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71.
Eduard?P.?KontarEmail author A.?Gordon?Emslie Michele?Piana Anna?Maria?Massone John?C.?Brown 《Solar physics》2005,226(2):317-325
Kontar et al. (2004) have shown how to recover mean source electron spectra
in solar flares through a physical constraint regularization analysis of the bremsstrahlung photon spectra I() that they produce. They emphasize the use of non-square inversion techniques, and preconditioning combined with physical properties of the spectra to achieve the most meaningful solution to the problem. Higher-order regularization techniques may be used to generate
forms with certain desirable properties (e.g., higher-order derivatives). They further note that such analysis may be used to infer properties of the electron energy spectra at energies well above the maximum photon energy observed. In this paper we apply these techniques to data from a solar flare observed by RHESSI on 26 February, 2002. Results using different orders of regularization are presented and compared for various time intervals. Clear evidence is presented for a change in the value of the high-energy cutoff in the mean source electron spectrum with time. We also show how the construction of the injected electron spectrum F0(E0) (assuming that Coulomb collisions in a cold target dominate the electron transport) is facilitated by the use of higher-order regularization methods. 相似文献
72.
Eduard Helgers 《International Journal of Earth Sciences》1913,4(1):7-14
Ohne Zusammenfassung 相似文献
73.
Eduard Petrovský Mark J. Dekkers Vladimír Kropáček Pavel Hejda Tomáš Zelinka 《Studia Geophysica et Geodaetica》1994,38(1):46-56
Summary The results of a magnetic study of two batches of sized natural haematite fractions (from Kada, Czech Republic) are reported. One of the sample batches was prepared by ultrasonic micro precision sieving in propanon (acetone), the other in ethanol (alcohol). Surprisingly, the magnetic behaviour of the ethanol-sieved fractions was much softer (e.g. Hcr 20 kA/m) as compared with the propanon-sieved fractions (Hcr > 200 kA/m). Thermomagnetic measurements suggest a maghemite portion is present in the material used for the preparation of the ethanol-sieved samples. Possible causes of this puzzling behaviour are discussed. However, no definite conclusion can be drawn on the basis of the data presently available.Presented at 3rd Biennial Meeting on New Trends in Geomagnetism, Smolenice Castle, West Slovakia, June 22–29, 1992. 相似文献
74.
This paper is concerned with the design of steel frames using friction damped slotted bolted connections (SBCs) in the diagonal braces. A dynamic model is developed to describe the behaviour of a single‐degree‐of‐freedom (SDOF) steel frame that uses bilinear hysteretic behaviour for the damper. This model is generalized to MDOF systems. A novel algorithm for displacement reversal in the transition from slip to stick is presented. It uses numerical noise for its success. A design procedure that attains the stiffness of the individual braces and their elongation at the threshold of activation is then applied to a 10‐storey steel frame. This design process is a two‐phase iterative procedure that converges quite fast. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
75.
The phenomena observed at the Sun have a variety of unique radio signatures that can be used to diagnose the processes in the solar atmosphere. The insights provided by radio observations are further enhanced when they are combined with observations from space-based telescopes. This Topical collection demonstrates the power of combination methodology at work and provides new results on i) type I solar radio bursts and thermal emission to study active regions; ii) type II and IV bursts to better understand the structure of coronal mass ejections; and iii) non-thermal gyro-synchrotron and/or type III bursts to improve the characterisation of particle acceleration in solar flares. The ongoing improvements in time, frequency, and spatial resolutions of ground-based telescopes reveal new levels in the complexity of solar phenomena and pose new questions. 相似文献
76.
This article is devoted to studying the dynamical evolution and orbital stability of compact extrasolar three-planetary system GJ 3138.In this system,all semima... 相似文献
77.
