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101.
Abhijit Ghosh Biswas Debasish Hazra Pranab Guha Gautam De S. S. 《Geomagnetism and Aeronomy》2019,59(8):980-994
Geomagnetism and Aeronomy - Discrete spectra of frequencies at 8, 14, 20, 26, … Hz are generated by electromagnetic emission from lightning sources and can be regarded as excitation of AC... 相似文献
102.
We point out that several independent considerations rule out the hypothesis that the missing mass in galactic halos is dominated by massive neutral fermions such as neutrinos, gravitinos or photinos. 相似文献
103.
Cosmic-ray propagation in the vicinity of 1 kpc from the Sun is considered. The data on the 1012–1015 eV particle anisotropy, on 1012 eV electron spectrum, and on temporal cosmic-ray variations are analyzed. The diffusion coefficientD(1012–1013 eV)=1029–1030 cm2s–1 inferred from the analysis coincides with its standard value in the large-halo model withh=15 kpc. The total power of cosmic-ray generation, about 3×1049 erg per SN in the proton component and about 1048 erg per SN in the electron component, typical of the galactic diffusion model is in agreement with the obtained parameters of local sources. 相似文献
104.
Pranab Ghosh 《Journal of Astrophysics and Astronomy》1995,16(2):289-305
I review our understanding of the evolution of the spin periods of neutron stars in binary stellar systems, from their birth
as fast, spin-powered pulsars, through their middle life as accretion-powered pulsars, upto their recycling or “rebirth” as
spin-powered pulsars with relatively low magnetic fields and fast rotation. I discuss how the new-born neutron star is spun
down by electromagnetic and “propeller” torques, until accretion of matter from the companion star begins, and the neutron
star becomes an accretion-powered X-ray pulsar. Detailed observations of massive radio pulsar binaries like PSR 1259-63 will
yield valuable information about this phase of initial spindown. I indicate how the spin of the neutron star then evolves
under accretion torques during the subsequent phase as an accretion-powered pulsar. Finally, I describe how the neutron star
is spun up to short periods again during the subsequent phase of recycling, with the accompanying reduction in the stellar
magnetic field, the origins of which are still not completely understood. 相似文献
105.
Sudden brightening of FeII and Balmer (H and H) lines of X Oph was observed on 28–29 May, 1986. Equivalent width of FeII and H lines increased by a factor of two and that for H line by a factor of four, during the brigtening phase of the star. This brightening phenomena has been explained in the framework of Coronal Radiative Instability. 相似文献
106.
107.
Dynamic Response of Machine Foundation on Layered Soil: Cone Model Versus Experiments 总被引:1,自引:0,他引:1
P. K. Pradhan A. Mandal D. K. Baidya D. P. Ghosh 《Geotechnical and Geological Engineering》2008,26(4):453-468
This paper presents the experimental validation of analytical solution based on cone model for machine foundation vibration
analysis on layered soil. Impedance functions for a rigid massless circular foundation resting on a two layered soil system
subjected to vertical harmonic excitation are found using cone model. Linear hysteretic material damping is introduced using
correspondence principle. The frequency-amplitude response of a massive foundation is then computed using impedance functions.
To verify the solution field experiments are conducted in two different layered soil systems such as gravel layer over in situ
soil and gravel layer over concrete slab (rigid base). A total 72 numbers of vertical vibration tests on square model footing
were conducted using Lazan type mechanical oscillator, varying the influencing parameters such as depth of top layer, static
weight of foundation and dynamic force level. The frequency-amplitude response in general and in particular the resonant frequencies
and resonant amplitudes predicted by cone model is compared with the results of experimental investigation, which shows a
close agreement. Thus the cone model is reliable in its application to machine foundation vibration on layered soil. 相似文献
108.
Amitabha Ghosh 《Astrophysics and Space Science》1995,227(1-2):41-52
According to the convention normally followed the redshifts of the galaxies in a cluster are assumed to be of purely dopplerian origin. The resulting velocity dispersion, when used in the virial theorem, leads to a very large proportion of dark matter to be present in the galaxy clusters. However, the recently proposed model of velocity dependent cosmic drag cause redshifts of photons and it is necessary to develop a procedure to determine the true velocity dispersion from the gross redshift data. A method for this has been presented in the paper. Coma and Perseus clusters have been investigated using this procedure and theM/L ratios for both were found to be approximately of the order of 30, i.e., approximately the order ofM/L ratios for individual galaxies. A study of them -z relation indicates that the galaxies with higher redshifts have fainter magnitudes. Distortion of the redshift plots and the typical elongation of the core regions along the line-of-sight is also explained. 相似文献
109.
Rupa Ghosh R. K. Sehgal Pradeep Srivastava U. K. Shukla A. C. Nanda D. S. Singh 《Journal of the Geological Society of India》2016,88(5):559-568
We describe an elephant skull recovered from a cliff section of Dhasan river of Marginal Ganga Plain. The dental morphology and cranial features of the skull have been compared with the known species of Elephas from the Indian subcontinent. Although it shows very near resemblance to Elephas namadicus, but being an isolated specimen its specific identity cannot be proclaimed with certainty. As such, the specimen is provisionally referred as E. cf. namadicus. The Optically Stimulated Luminescence ages place this find at ~56 ka BP. This is the first chronologically well constrained report of E. cf. namadicus from the Ganga Plain. 相似文献
110.