全文获取类型
收费全文 | 1370篇 |
免费 | 71篇 |
国内免费 | 13篇 |
专业分类
测绘学 | 35篇 |
大气科学 | 108篇 |
地球物理 | 330篇 |
地质学 | 558篇 |
海洋学 | 118篇 |
天文学 | 229篇 |
综合类 | 2篇 |
自然地理 | 74篇 |
出版年
2023年 | 8篇 |
2021年 | 14篇 |
2020年 | 19篇 |
2019年 | 34篇 |
2018年 | 37篇 |
2017年 | 37篇 |
2016年 | 42篇 |
2015年 | 50篇 |
2014年 | 59篇 |
2013年 | 87篇 |
2012年 | 53篇 |
2011年 | 74篇 |
2010年 | 55篇 |
2009年 | 92篇 |
2008年 | 65篇 |
2007年 | 58篇 |
2006年 | 61篇 |
2005年 | 59篇 |
2004年 | 60篇 |
2003年 | 43篇 |
2002年 | 37篇 |
2001年 | 26篇 |
2000年 | 17篇 |
1999年 | 21篇 |
1998年 | 15篇 |
1997年 | 17篇 |
1996年 | 16篇 |
1995年 | 17篇 |
1994年 | 7篇 |
1993年 | 14篇 |
1992年 | 18篇 |
1991年 | 8篇 |
1990年 | 6篇 |
1989年 | 15篇 |
1988年 | 9篇 |
1987年 | 13篇 |
1986年 | 6篇 |
1985年 | 8篇 |
1984年 | 7篇 |
1983年 | 20篇 |
1982年 | 11篇 |
1981年 | 15篇 |
1980年 | 7篇 |
1979年 | 7篇 |
1978年 | 13篇 |
1977年 | 6篇 |
1976年 | 11篇 |
1975年 | 9篇 |
1974年 | 9篇 |
1969年 | 6篇 |
排序方式: 共有1454条查询结果,搜索用时 15 毫秒
101.
Hans J. Albrecht 《Meteorology and Atmospheric Physics》1959,11(3):383-391
Zusammenfassung Unter Benutzung seiner früheren Untersuchungen über Geräteeinflüsse bei Ionosphärenmessungen behandelt der Verfasser in der vorliegenden Arbeit eine Erweiterung des theoretischen Ausgleichverfahrens. Mit Bezug auf diese Ergebnisse wird in den anderen Abschnitten die moderne technische Einrichtung von Ionosonden diskutiert.
Mit 3 Textabbildungen 相似文献
Summary Using his previous investigations on instrument effects with ionosphere measurements the author deals, in the present paper, with an extension of the theoretical adaptation method. With reference to these results, the modern equipment of ionosphere stations is discussed in the other sections.
Résumé S'appuyant sur ses recherches antérieures relatives à l'effet instrumental lors des mesures ionosphériques, l'auteur expose ici une extension du procédé théorique de compensation. Puis se référant à ces résultats, il traite de l'aménagement technique des sondes ionosphériques.
Mit 3 Textabbildungen 相似文献
102.
Hans J. Albrecht 《Meteorology and Atmospheric Physics》1958,11(1):84-92
Summary This paper presents new results of the author's investigations on ionospheric propagation in Australia from 1952 to 1957. Considerations on path attenuation are followed by a discussion on the propagation paths to North America and Western Europe. Conclusions are in agreement with the author's previous publications in this field.
With 1 Figure 相似文献
Zusammenfassung In dieser Arbeit behandelt der Verfasser neue Ergebnisse seiner Untersuchungen über ionosphärische Ausbreitung in Australien von 1952 bis 1957. Auf eine Betrachtung über die Signalschwächung folgt eine Diskussion über die Ausbreitungswege nach Nordamerika und Westeuropa. Die Folgerungen stimmen mit den früheren Veröffentlichungen des Verfassers auf diesem Gebiet überein.
