全文获取类型
收费全文 | 99篇 |
免费 | 0篇 |
专业分类
化学 | 20篇 |
晶体学 | 1篇 |
力学 | 1篇 |
数学 | 23篇 |
物理学 | 54篇 |
出版年
2022年 | 2篇 |
2020年 | 2篇 |
2019年 | 1篇 |
2018年 | 2篇 |
2017年 | 1篇 |
2016年 | 1篇 |
2015年 | 1篇 |
2013年 | 7篇 |
2012年 | 5篇 |
2011年 | 5篇 |
2010年 | 3篇 |
2009年 | 3篇 |
2008年 | 6篇 |
2007年 | 3篇 |
2006年 | 3篇 |
2005年 | 6篇 |
2004年 | 3篇 |
2003年 | 1篇 |
2002年 | 3篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 3篇 |
1995年 | 9篇 |
1994年 | 2篇 |
1993年 | 4篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 4篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1979年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有99条查询结果,搜索用时 46 毫秒
1.
2.
Roberto Andreani Gabriel Haeser María Laura Schuverdt Paulo J. S. Silva 《Mathematical Programming》2012,135(1-2):255-273
In this work we introduce a relaxed version of the constant positive linear dependence constraint qualification (CPLD) that we call RCPLD. This development is inspired by a recent generalization of the constant rank constraint qualification by Minchenko and Stakhovski that was called RCRCQ. We show that RCPLD is enough to ensure the convergence of an augmented Lagrangian algorithm and that it asserts the validity of an error bound. We also provide proofs and counter-examples that show the relations of RCRCQ and RCPLD with other known constraint qualifications. In particular, RCPLD is strictly weaker than CPLD and RCRCQ, while still stronger than Abadie’s constraint qualification. We also verify that the second order necessary optimality condition holds under RCRCQ. 相似文献
3.
R. Andreani C. E. Echagüe M. L. Schuverdt 《Journal of Optimization Theory and Applications》2010,146(2):255-266
The constant-rank condition for feasible points of nonlinear programming problems was defined by Janin (Math. Program. Study
21:127–138, 1984). In that paper, the author proved that the constant-rank condition is a first-order constraint qualification. In this work,
we prove that the constant-rank condition is also a second-order constraint qualification. We define other second-order constraint
qualifications. 相似文献
4.
R. Andreani E. G. Birgin J. M. Martínez M. L. Schuverdt 《Computational Optimization and Applications》2010,45(2):209-236
A Nonlinear Programming algorithm that converges to second-order stationary points is introduced in this paper. The main tool
is a second-order negative-curvature method for box-constrained minimization of a certain class of functions that do not possess
continuous second derivatives. This method is used to define an Augmented Lagrangian algorithm of PHR (Powell-Hestenes-Rockafellar)
type. Convergence proofs under weak constraint qualifications are given. Numerical examples showing that the new method converges
to second-order stationary points in situations in which first-order methods fail are exhibited. 相似文献
5.
R. Andreani E. G. Birgin J. M. Martínez M. L. Schuverdt 《Mathematical Programming》2008,111(1-2):5-32
Two Augmented Lagrangian algorithms for solving KKT systems are introduced. The algorithms differ in the way in which penalty
parameters are updated. Possibly infeasible accumulation points are characterized. It is proved that feasible limit points
that satisfy the Constant Positive Linear Dependence constraint qualification are KKT solutions. Boundedness of the penalty
parameters is proved under suitable assumptions. Numerical experiments are presented.
The authors were supported by PRONEX - CNPq / FAPERJ E-26 / 171.164/2003 - APQ1, FAPESP (Grants 2001/04597-4, 2002/00094-0,
2003/09169-6, 2002/00832-1 and 2005/56773-1) and CNPq. 相似文献
6.
Studies of single-particle momentum distributions in light atoms and molecules are reviewed with specific emphasis on experimental measurements using the deep inelastic neutron scattering technique at eV energies. The technique has undergone a remarkable development since the mid-1980s, when intense fluxes of epithermal neutrons were made available from pulsed neutron sources. These types of measurements provide a probe of the short-time dynamics of the recoiling atoms or molecules as well as information on the local structure of the materials. The paper introduces both the theoretical framework for the interpretation of deep inelastic neutron scattering experiments and thoroughly illustrates the physical principles underlying the impulse approximation from light atoms and molecules. The most relevant experimental studies performed on a variety of condensed matter systems in the last 20 years are reviewed. The experimental technique is critically presented in the context of a full list of published work. It is shown how, in some cases, these measurements can be used to extract directly the effective Born–Oppenheimer potential. A summary of the progress made to date in instrument development is also provided. Current data analysis and the interpretation of the results for a variety of physical systems is chosen to illustrate the scope and power of the method. The review ends with a brief consideration of likely developments in the foreseeable future. Particular discussion is given to the use of the VESUVIO spectrometer at ISIS.
