全文获取类型
收费全文 | 495篇 |
免费 | 26篇 |
国内免费 | 2篇 |
专业分类
测绘学 | 5篇 |
大气科学 | 22篇 |
地球物理 | 131篇 |
地质学 | 213篇 |
海洋学 | 24篇 |
天文学 | 111篇 |
综合类 | 1篇 |
自然地理 | 16篇 |
出版年
2022年 | 6篇 |
2021年 | 6篇 |
2020年 | 8篇 |
2019年 | 10篇 |
2018年 | 21篇 |
2017年 | 13篇 |
2016年 | 32篇 |
2015年 | 23篇 |
2014年 | 37篇 |
2013年 | 64篇 |
2012年 | 17篇 |
2011年 | 28篇 |
2010年 | 37篇 |
2009年 | 28篇 |
2008年 | 22篇 |
2007年 | 7篇 |
2006年 | 15篇 |
2005年 | 7篇 |
2004年 | 7篇 |
2003年 | 5篇 |
2002年 | 6篇 |
2001年 | 7篇 |
2000年 | 6篇 |
1999年 | 6篇 |
1998年 | 5篇 |
1997年 | 12篇 |
1996年 | 7篇 |
1994年 | 3篇 |
1992年 | 2篇 |
1991年 | 3篇 |
1990年 | 6篇 |
1989年 | 6篇 |
1988年 | 5篇 |
1987年 | 3篇 |
1985年 | 4篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 6篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 5篇 |
1974年 | 3篇 |
1973年 | 7篇 |
1972年 | 3篇 |
1970年 | 2篇 |
1969年 | 2篇 |
1968年 | 2篇 |
1964年 | 1篇 |
1935年 | 1篇 |
排序方式: 共有523条查询结果,搜索用时 15 毫秒
101.
102.
103.
Yngve Öhman 《Solar physics》1985,96(1):209-212
It is suggested, that effects of total reflection and refraction may appear sometimes in various objects on the Sun in connection with grazing incidence towards layers formed by magnetic fields and perhaps also by electrostatic double layers or shock waves. It seems possible that such effects may influence sometimes the contrast of bright structures as well as dark structures at selective wavelengths as well as in white light. 相似文献
104.
Kâmuran Avcioglu M. Türker Özkan H. Hüseyin Mentese 《Astrophysics and Space Science》1990,164(2):263-276
We investigate the near-ultraviolet high-resolution LWR spectra of the stars Cas, And, Tau, Gem, Cru, Boo, and Peg, obtained with the aid of the International Ultraviolet Explorer Satellite. We have given here a list of the strongest and most prevalent emission lines in the near-ultraviolet spectra of Boo, KlIIIp, and Peg, M2.5II-III which have the same luminosity class and different spectral type. The near-ultraviolet continuum flux measurements and integrated emission line fluxes of these stars for the 2500–3200 Å region are presented in order to compare the variations in the appearance of the near-ultraviolet flux distribution with the temperature structure of their chromospheres for K and M giant stars. We also discuss differences between observed and calculated fluxes found from the Planck function. 相似文献
105.
In this work the rotational perturbations of the Friedmann universes are investigated. In the general case where none of the terms including (r, t) are neglected, for perfect fluid, the field equations belonging to the perturbed metric give =(t). In this case, since the condition =0 can be accomplished by a coordinate transformation, the solutions of the field equations reduce to those of the classical Friedmann equations. For this reason, the approximate solutions obtained by other authors become formal solutions without physical interest. 相似文献
106.
107.
108.
This paper reports the results of a study of the N-S asymmetry in the flare index using the results of Knoka (1985) combined with our results for the solar cycles 17 to the current cycle 22. By comparing the time-variation of the asymmetry curve with the solar activity variation of the 11-year cycle, we have found that the flare index asymmetry curve is not in phase with the solar cycle and that the asymmetry peaks during solar minimum. A periodic behaviour in the N-S asymmetry appears: the activity in one hemisphere is more important during the ascending part of the cycle whereas during the descending part the activity becomes more important in the other hemisphere. The dominance of flare activity in the southern hemisphere continues during cycle 22 and, according to our findings, this dominance will increase gradually during the following cycle 23. 相似文献
109.
Bertaux Jean-Loup QuÉmerais Eric Lallement Rosine KyrÖlÄ Erkki Summanen Tuula 《Solar physics》1997,170(2):365-370
In a recently published paper, Scherer and Fahr (1995) claimed that the departures of sky L emission measured by Prognoz 5 and 6 from an optically thin model can be attributed entirely to deficiencies of the optically thin approximation, and are not due to variations of solar wind ionization rate with latitude, as advocated since many years by our research group. They base their claim on the result of their new sophisticated model of L radiation transport.It is shown here that their new model, in the simple case of isotropic solar wind, predicts a distribution of intensity in a simple geometry which is completely contradicted by the observations: they find a minimum of intensity near the upwind direction, where a maximum has been observed consistently by all L instruments. Therefore, their conclusion based on an erroneous model must be rejected. 相似文献
110.
In this paper, the Einstein field equations have been solved for cylindrically symmetric and inhomogeneous cosmological models with viscous fluid. Various physical and geometrical properties of the models are also discussed. 相似文献