The physical properties of young stellar objects are studied as functions of the initial spatial distributions of the gas
surface density Σ and angular velocity Ω in pre-stellar cores using numerical hydrodynamic simulations. Two limiting cases
are considered: spatially homogeneous cores with Σ = const and Ω = const and centrally concentrated cores with radius-dependent
densities Σ ∝ r
−1 and Ω ∝ r
−1. The degree of gravitational instability and protostellar disk fragmentation is mostly determined by the initial core mass
and the ratio of the rotational to the gravitational energy, and depends only weakly on the initial spatial configuration
of pre-stellar cores, except for the earliest stages of evolution, when models with spatially homogeneous cores can be more
gravitationally unstable. The accretion of disk matter onto a protostar also depends weakly on the initial distributions of
Σ and Ω, with matter from the collapsing core falling onto the disk at a rate that is slightly higher in models with spatially
homogeneous cores. An appreciable dependence of the disk mass, disk radius, and the disk-to-protostar mass ratio on the initial
density and angular velocity profiles of the parent core is found only for class 0 young objects; this relationship is not
systematic in the later I and II stages of stellar evolution. The mass of the central protostar depends weakly on the initial
core configuration in all three evolutionary stages. 相似文献
78.
79.
Eduard F. Kostylev Fedor P. Tkachenko Irina P. Tretiak 《Ocean & Coastal Management》2010,53(5-6):203-208
“Zernov’s Phyllophora field” is a unique habitat located in the northwestern Black Sea. At the site, there is a dense stand of agarophytes (red algae) and a high diversity of associated fauna. On November 21 2008, the president of Ukraine (Victor Yuschenko) declared this area a botanical reserve of state-wide importance; it was established to protect and restore a unique natural environment. “Zernov’s Phyllophora field” is the first offshore, fully marine MPA in the Black Sea, and it is the largest. The total area is 402,500 ha, covering 12.5% of the northwestern shelf of the Black Sea. The Ukrainian Scientific Centre for the Ecology of Sea has developed a program for (1) preservation, (2) restoration and (3) further rational use of biological resources at the site. It contains three conforming and interdependent sub-programs that put forward a series of measures for implementing the objectives (preservation, restoration, sustainable resource use).The northwestern Black Sea was heavily impacted by anthropogenic loading in the period 1970–1980, and Zernov’s Phyllophora field was considerably degraded and reduced in area. During recent years the perimeter of the Phyllophora field has slightly extended, and restoration of the benthic phytocoenosis has begun. Assigning this area the status of a marine reserve (Marine Protected Area) will further promote processes of restoring faunal and floristic biodiversity to historically healthy levels. 相似文献
80.
Jana Kašparová Marian KarlickÝ Eduard P. Kontar Richard A. Schwartz Brian R. Dennis 《Solar physics》2005,232(1-2):63-86
A multi-wavelength spatial and temporal analysis of solar high-energy electrons is conducted using the August 20, 2002 flare
of an unusually flat (γ1 = 1.8) hard X-ray spectrum. The flare is studied using RHESSI, Hα, radio, TRACE, and MDI observations with advanced methods
and techniques never previously applied in the solar flare context. A new method to account for X-ray Compton backscattering
in the photosphere (photospheric albedo) has been used to deduce the primary X-ray flare spectra. The mean electron flux distribution
has been analysed using both forward fitting and model-independent inversion methods of spectral analysis. We show that the
contribution of the photospheric albedo to the photon spectrum modifies the calculated mean electron flux distribution, mainly
at energies below ∼100 keV. The positions of the Hα emission and hard X-ray sources with respect to the current-free extrapolation
of the MDI photospheric magnetic field and the characteristics of the radio emission provide evidence of the closed geometry
of the magnetic field structure and the flare process in low altitude magnetic loops. In agreement with the predictions of
some solar flare models, the hard X-ray sources are located on the external edges of the Hα emission and show chromospheric
plasma heated by the non-thermal electrons. The fast changes of Hα intensities are located not only inside the hard X-ray
sources, as expected if they are the signatures of the chromospheric response to the electron bombardment, but also away from
them. 相似文献