全文获取类型
收费全文 | 3010篇 |
免费 | 113篇 |
国内免费 | 24篇 |
专业分类
化学 | 1856篇 |
晶体学 | 20篇 |
力学 | 80篇 |
数学 | 481篇 |
物理学 | 530篇 |
无线电 | 180篇 |
出版年
2023年 | 28篇 |
2022年 | 39篇 |
2021年 | 56篇 |
2020年 | 65篇 |
2019年 | 69篇 |
2018年 | 59篇 |
2017年 | 47篇 |
2016年 | 94篇 |
2015年 | 96篇 |
2014年 | 112篇 |
2013年 | 172篇 |
2012年 | 206篇 |
2011年 | 269篇 |
2010年 | 133篇 |
2009年 | 123篇 |
2008年 | 181篇 |
2007年 | 147篇 |
2006年 | 152篇 |
2005年 | 128篇 |
2004年 | 125篇 |
2003年 | 99篇 |
2002年 | 66篇 |
2001年 | 47篇 |
2000年 | 30篇 |
1999年 | 24篇 |
1998年 | 18篇 |
1997年 | 26篇 |
1996年 | 35篇 |
1995年 | 11篇 |
1994年 | 20篇 |
1993年 | 16篇 |
1992年 | 26篇 |
1990年 | 17篇 |
1989年 | 11篇 |
1988年 | 19篇 |
1987年 | 12篇 |
1986年 | 13篇 |
1985年 | 23篇 |
1984年 | 16篇 |
1983年 | 24篇 |
1982年 | 15篇 |
1981年 | 11篇 |
1980年 | 13篇 |
1979年 | 12篇 |
1978年 | 21篇 |
1977年 | 11篇 |
1976年 | 14篇 |
1975年 | 13篇 |
1973年 | 14篇 |
1971年 | 12篇 |
排序方式: 共有3147条查询结果,搜索用时 15 毫秒
11.
Alexandre Munnier 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2003,9(2):977-1000
This article deals with stability and small linear
oscillations of liquid bridges between fixed solid surfaces
(parallel plates, spheres, ...) under zero gravity. A general
investigation method for any kind of axisymmetric liquid bridge is
exposed but the author focus his work on the spherical liquid
bridge cases. In particular, he exposes a full theoretical study
of spherical liquid bridges between two spheres, plates and
cones. 相似文献
12.
Alexandre Stojanovic 《Mathematical Physics, Analysis and Geometry》2004,7(4):347-349
The errata concern mainly the last computations for the universality of the local statistics of eigenvalues at the edge of the spectrum in parts (iii) of Theorems 2.3 and 2.4. 相似文献
13.
Two distinct humic acids, one extracted from Brazilian peat soil, HAPS, and another one obtained from commercial source, HAFL, were attachment onto silica gel modified with aminopropyltrimethoxysilane, producing two material named SiHAPS and SiHAFL, respectively. The ability of these materials in removing indigo carmine dye from aqueous solution was followed through series of adsorption isotherms adjusted to modified Langmuir equation. The maximum number of moles adsorbed gave 6.82 ± 0.12 × 10−4 and 2.15 ± 0.17 × 10−4 mol g−1 for SiHAPS and SiHAFL, respectively. Same interactions were calorimetrically followed and the thermodynamic data showed endothermic enthalpic values: 12.31 ± 0.55 and 24.69 ± 1.05 kJ mol−1 for SiHAPS and SiHAFL surfaces, respectively. Gibbs free energies for two adsorption processes of indigo carmine dye presented negative values, reflecting dye/surface interactions must be accompanied by an increased in entropy values, which are 65 ± 3 and 98 ± 5 J mol−1 K−1 for SiHAPS and SiHAFL materials, respectively. The adsorption processes for both materials were spontaneous in nature although they presented an endothermic enthalpy for the interaction, resulting in an entropically favored process. 相似文献
14.
