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91.
J. Zverko I. Iliev I. I. Romanyuk I. Stateva D. O. Kudryavtsev E. A. Semenko 《Astrophysical Bulletin》2018,73(3):351-362
In this paper of the series we analyze three stars listed among stars with discrepant v sin i: HD9531 and HD31592, which also show radial velocity variations inherent to spectroscopic binaries, and HD129174 which is an Mn-type star with a possible magnetic field. In HD9531 we confirm the radial velocity derived fromthe hydrogen lines as well as fromthe Ca II line at 3933 Å as variable. The profile of the calcium line also appears variable, and with the estimated magnetic induction Be = ?630 ± 1340 G, this suggests that the abundance of calcium possibly varies over the surface of the star. We identified the lines of the secondary component in the spectrum of HD31592 revealing thus it is an SB2 binary with B9.5V and A0V components. While the primary star rotates with v sin i = 50 km s?1, the secondary star is faster with v sin i = 170 km s?1. We find that only 60% of the Mn lines identified in the spectrum of HD129174 can be fitted with a unique abundance value, whereas the remaining lines are stronger or fainter. We also identified two Xe II lines at 5339.33 Å and 5419.15 Å and estimated their log g f. 相似文献
92.
Model results on starspots in 15 chromospherically active type RS CVn binary systems are presented. The dependences of the
parameters of the spots on the principal characteristics of the stars (spectral class, luminosity class, rotation, Rossby
number) are examined. Latitudinal drift of the spots, cycles in the spot activity, and differential rotation are found in
9 of the stars.
__________
Translated from Astrofizika, Vol. 48, No. 4, pp. 535–552 (November 2005). 相似文献
93.
We study the relationship of the 27-day variations of the galactic cosmic ray intensity with similar variations of the solar
wind velocity and the interplanetary magnetic field based on observational data for the Bartels rotation period # 2379 of
23 November 2007 – 19 December 2007. We develop a three-dimensional (3-D) model of the 27-day variation of galactic cosmic
ray intensity based on the heliolongitudinally dependent solar wind velocity. A consistent, divergence-free interplanetary
magnetic field is derived by solving Maxwell’s equations with a heliolongitudinally dependent 27-day variation of the solar
wind velocity reproducing in situ observations. We consider two types of 3-D models of the 27-day variation of galactic cosmic ray intensity, i) with a plane heliospheric neutral sheet, and ii) with the sector structure of the interplanetary magnetic field. The theoretical calculations show that the sector structure
does not significantly influence the 27-day variation of galactic cosmic ray intensity, as had been shown before, based on
observational data. Furthermore, good agreement is found between the time profiles of the theoretically expected and experimentally
obtained first harmonic waves of the 27-day variation of the galactic cosmic ray intensity (with a correlation coefficient
of 0.98±0.02). The expected 27-day variation of the galactic cosmic ray intensity is inversely correlated with the modulation
parameter ζ (with a correlation coefficient of −0.91±0.05), which is proportional to the product of the solar wind velocity
V and the strength of the interplanetary magnetic field B (ζ∼VB). The high anticorrelation between these quantities indicates that the predicted 27-day variation of the galactic cosmic
ray intensity mainly is caused by this basic modulation effect. 相似文献
94.
The effect of the extragalactic magnetic field on the propagation of ultra-high-energy cosmic rays (UHECRs) is investigated. We use the infrared galaxy catalog IRAS PSCz to reconstruct the magnetic field distribution in the Local Universe. The magnetic field induction is considered as a power function of the galactic infrared luminosity density: B = Kρβ. In contrast to some earlier studies in which the exponent β = 2/3 corresponded to the freezing-in condition, the parameters K and β are estimated from the field inductions normalized by the expected maximum inductions (strong field) and minimum inductions (weak field) in galaxy clusters and voids, respectively. Maps of angular deflections of UHECRs are presented for these magnetic field models. We found that the protons with energies E > 4 × 1019 eV are not significantly deflected from their sources in a sphere with a radius of 100 Mpc only in the case of the weak magnetic field model (the deflections are comparable to the errors of modern detectors). The effect of the extragalactic magnetic field on the UHECR spectrum is investigated, with Virgo A and Arp 299 taken as potential sources. 相似文献
95.
Abstract— The Vredefort Granophyre represents impact melt that was injected downward into fractures in the floor of the Vredefort impact structure, South Africa. This unit contains inclusions of country rock that were derived from different locations within the impact structure and are predominantly composed of quartzite, feldspathic quartzite, arkose, and granitic material with minor proportions of shale and epidiorite. Two of the least recrystallized inclusions contain quartz with single or multiple sets of planar deformation features. Quartz grains in other inclusions display a vermicular texture, which is reminiscent of checkerboard feldspar. Feldspars range from large, twinned crystals in some inclusions to fine‐grained aggregates that apparently are the product of decomposition of larger primary crystals. In rare inclusions, a mafic mineral, probably biotite or amphibole, has been transformed to very fine‐grained aggregates of secondary phases that include small euhedral crystals of Fe‐rich spinel. These data indicate that inclusions within the Vredefort Granophyre were exposed to shock pressures ranging from <5 to 8–30 GPa. Many of these inclusions contain small, rounded melt pockets composed of a groundmass of devitrified or metamorphosed glass containing microlites of a variety of minerals, including K‐feldspar, quartz, augite, low‐Ca pyroxene, and magnetite. The composition of this devitrified glass varies from inclusion to inclusion, but is generally consistent with a mixture of quartz and feldspar with minor proportions of mafic minerals. In the case of granitoid inclusions, melt pockets commonly occur at the boundaries between feldspar and quartz grains. In metasedimentary inclusions, some of these melt pockets contain remnants of partially melted feldspar grains. These melt pockets may have formed by eutectic melting caused by inclusion of these fragments in the hot (650 to 1610 °C) impact melt that crystallized to form the Vredefort Granophyre. 相似文献
96.