Measurement of momentum distribution of lightatoms and molecules in condensed matter systems using inelastic neutron scattering
Published online:
19 February 2007Table 相似文献
7.
A theoretical study of cavity modes in one-dimensional photonic crystal slabs embedded in Silicon-on-Insulator structures is reported. Three different methods are employed, namely a guided-mode expansion in which the coupling to radiative modes is treated by perturbation theory, a grating or scattering-matrix method for calculating the surface reflectance, and a Fourier modal expansion for in-plane transmission calculations. It is shown that all methods lead to the same values for the quality factors of cavity modes for both first- and second-order Bragg mirrors. We conclude that the quality factor of a cavity mode can be determined with optical reflectance from the surface of the slab. 相似文献
8.
Summary We show how the breaking of the translational invariance in a quantum well modifies the concept of polariton with respect
to that defined for bulk material. Polaritons in quantum wells result from the combination of the exciton states with the
radiation field. They are here obtained as the solutions of Maxwell equations with retardation, provided an appropriate nonlocal
response function is used for the electric susceptibility, and Maxwell boundary conditions are imposed. We find two types
of polaritons depending on the values of the in-plane wavevectork
II: those atk
II<ω/v (wherev=c/n is the velocity of light in the sample) are resonant with the radiation field in the barrier and those atk
II>ω/v cannot be coupled to waves in the barrier. In both cases explicit expressions are given for radiative shifts and radiative
broadenings as functions ofk
II. Numerical results are obtained for GaAs-Ga1−x
Al
x
As and for CuCl quantum wells and new experiments are suggested. The existence of resonant and surface polaritons justifies
an interpretation of the temperature dependence of the radiative lifetime suggested by the same authors. It also decreases
the radiative efficiency in the direction perpendicular to the planes and increases the radiative efficiency parallel to the
planes with increasing temperature.
Due to the relevance of its scientific content, this paper has been given priority by the Journal Direction. 相似文献
9.
A theoretical model of disorder for the etched holes or pillars in a generic two-dimensional photonic crystal slab is presented. This model is employed to calculate the effects of size disorder on propagation losses in linear photonic crystal waveguides as well as on quality (Q)-factors in photonic crystal nano-cavities. The main results obtained by the present theory and shown in this work are: (a) large single-mode bandwidth and low-loss (<0.1 dB/mm) propagation of light is predicted for increased-width membrane-type photonic crystal waveguides, (b) pillar-based lattices show reduced sensitivity to size fluctuations than hole-based ones, (c) the effects of disorder on cavity Q-factors are quantitatively evaluated. An extension of the model is also introduced in order to take into account the side-wall micro-roughness of the perfectly vertical holes, and preliminary results of this more general approach are discussed. 相似文献
10.
C. Comaschi G. Vecchi A. M. Malvezzi M. Patrini G. Guizzetti M. Liscidini L. C. Andreani D. Peyrade Y. Chen 《Applied physics. B, Lasers and optics》2005,81(2-3):305-311
Enhanced third harmonic (TH) generation from Silicon-On-Insulator (SOI) planar waveguides as well as SOI photonic crystal (PhC) slabs is studied in different angular configurations, both in the visible and infrared energy ranges. In the SOI planar waveguide, the multilayer structure causes the optical properties such as TH reflection to be different from those of bulk silicon samples. This behavior is well reproduced by calculations of TH reflectance.Measurements of third-harmonic reflection and diffraction from one-dimensional PhC slabs etched in the SOI waveguide are also reported. The angular positions of TH peaks at various diffraction orders agree well with those calculated from a nonlinear grating equation. Both reflection and diffraction processes contribute to enhanced TH generation efficiency in the PhC slabs.TH reflectance measurements performed on PhC slabs in the near infrared show a resonant interaction between the incident beam and the photonic structure, dependent on the angle of incidence. This leads to a nonlinear conversion efficiency which is strongly enhanced with respect to that of the SOI waveguide, due to the excitation of strong local fields associated with the presence of photonic modes in the PhC slab. 相似文献