全文获取类型
收费全文 | 2439篇 |
免费 | 42篇 |
国内免费 | 5篇 |
专业分类
化学 | 1600篇 |
晶体学 | 5篇 |
力学 | 28篇 |
数学 | 506篇 |
物理学 | 347篇 |
出版年
2021年 | 15篇 |
2019年 | 17篇 |
2018年 | 19篇 |
2016年 | 36篇 |
2015年 | 33篇 |
2014年 | 36篇 |
2013年 | 65篇 |
2012年 | 65篇 |
2011年 | 85篇 |
2010年 | 52篇 |
2009年 | 49篇 |
2008年 | 68篇 |
2007年 | 73篇 |
2006年 | 68篇 |
2005年 | 54篇 |
2004年 | 70篇 |
2003年 | 33篇 |
2002年 | 46篇 |
2001年 | 49篇 |
2000年 | 33篇 |
1999年 | 25篇 |
1998年 | 26篇 |
1997年 | 31篇 |
1996年 | 44篇 |
1995年 | 39篇 |
1994年 | 41篇 |
1993年 | 29篇 |
1992年 | 29篇 |
1991年 | 21篇 |
1990年 | 35篇 |
1989年 | 23篇 |
1988年 | 27篇 |
1987年 | 31篇 |
1986年 | 17篇 |
1985年 | 53篇 |
1984年 | 43篇 |
1983年 | 40篇 |
1982年 | 19篇 |
1981年 | 43篇 |
1980年 | 39篇 |
1979年 | 26篇 |
1978年 | 39篇 |
1977年 | 36篇 |
1976年 | 26篇 |
1975年 | 35篇 |
1974年 | 32篇 |
1973年 | 22篇 |
1972年 | 17篇 |
1960年 | 19篇 |
1885年 | 15篇 |
排序方式: 共有2486条查询结果,搜索用时 15 毫秒
111.
We used CR39 plastic nuclear track detectors (C12H18O7) in combination with automatic track measurement techniques to determine total charge changing and partial cross sections for the production of fragments of chargeZ F =6 toZ F =15 in collisions of32S beam nuclei at energies of 0.7, 1.2 and 200 GeV/nucleon in targets H, C, CR39, CH2, Al, Cu, Ag and Pb. By application of factorization rules measured partial cross sections are separated into pure nuclear and electromagnetic components. Total and partial cross sections for electromagnetic dissociation are compared with theoretical models. The energy dependence of pure nuclear cross sections is investigated. 相似文献
112.
The three sheet-shaped palladium organyls 1a-c exhibit lyotropic nematic properties in apolar organic solvents. The occurrence of two nematic lyomesophases was verified by the investigation of the orientational properties of these liquid crystalline systems. In cells with obliquely deposited SiOx layers, the director of the high temperature phase N2 is aligned in a homogeneous, planar manner. In the low temperature phase N1, a different orientational pattern is observed. The specific pattern type depends on the deposition conditions of the SiOx layers. In samples homeotropically aligned in the N2 phase, the director is tilted away from the cell normal after the transition into the N1 phase. These changes of orientation are reversible. The experimental observations presented here support our proposed model for the structural change at the nematic-nematic phase transition. 相似文献
113.
114.
115.
Possible spin arrangements of the ferromagnetoelectric Ni-I boracite are discussed from a microphysical point of view. Rotation of the spontaneous magnetization by 90° with reversal of the spontaneous polarization is explained. 相似文献
116.
117.
Heinrich Hermelink 《Historia Mathematica》1975,2(3):299-303
Two reckoning books edited recently in Teheran help to form an image of the hitherto almost unknown astronomer and mathematician Ab Ja'far Muh. b. Ayyb abar who lived in mul near the Caspian during the Saljuq period and observed from 1068 to 1092 A.D. The first of the said books is a textbook of Hindi reckoning similar to al-Nasaw's reckoning book (1029); the second one teaches mental calculation and application of both methods to everyday problems, much in the line of Ab al-Waf's reckoning book (c. 980 A.D.). Both texts are on a rather elementary level and include some errors, but they reveal their author as a skilled teacher and expound some interesting problems not found elsewhere. Moreover, they deserve our attention as the most ancient existing arithmetic treatises in the Persian language known so far. 相似文献
118.
Dr. Heinrich Begehr 《Mathematische Zeitschrift》1970,116(4):349-354
Ohne Zusammenfassung 相似文献
119.
120.