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861.
用集集主震记录研究近断层强震记录的基线校正方法 总被引:2,自引:0,他引:2
从集集主震记录中选取有代表性的246个台站的记录作为数据集。在总结国内外基线校正方法的基础上,提出以下校正步骤:(1)初步判定记录中是否包含永久位移信息以便选用不同的校正方法。(2)以积分位移时程的末端平稳为标准,来确定积分速度时程末端拟合出的最优直线斜率作为校正量,去校正原始加速度时程,从而保留永久位移信息。永久位移等值线结果与GPS测量结果大体相符。根据校正结果推测认为:瞬变后保持或扩张或部分回弹,可能是决定永久位移形态的主要物理机制。 相似文献
862.
863.
马氏珠母贝选群F1的表型性状的相关和通径分析 总被引:3,自引:0,他引:3
从7月龄的F1群体随机取样120个体,测量表型性状并进行相关和路径分析。所测量的表型性状包括壳长、壳高、壳宽、壳重和仝湿重共5个指标。结果表明:(1)壳长、壳高、壳宽、壳重和全湿重存在显著的相关性(P〈0.05)。全湿重与壳长、壳高、壳宽和壳重存在显著的正相关(P〈0.05),相关系数分别为0.8970、0.6974、0.6521和0.5486。(2)壳重、壳高、壳宽和壳长对全湿重具有正直接影响,其值分别为0.6356、0.1872、0.1814和0.0599。结果说明了通过直接选择或间接选择可以改良马氏珠母贝选群F1的壳长、壳高、壳宽、壳重和全湿重等生长性状。 相似文献
864.
We present hydrogen emission-line profile models of magnetospheric accretion on to classical T Tauri stars. The models are computed under the Sobolev approximation using the three-dimensional Monte Carlo radiative-transfer code torus . We have calculated four illustrative models in which the accretion flows are confined to azimuthal curtains – a geometry predicted by magnetohydrodynamic simulations. Properties of the line profile variability of our models are discussed, with reference to dynamic spectra and cross-correlation images. We find that some gross characteristics of the observed line profile variability are reproduced by our models, although in general the level of variability predicted is larger than that observed. We conclude that this excessive variability probably excludes dynamical simulations that predict accretion flows with low degrees of axisymmetry. 相似文献
865.
866.
C. Jordan G. R. Smith E. R. Houdebine 《Monthly notices of the Royal Astronomical Society》2005,362(2):411-423
Observations made with the Coronal Diagnostic Spectrometer (CDS) onboard the Solar and Heliospheric Observatory ( SOHO ) are used to investigate the behaviour of the intensities of the emission lines of He i , He ii and O iii at the quiet Sun-centre and at θ= 60° towards the equatorial limb. The aim is to examine the possible effects of photon scattering on the spatial variation of the optically thick helium lines. At the quiet Sun-centre, we find that, in agreement with previous work, the ratios of the intensities of the He i 584-Å and He ii 304-Å lines to those of the O iii 600-Å line decrease systematically as the intensity of the O iii line increases. However, we find that the dependence of these ratios on the O iii intensity is not unique, but differs between the individual regions studied. Similar results are found at θ= 60° . We have also used line intensities and intensity ratios to investigate limb-to-disc effects and variations across a sample of supergranulation cell boundaries and adjacent cell interiors at both locations. The results do not exclude photon scattering as the cause of the larger observed ratios in cell interiors. The differences between the apparent widths of boundaries in O iii at Sun-centre and 60° show that the emitting material is extended in height, which will aid the process of scattering into cell interiors. Photon scattering could also account for the lack of oscillations in the He i intensities in a cell interior studied by Pietarila & Judge. Three-dimensional radiative transfer calculations in chosen geometries are now needed to account for the observations in detail. 相似文献
867.
Near infrared coronal line emission at 1.98 ± 0.02Μm due to [Si VI] detected in the spectrum of Nova Herculis 1991 about 17
days after optical maximum is reported. The early appearance of coronal emission is yet another unusual feature of this fast
nova in which early onset of dust formation processes and X-ray detection five days after outburst have already been reported.
