全文获取类型
收费全文 | 246篇 |
免费 | 4篇 |
专业分类
化学 | 167篇 |
晶体学 | 1篇 |
力学 | 4篇 |
数学 | 31篇 |
物理学 | 47篇 |
出版年
2022年 | 5篇 |
2021年 | 6篇 |
2020年 | 2篇 |
2019年 | 1篇 |
2017年 | 2篇 |
2016年 | 4篇 |
2015年 | 10篇 |
2014年 | 6篇 |
2013年 | 8篇 |
2012年 | 14篇 |
2011年 | 11篇 |
2010年 | 6篇 |
2009年 | 10篇 |
2008年 | 22篇 |
2007年 | 13篇 |
2006年 | 11篇 |
2005年 | 13篇 |
2004年 | 11篇 |
2003年 | 12篇 |
2002年 | 15篇 |
2001年 | 3篇 |
2000年 | 7篇 |
1999年 | 4篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 8篇 |
1992年 | 4篇 |
1990年 | 4篇 |
1989年 | 1篇 |
1986年 | 4篇 |
1985年 | 4篇 |
1984年 | 4篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有250条查询结果,搜索用时 15 毫秒
21.
Giampaolo?Liuzzi Stefano?LucidiEmail author Veronica?Piccialli Antonello?Sotgiu 《Mathematical Programming》2004,101(2):339-364
In this paper we are concerned with the design of a small low-cost, low-field multipolar magnet for Magnetic Resonance Imaging with a high field uniformity. By introducing appropriate variables, the considered design problem is converted into a global optimization one. This latter problem is solved by means of a new derivative free global optimization method which is a distributed multi-start type algorithm controlled by means of a simulated annealing criterion. In particular, the proposed method employs, as local search engine, a derivative free procedure. Under reasonable assumptions, we prove that this local algorithm is attracted by global minimum points. Additionally, we show that the simulated annealing strategy is able to produce a suitable starting point in a finite number of steps with probability one.This work was supported by CNR/MIUR Research Program Metodi e sistemi di supporto alle decisioni, Rome, Italy.Mathematics Subject Classification (1991):65K05, 62K05, 90C56 相似文献
22.
We introduce a cycle-expansion (fully deterministic) technique to compute the asymptotic behavior of arbitrary order transport moments. The theory is applied to different kinds of one-dimensional intermittent maps and Lorentz gas with an infinite horizon, confirming the typical appearance of phase transitions in the transport spectrum. 相似文献
23.
24.
25.
Pier Luigi Barili Giancarlo Berti Giorgio Catelani Felicia D'Andrea Francesco De Rensis Giampaolo Goracci 《Journal of carbohydrate chemistry》2013,32(8):1167-1180
Abstract The unreported title compound and its 2,6-di-O-benzyl derivative have been prepared from methyl β-D-galactopyranoside through a sequence involving the bisglycoside methyl 2,6-di-O-benzyl-5-O-methoxv-β-D-galactopyranoside 8, the precursor of L-orabino-hexos-5-ulose, that was converted to the L-lyxo series by inversion at C-3. The inversion was achieved in acceptable yields by selective triflation, followed by displacement with benzoate, and by an oxidation/reduction sequence. Whereas 2,5-di-O-benzyl-L-lyxo-hexos-5-ulose exists entirely as a mixture of the two anomeric 1,4-furanosic forms, the unprotected hexos-5-ulose involves at equilibrium in CD3CN/D2O at least eight tautomers, one of which is predominant. 相似文献
26.
Roberto Franzosi Salvatore M. Giampaolo Fabrizio Illuminati Roberto Livi Gian-Luca Oppo Antonio Politi 《Central European Journal of Physics》2011,9(5):1248-1254
The dynamics of repulsive bosons condensed in an optical lattice is effectively described by the Bose-Hubbard model. The classical limit of this model, reproduces the dynamics of Bose-Einstein condensates, in a periodic potential, and in the superfluid regime. Such dynamics is governed by a discrete nonlinear Schrödinger equation. Several papers, addressing the study of the discrete nonlinear Schrödinger dynamics, have predicted the spontaneous generation of (classical) breathers in coupled condensates. In the present contribute, we shall focus on localized solutions (quantum breathers) of the full Bose-Hubbard model. We will show that solutions exponentially localized in space and periodic in time exist also in absence of randomness. Thus, this kind of states, reproduce a novel quantum localization phenomenon due to the interplay between bounded energy spectrum and non-linearity. 相似文献
27.
Roberto Artuso Giampaolo Cristadoro 《Communications in Nonlinear Science & Numerical Simulation》2003,8(3-4):137
We review how transport properties for chaotic dynamical systems may be studied through cycle expansions, and show how anomalies can be quantitatively described by hierarchical sequences of periodic orbits. 相似文献
28.
We investigate the transfer of w-stability and Clifford w-regularity from a domain D to the polynomial ring D[X]. We show that these two properties pass from D to D[X] when D is either integrally closed or it is Mori and w-divisorial. 相似文献
29.
Antonino Lauria Ilenia Abbate Noemi Gambino Giampaolo Barone 《Tetrahedron letters》2008,49(35):5125-5128
Derivatives of the new ring system pyrazolo[3,4-d][1,2,3]triazolo[1,5-a]pyrimidine were synthesized from the corresponding angular isomers, through a Dimroth rearrangement, in quantitative yields. Preliminary computational studies demonstrated that this class of compounds could be a good candidate as DNA intercalating agents. 相似文献
30.
Passive mode-locking of a rhodamine 6G dye laser has been achieved, using a pulsed xenon ion laser as a pumping source. A pulse width of 5 ps and a peak power of 4 kW have been obtained. Thermal problems were encountered, which adversely affected the operation of the dye laser. Work is in progress to improve these results. 相似文献