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201.
The landscape evolution of the Mepal area from Late Devensian Block Fen Terrace times to the beginning of the Flandrian, a period of ca. 8000 radiocarbon years, is reconstructed. Stratigraphy is based on borehole transects and single boreholes, centred on a depression between the Block Fen Terrace and the Isle of Ely. Within the depression is a Devensian late‐glacial sequence, with the Windermere Interstadial represented by radiocarbon‐dated organic sediments. Pollen and plant macroscopic remains of the late‐glacial sediments are analysed. Plant communities with Betula developed in the interstadial. Before and after the interstadial there is much reworked pollen in the inorganic sediments, derived from local pre‐Devensian Pleistocene sediments, including temperate Ipswichian Stage sediments, and from mass‐wasting of the local Jurassic bedrock. Periods of such mass‐movement occur before and after the deposition of the late‐glacial lake sediments. Deposition of aeolian sediment occurs later than the main period of mass movement, but before the Windermere Interstadial. The relationship of the aeolian sediments in time and space to permafrost, indicated by local contraction polygons and cracks, is discussed. Solifluction diverted the flow of the River Great Ouse from a northeast direction in Block Fen Terrace times to a southwest direction as a channel developed to the west of the Chatteris–March ‘island’. This led to a drainage divide in Flandrian times. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
202.
Ralph D Lorenz Jessica M DooleyJ.Doug West Mitsugu Fujii 《Planetary and Space Science》2003,51(2):113-125
We present and discuss observations of Titan (photometry and spectroscopy) and Uranus and Neptune (spectroscopy only) obtained using off-the-shelf equipment, affordable and available to many amateur astronomers and small colleges. Spectral observations compare well with published results from front-line observatories, and some evidence of seasonal change is evident in both spectra and narrowband photometry. Scattered Saturn light presents a significant problem for Titan observations, in particular, for slitless spectroscopy, and our attempts to reproduce Titan's lightcurve have so far been unsuccessful. 相似文献
203.
D. J. Christian D. L. Pollacco I. Skillen R. A. Street F. P. Keenan W. I. Clarkson A. Collier Cameron S. R. Kane T. A. Lister R. G. West B. Enoch A. Evans A. Fitzsimmons C. A. Haswell C. Hellier S. T. Hodgkin K. Horne J. Irwin A. J. Norton J. Osborne R. Ryans P. J. Wheatley D. M. Wilson 《Monthly notices of the Royal Astronomical Society》2006,372(3):1117-1128
204.
M. J. Gaylard G. C. MacLeod D. P. Smits M. E. West D. J. van der Walt 《Astrophysics and Space Science》1995,230(1-2):341-350
Research into star-forming regions, evolved HII regions, late-type stars with circumstellar dust shells and comet Halley using spectroscopic observations made with the Hartebeesthoek radio telescope is reviewed. 相似文献
205.
Ian Kraucunas Leon Clarke James Dirks John Hathaway Mohamad Hejazi Kathy Hibbard Maoyi Huang Chunlian Jin Michael Kintner-Meyer Kerstin Kleese van Dam Ruby Leung Hong-Yi Li Richard Moss Marty Peterson Jennie Rice Michael Scott Allison Thomson Nathalie Voisin Tristram West 《Climatic change》2015,129(3-4):573-588
206.
207.
D. Pollacco I. Skillen A. Cameron D. Christian J. Irwin T. Lister R. Street R. West W. Clarkson N. Evans A. Fitzsimmons C. Haswell C. Hellier S. Hodgkin K. Horne B. Jones S. Kane F. Keenan A. Norton J. Osborne R. Ryans P. Wheatley 《Astrophysics and Space Science》2006,304(1-4):253-255
The WASP project and infrastructure supporting the SuperWASP Facility are described. As the instrument, reduction pipeline and archive system are now fully operative we expect the system to have a major impact in the discovery of bright exo-planet candidates as well in more general variable star projects. 相似文献
208.
Christopher A.Tout 《中国天文和天体物理学报》2007,(2)
Based on previous works of OPAL, we construct a series of opacity tables for various metallicities Z=0, 0.000 01, 0.000 03, 0.000 1, 0.000 3, 0.001, 0.004, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.08 and 0.1. These tables can be easily used in Eggleton's stellar evolution code in place of the old tables without changing the code. The OPAL tables are used for log10(T/K) > 3.95 and Alexander's for log10(T/K) < 3.95. At log10(T/K) = 3.95, the two groups' data fit well for all hydrogen mass fractions. Conductive opacities are included by reciprocal addition according to the formulae of Yakovlev and Urpin. A comparison of 1 and 5 M models constructed with the older OPAL tables of Iglesias and Rogers shows that the new opacities have most effect in the late stages of evolution, the extension of the blue loop during helium burning for intermediate-mass and massive stars. 相似文献
209.
F. Paganelli M.A. Janssen R. West J.I. Lunine S.D. Wall R.M. Lopes R.L. Kirk L. Roth the Radar Team 《Icarus》2007,191(1):211-222
The first five Titan flybys with Cassini's Synthetic Aperture RADAR (SAR) and radiometer are examined with emphasis on the calibration and interpretation of the high-resolution radiometry data acquired during the SAR mode (SAR-radiometry). Maps of the 2-cm wavelength brightness temperature are obtained coincident with the SAR swath imaging, with spatial resolution approaching 6 km. A preliminary calibration shows that brightness temperature in these maps varies from 64 to 89 K. Surface features and physical properties derived from the SAR-radiometry maps and SAR imaging are strongly correlated; in general, we find that surface features with high radar reflectivity are associated with radiometrically cold regions, while surface features with low radar reflectivity correlate with radiometrically warm regions. We examined scatterplots of the normalized radar cross-section σ0 versus brightness temperature, finding differing signatures that characterize various terrains and surface features. Implications for the physical and compositional properties of these features are discussed. The results indicate that volume scattering is important in many areas of Titan's surface, particularly Xanadu, while other areas exhibit complex brightness temperature variations consistent with variable slopes or surface material and compositional properties. 相似文献
210.
R. A. Street D. J. Christian W. I. Clarkson A. Collier Cameron B. Enoch S. R. Kane T. A. Lister R. G. West D. M. Wilson A. Evans A. Fitzsimmons C. A. Haswell C. Hellier S. T. Hodgkin K. Horne J. Irwin F. P. Keenan A. J. Norton J. Osborne D. L. Pollacco R. Ryans I. Skillen P. J. Wheatley J. Barnes 《Monthly notices of the Royal Astronomical Society》2007,379(2):816-832