Manasi Buzar Baruah Samiran Chatterjee Madhurjya P. Bora 《Astrophysics and Space Science》2010,325(2):217-225
In this work, we consider radiation (thermal) instability in a weakly ionized plasma with continuous ionization and recombination.
The situation can be visualized in the case of envelopes of planetary nebulae, which are envelopes of ionized plasmas surrounding
red giant stars. Various observations report continuous photoionization of these plasmas by the highly energetic streams of
photons emanating from the parent star. Recently, it has been shown that thermal instability can be a probable candidate in
such plasmas for the existence of small scale structures (viz., striations) whose kinematic age is much smaller than that
of the parent nebula. We therefore report a systematic study of these plasmas with photoionization and determine the instability
domain. We have shown that the continuous ionization and recombination may lead to modification of the underlying instability,
which may limit the size of the small structures that are believed to form from these instabilities, and may thus provide
an explanation of the physical processes responsible for the existence of these structures. We further show that in many cases
the system bifurcates to an ovserstable (growing wave) state from a condensation instability (monotonic) and vice versa. 相似文献
97.
This paper reviews original and published data on the abundance and composition of pyroclastics due to explosive discharges
by volcanoes on the Iceland Plume. The pyroclastics were deposited in the Cenozoic sediments in the North Atlantic Ocean and
in the Norwegian-Greenland basin. The DSDP and ODP initial reports (70 deep wells), 100 geologic columns sampled during cruises
of the R/Vs Akademik Kurchatov and Mikhail Lomonosov furnished the database from which we constructed stratigraphic and areal-maps of pyroclastics abundance and computed the
distribution of the volumes and amounts of pyroclastic layers over the stratigraphic intervals of the Cenozoic sedimentary
sequence. The distribution of these layers was found to be cyclic; the highest frequency occurred during the Quaternary. Basaltoid
pyroclastics prevailed in the late Paleocene and Early Eocene. The Oligocene has typically subalkaline ankaramite pyroclastics.
From the Miocene until the Quaternary the pyroclastics became bimodal (basalt-rhyolite) and high potassium rhyolite pyroclastics
appeared. This evolution seems to have been caused by crystallization differentiation of basaltoid magmas in magma chambers
that came into being in prespreading grabens where a thick (> 20 km) sequence of volcanic rocks accumulated to produce a dipping
reflector. 相似文献
98.
Decorrelated GRACE time-variable gravity solutions by GFZ,and their validation using a hydrological model 总被引:8,自引:6,他引:8
We have analyzed recent gravity recovery and climate experiment (GRACE) RL04 monthly gravity solutions, using a new decorrelating
post-processing approach. We find very good agreement with mass anomalies derived from a global hydrological model. The post-processed
GRACE solutions exhibit only little amplitude damping and an almost negligible phase shift and period distortion for relevant
hydrological basins. Furthermore, these post-processed GRACE solutions have been inspected in terms of data fit with respect
to the original inter-satellite ranging and to SLR and GPS observations. This kind of comparison is new. We find variations
of the data fit due to solution post-processing only within very narrow limits. This confirms our suspicion that GRACE data
do not firmly ‘pinpoint’ the standard unconstrained solutions. Regarding the original Kusche (J Geod 81:733–749, 2007) decorrelation
and smoothing method, a simplified (order-convolution) approach has been developed. This simplified approach allows to realize
a higher resolution—as necessary, e.g., for generating computed GRACE observations—and needs far less coefficients to be stored. 相似文献
99.
The paper proposes a method for studying long-term anomalies of the radon concentration that are produced by an impulse generated in a fracture source over a finite time interval. Using this method, experimental data are interpreted numerically in order to determine the space-time characteristics of the fracture region and parameters of fluid migration. 相似文献
100.
Z. Vencelides Z. Hrkal H. Nováková H. Prchalová 《Journal of Atmospheric Chemistry》2011,68(2):127-138
In harmony with requirements of Water Framework Directive the natural backgrounds of selected metals were established on the
territory of Czech Republic. This paper is intended to provide characteristics and results of testing methods focused on quantification
of the impacts of anthropogenic activities based on data of regional monitoring and their separation from acid atmospheric
deposition including an appropriate discussion regarding the natural backgrounds of relevant metals. The results indicate
that even in regions extremely affected by acid atmospheric deposition as is the territory of the Czech Republic this acid
deposition will not have direct impact on the quality of ground waters on a regional scale. Consequently, the proved changes
in quality of ground waters seem to have been caused by secondary processes, specifically by mobilization of metals in a rock
environment due to increased acidity. 相似文献