全文获取类型
收费全文 | 6021篇 |
免费 | 211篇 |
国内免费 | 22篇 |
专业分类
化学 | 4104篇 |
晶体学 | 37篇 |
力学 | 91篇 |
数学 | 731篇 |
物理学 | 1291篇 |
出版年
2022年 | 54篇 |
2021年 | 60篇 |
2020年 | 101篇 |
2019年 | 65篇 |
2018年 | 47篇 |
2017年 | 57篇 |
2016年 | 160篇 |
2015年 | 149篇 |
2014年 | 152篇 |
2013年 | 257篇 |
2012年 | 324篇 |
2011年 | 370篇 |
2010年 | 211篇 |
2009年 | 165篇 |
2008年 | 277篇 |
2007年 | 284篇 |
2006年 | 252篇 |
2005年 | 267篇 |
2004年 | 247篇 |
2003年 | 202篇 |
2002年 | 187篇 |
2001年 | 124篇 |
2000年 | 104篇 |
1999年 | 97篇 |
1998年 | 65篇 |
1997年 | 65篇 |
1996年 | 77篇 |
1995年 | 82篇 |
1994年 | 76篇 |
1993年 | 83篇 |
1992年 | 98篇 |
1991年 | 73篇 |
1990年 | 62篇 |
1989年 | 53篇 |
1988年 | 60篇 |
1987年 | 61篇 |
1986年 | 47篇 |
1985年 | 77篇 |
1984年 | 69篇 |
1983年 | 63篇 |
1982年 | 61篇 |
1981年 | 61篇 |
1980年 | 56篇 |
1979年 | 57篇 |
1978年 | 57篇 |
1977年 | 53篇 |
1976年 | 44篇 |
1975年 | 35篇 |
1974年 | 48篇 |
1973年 | 53篇 |
排序方式: 共有6254条查询结果,搜索用时 31 毫秒
11.
Alvaro P. Raposo Hans J. Weber David E. Alvarez-Castillo Mariana Kirchbach 《Central European Journal of Physics》2007,5(3):253-284
We briefly review the five possible real polynomial solutions of hypergeometric differential equations. Three of them are
the well known classical orthogonal polynomials, but the other two are different with respect to their orthogonality properties.
We then focus on the family of polynomials which exhibits a finite orthogonality. This family, to be referred to as the Romanovski
polynomials, is required in exact solutions of several physics problems ranging from quantum mechanics and quark physics to
random matrix theory. It appears timely to draw attention to it by the present study. Our survey also includes several new
observations on the orthogonality properties of the Romanovski polynomials and new developments from their Rodrigues formula. 相似文献
12.
Mihel Weber 《Acta Mathematica Hungarica》2004,105(1-2):39-83
We show how the metric entropy method can be substituted for the dyadic chaining, to prove in a unified setting several classical results. Among them are Stechkin's theorem, Gál--Koksma theorems and quantitative Borel--Cantelli lemmas. We give simpler proofs and improve some of these results. Two classes of examples are given: firstly stationary Gaussian sequences with applications to upper and lower classes and the law of the iterated logarithm for subsequences, and secondly in Diophantine approximation relatively to Gál and Schmidt's theorems. 相似文献
13.
G. Weber 《Fresenius' Journal of Analytical Chemistry》1993,346(6-9):639-642
Summary For accurate speciation analyses it is important to know the stability of the respective species, especially in the case of metal complexes. Factors affecting the chromatographic stability of such metal species are investigated. By using thermodynamic models for complex formation and chromatographic retention equilibria the influence of species concentration, stoichiometry and excess of ligand is calculated and compared with experimental results for iron complexes (lactate, gluconate and citrate species). Iron citrate is the only species, that is chromatographed as 1:2 complex (metal: ligand), while iron lactate and gluconate are transformed to 1:1 species. Problems resulting from the coelution of different species are discussed.Dedicated to Professor Dr. Wilhelm Fresenius on the occasion of his 80th birthday 相似文献
14.
G.Biju Kumar Hetal.V Patel Amrish C Shah Markus Trenkle Christine J Cardin 《Tetrahedron: Asymmetry》1996,7(12):3391-3396
N-Arylsulfonamides of (R)- and (S)-2-amino-1-butanol, on condensation with aromatic aldehydes produced diastereomerically pure 2-aryl-3-arenesulfonyl 4-ethyl-1,3-oxazolidines. The absolute configurations of one enantiomeric pair have been determined from two fully refined X-ray structures, supplemented by nmr data. 相似文献
15.
16.
Christine Bessenrodt 《Annals of Combinatorics》1998,2(2):103-110
The well-known fact that there is always one more addable than removable box for a Young diagram is generalized to arbitrary hooks. As an application, this immediately implies a simple proof of a conjecture of Regev and Vershik [3] for which inductive proofs have recently been given by Regev and Zeilberger [4] and Janson [1]. 相似文献
17.
E. Lippelt P. Birrer F. N. Gygax B. Hitti A. Schenck M. Weber 《Hyperfine Interactions》1991,64(1-4):477-487
The angular dependence of the muon Knight shift,K
μ, and the muon relaxation rate in Bi at 11 K were measured in external magnetic fields up to 1 T. BothK
μ and the second moment,M
2, are field dependent and involveP
4
0(cos θ) andP
4
3(cos θ) terms in the angular dependence. The Knight shift behaviour is discussed in terms of the dipole-dipole interaction
and the de Haas-van Alphen effect, a consistent interpretation was not achieved in either case. The field dependence ofM
2 is in complete contrast to the second moment calculations and points to a field dependent redistribution of the charge distribution
around the interstitial site. 相似文献
18.
A model for the interaction of near-infrared laser pulses with metal powders in selective laser sintering 总被引:4,自引:0,他引:4
P. Fischer N. Karapatis V. Romano R. Glardon H.P. Weber 《Applied Physics A: Materials Science & Processing》2002,74(4):467-474
A thermal model of the interaction of pulsed near-infrared laser radiation from a Nd:YAG laser was made, taking the measured
powder properties such as reflectance, optical penetration depth and thermal conductivity into account. It allows an estimation
of the evolution of two different temperatures: the average temperature of the powder (taken over the grains in a volume given
by the laser beam diameter and the optical penetration depth) and the temperature distinction within a single grain. It showed
that in pulsed mode consolidation can be achieved at much lower average power as the surface of the powder particles are molten
but their cores remain at nearly room temperature. This leads to a much lower average temperature and therefore a dramatic
decrease in residual thermal stresses in the finished piece. The results of the model were experimentally tested and confirmed.
Received: 26 July 2001 / Accepted: 23 November 2001 / Published online: 23 January 2002 相似文献
19.
20.