The synthesis of enantiopure bis-THF is described, starting from d-mannitol. Bis-THF is used as chiral ligand for organolithium reagents in four different reactions. The enantioselectivity provided by this ligand is moderate, and the asymmetric induction is in line with the expected model. 相似文献
15.
R. Brunner R. Meisels F. Kuchar M. ElHassan J. Bird K. Ishibashi 《Physica E: Low-dimensional Systems and Nanostructures》2004,21(2-4):491
The properties of open quantum dots are examined in magneto-transport. The quantum dots are prepared from a two-dimensional electron system (2DES) in AlGaAs/GaAs by lateral gate structures. These quantum dots are open, i.e. they are still connected to the surrounding 2DES regions. The low magnetic field magnetoresistance shows peak structures. These structures can be related to semi-classical ballistic trajectories in the confining potential of a dot. The calculations of different confining potentials (abrupt “hard-wall” and parabolic “soft-wall”) are compared with the experimental results. The experiments are better described by a soft-wall potential. 相似文献
16.
A.B. Dalton A. Ortiz‐Acevedo V. Zorbas E. Brunner W.M. Sampson S. Collins J.M. Razal M. MikiYoshida R.H. Baughman R.K. Draper I.H. Musselman M. Jose‐Yacaman G.R. Dieckmann 《Advanced functional materials》2004,14(12):1147-1151
Numerous applications, from molecular electronics to super‐strong composites, have been suggested for carbon nanotubes. Despite this promise, difficulty in assembling raw carbon nanotubes into functional structures is a deterrent for applications. In contrast, biological materials have evolved to self‐assemble, and the lessons of their self‐assembly can be applied to synthetic materials such as carbon nanotubes. Here we show that single‐walled carbon nanotubes, coated with a designed amphiphilic peptide, can be assembled into ordered hierarchical structures. This novel methodology offers a new route for controlling the physical properties of nanotube systems at all length scales from the nano‐ to the macroscale. Moreover, this technique is not limited to assembling carbon nanotubes, and could be modified to serve as a general procedure for controllably assembling other nanostructures into functional materials. 相似文献
17.
The determination of the enantiomeric purity of 2 or 3-substituted cyclanones, particularly cyclohexanones, is conveniently achieved by derivatisation into cyclic aminals with commercially available (R, R)-1,2-diphenylethylenediamine. The derivatisation procedure is directly done into the NMR tube, instantaneously, and 13C NMR allows an accurate measure of the ee. 相似文献
18.
Alexandre N. Carvalho German Lozada-Cruz 《Journal of Mathematical Analysis and Applications》2007,325(2):1216-1239
We obtain existence of asymptotically stable nonconstant equilibrium solutions for semilinear parabolic equations with nonlinear boundary conditions on small domains connected by thin channels. We prove the convergence of eigenvalues and eigenfunctions of the Laplace operator in such domains. This information is used to show that the asymptotic dynamics of the heat equation in this domain is equivalent to the asymptotic dynamics of a system of two ordinary differential equations diffusively (weakly) coupled. The main tools employed are the invariant manifold theory and a uniform trace theorem. 相似文献
19.
Alexandre Joel Chorin 《Communications in Mathematical Physics》1991,141(3):619-631
The thermodynamic functions and scaling exponents (including the Kolmogorov and Flory exponents) of a vortex filament in thermal equilibrium are calculated, giving a quantitative content to earlier qualitative analyses. The numerical results uncover a percolation property of vortex filaments near the maximum entropy state. The implications of the results for the onset of turbulence, for the structure of its inertial range, and for superfluid vortices are discussed. In particular, it is shown that vortex stretching pushes a vortex system to a polymeric state and a Kolmogorov spectrum.This work was supported in part by the Applied Mathematical Sciences subprogram of the Office of Energy Research, U.S. Department of Energy, under contract DE-AC03-76SF-00098, and in part by the National Science Foundation under grant number DMS89-19074 相似文献
20.