全文获取类型
收费全文 | 108篇 |
免费 | 5篇 |
国内免费 | 2篇 |
专业分类
化学 | 47篇 |
晶体学 | 1篇 |
力学 | 1篇 |
数学 | 41篇 |
物理学 | 25篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 2篇 |
2019年 | 6篇 |
2018年 | 1篇 |
2016年 | 3篇 |
2015年 | 8篇 |
2014年 | 5篇 |
2013年 | 3篇 |
2012年 | 3篇 |
2011年 | 8篇 |
2010年 | 2篇 |
2009年 | 2篇 |
2008年 | 8篇 |
2007年 | 6篇 |
2006年 | 1篇 |
2005年 | 2篇 |
2004年 | 2篇 |
2003年 | 2篇 |
2002年 | 2篇 |
2001年 | 3篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 5篇 |
1995年 | 2篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1983年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1972年 | 2篇 |
1968年 | 1篇 |
1962年 | 1篇 |
1919年 | 1篇 |
排序方式: 共有115条查询结果,搜索用时 31 毫秒
1.
Ledzewicz U. Nowakowski A. Schättler H. 《Journal of Optimization Theory and Applications》2004,122(2):345-370
It is shown that, if a parametrized fämily of extremals F can be stratified in a way compatible with the flow map generated by F, then those trajectories of the family which realize the minimal values of the cost in F are indeed optimal in comparison with all trajectories which lie in the region R covered by the trajectories of F. It is not assumed that F is a field covering the state space injectively. As illustration, an optimal synthesis is constructed for a system where the flow of extremals exhibits a simple cusp singularity. 相似文献
2.
Least-Squares Fitting of Algebraic Spline Surfaces 总被引:11,自引:0,他引:11
We present an algorithm for fitting implicitly defined algebraic spline surfaces to given scattered data. By simultaneously approximating points and associated normal vectors, we obtain a method which is computationally simple, as the result is obtained by solving a system of linear equations. In addition, the result is geometrically invariant, as no artificial normalization is introduced. The potential applications of the algorithm include the reconstruction of free-form surfaces in reverse engineering. The paper also addresses the generation of exact error bounds, directly from the coefficients of the implicit representation. 相似文献
3.
A. Bachem W. Hochstättler B. Steckemetz A. Volmer 《Computational Optimization and Applications》1996,6(3):213-225
We report on computational experience with an implementation of three algorithms for the general economic equilibrium problem. As a result we get that the projection algorithm for variational inequalities increases the size of solvable models by a factor of 5–10 in comparison with the classical homotopy method. As a third approach we implemented a simulated annealing heuristic which might be suitable to estimate equilibria for very large models.Supported by the German Research Association (Deutsche Forschungsgemeinschaft, SFB 303). 相似文献
4.
5.
6.
K. H. Richter W. Güttler M. Schwoerer 《Applied Physics A: Materials Science & Processing》1983,32(1):1-11
Holographic gratings with grating periods between 0.37 m and 4.4 m, respectively, were recorded on the surface of TS-diacetylene single crystals by two interfering 257 nm laser beams. Diffraction efficiencies of up to 35 % were obtained for readout with red light of = 633 nm. The main modulation mechanism was phase modulation. The spatial resolution was better than 1600 lines/mm. The upper limit of the polymer chain length was 0.6 m. The holographic sensitivity was 4.5 cm2/J for immediate read-out at 633 nm without processing after exposure. — A weakly exposed latent hologram may be developed simply by gentle annealing the crystal which increases the sensitivity by one order of magnitude. 相似文献
7.
8.
Zusammenfassung Das Iterationsverfahren der Simplexmethode besteht bekanntlich darin, von einer (gegebenen, aber noch nicht optimalen) Basislösung eine Variable auszuwählen und diese gegen eine Nichtbasisvariable auszutauschen, so daß hierbei eine im Sinne des Extremalwertes der Zielfunktion günstigere Basislösung entsteht. Die hier dargestellte Variante gestattet es, gegebenenfalls mehrere Basisvariable gegen eine gleiche Anzahl von Nichtbasisvariablen bei einem Iterationsschritt auszutauschen. Dieses Verfahren kürzt beispielsweise den Lösungsprozeß des Transportproblems im allgemeinen beträchtlich ab.
Vorgel. v.:H. P. Künzi 相似文献
Summary Solving a linear programming problem by the Simplexmethod the usual procedure is as follows: from a (given not yet optimal) basic solution one basic variable is chosen for being changed with a non-basic variable to get a better approximation to the extremum of the given linear equation. The described method sometimes allows exchanging several basic variables in each Simplex-step. Using this method usually the solution process of the transportation problem for example may be abbreviated efficiently.
Vorgel. v.:H. P. Künzi 相似文献
9.
N.A. Babushkina L.M. Belova E.A. Chistotina O.Yu. Gorbenko A.R. Kaul B. Güttler K.I. Kugel 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,19(3):409-415
The effect of
16
O
→
18
O isotope substitution on electrical resistivity, magnetoresistance, and ac magnetic susceptibility was studied for La0.35Pr0.35Ca0.3MnO3 epitaxial thin films deposited onto LaAlO3 and SrTiO3 substrates. For the films on LaAlO3, the isotope substitution resulted in the reversible transition from a metal-like to insulating state. The applied magnetic
field ( H
≥ 2
T) transformed the sample with 18O back to the metallic state. The films on SrTiO3 remained metallic at low temperatures for both 16O and 18O, but the shift of the resistivity peak corresponding to onset of metallic state exceeded 63 K after
16
O
→
18
O substitution. The temperature dependence of both resistivity and magnetic susceptibility was characterized by hysteresis,
especially pronounced in the case of the films on LaAlO3. Such a behavior gives certain indications of the phase separation characteristic of interplay between ferromagnetism and
charge ordering.
Received 11 February 2000 and Received in final form 13 September 2000 相似文献
10.