全文获取类型
收费全文 | 532篇 |
免费 | 30篇 |
国内免费 | 3篇 |
专业分类
测绘学 | 13篇 |
大气科学 | 87篇 |
地球物理 | 112篇 |
地质学 | 205篇 |
海洋学 | 30篇 |
天文学 | 99篇 |
综合类 | 2篇 |
自然地理 | 17篇 |
出版年
2021年 | 5篇 |
2020年 | 6篇 |
2019年 | 7篇 |
2018年 | 24篇 |
2017年 | 25篇 |
2016年 | 53篇 |
2015年 | 29篇 |
2014年 | 37篇 |
2013年 | 31篇 |
2012年 | 18篇 |
2011年 | 23篇 |
2010年 | 29篇 |
2009年 | 28篇 |
2008年 | 18篇 |
2007年 | 21篇 |
2006年 | 12篇 |
2005年 | 7篇 |
2004年 | 8篇 |
2003年 | 9篇 |
2002年 | 8篇 |
2001年 | 5篇 |
2000年 | 6篇 |
1999年 | 2篇 |
1998年 | 12篇 |
1997年 | 8篇 |
1996年 | 12篇 |
1995年 | 5篇 |
1994年 | 4篇 |
1993年 | 13篇 |
1992年 | 7篇 |
1991年 | 7篇 |
1990年 | 9篇 |
1989年 | 7篇 |
1988年 | 3篇 |
1986年 | 6篇 |
1985年 | 4篇 |
1984年 | 6篇 |
1983年 | 3篇 |
1981年 | 3篇 |
1978年 | 3篇 |
1977年 | 4篇 |
1976年 | 2篇 |
1974年 | 2篇 |
1973年 | 3篇 |
1972年 | 3篇 |
1971年 | 5篇 |
1970年 | 3篇 |
1969年 | 4篇 |
1965年 | 4篇 |
1963年 | 2篇 |
排序方式: 共有565条查询结果,搜索用时 15 毫秒
61.
The paper is concerning with the light curve analysis of an active binary system of OO Aql. Basic orbital and physical parameters of this system were estimated by analysing photometric observations by Lafta and Grainger (1985) and Essam et al. (1992). Both groups of observations gave quite different light curves with a conspicuous asymmetry arising from unequal height of successive maxima. A slightly changed programme by Djuraevi (1992a) was applied. The programme was based on the Roche model and it included an option of overcontact configuration and active (bright or dark) spotted regions on the system's components. An inverse-problem method by Djuraevi (1992b) was used to estimate the parameters of the system and active regions. The light-curve analysis suggested a significant change in the system. For Lafta and Grainger's light curves our analysis showed the presence of a dark spotted area near the polar region of the primary component. This dark area covered about 22% of the primary's hemisphere. Essam et al.'s light curves had very complex shape. In this case the mechanism of the mass transfer and the exchange of the thermal energy between the components could produce a bright-spot (bs) area on the secondary, near the Lagrange equilibrium point L1 around the neck region between the stars. To explain a sharp increase of the system's brightness in the B filter immediately after the secondary minimum, we had to introduce also a hot-spot (hs) area of a high temperature contrast on the secondary. With the increase of the brightness in the V-filter being of much lower intensity, this hot spot region could be taken as a local eruption. The behaviour of the B–V colour index with the orbital phase is in favour of this hypothesis also. The obtained results show that the light-curve changes are due to development and moving of active spot regions on the components. 相似文献
62.
Kristen E. K. Coppin Christopher J. Davis & Milena Micono 《Monthly notices of the Royal Astronomical Society》1998,301(1):L10-L14
We discuss the formation of spectral features in the decelerating ejecta of gamma-ray bursts, including the possible effect of inhomogeneities. These should lead to blueshifted and broadened absorption edges and resonant features, especially from H and He. An external neutral ISM could produce detectable H and He, as well as Fe X-ray absorption edges and lines. Hypernova scenarios may be diagnosed by Fe Kα and H Lyα emission lines. 相似文献
63.
Age of amphibolites associated with alpine peridotites in the Dinaride ophiolite zone,Yugoslavia 总被引:1,自引:0,他引:1
Marvin A. Lanphere Robert G. Coleman Steven Karamata Jakob Pamić 《Earth and Planetary Science Letters》1975,26(3):271-276
Amphibolites associated with alpine peridotites in the Central Ophiolite zone in Yugoslavia have K-Ar ages of 160–170 m.y. These amphibolites and associated peridotites underwent deep-seated metamorphism prior to tectonic emplacement into the sedimentary-volcanic assemblage of the Dinarides. The alpine peridotites and associated local rocks of the ophiolite suite are interpreted as Jurassic oceanic crust and upper mantle. 相似文献
64.
