全文获取类型
收费全文 | 327篇 |
免费 | 4篇 |
国内免费 | 1篇 |
专业分类
化学 | 205篇 |
力学 | 7篇 |
数学 | 41篇 |
物理学 | 79篇 |
出版年
2022年 | 4篇 |
2021年 | 2篇 |
2018年 | 2篇 |
2017年 | 2篇 |
2015年 | 3篇 |
2014年 | 10篇 |
2013年 | 13篇 |
2012年 | 12篇 |
2011年 | 23篇 |
2010年 | 18篇 |
2009年 | 14篇 |
2008年 | 12篇 |
2007年 | 16篇 |
2006年 | 16篇 |
2005年 | 12篇 |
2004年 | 15篇 |
2003年 | 8篇 |
2002年 | 13篇 |
2001年 | 6篇 |
2000年 | 2篇 |
1999年 | 6篇 |
1996年 | 5篇 |
1995年 | 3篇 |
1994年 | 5篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 9篇 |
1984年 | 6篇 |
1983年 | 4篇 |
1982年 | 8篇 |
1981年 | 12篇 |
1980年 | 3篇 |
1979年 | 7篇 |
1978年 | 3篇 |
1977年 | 5篇 |
1976年 | 7篇 |
1974年 | 4篇 |
1973年 | 5篇 |
1972年 | 1篇 |
1971年 | 2篇 |
1970年 | 1篇 |
1965年 | 1篇 |
1912年 | 4篇 |
1911年 | 1篇 |
排序方式: 共有332条查询结果,搜索用时 31 毫秒
1.
Well-Posedness by Perturbations of Variational Problems 总被引:3,自引:0,他引:3
Lemaire B. Ould Ahmed Salem C. Revalski J. P. 《Journal of Optimization Theory and Applications》2002,115(2):345-368
In this paper, we consider the extension of the notion of well-posedness by perturbations, introduced by Zolezzi for optimization problems, to other related variational problems like inclusion problems and fixed-point problems. Then, we study the conditions under which there is equivalence of the well-posedness in the above sense between different problems. Relations with the so-called diagonal well-posedness are also given. Finally, an application to staircase iteration methods is presented. 相似文献
2.
Sébastien Lemaire Giuliano Giambastiani Barbara Pacini Giovanni Poli 《Journal of organometallic chemistry》2003,687(2):291-300
A new type I palladium-catalyzed pseudo-domino process is developed, in which a single Pd-based catalytic system promotes two mechanistically unrelated, sequential catalytic cycles in chronologically distinct order. Suitable precursors undergo an allylic alkylation and a Heck coupling in sequence, affording polycondensed pyrrolidone derivatives. Depending on the starting precursors, intra/inter or doubly intramolecular processes can be obtained. The allylic alkylation process takes place always very smoothly. On the other hand, the Heck coupling turns out to be rather difficult either when the process is intermolecular, or when an intramolecular process generates polycondensed structures featuring three fused bonds connected to a common carbon atom. In such difficult cases, use of the Herrmann-Beller phosphapalladacycle allowed to catalyze the coupling. This study demonstrates also that allylic alkylations can be catalyzed by the Herrmann-Beller phosphapalladacycle. 相似文献
3.
We propose a new scheme for the long time approximation of a diffusion when the drift vector field is not globally Lipschitz. Under this assumption, a regular explicit Euler scheme–with constant or decreasing step–may explode and implicit Euler schemes are CPU-time expensive. The algorithm we introduce is explicit and we prove that any weak limit of the weighted empirical measures of this scheme is a stationary distribution of the stochastic differential equation. Several examples are presented including gradient dissipative systems and Hamiltonian dissipative systems. 相似文献
4.
5.
Dupieux P Alard JP Augerat J Babinet R Bastid N Brochard F Charmensat P De Marco N Fanet H Fodor Z Fraysse L Girard J Gorodetzky P Gosset J Laspalles C Lemaire MC L'Hôte D Lucas B Marroncle J Montarou G Parizet MJ Poitou J Qassoud D Racca C Schimmerling W 《Physics letters. [Part B]》1988,200(1-2):17-21
Proton-proton small angle correlations have been measured in neon-nucleus collisions, using the 4 pi detector Diogene, at 400 and 800 MeV per nucleon incident energies. Values of the size of the emitting region are obtained by comparison with the Koonin formula, taking into account the biases of the apparatus. The dependence of the density on target mass and incident energy is also analysed. 相似文献
6.
A sensitive method for the detection, quantitation and purification of peptides is described. The method is based on pre-column derivatization of peptides with phenyl isothiocyanate to form phenylthiocarbamoyl derivatives (PTC peptides). The derivatized peptides are analysed by reversed-phase high-performance liquid chromatography on a Zorbax ODS column (5 micron) and detected at 269 nm with a sensitivity limit of 1-5 pmol. The technique was utilized for the separation of a mixture of closely related synthetic peptides. The eluted PTC peptides were collected with an average recovery yield of 75% as determined by amino acid analysis. This method of separation of PTC peptides was also combined with the determination of the complete structure of recovered PTC-dynorphin A-(1-13) using the solid-phase sequenator (Sequemat). The advantages of the derivatization method are the rapidity and completeness of the reaction, the stability of the product, the sensitivity and specificity of the detection of derivatized peptides and the compatibility of the technique with subsequent analytical procedures. A particular application of this method was exemplified by the dosage of enkephalins secreted from perfused bovine adrenal glands. 相似文献
7.
LetX be a real normed linear space,f, f
n, n , be extended real-valued proper closed convex functions onX. A sequence {x
n} inX is called diagonally stationary for {f
n} if for alln there existsx*
n f
n (x
n) such that x*
n * 0. Such sequences arise in approximation methods for the problem of minimizingf. Some general convergence results based upon variational convergence theory and appropriate equi-well-posedness are presented. 相似文献
8.
9.
[reaction: see text] We report here the first heterogenization of a bis(oxazoline) ligand on an inorganic (silica) surface. The activity and enantioselectivity of this new material as a catalyst for the Diels-Alder reaction were checked, and it was shown that under certain conditions enantioselectivities similar to those of the homogeneous catalyst are reached. It was also shown that under these conditions the catalyst can be recycled without loss of activity or selectivity. 相似文献
10.
Jérémie Fournier Dit Chabert Stéphane Pellet-Rostaing Marc Lemaire 《Tetrahedron letters》2006,47(6):1015-1018
An original methodology starting from 3-aroyl-2-(2′-nitro-4′-methoxyphenyl)-benzo[b]thiophene allows the synthesis of unusual fused heterocycles. Direct hydrogenation with nickel catalysts followed by desulfurisation led to 2,3-diarylquinolines or 2,3-diaryltetrahydroquinolines. 相似文献