of the surface temperature is important to a range of issues and themes in earth sciences central to urban climatology,
global environmental change and human-environment interactions. The study analyses land surface temperature (LST) estimation
using temporal ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) datasets (day time and night time) over
National Capital Territory Delhi using the surface emissivity information at pixel level. The spatial variations of LST over
different land use/land cover (LU/LC) at day time and night time were analysed and relationship between the spatial distribution
of LU/LC and vegetation density with LST was developed. Minimum noise fraction (MNF) was used for LU/LC classification which
gave better accuracy than classification with original bands. The satellite derived emissivity values were found to be in
good agreement with literature and field measured values. It was observed that fallow land, waste land/bare soil, commercial/industrial
and high dense built-up area have high surface temperature values during day time, compared to those over water bodies, agricultural
cropland, and dense vegetation. During night time high surface temperature values are found over high dense built-up, water
bodies, commercial/industrial and low dense built-up than over fallow land, dense vegetation and agricultural cropland. It
was found that there is a strong negative correlation between surface temperature and NDVI over dense vegetation, sparse vegetation
and low dense built-up area while with fraction vegetation cover, it indicates a moderate negative correlation. The results
suggest that the methodology is feasible to estimate NDVI, surface emissivity and surface temperature with reasonable accuracy
over heterogeneous urban area. The analysis also indicates that the relationship between the spatial distribution of LU/LC
and vegetation density is closely related to the development of urban heat islands (UHI). 相似文献
78.
Takeshi Mikumo Miguel A. Santoyo & Shri Krishna Singh 《Geophysical Journal International》2000,140(3):611-620
A large nearly vertical, normal faulting earthquake ( M w = 7.1) took place in 1997 in the Cocos plate, just beneath the ruptured fault zone of the great 1985 Michoacan thrust event ( M w = 8.1). Dynamic rupture and resultant stress change during the 1997 earthquake have been investigated on the basis of near-source strong-motion records together with a 3-D dynamic model.
Dynamically consistent waveform inversion reveals a highly heterogeneous distribution of stress drop, including patch-like asperities and negative stress-drop zones. Zones of high stress drop are mainly confined to the deeper, southeastern section of the vertical fault, where the maximum dynamic stress drop reaches 280 bars (28 MPa). The dynamically generated source time function varies with location on the fault, and yields a short slip duration, which is caused by a short scalelength of stress-drop heterogeneities. The synthetic seismograms calculated from the dynamic model are generally consistent with the strong-motion velocity records in the frequency range lower than 0.5 Hz.
The pattern of stress-drop distribution appears, in some sense, to be consistent with that of coseismic changes in shear stress resulting from the 1985 thrust event. This consistency suggests that the stress transfer from the 1985 event to the subducting plate could be one of the possible mechanisms that increased the chance of the occurrence of the 1997 earthquake. 相似文献
Dynamically consistent waveform inversion reveals a highly heterogeneous distribution of stress drop, including patch-like asperities and negative stress-drop zones. Zones of high stress drop are mainly confined to the deeper, southeastern section of the vertical fault, where the maximum dynamic stress drop reaches 280 bars (28 MPa). The dynamically generated source time function varies with location on the fault, and yields a short slip duration, which is caused by a short scalelength of stress-drop heterogeneities. The synthetic seismograms calculated from the dynamic model are generally consistent with the strong-motion velocity records in the frequency range lower than 0.5 Hz.
The pattern of stress-drop distribution appears, in some sense, to be consistent with that of coseismic changes in shear stress resulting from the 1985 thrust event. This consistency suggests that the stress transfer from the 1985 event to the subducting plate could be one of the possible mechanisms that increased the chance of the occurrence of the 1997 earthquake. 相似文献
79.
Salgado-Gálvez Mario A. Ordaz Mario Huerta Benjamín Singh Shri K. Pérez-Campos Xyoli 《Natural Hazards》2020,103(1):639-657
Natural Hazards - Rainfall-triggered landslides are the most common type of mass movement seen along the tropical belt due to the prevalence of monsoons. These landslides can be forecasted by... 相似文献
80.
Kailas L. Wasewar Pradeep Kumar Shri Chand Bina N. Padmini Tjoon Tow Teng 《洁净——土壤、空气、水》2010,38(7):649-656
The present study was aimed at removing cadmium ions from aqueous solution through batch studies using adsorbents, such as, granular activated carbon (GAC) and activated clay (A‐clay). GAC was of commercial grade where as the A‐clay was prepared by acid treatment of clay with 1 mol/L of H2SO4. Bulk densities of A‐clay and GAC were 1132 and 599 kg/m3, respectively. The surface areas were 358 m2/g for GAC and 90 m2/g for A‐clay. The adsorption studies were carried out to optimize the process parameters, such as, pH, adsorbent dosage, and contact time. The results obtained were analyzed for kinetics and adsorption isotherm studies. The pH value was optimized at pH 6 giving maximum Cd removal of 84 and 75.2% with GAC and A‐clay, respectively. The adsorbent dosage was optimized and was found to be 5 g/L for GAC and 10 g/L for A‐clay. Batch adsorption studies were carried out with initial adsorbate (Cd) concentration of 100 mg/L and adsorbent dosage of 10 g/L at pH 6. The optimum contact time was found to be 5 h for both the adsorbents. Kinetic studies showed Cd removal a pseudo second order process. The isotherm studies revealed Langmuir isotherm to better fit the data than Freundlich isotherm. 相似文献