The coronal line observations reported here are consistent with X-ray detection and support a hot shocked circumstellar envelope
at the periphery of the dust formation zone in the nova. 相似文献
868.
J. R. Barnes C. J. Leigh H. R. A. Jones Travis S. Barman D. J. Pinfield A. Collier Cameron J. S. Jenkins 《Monthly notices of the Royal Astronomical Society》2007,379(3):1097-1107
We present a search for the near-infrared spectroscopic signature of the close orbiting extrasolar giant planet HD 75289b. We obtained ∼230 spectra in the wavelength range 2.18–2.19 μm using the Phoenix spectrograph at Gemini South. By considering the direct spectrum, derived from irradiated model atmospheres, we search for the absorption profile signature present in the combined star and planet light. Since the planetary spectrum is separated from the stellar spectrum at most phases, we apply a phase-dependent orbital model and tomographic techniques to search for absorption signatures.
Because the absorption signature lies buried in the noise of a single exposure we apply a multiline deconvolution to the spectral lines available in order to boost the effective signal-to-noise ratio (S/N) of the data. The wavelength coverage of 80 Å is expected to contain ∼100 planetary lines, enabling a mean line with S/N of 800 to be achieved after deconvolution. We are nevertheless unable to detect the presence of the planet in the data and carry out further simulations to show that broader wavelength coverage should enable a planet like HD 75289b to be detected with 99.9 per cent confidence. We investigate the sensitivity of our method and estimate detection tolerances for mismatches between observed and model planetary atmospheres. 相似文献
Because the absorption signature lies buried in the noise of a single exposure we apply a multiline deconvolution to the spectral lines available in order to boost the effective signal-to-noise ratio (S/N) of the data. The wavelength coverage of 80 Å is expected to contain ∼100 planetary lines, enabling a mean line with S/N of 800 to be achieved after deconvolution. We are nevertheless unable to detect the presence of the planet in the data and carry out further simulations to show that broader wavelength coverage should enable a planet like HD 75289b to be detected with 99.9 per cent confidence. We investigate the sensitivity of our method and estimate detection tolerances for mismatches between observed and model planetary atmospheres. 相似文献
869.
Sabine Richling 《Astrophysics and Space Science》2003,284(2):361-364
The Lyα line emission of high-redshift galaxies depends on the density and temperature distribution of the gas, the kinematics
and the dust content. We use a finite element method to model theLyα radiation of different 3D configurations considering
complete frequency redistribution and the influence of velocity fields. Our results show that the central absorption feature
of the double-peaked Lyα line profile observed in many radio galaxies with z=2-4 is probably the consequence of frequency redistribution rather than foreground absorption. The blue peak of the profile
is enhanced for models with in fall motion and the red peak for models with outflow motion. In particular, we attempt to model
the extendedLyα emission of high-redshift radio galaxies, where we consider results of corresponding hydrodynamical simulations
to select possible model configurations. We find that Lyα photons scattered outside a jet-influenced low-density region are
able to produce an extended Lyα halo.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
870.
J. Campos M. Ortiz R. Mayo E. Biémont † P. Quinet K. Blagoev G. Malcheva 《Monthly notices of the Royal Astronomical Society》2005,363(3):905-910
Radiative parameters for transitions depopulating the levels belonging to the 4d8 5s2 , 4d9 6s and 4d9 5d configurations of Ag ii have been obtained from a combination of theoretical lifetimes and experimental branching fractions. On the experimental side, a laser-produced plasma was used as a source of Ag+ ions. The light emitted by the plasma was analysed by a grating monochromator coupled with a time-resolved optical multichannel analyser system. Spectral response calibration of the experimental system was performed using a deuterium lamp in the wavelength range from 200 to 400 nm, and a standard tungsten lamp in the range from 350 to 600 nm. The transition probabilities were obtained from measured branching ratios and theoretical radiative lifetimes of the corresponding states calculated with a relativistic Hartree–Fock approach including core-polarization effects and configuration interaction in an extensive way. Theoretical and experimental data have been compared and the new data have also been compared with the few previous results available in the literature. 相似文献