全文获取类型
收费全文 | 110篇 |
免费 | 3篇 |
国内免费 | 2篇 |
专业分类
化学 | 51篇 |
力学 | 5篇 |
数学 | 28篇 |
物理学 | 31篇 |
出版年
2023年 | 1篇 |
2021年 | 2篇 |
2019年 | 1篇 |
2017年 | 1篇 |
2016年 | 7篇 |
2015年 | 1篇 |
2014年 | 9篇 |
2013年 | 7篇 |
2012年 | 7篇 |
2011年 | 8篇 |
2010年 | 3篇 |
2009年 | 10篇 |
2008年 | 5篇 |
2007年 | 2篇 |
2006年 | 1篇 |
2005年 | 5篇 |
2004年 | 5篇 |
2003年 | 2篇 |
2002年 | 4篇 |
2001年 | 1篇 |
2000年 | 4篇 |
1999年 | 3篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1995年 | 3篇 |
1994年 | 4篇 |
1993年 | 1篇 |
1992年 | 3篇 |
1990年 | 3篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1981年 | 1篇 |
1976年 | 2篇 |
1970年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有115条查询结果,搜索用时 15 毫秒
1.
Abdel Raouf F. Elhefnawy Galal M. Moatimid Abd Elmonem Khalil Elcoot 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2004,86(2):63-91
The nonlinear electrohydrodynamic stability of
cylindrical interface, supporting surface charge, among two
conducting fluids is investigated. The two fluids are subjected to
a radial electric field. The analysis based on the multiple scale
technique. It is shown that the evolution of the amplitude is
governed by two partial differential equations. These equations
are combined to yield two alternate Schrödinger equations with
cubic nonlinearity. One of which calculates the nonlinear cutoff
electric field, separating stable and unstable disturbances, while
the other is used to analyze the stability of the system. The
stability criteria are analytically discussed and numerically
confirmed. Numerical calculations resulted in set of graphs to
indicate the stability picture of the considered system. 相似文献
2.
DEBACHE Abdelmadjid BOULCINA Raouf TAFER Radia BELFAITAH Ali RHOUATI Salah CARBONI Bertrand 《中国化学》2008,26(11):2112-2116
The synthesis of 1,2,3,4-dihydropyrimidinone/thione derivatives was achieved in good to excellent yields using calcium(II) nitrate as catalyst to promote the Biginelli three-component condensation reaction from a diversity of aromatic aldehydes, β-keto compounds and urea or thiourea. The reaction was carried out under solvent-free conditions. 相似文献
3.
Abdel Raouf F. Elhefnawy 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1993,44(3):495-509
A weakly nonlinear evolution of two dimensional wave packets on the surface of a magnetic fluid in the presence of an uniform magnetic field is presented, taking into account the surface tension. The method used is that of multiple scales to derive two partial differential equations. These differential equations can be combined to yield two alternate nonlinear Schrödinger equations. The first equation is valid near the cutoff wavenumber while the second equation is used to show that stability of uniform wave trains depends on the wavenumber, the density, the surface tension and the magnetic field. At the critical point, a generalized formulation of the evolution equation governing the amplitude is developed which leads to the nonlinear Klein-Gordon equation. From the latter equation, the various stability crteria are obtained. 相似文献
4.
Abdel Raouf F. Elhefnawy 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1995,46(2):239-254
The nonlinear evolution of interfacial waves separating two magnetic fluids subjected to an oblique magnetic field is studied in two dimensions, with the use of the method of multiple scales. It is shown that the evolution of the envelope is governed by two partial differential equations. These equations can be combined to yield two alternate Schrödinger equations with cubic nonlinearity; one of them leads to the determination of the cutoff wave number separating stable from unstable deformations while the other Schrödinger equation is used to analyze the stability of the system. The stability of the system is discussed both theoretically and computationally, and the stability diagrams are obtained. It is found in the linear theory that the oblique magnetic field has a stabilizing influence if 0 1 + 2 < /2, or 3/2 < 1 + 2 2 and a destabilizing influence if /2 < 1 + 2 < 3/2, where 0 j
, (j=1, 2) and , is the angle between the field and the horizontal axis.In the nonlinear theory, the stability analysis reveals that there exist different regions of stability and instability. It is reported that the oblique magnetic field plays a dual role in the stability criterion and the angles 1 and 2 play a distinctive role in this analysis besides the effect of the variation of the magnetic permeabilities. 相似文献
5.