65.
Dr. Djuro Radinović 《Meteorology and Atmospheric Physics》1965,14(3):279-299
Summary Changes occurring in the thermal structure of air masses in the Alps area and the West Mediterranean region, during cyclonic developments in the Gulf of Genoa, have been considered. The effect of the height and the form of the mountain ranges as well as that of the nonadiabatic processes, on the deformation of the thickness pattern, have been discussed. These factors have been further taken into consideration for a modification of the equations used inEstoque's method for the baroclinic model, and a new method has been developed for forecasting cyclogenesis in regions bounded by mountain ranges.
With 5 Figures 相似文献
Zusasmmenfassung Es werden die Änderungen der thermischen Struktur der Luftmassen im Alpengebiet und im westlichen Mittelmeerraum bei der Entwicklung von Zyklonen im Golf von Genua aufgezeigt und die Einflüsse von Höhe und Form der Gebirgszüge sowie von nichtadiabatischen Vorgängen auf die Deformation der relativen Topographie besprochen. Diese Faktoren werden auch zur Modifikation der in der Methode vonEstoque für ein baroklines Modell verwendeten Gleichungen in Betracht gezogen und damit wird eine neue Methode zur Vorhersage der Zyklogenese unter dem Einfluß von Gebirgszügen entwickelt.
Résumé On expose dans ce mémoire à quelles modifications la structure thermique des masses d'air est soumise dans la région des Alpes et dans le bassin occidental de la Méditerranée lors du développement de dépressions sur le Golfe de Gênes. On y discute en outre l'influence de la hauteur et de la forme des chaînes de montagnes ainsi que celle des processus non-adiabatiques sur des déformations de la topographie relative. Tous ces éléments sont pris en considération pour leur adapter les équations utilisées dans le modèle baroclined'Estoque. Par là, on accède à une nouvelle méthode de prévision de la cyclogénèse, méthode qui tient compte de l'influence des chaînes de montagnes.
With 5 Figures 相似文献
66.
Dr. Stjepko Golubić 《Aquatic Sciences - Research Across Boundaries》1965,27(2):218-232
Ohne Zusammenfassung
Die vorliegende Arbeit entstand dank der Unterstützung der Alexander-von-Humboldt-Stiftung, Bad Godesberg. 相似文献
67.
Summary A simple two-dimensional quasi-geostrophic linearized model of the atmosphere is used to investigate the behaviour of the quasi-geostrophic modes for five horizontal rectangular grids. Numerical expressions for frequencies of Rossby waves for all grids are evaluated. It was found that the B and C grids produce only negative frequencies as well as the continuous case. The D grid has negative and zero frequencies. Finally, it was found that the A and E grids produce positive frequencies and eastward moving Rossby waves.With 2 Figures 相似文献
68.
SummarySome Foundation Stability Problems of the Railway Bridge over the Mala Rijeka The authors presented an outlay of problems occurring in estimating the stability of rocky slopes loaded by large vertical forces. General attitudes, kept by the authors during the stability analysis for an actual case — foundation of piers No. 3 and 4 of the railway bridge across the Mala Rijeka, are also presented. The results of calculation as well as the advantages of the approach applied are outlined in the paper. Finally, general conclusions are drawn regarding the method to be kept in solving the stability of slopes loaded by large artificial loading.With 7 Figures 相似文献
69.
We propose a new formal definition of discovery for a Solar System object. It is based on an objective and mathematically
rigorous algorithm to assess when a set of observations is enough to constitute a discovery. When this definition is satisfied,
in almost all cases the orbit is defined well enough to establish the nature of the object discovered (Main Belt vs. Near
Earth Asteroid, Trans-Neptunian vs. long period comet). The frequency of occurrence of exceptions is estimated by a set of
numerical experiments.
The availability of a non-subjective definition of discovery allows some rules to be adopted for the assignment of discovery
credit with a minimum risk of dispute. Such rules should be fair, encourage good practice by the observers and acknowledge
the contribution of the orbit computers providing the identifications and the orbits, as well as the one of all the contributing
observers. 相似文献
70.