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81.
An Open Source C++ inversion framework for magnetic interpretation, including UXO applications, has been developed. The point dipole model is used to approximate a small magnetic object. However, alternative object models can be easily accommodated. Input data can be presented in a variety of formats and physical units including, but not limited to, profiles of the total magnetic field, uniform data grids, random data points, magnetic gradients, and finite magnetic difference measurements. Well-established external numerical optimization software modules such as the SLATEC (Common Mathematical Library, Los Alamos National Laboratory) package are used to solve numerical problems. Other software modules can easily be incorporated as they become available. Some practical examples of the application of the framework using total field data and vertical total field gradient data from a UXO test range are presented. We have decided to “open-source” the toolkit. It can be downloaded without charge under GNU Public License via anonymous FTP from ftp://geom.geometrics.com/pub/mag/Software/magtoolkit-1.0.zip. 相似文献
82.
N.N.Chugai S.I.Blinnikov A.Fassia P.Lundqvist W.P.S.Meikle E.I.Sorokina 《Monthly notices of the Royal Astronomical Society》2002,330(2):473-480
Modelling of high-resolution Balmer line profiles in the early-time spectra of SN 1998S shows that the inferred fast (≈400 km s−1 ) circumstellar (CS) gas on days 23 and 42 post-explosion is confined to a narrow, negative velocity gradient shell just above the photosphere. This gas may be identified with a slow (v<40 km s−1 ) progenitor wind accelerated at the ejecta–wind interface. In this scenario, the photosphere coincides with a cool dense shell formed in the reverse shock. Acceleration by radiation from the supernova or by a shock-accelerated relativistic particle precursor are both possible explanations for the observed fast CS gas. An alternative, equally plausible scenario is that the fast CS gas is accelerated within shocked clouds engulfed by the outer shock, as it propagates through the intercloud wind. 相似文献
83.
Joseph Sidky Mikhail 《Earth, Moon, and Planets》1970,2(2):167-201
The four colour photometric observations of 15 regions of the lunar surface are reported in this paper. They all confirm the reddening with increasing phase. Observed regions at wide range of phase show an appreciable colour opposition effect. Reddening factors obtained, are larger near full Moon, and smaller at larger phase angles. 相似文献
84.
Based on observations of SN 1999em, we determined the physical parameters of this supernova using hydrodynamic calculations including nonequilibrium radiative transfer. Taking the distance to SN 1999em estimated by the expanding photosphere method (EPM) to be D = 7.5 Mpc, we found the parameters of the presupernova: radius R = 450R⊙, mass M = 15M⊙, and explosion energy E = 7 × 1050 erg. For the distance D = 12 Mpc determined from Cepheids, R, M, and E must be increased to the following values: R = 1000R⊙, M = 18M⊙, and E = 1051 erg. We show that one cannot restrict oneself to using the simple analytical formulas relating the supernova and presupernova parameters to obtain reliable parameters for type-IIP presupernovae. 相似文献
85.
86.
Ice cores contain an abundance of information about the Earth''s climate in the past,and recovered from shallow drilling down to 300--350 m give sufficient information for reconstructing of the last climatic chan- ges and for monitoring of pollution from human being. Cable-suspended core auger drills use an armored cable with a winch to provide power to the down-hole motor system and to retrieve the down-hole unit. Because of their lightweight,convenient transportation and installation,high penetration rates and low power consumption, core auger drills are widely used for shallow drilling in ice. Nowadays at least 14 types of auger electromechani- cal drills were designed and tested in different foreign and national glaciological laboratories. However,auger options were usually determined by experience,and the main parameters (helix angle of the fights and rotational speed) are varied in a wide range from drill to drill. If parameters of auger are not chosen properly,poorly en- gineered drills had troubles with low efficiency of cuttings transportation,jam of ice cuttings,repeated fragmen- tation,cutters icing and stop penetration,abnormal power consumption,high rotation torques,and so on. Thus,this paper presents the method of optimization of ice cuttings transportation of cable-suspended core auger drill on the base of the theory of rotary auger. As the result,the optimal helix angle was determined correspond- ing to the rotational speed from the transportation efficiency point of view. 相似文献
87.
Ruben Buaba Abdollah Homaifar Mohamed Gebril Eric Kihn Mikhail Zhizhin 《Earth Science Informatics》2011,4(1):17-28
This paper presents the use of the Low Memory Locality Sensitive Hashing (LMLSH) technique operating in Euclidean space to
build a data structure for the Defense Meteorological Satellite Program (DMSP) satellite imagery database. The LMLSH technique
finds satellite image matches in sublinear search time. The texture feature vectors of the images are extracted using pyramid-structured
wavelet transform coupled with Gaussian central moment technique. These feature vectors and families of hash functions, drawn
randomly and independently from a Gaussian distribution, are used to build hash tables. Given a query, the hash tables are
used to pull out the best matches to that query and this is done in a sublinear search time complexity. When tested, our algorithm
has proven to be approximately twenty six times faster than the Linear Search (LS) algorithm. In addition, the LMLSH algorithm searches about two percent of the entire
database randomly to find the possible matches to any given query without loss of accuracy compared to the absolute best matches
returned by its LS counterpart. 相似文献
88.
Hydrogen penetration in water through porous medium: application to a radioactive waste storage site
Hydrogen penetration in water through porous medium was analyzed in the paper. A two-phase compositional model approach was
considered. The first part of the work deals with the thermodynamic analysis of the hydrogen–water system. The thermodynamic
model was calibrated using the experimental data of hydrogen solubility in water. The phase densities, viscosities and phase
concentrations were presented in an analytical form. Moreover, the domain of validity of analytical laws—such as Henry’s,
Raoult’s and Kelvin’s laws—for the estimation of phase properties was presented for the analyzed system. The second part deals
with two-phase hydrodynamic behaviors. An analytical solution for the non-compressible flow was constructed. In general case,
the influence of relative permeabilities on the flow regimes was analyzed numerically. The notion pseudo-saturation was introduced
to define phase appearance. Actually, mobile gas created a time displaced front relatively slower than mobile gas flow. Diffusion
becomes really important for low mobile gas case as the penetration accelerates for the large range of saturation. In contrast,
the mass exchange phenomena have a small influence on the flow type. Thus, the regimes of hydrogen penetration in liquid were
shown really sensitive to the relative permeability form. 相似文献
89.
Alexander Boyarchuk Igor Savanov Evgeny Kanev Boris Shustov Mikhail Sachkov 《Astrophysics and Space Science》2014,354(1):247-250
2013 marks the 30th anniversary since the launch of Soviet Spacecraft Astron that had been operated for 6 years as the largest ultraviolet telescope during its lifetime. The Astron orbital station was designed for the astrophysical observations. It was launched into orbit by Proton launch system on March 23, 1983. Astron had a 80 cm ultraviolet telescope with mass of 400 kg and a complex of X-ray spectrographs with mass of 300 kg on board as a payload. It’s high apogee orbit (with apogee 200000 km and perigee 2000 km) permitted the influences of the Earth’s umbra and radiation belts to be excluded from the measurements. The main astrophysical results are summarized in this paper. 相似文献
90.