全文获取类型
收费全文 | 432篇 |
免费 | 28篇 |
国内免费 | 14篇 |
专业分类
测绘学 | 12篇 |
大气科学 | 55篇 |
地球物理 | 94篇 |
地质学 | 137篇 |
海洋学 | 39篇 |
天文学 | 82篇 |
自然地理 | 55篇 |
出版年
2024年 | 3篇 |
2023年 | 3篇 |
2022年 | 3篇 |
2021年 | 14篇 |
2020年 | 10篇 |
2019年 | 15篇 |
2018年 | 17篇 |
2017年 | 16篇 |
2016年 | 21篇 |
2015年 | 22篇 |
2014年 | 20篇 |
2013年 | 24篇 |
2012年 | 17篇 |
2011年 | 30篇 |
2010年 | 25篇 |
2009年 | 30篇 |
2008年 | 17篇 |
2007年 | 29篇 |
2006年 | 16篇 |
2005年 | 19篇 |
2004年 | 12篇 |
2003年 | 15篇 |
2002年 | 10篇 |
2001年 | 9篇 |
2000年 | 11篇 |
1999年 | 12篇 |
1998年 | 7篇 |
1997年 | 2篇 |
1996年 | 4篇 |
1995年 | 2篇 |
1994年 | 5篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 1篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1981年 | 1篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有474条查询结果,搜索用时 0 毫秒
471.
472.
Previous studies showed that 4 D-Var technique used for data assimilation could be modified for weather control. This study demonstrates the ability of 4 D-Var to influence the future path of a tropical cyclone by calculating perturbations in WRF simulation. Given the background error covariance matrix, the initial field is improved by the vortex dynamic initialization technique. Our results show that 4 D-Var can be applied to control the trajectory of simulated tropical cyclones by producing "optimal" perturbations. In the numerical simulation experiment of Typhoon Mitag in 2019, after this kind of weather control similar to data assimilation, the tropical cyclone moved obviously,and the damaging wind over the coastline weakened. The prediction results after the initial field modified by 4 D-Var have a great change, and the position of the tropical cyclone moved about 0.5° southeastward after assimilation,which misses the southeast coast of China. Moreover, the damaging wind is also weakened. Since the 4 D-Var is premised on the assumption that the model is perfect and does not consider the model error, then the research plan to consider model error and introduce new methods is discussed in the paper. 相似文献
473.
George E Harlow Jeremy S Delaney C.E Nehru Martin Prinz 《Geochimica et cosmochimica acta》1982,46(3):339-348
The high modal abundances of merrillite [Ca3(PO4)2] and tridymite in most mesosiderites are not the result of igneous fractionation but are attributed to redox reactions between silicates and P-bearing Fe-Ni metal within a limited T-fO2 range at low pressure. The Emery mesosiderite is the most tridymite- and merrillite-rich mesosiderite so it is used as the model for this study. Examination of reactions in the system CaO-SiO2-MgSiO3-Fe-P-O indicate that essentially all of the present phosphorus in Emery should have been dissolved in the metallic portion (calculated to have contained 0.65 wt% P originally), and that it largely reacted to form phosphate. The thermodynamic calculations predict that the reactions would have occurred between 970°C, log fO2 = ?16.5 and 1030°C, log fO2 = ?15.0 for the range of phase compositions in Emery. A narrower range of conditions is expected for other mesosiderites. Phosphide (schreibersite) formed only later at temperatures < 600°C during slow cooling. The recalculated amounts of dissolved P and S in the metallic portion of Emery reduce the temperature of the metal liquidus to < 1350°C and the solidus to < 800°C. Thus mixing of liquid metal with cold silicates near the parent body's surface would not have resulted in substantial melting of the silicates but would have resulted in their metamorphism, which is consistent with the textural relationships observed in Emery. This scenario of redox reactions and redistributions of components between metal and silicates represents a new insight into the complexities of mesosiderite processing that helps unravel the mesosiderite history and recalculate their original components. 相似文献
474.
Edward S. Gilfillan Nicole P. Maher Cecile M. Krejsa Mary E. Lanphear Christopher D. Ball Jeremy B. Meltzer David S. Page 《Marine pollution bulletin》1995,30(12):780-787
Image analysis of historical aerial photographs was used to examine the effects of the Amoco Cadiz oil spill and resulting clean-up on marsh ecology. Two heavily oiled marsh systems were compared. The marsh which received no clean-up recovered to its prior condition. The marshes in the system cleaned by sediment removal were extensively altered as a result of changes in intertidal height of the sediment surface. 相似文献