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511.
应用特征参数GU、FU、B处理区域伽玛能谱资料的效果初探 总被引:2,自引:0,他引:2
从U、Th元素的地球化学特性出发,探讨了利用“古铀丰度”(Gu)、“活化铀”(Fu)和“相对变迂系数”(B)等特征参数处理区域伽玛能谱测量资料的可能性和实际应用效果。文中阐述了选用的能谱特征参数的理论基础及地球化学意义。同时,利用这些特征参数对成矿带上所作的区域地面伽玛能谱测量资料进行了处理。结果表明,利用这些参数在确定区域铀源体、研究该区铀元素活化运移和沉积富集规律、探讨该区控制铀矿化形成的主要地质因素以及预测区内铀矿找矿远景地段等方面都取得了较满意的效果,是一种值得进一步探索和完善的伽玛能谱资料处理方法。 相似文献
512.
513.
It has been suggested by Usov (1992) that accreting white dwarfs, collapsing to neutron stars may be the sources of the gamma-ray bursts observed at cosmological distances, provided they rotate very fast and have enormously high magnetic fields. In this model the burst's duration is given by the ratio of pulsar kinetic energy and magneticdipole luminosity, so that in order to account for the shortest ( 0.1 s) bursts, the pulsars must rotate very fast (with periodP 0.5 ms) and have magnetic fields of 1016 - 1017 G. Though the high pulsar frequency was anticipated (Qadir and Rafique, 1986) and has been shown to be plausible (Abramowicz, 1990), the extremely high magnetic fields seem anomalous as observed neutron stars have fields below 1013 G.The problem with Usov's proposal is reduced by incorporating the relativistic corrections for fast rotating magnetic dipoles (Belinskyet al., 1994) or magnetic stars (De Paolis and Qadir, 1994). These corrections substantially enhance the radiation efficiency due to the existence of a magnetic synchrotron effect so that the magnetic field required for the explanation of the shortest gamma-ray bursts is strongly reduced. As such the model becomes much more plausible. 相似文献
514.
Hakkila J. Meegan C. Horack J. Pendleton G. Briggs M. Paciesas W. Emslie G. Mallozzi R. 《Astrophysics and Space Science》1995,231(1-2):369-372
Constraints are found on the gamma-ray burst luminosity function from an analysis of the combined BATSE/PVO intensity distribution. If bursts originate in an extended Galactic halo, then the intrinsic luminosity range is narrow, with bursts spanning only a factor of five or less in luminosity. If bursts originate in a simple Friedmann cosmology with = 1 and = 0, then very few luminosity constraints exist.National Research Council Fellow at NASA/MSFC 相似文献
515.
R. D. Preece M. S. Briggs G. N. Pendleton W. S. Paciesas D. L. Band L. A. Ford 《Astrophysics and Space Science》1995,231(1-2):149-152
It is a well-known observation that many GRBs have spectra with curvature in the less than 1 MeV regime, but flatten out to approximately a -2 power law at higher energies. The large collecting area of BATSE allows spectral studies with unprecedented time resolution. We are conducting a systematic study of time-resolved spectroscopy of GRBs observed by BATSE. Several aspects of this survey are discussed: correlations among fit parameters and between fit parameters and intensity; screening for spectral features using-residual contour maps; and an introduction to the GRB topographic map and its possible qualitative diagnostic abilities. 相似文献
516.
J. Hakkila V. Vo C. Meegan J. Horack G. Fishman D. Hartmann G. Pendleton M. Briggs W. Paciesas 《Astrophysics and Space Science》1995,231(1-2):23-26
A repeater statistic (derived from the two-point angular correlation function and accounting for location errors) is used to identify constraints on the rate of burst repetition from the BATSE 1B catalog. Because of the anisotropic sky exposure, repeating sources should create additional effects in the large-scale distribution of close burst pairs.National Research Council Fellow at NASA/MSFC 相似文献
517.
Alberto J. Castro-Tirado 《Astrophysics and Space Science》1995,231(1-2):467-470
MARIA (Maxi Array for Rapid Imaging of -ray burst Activity) is a large-area instrument that could be flown on a balloon in 1997–1999. It is expected to contribute significantly to the GRB log N - log S distribution and to provide rapid GRB localizations by means of a rapidly moving gamma-camera. 相似文献
518.
L. O. Hanlon K. Bennett O. R. Williams C. Winkler R. D. Preece 《Astrophysics and Space Science》1995,231(1-2):157-160
Although the earliest observed gamma-ray burst spectra were well described by thermal bremsstrahlung models, subsequent observations above 1 MeV showed the existence of high energy power law tails in 60% of events. In order to accurately characterise burst spectra, both the low energy turnover and the high energy tail must be accounted for. We have addressed this issue by jointly deconvolving spectra obtained by BATSE and COMPTEL onboard theCompton Observatory. We present preliminary results obtained by application of this method to the gamma-ray burst of February 17, 1994. 相似文献
519.
太阳射电爆发的起因:耀斑或/和日冕物质抛射 总被引:2,自引:0,他引:2
本文分析了近二十年来的地面和空间太阳有关观测资料,得出太阳射电爆发的起因为耀斑和/ 或日冕物质抛射(CME) 而不仅仅是耀斑,这将有利于更深刻地了解太阳射电爆发和共生高能现象的物理过程 相似文献
520.