全文获取类型
收费全文 | 3221篇 |
免费 | 67篇 |
国内免费 | 12篇 |
专业分类
化学 | 1824篇 |
晶体学 | 15篇 |
力学 | 25篇 |
数学 | 570篇 |
物理学 | 866篇 |
出版年
2020年 | 38篇 |
2019年 | 31篇 |
2016年 | 48篇 |
2015年 | 41篇 |
2014年 | 60篇 |
2013年 | 104篇 |
2012年 | 72篇 |
2011年 | 117篇 |
2010年 | 84篇 |
2009年 | 62篇 |
2008年 | 89篇 |
2007年 | 114篇 |
2006年 | 101篇 |
2005年 | 80篇 |
2004年 | 71篇 |
2003年 | 72篇 |
2002年 | 68篇 |
2001年 | 57篇 |
2000年 | 49篇 |
1999年 | 23篇 |
1998年 | 34篇 |
1997年 | 39篇 |
1996年 | 52篇 |
1995年 | 65篇 |
1994年 | 64篇 |
1993年 | 51篇 |
1992年 | 51篇 |
1991年 | 37篇 |
1990年 | 41篇 |
1989年 | 44篇 |
1988年 | 45篇 |
1987年 | 34篇 |
1986年 | 36篇 |
1985年 | 56篇 |
1984年 | 36篇 |
1983年 | 25篇 |
1982年 | 35篇 |
1981年 | 40篇 |
1980年 | 33篇 |
1979年 | 40篇 |
1978年 | 44篇 |
1977年 | 44篇 |
1976年 | 24篇 |
1975年 | 29篇 |
1974年 | 37篇 |
1973年 | 31篇 |
1970年 | 28篇 |
1969年 | 31篇 |
1968年 | 25篇 |
1966年 | 31篇 |
排序方式: 共有3300条查询结果,搜索用时 15 毫秒
1.
2.
Ludwig Erkmann 《Fresenius' Journal of Analytical Chemistry》1872,11(1):37-38
Ohne Zusammenfassung 相似文献
3.
4.
5.
W. Kockelmann M. Hofmann O. Moze S.J. Kennedy K.H.J. Buschow 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,30(1):25-32
The element distributions and the magnetic ordering behaviour of compounds RNi10Si2 (R
=
Tb, Dy, Ho, Er, Tm) have been studied by neutron powder diffraction down to temperatures of 1.6 K. The compounds crystallize
in an ordered variant of the ThMn12 structure type in the tetragonal space group P4/nmm. An ordered 1:1 distribution of Ni and Si on sites 4d and 4e, respectively,
corresponds to a modulation vector [0, 0, 1] with respect to the space group I4/mmm of the ThMn12 structure. TbNi10Si2 orders antiferromagnetically below T
N
= 4.5 K with a magnetic propagation vector of [0, 0, 1/2]. The magnetic Tb moments, 8.97(2) /Tb atom at 1.6 K, are aligned along the c-axis. The Ni sites in TbNi10Si2 do not carry any ordered magnetic moments. The compounds with R
=
Dy, Ho, Er, and Tm are paramagnetic down to 1.6 K and 3.0 K, respectively.
Received 10 July 2002 / Received in final form 12 September 2002 Published online 29 October 2002 相似文献
6.
The magnetic properties of annealed Fe-Pt multilayer thin films with a broad composition range were investigated in order to identify the effects of composition and annealing temperature on the achievable coercive field, and to identify its maximum at low processing temperatures. Two types of multilayer systems were deposited as materials libraries to vary the composition from Fe20Pt80 to Fe75Pt25. The first type of multilayer was comprised of alternating opposing wedges, whereas the second type consisted of repeated uniform Fe and Pt layers interspersed periodically with Fe wedge layers. It was found that coercive fields μ0HC > 0.7 T can be achieved at an annealing temperature of about 300 °C (60 min) for both types of multilayers as long as the composition is close to 50:50. Higher annealing temperatures are needed for films, which deviate from this composition. Increasing the annealing temperature up to 700 °C leads to increased coercivity values. Multilayers with additional Fe layers showed increased remanence but reduced coercive fields. 相似文献
7.
Ludwig Scheeffer 《Acta Mathematica》1884,5(1):49-82
Ohne Zusammenfassung 相似文献
8.
E. García-Matres N. Stüßer M. Hofmann M. Reehuis 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,32(1):35-42
The magnetic structures of Mn1-xFexWO4 with x
= 0.0, 0.16, 0.21, 0.225, 0.232, 0.24, 0.27, 0.29, and 1.0 were refined from neutron powder diffraction data. The magnetic phase
diagram could be completed in the coexistence range of different magnetic structures up to x
= 0.29. For the magnetic state at 1.5 K a commensurate antiferromagnetic structure with a propagation vector
= (±1/4, 1/2, 1/2) was found for x
⩽ 0.22 while the magnetic spins order with
= (1/2, 0, 0) for x
≥ 0.22. In the latter phase, additionally, weak magnetic reflections indexed to an incommensurate ordering with
= (- 0.214, 1/2, 0.457) occur in the diffraction pattern up to x
= 0.29 indicating the occurence of a reentrant phase. For 0.12 ⩽
x
⩽ 0.29 the low temperature phases are separated from a magnetic high temperature phase showing only magnetic reflections indexed
to a spin arrangement with
= (1/2, 0, 0). The magnetic phase diagram is discussed qualitatively considering random superexchange between the statistically distributed
Mn2+- and Fe2+-ions in the coexistence range 0.12 ⩽
x
⩽ 0.29 of different magnetic structures related to those of pure MnWO4 and FeWO4.
Received 9 October 2002 Published online 14 March 2003 相似文献
9.
Ulf Pindur Ludwig Pfeuffer Manfred Eitel Martina Rogge Manfred Haber 《Monatshefte für Chemie / Chemical Monthly》1991,122(4):291-298
Summary Diels-Alder reactions of 2- and 3-vinylindoles with aryne, 1,4-benzo- and 1,4-naphtho-quinone lead to new six-ring annellated carbazoles. Molecular modeling studies predict that the compounds with coplanar framework are able to intercalate with the B-DNA. 相似文献
10.