全文获取类型
收费全文 | 2951篇 |
免费 | 395篇 |
国内免费 | 486篇 |
专业分类
测绘学 | 262篇 |
大气科学 | 883篇 |
地球物理 | 452篇 |
地质学 | 408篇 |
海洋学 | 363篇 |
天文学 | 929篇 |
综合类 | 144篇 |
自然地理 | 391篇 |
出版年
2024年 | 13篇 |
2023年 | 25篇 |
2022年 | 61篇 |
2021年 | 85篇 |
2020年 | 72篇 |
2019年 | 75篇 |
2018年 | 72篇 |
2017年 | 76篇 |
2016年 | 79篇 |
2015年 | 108篇 |
2014年 | 131篇 |
2013年 | 140篇 |
2012年 | 131篇 |
2011年 | 141篇 |
2010年 | 118篇 |
2009年 | 248篇 |
2008年 | 206篇 |
2007年 | 247篇 |
2006年 | 209篇 |
2005年 | 203篇 |
2004年 | 183篇 |
2003年 | 168篇 |
2002年 | 156篇 |
2001年 | 130篇 |
2000年 | 98篇 |
1999年 | 93篇 |
1998年 | 98篇 |
1997年 | 76篇 |
1996年 | 67篇 |
1995年 | 69篇 |
1994年 | 55篇 |
1993年 | 48篇 |
1992年 | 30篇 |
1991年 | 34篇 |
1990年 | 19篇 |
1989年 | 19篇 |
1988年 | 17篇 |
1987年 | 9篇 |
1986年 | 5篇 |
1985年 | 1篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 5篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有3832条查询结果,搜索用时 62 毫秒
371.
本文简要介绍了云南天文台新建立的21cm波段快速(不中断采样)记录系统,及使用该系统观测到的快速尖峰事件。系统得到的太阳分米波段爆发中不同时间尺度的精细结构与Stu-rroch等提出的太阳耀斑中能量释放的模式相一致。 相似文献
372.
None of the tentative black-hole identifications has remained without serious difficulties. As a class, the black-hole candidates
differ in no obvious property from neutron-star binaries other than in their estimated high mass. We favour an interpretation
of the black-hole candidates as binary neutron stars surrounded by a more or less massive accretion disc 相似文献
373.
374.
Gamma—Ray Bursts:Afterglows and Central Engines 总被引:5,自引:0,他引:5
K.S.Cheng T.Lu 《中国天文和天体物理学报》2001,1(1):1-20
Gamma-ray bursts (GRBs) are the most intense transient gamma-ray events in the sky; this, together with the strong evidence (the isotropic and inhomogeneous distribution of GRBs detected by BASTE) that they are located at cosmological distances, makes them the most energetic events ever known. For example, the observed radiation energies of some GRBs are equivalent to the total convertion into radiation of the mass energy of more than one solar mass. This is thousand times stronger than the energy of a supernova explosion. Some unconventional energy mechanism and extremely high conversion efficiency for these mysterious events are required. The discovery of host galaxies and association with supernovae at cosmoligical distances by the recently launched satellite of BeppoSAX and ground based radio and optical telescopes in GRB afterglow provides further support to the cosmological origin of GRBs and put strong constraints on their central engine. It is the aim of this article to review the possible central engines, energy mechanisms, dynamical and spectral evolution of GRBs, especially focusing on the afterglows in multi-wavebands. 相似文献
375.
K. D. Kokkotas T. A. Apostolatos N. Andersson 《Monthly notices of the Royal Astronomical Society》2001,320(3):307-315
We study the problem of detecting, and inferring astrophysical information from, gravitational waves from a pulsating neutron star. We show that the fluid f and p modes, as well as the gravitational-wave w modes, may be detectable from sources in our own Galaxy, and investigate how accurately the frequencies and damping rates of these modes can be inferred from a noisy gravitational-wave data stream. Based on the conclusions of this discussion we propose a strategy for revealing the supranuclear equation of state using the neutron star fingerprints: the observed frequencies of an f and a p mode. We also discuss how well the source can be located in the sky using observations with several detectors. 相似文献
376.
R.A. Laing 《Monthly notices of the Royal Astronomical Society》2002,329(2):417-422
We derive expressions for the total and linearly polarized synchrotron emissivity of an element of plasma containing relativistic particles and disordered magnetic field that has been sheared or compressed along three independent directions. Our treatment follows that given by Matthews & Scheuer in the special case of a power-law electron energy spectrum. We show that the emissivity integrals depend on a single parameter, making it straightforward to generate one-dimensional look-up tables. We also demonstrate that our formulae give identical results to those in the literature in special cases. 相似文献
377.
378.
379.
380.
In-situ particle acceleration in extragalactic radio hot spots: observations meet expectations 总被引:1,自引:0,他引:1
G. Brunetti K.-H. Mack M. A. Prieto S. Varano 《Monthly notices of the Royal Astronomical Society》2003,345(3):L40-L44
We discuss, in terms of particle acceleration, the results from optical VLT observations of hot spots associated with radio galaxies. On the basis of observational and theoretical grounds, the following is shown. (i) Relatively low radio-radio power hot spots are the optimum candidates for being detected at optical waves. This is supported by an unprecedented optical detection rate of 70 per cent out of a sample of low radio power hot spots. (ii) The shape of the synchrotron spectrum of hot spots is mainly determined by the strength of the magnetic field in the region. In particular, the break frequency, related to the age of the oldest electrons in the hot spots, is found to increase with decreasing synchrotron power and magnetic field strength. Both observational results are in agreement with an in-situ particle acceleration scenario. 相似文献