Résumé L'auteur expose les nouveaux résultats de ses recherches sur la propagation ionosphérique en Australie de 1952 à 1957; il considère l'affaiblissement de la propagation des signaux et les chemins suivis par les ondes vers l'Amérique du Nord et vers l'Europe occidentale. Ces résultats concordent avec ceux qu'il a publiés précédemment.
With 1 Figure 相似文献
103.
104.
Pierre Choukroune Xavier Le Pichon Michel Seguret Jean-Claude Sibuet 《Earth and Planetary Science Letters》1973,18(1):109-118
The different hypotheses proposed for the creation of the Bay of Biscay are reviewed. New geological and geophysical data collected in the last two years in the Bay and in the Pyrenean domain give new insight into the tectogenesis of the Pyrenees. Geological data of the Pyrenean area provide tight constraints on the hypothesis of formation of the Bay. The most probable hypothesis is an opening by rotation of the Iberian Peninsula around a pole of rotation situated near Paris, which resulted in strike-slip motion along the North Pyrenean fault during the Upper Mesozoic. A progressive westward migration of the pole initiated in the late Cretaceous blocked the motion along the fault and led to the main Eocene tectogenetic Pyrenean phase. 相似文献
105.
106.
ABSTRACTWhat implications do societies’ risk perceptions have for flood losses? This study uses a stylized, socio-hydrological model to simulate the mutual feedbacks between human societies and flood events. It integrates hydrological modelling with cultural theory and proposes four ideal types of society that reflect existing dominant risk perception and management: risk neglecting, risk monitoring, risk downplaying and risk controlling societies. We explore the consequent trajectories of flood risk generated by the interactions between floods and people for these ideal types of society over time. The results suggest that flood losses are substantially reduced when awareness-raising attitudes are promoted through inclusive, participatory approaches in the community. In contrast, societies that rely on top-down hierarchies and structural measures to protect settlements on floodplains may still suffer significant losses during extreme events. This study illustrates how predictions formed through social science theories can be applied and tested in hydrological modelling. 相似文献
107.
Pierre Kaufmann 《Solar physics》1976,50(1):197-199
No fluctuations in polarization have been found during a 7 GHz solar burst showing 17 s periodic pulses in intensity. Polarization effects can be produced by the propagation media in the active centre, which are not affected directly by the burst source, but situated more deeply than the observed heights at that microwave frequency. 相似文献
108.
Solute recycling from irrigation can be described as the process that occurs when the salt load that is extracted from irrigation wells and distributed on the fields is returned to the groundwater below irrigated surfaces by deep percolation. Unless the salt load leaves the system by means of drains or surface runoff, transfer to the groundwater will take place, sooner or later. This can lead to solute accumulation and thus to groundwater degradation, particularly in areas where extraction rates exceed infiltration rates (semi-arid and arid regions). Thus, considerable errors can occur in a predictive solute mass budget if the recycling process is not accounted for in the calculation. A method is proposed which allows direct simulation of solute recycling. The transient solute response at an extraction well is shown to be a superposition of solute mass flux contributions from n recycling cycles and is described as a function of the travel time distribution between a recycling point and a well. This leads to an expression for a transient ‘recycling source’ term in the advection–dispersion equation, which generates the effect of solute recycling. At long times, the ‘recycling source’ is a function of the local capture probability of the irrigation well and the solute mass flux captured by the well from the boundaries. The predicted concentration distribution at steady state reflects the maximum spatial concentration distribution in response to solute recycling and can thus be considered as the solute recycling potential or vulnerability of the entire domain for a given hydraulic setting and exploitation scheme. Simulation of the solute recycling potential is computationally undemanding and can therefore, for instance, be used for optimisation purposes. Also, the proposed method allows transient simulation of solute recycling with any standard flow and transport code. 相似文献
109.
John Wilson Stewart Fotheringham Gary Hunter Jochen Albrecht 《Transactions in GIS》2006,10(2):153-153
110.