全文获取类型
| 收费全文 | 11738篇 |
| 免费 | 1039篇 |
| 国内免费 | 1856篇 |
专业分类
| 测绘学 | 465篇 |
| 大气科学 | 373篇 |
| 地球物理 | 1231篇 |
| 地质学 | 4355篇 |
| 海洋学 | 1841篇 |
| 天文学 | 5138篇 |
| 综合类 | 572篇 |
| 自然地理 | 658篇 |
出版年
| 2024年 | 27篇 |
| 2023年 | 78篇 |
| 2022年 | 233篇 |
| 2021年 | 248篇 |
| 2020年 | 291篇 |
| 2019年 | 349篇 |
| 2018年 | 280篇 |
| 2017年 | 265篇 |
| 2016年 | 286篇 |
| 2015年 | 348篇 |
| 2014年 | 558篇 |
| 2013年 | 621篇 |
| 2012年 | 658篇 |
| 2011年 | 798篇 |
| 2010年 | 807篇 |
| 2009年 | 1092篇 |
| 2008年 | 1061篇 |
| 2007年 | 968篇 |
| 2006年 | 898篇 |
| 2005年 | 800篇 |
| 2004年 | 639篇 |
| 2003年 | 573篇 |
| 2002年 | 450篇 |
| 2001年 | 401篇 |
| 2000年 | 370篇 |
| 1999年 | 333篇 |
| 1998年 | 238篇 |
| 1997年 | 133篇 |
| 1996年 | 103篇 |
| 1995年 | 95篇 |
| 1994年 | 116篇 |
| 1993年 | 112篇 |
| 1992年 | 53篇 |
| 1991年 | 49篇 |
| 1990年 | 46篇 |
| 1989年 | 36篇 |
| 1988年 | 36篇 |
| 1987年 | 14篇 |
| 1986年 | 23篇 |
| 1985年 | 26篇 |
| 1984年 | 23篇 |
| 1983年 | 16篇 |
| 1982年 | 19篇 |
| 1981年 | 18篇 |
| 1980年 | 11篇 |
| 1979年 | 5篇 |
| 1978年 | 9篇 |
| 1977年 | 15篇 |
| 1877年 | 1篇 |
| 1875年 | 1篇 |
排序方式： 共有10000条查询结果，搜索用时 16 毫秒
111.
Alon Retter Bing Zhang Lionel Siess Amir Levinson 《Monthly notices of the Royal Astronomical Society》2006,370(3):1573-1580
V838 Mon is the prototype of a new class of objects. Understanding the nature of its multistage outburst and similar systems is challenging. So far, several scenarios have been invoked to explain this group of stars. In this work, the planets-swallowing model for V838 Mon is further investigated, taking into account the findings that the progenitor is most likely a massive B-type star. We find that the super-Eddington luminosity during the eruption can explain the fast rising times of the three peaks in the optical light curve. We used two different methods to estimate the location where the planets were consumed. There is a nice agreement between the values obtained from the luminosities of the peaks and from their rising time-scale. We estimate that the planets were stopped at a typical distance of one solar radius from the centre of the host giant star. The planets-devouring model seems to give a satisfying explanation to the differences in the luminosities and rising times of the three peaks in the optical light curve of V838 Mon. The peaks may be explained by the consumption of three planets or alternatively by three steps in the terminal falling process of a single planet. We argue that only the binary merger and the planets-swallowing models are consistent with the observations of the new type of stars defined by V838 Mon. 相似文献
112.
113.
114.
115.
116.
117.
P. G. Jonker M. van der Klis C. Kouveliotou M. Méndez W. H. G. Lewin T. Belloni 《Monthly notices of the Royal Astronomical Society》2003,346(2):684-688
We have observed the eclipsing low-mass X-ray binary MS 1603.6+2600 with Chandra for 7 ks. The X-ray spectrum is well fit with a single absorbed power law with an index of ∼2. We find a clear sinusoidal modulation in the X-ray light curve with a period of 1.7 ± 0.2 h , consistent with the period of 1.85 h found before. However, no (partial) eclipses were found. We argue that if the X-ray flare observed in earlier X-ray observations was a type I X-ray burst, then the source can only be an accretion disc corona source at a distance of ∼11–24 kpc (implying a height above the Galactic disc of ∼8–17 kpc). It has also been proposed in the literature that MS 1603.76+2600 is a dipper at ∼75 kpc. We argue that, in this dipper scenario, the observed optical properties of MS 1603.6+2600 are difficult to reconcile with the optical properties one would expect on the basis of comparisons with other high-inclination, low-mass X-ray binaries, unless the X-ray flare was not a type I X-ray burst. In that case, the source can be a nearby soft X-ray transient accreting at a quiescent rate, as was proposed by Hakala et al., or a high-inclination source at ∼15–20 kpc. 相似文献
118.
119.
R. K. Manchanda 《Journal of Astrophysics and Astronomy》2001,22(2-3):145-154
Spectral measurement of Mkn 421 were made in the hard X-ray energy band of 20–200 keV using a high sensitivity, large area
scintillation counter telescope on November 21, 2000 and these coincided with the onset of an active X-ray phase as seen in
the ASM counting rates on board RXTE. The observed spectrum can not be fitted to a single power law similar to the PDS data
of BeppoSAX. The data can be fitted both by a two component power-law function or a combination of an exponential function
with a power law component at the high energies above 80 keV. We identify these components with those arising from the synchrotron
self compton and the high energy power-law tail arising from the upgrading of the thermal photons due to multiple Compton
scattering a la Cyg X-1. A comparison with the earlier data clearly suggests a spectral variability in the hard X-ray spectrum
of the source. We propose a continuously flaring geometry for the source as the underlying mechanism for energy release. 相似文献
120.