全文获取类型
收费全文 | 440篇 |
免费 | 12篇 |
国内免费 | 9篇 |
专业分类
测绘学 | 33篇 |
大气科学 | 20篇 |
地球物理 | 73篇 |
地质学 | 191篇 |
海洋学 | 10篇 |
天文学 | 116篇 |
综合类 | 7篇 |
自然地理 | 11篇 |
出版年
2022年 | 14篇 |
2021年 | 16篇 |
2020年 | 10篇 |
2019年 | 14篇 |
2018年 | 35篇 |
2017年 | 33篇 |
2016年 | 29篇 |
2015年 | 18篇 |
2014年 | 24篇 |
2013年 | 26篇 |
2012年 | 24篇 |
2011年 | 19篇 |
2010年 | 21篇 |
2009年 | 13篇 |
2008年 | 9篇 |
2007年 | 11篇 |
2006年 | 14篇 |
2004年 | 5篇 |
2001年 | 2篇 |
2000年 | 10篇 |
1999年 | 4篇 |
1998年 | 3篇 |
1996年 | 5篇 |
1994年 | 4篇 |
1993年 | 5篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1988年 | 5篇 |
1987年 | 4篇 |
1986年 | 6篇 |
1985年 | 3篇 |
1984年 | 4篇 |
1983年 | 5篇 |
1982年 | 3篇 |
1980年 | 5篇 |
1979年 | 5篇 |
1978年 | 7篇 |
1976年 | 3篇 |
1975年 | 4篇 |
1974年 | 2篇 |
1973年 | 4篇 |
1972年 | 3篇 |
1971年 | 6篇 |
1970年 | 4篇 |
1968年 | 1篇 |
1967年 | 1篇 |
1966年 | 1篇 |
1959年 | 1篇 |
1954年 | 1篇 |
1953年 | 1篇 |
排序方式: 共有461条查询结果,搜索用时 0 毫秒
461.
The present investigation attempts to quantify the temporal variation of Solar Flare Index(SFI)with other activity indices during solar cycles 21-24 by using different techniques such as linear regression,correlation,cross-correlation with phase lag-lead,etc.Different Solar Activity Indices(SAI)considered in this present study are Sunspot Number(SSN),10.7 cm Solar Radio Flux(F10.7),Coronal Index(CI)and MgⅡCore-to-Wing Ratio(MgⅡ).The maximum cycle amplitude of SFI and considered SAI has a decreasing trend from solar cycle 22,and cycle 24 is the weakest solar cycle among all other cycles.The SFI with SSN,F10.7,CI and MgⅡshows hysteresis during all cycles except for solar cycle 22 where both paths for ascending and descending phases are intercepting each other,thereby representing a phase reversal.A positive hysteresis circulation exists between SFI and considered SAI during solar cycles 22 and 23,whereas a negative circulation exists in cycles 21 and 24.SFI has a high positive correlation with coefficient values of 0.92,0.94,0.84 and 0.81 for SSN,F10.7,CI and MgⅡrespectively.According to crosscorrelation analysis,SFI has a phase lag with considered SAI during an odd-number solar cycle(solar cycles21 and 23)but no phase lag/lead during an even-numbered solar cycle(solar cycles 22 and 24).However,the entire smoothed monthly average SFI data indicate an in-phase relationship with SSN,F10.7 and MgⅡ,and a one-month phase lag with CI.The presence of those above characteristics strongly confirms the outcomes of different research work with various solar indices and the highest correlation exists between SFI and SSN as well as F10.7 which establishes that SFI may be considered as one of the prime activity indices to interpret the characteristics of the Sun’s active region as well as for more accurate short-range or long-range forecasting of solar events. 相似文献