Chafia Bennaceur Carlos Afonso Sandra Alves Anne Bossée Jean-Claude Tabet 《Journal of the American Society for Mass Spectrometry》2013,24(8):1260-1270
Structural elucidation and distinction of isomeric neurotoxic agents remain a challenge. Tandem mass spectrometry can be used for this purpose in particular if a “diagnostic” product ion is observed. Different vibrational activation methods were investigated to enhance formation of diagnostic ions through consecutive processes from O,O-dialkyl alkylphosphonates. Resonant and non-resonant collisional activation and infrared multiphoton dissociation (IRMPD) were used with different mass spectrometers: a hybrid quadrupole Fourier transform ion cyclotron resonance (Qh-FTICR) and a hybrid linear ion trap-Orbitrap (LTQ/Orbitrap). Double resonance (DR) experiments, in ion cyclotron resonance (ICR) cell, were used for unambiguous determination of direct intermediate yielding diagnostic ions. From protonated n-propyl and isopropyl O-O-dialkyl-phosphonates, a diagnostic m/z 83 ion characterizes the isopropyl isomer. This ion is produced through consecutive dissociation processes. Conditions to favor its formation and observation using different activation methods were investigated. It was shown that with the LTQ, consecutive experimental steps of isolation/activation with modified trapping conditions limiting the low mass cut off (LMCO) effect were required, whereas with FT-ICR by CID and IRMPD the diagnostic ion detection was provided only by one activation step. Among the different investigated activation methods it was shown that by using low-pressure conditions or using non-resonant methods, efficient and fast differentiation of isomeric neurotoxic agents was obtained. This work constitutes a unique comparison of different activation modes for distinction of isomers showing the instrumental dependence characteristic of the consecutive processes. New insights in the dissociation pathways were obtained based on double-resonance IRMPD experiments using a FT-ICR instrument with limitation at low mass values.
? 相似文献
6.
Haddad S Charfi-Kaddour S Nickel C Héritier M Bennaceur R 《Physical review letters》2002,89(8):087001
A model is presented for the high field phase diagram of (TMTSF)(2)ClO(4), taking into account the anion ordering, which splits the Fermi surface into two bands. For strong enough field, the largest metal spin density wave critical temperature corresponds to the N=0 phase, which originates from two intraband nesting processes. At lower temperature, the competition between these processes puts at disadvantage the N=0 phase vs the N=1 phase, which is due to interband nesting. A first order transition then takes place from the N=0 to N=1 phase. We ascribe to this effect the experimentally observed phase diagrams. 相似文献
7.
M. Triki D. Elmaghraoui S. Jaziri R. Bennaceur 《Solid State Communications》2010,150(43-44):2197-2200
Using a numerical method via the electron effective mass theory, a model of a quantum ring (QR) with a shape very close to the real one and taken from an experimental work, we investigate the electron states in a semi-conductor QR, studying the influence of the ring’s geometrical parameters on the electron spectrum and on the optical transitions. Our hetero structure evolves from a single quantum dot (QD) to a QR. We find that the one-electron ground state presents an absolute minimum when studied as a function of the ring radius. The reliability of the calculations is checked with experimental data. 相似文献
8.
Solvent-free and high yielding one-pot synthesis of 1,8-dioxodecahydroacridine and polyhydroquinoline derivatives have been described through Hantzsch condensation of various aldehydes, ammonium acetate with cyclic 1,3-dicarbonyl compounds and ethyl acetoacetate in a very simple, efficient, and environmentally benign method using ascorbic acid as a nontoxic organocatalyst. 相似文献
9.
A. Raouf Chouikha 《Indagationes Mathematicae》1999,10(4):495
In this paper we are interested in some Bonnesen-type isoperimetric inequalities for plane n-gons in relation with the two conjectures proposed by P. Levy and X.M. Zhang. 相似文献
10.
From a quantum collective approach, the momentum relaxation time, through both electron-electron and electron-ion interactions, is obtained based on electron wave functions interacting with the continuum oscillations (plasma waves). The theoretical model presented gives a consistent and complete set of transport coefficients for a dense magnetized plasma. This unified scheme of long- and short-range interactions gives conductivity formulas which are free from the usual Debye length, which loses its physical meaning as an upper impact parameter for relatively high-density, coupled plasma. 相似文献