全文获取类型
收费全文 | 2349篇 |
免费 | 83篇 |
国内免费 | 5篇 |
专业分类
化学 | 1486篇 |
晶体学 | 7篇 |
力学 | 70篇 |
数学 | 473篇 |
物理学 | 401篇 |
出版年
2024年 | 2篇 |
2023年 | 26篇 |
2022年 | 43篇 |
2021年 | 63篇 |
2020年 | 60篇 |
2019年 | 66篇 |
2018年 | 35篇 |
2017年 | 32篇 |
2016年 | 101篇 |
2015年 | 74篇 |
2014年 | 83篇 |
2013年 | 130篇 |
2012年 | 191篇 |
2011年 | 165篇 |
2010年 | 98篇 |
2009年 | 105篇 |
2008年 | 148篇 |
2007年 | 144篇 |
2006年 | 131篇 |
2005年 | 107篇 |
2004年 | 109篇 |
2003年 | 81篇 |
2002年 | 90篇 |
2001年 | 40篇 |
2000年 | 25篇 |
1999年 | 17篇 |
1998年 | 22篇 |
1997年 | 14篇 |
1996年 | 23篇 |
1995年 | 14篇 |
1994年 | 22篇 |
1993年 | 19篇 |
1992年 | 11篇 |
1991年 | 13篇 |
1990年 | 11篇 |
1989年 | 18篇 |
1988年 | 11篇 |
1987年 | 7篇 |
1986年 | 6篇 |
1985年 | 10篇 |
1984年 | 15篇 |
1983年 | 9篇 |
1982年 | 9篇 |
1981年 | 4篇 |
1980年 | 9篇 |
1979年 | 8篇 |
1978年 | 5篇 |
1966年 | 2篇 |
1936年 | 2篇 |
1910年 | 1篇 |
排序方式: 共有2437条查询结果,搜索用时 692 毫秒
11.
In this paper a tripartite qualitative design combining abservation, stimulated recall and interview is presented and discussed. This three-step-design makes it possible to get insight into the interaction of internal and external processes when solving mathematical tasks. The data analysis depends on the research question and the methodological approach. In the light of two research projects in mathematics education two different methods of data analysis are presented and methodologically reflected. 相似文献
12.
Andrea Grosso Marco Locatelli Fabio Schoen 《Computational Optimization and Applications》2007,38(3):351-370
In this paper we perform a computational analysis of a population based approach for global optimization, Population Basin
Hopping (PBH), which was proven to be very efficient on very challenging global optimization problems by the authors (see
). The experimental analysis aims at understanding more deeply how the approach works and why it is successful on challenging
problems. 相似文献
13.
In this paper we determine which vanishing order of a holomorphic map f at a point of the (non necessarily regular) boundary of a very generic domain of
is required for f to be constant. In particular this vanishing order is 1 if the boundary is Dini-smooth whereas it is at least β/α if f locally maps a Dini-smooth corner of opening πα into a Dini-smooth corner of opening πβ. Finally an analogous result is stated for the case of a holomorphic map f which maps a cusp into a cusp. 相似文献
14.
M.A.C. Potenza M.D. Alaimo D. Pescini D. Magatti F. Ferri M. Giglio 《Optics and Lasers in Engineering》2006,44(7):722
We show that the time evolution of near-field scattering speckles, originated by a fluid suspension of particles, provides information about the velocity field in the fluid. This information can be extracted from a statistical analysis of speckle fields taken at different times, either by measuring their cross-correlation function or by recovering the power spectrum corresponding to the difference between the two speckle fields. Experimental data are in accordance to the expected behaviors. The results are independent of the scatterer's size, allowing one to exploit the technique also with sub-wavelength tracking particles. 相似文献
15.
Fabio Fantozzi Sauro Filippeschi Enrico Maria Latrofa 《Superlattices and Microstructures》2004,35(3-6):339
Upward and downward two-phase heat and mass transfer has been considered in the present paper. The heat and mass transfer with the condenser located below the evaporator has been obtained by inserting an accumulator tank in the liquid line of a loop thermosyphon and enforcing a pressure pulsation. In previous papers these heat transfer devices have been called pulsated two phase thermosyphons (PTPT). A mini PTPT has been experimentally investigated. It has shown a stable periodic heat transfer regime weakly influenced by the position of the condenser with respect to the evaporator. In contrast a classical loop mini thermosyphon (diameter of connecting pipes 4 mm) did not achieve a stable functioning for the investigated level differences between evaporator and condenser lower than 0.37 m. The present study shows that the functioning of a PTPT device does not directly depend on the level difference or the presence of noncondensable gas. In order to obtain a natural circulation in mini or micro loops, a periodically operating heat transfer regime should therefore be considered. 相似文献
16.
Modal logics with the binary operator Until are considered. It is shown that there exists a continuum of consistent U-logics without Kripke frames, and that each U-logic whose class of order does not have the finite frame property. 相似文献
17.
Fabio Schoen 《Journal of Global Optimization》1994,4(1):17-35
In this paper a new algorithm is proposed for global optimization problems. The main idea is that of modifying a standard clustering approach by sequentially sampling the objective function while adaptively deciding an appropriate sample size. Theoretical as well as computational results are presented. 相似文献
18.
Fabio Scardigli 《Foundations of Physics》2007,37(8):1278-1295
The Titius–Bode law for planetary distances is reviewed. A model describing the basic features of this rule in the “quantum-like”
language of a wave equation is proposed. Some considerations about the ’t Hooft idea on the quantum behavior of deterministic
systems with dissipation are discussed. 相似文献
19.
If
is a quasitriangular Lie bialgebra, the formal Poisson group
can be given a braiding structure. This was achieved by Weinstein and Xu using purely geometrical means, and independently by the authors by means of quantum groups. In this paper we compare these two approaches. First, we show that the braidings they produce share several similar properties (in particular, the construction is functorial); secondly, in the simplest case (G=SL2) they do coincide. The question then rises of whether they are always the same this is positively answered in a separate paper. 相似文献
20.
We obtain results of existence and multiplicity of solutions for the second-order equation x″+q(t)g(x)=0, with x(t) defined for all t∈]0,1[ and such that x(t)→+∞ as t→0+ and t→1−. We assume g having superlinear growth at infinity and q(t) possibly changing sign on [0,1]. 相似文献