全文获取类型
收费全文 | 28300篇 |
免费 | 1760篇 |
国内免费 | 1445篇 |
专业分类
化学 | 17114篇 |
晶体学 | 221篇 |
力学 | 2025篇 |
综合类 | 98篇 |
数学 | 3662篇 |
物理学 | 8385篇 |
出版年
2022年 | 422篇 |
2021年 | 498篇 |
2020年 | 577篇 |
2019年 | 631篇 |
2018年 | 620篇 |
2017年 | 601篇 |
2016年 | 893篇 |
2015年 | 598篇 |
2014年 | 950篇 |
2013年 | 1211篇 |
2012年 | 1325篇 |
2011年 | 1385篇 |
2010年 | 1130篇 |
2009年 | 1105篇 |
2008年 | 1200篇 |
2007年 | 1121篇 |
2006年 | 921篇 |
2005年 | 882篇 |
2004年 | 738篇 |
2003年 | 755篇 |
2002年 | 837篇 |
2001年 | 739篇 |
2000年 | 574篇 |
1999年 | 471篇 |
1998年 | 428篇 |
1997年 | 394篇 |
1996年 | 385篇 |
1995年 | 334篇 |
1994年 | 335篇 |
1993年 | 337篇 |
1992年 | 356篇 |
1991年 | 343篇 |
1990年 | 340篇 |
1989年 | 336篇 |
1986年 | 265篇 |
1985年 | 298篇 |
1984年 | 299篇 |
1983年 | 276篇 |
1982年 | 286篇 |
1979年 | 303篇 |
1978年 | 337篇 |
1977年 | 327篇 |
1976年 | 411篇 |
1975年 | 364篇 |
1974年 | 397篇 |
1973年 | 400篇 |
1972年 | 370篇 |
1971年 | 333篇 |
1970年 | 314篇 |
1969年 | 298篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
51.
The method of nonlinear moments, when used to solve the Boltzmann equation, necessitates the calculation of collision integral
matrix elements. The matrix elements are hard to calculate numerically, especially at large indices. The asymptotics of the
matrix elements are constructed. In terms of the model of pseudopower particle interaction, a formula free of summation is
derived. This makes it possible to find the asymptotic behavior of linear and nonlinear elements when two indices are large.
For an arbitrary interaction cross section, asymptotic expansions of linear and nonlinear matrix elements in one index are
obtained. For Maxwellian molecules, asymptotic formulas are derived for three large indices. 相似文献
52.
The goal of the paper is to analyse properties of solutions for linear thermoelastic systems of type III in one space variable. Our approach does not use energy methods, it bases on a special diagonalization procedure which is different in different parts of the phase space. This procedure allows to derive explicit representations of solutions. These representations help to prove results for well‐posedness of the Cauchy problem, LP–Lq decay estimates on the conjugate line and results for propagation of singularities. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
53.
B. Ya. Balagurov 《Technical Physics》2003,48(8):945-951
A sequential scheme for calculating the polarizability of a pair of parallel cylinders with an arbitrary (but fairly symmetric) form is suggested. An infinite set of algebraic equations is derived for coefficients involved in an expression for the potential. The numerical solution of this set makes it possible to find the polarizability with any degree of accuracy. This method is unrelated to the cylinder shape. The electrostatic properties of the cylinders are described in terms of the multipolar polarizability matrix. 相似文献
54.
V. V. Dvorkin N. N. Dzbanovskii A. F. Pal’ N. V. Suetin A. Yu. Yur’ev P. Ya. Detkov 《Physics of the Solid State》2004,46(4):729-732
A suspension of ultrafine-dispersed nanodiamond was used for introducing (in particular, selectively) high-density centers of diamond nucleation on various substrates. High-quality doped diamond films to be used as electrochemistry electrodes were deposited from the gas phase in a microwave discharge on certain substrates treated using ultrafine-dispersed nanodiamond. A uniform distribution of nucleation centers with concentrations greater than 1010 cm-2 on silicon substrates was obtained. Electrochemical current-potential curves were measured for continuous films. Diamond meshes of different transparency were grown using selective nucleation. Successful production of high-quality doped diamond meshes gives grounds to consider them the most promising electrodes for use in electrochemistry. 相似文献
55.
P. D. Kim I. A. Turpanov S. V. Stolyar R. S. Iskhakov V. I. Yushkov A. Ya. Beten’kova L. A. Li E. V. Bondareva T. N. Isaeva M. M. Karpenko 《Technical Physics》2004,49(4):431-434
The crystal structure and hysteretic magnetic properties of equiatomic single-crystal CoPt films applied on MgO substrates
by magnetron sputtering, as well as modification of these properties by thermal annealing, are studied. Heat-treated films
of thickness in the range 2<d≤16 nm exhibit perpendicular magnetic anisotropy. A correlation between the crystalline anisotropy constant of the CoPt films
and the order parameter of the LI0 superstructure in these alloys is found. The effect of a single-crystalline MgO substrate on the structure and magnetic properties
of equiatomic CoPt films is revealed. 相似文献
56.
57.
M. Ya. Izrailovich 《Acoustical Physics》2004,50(2):163-168
On the basis of the method of equivalent linearization combined with the method of moments, laws of self-oscillation excitation are obtained that provide the modes with maximum intensity of resonance (or quasi-resonance) oscillations in one-dimensional systems with distributed parameters. A restriction of a general type is imposed on the law of excitation. In the particular case of an integral quadratic restriction, the law of excitation leads to the generation of purely harmonic self-oscillations. The use of an extended (multiplicatively stabilizing) control provides the uniqueness and stability of the quasi-optimal mode of self-oscillation. 相似文献
58.
59.
Jem‐Kun Chen I‐Kuan Lin Fu‐Hsiang Ko Chih‐Feng Huang Kuo‐Shen Chen Chia‐Hao Chan Feng‐Chih Chang 《Journal of Polymer Science.Polymer Physics》2004,42(22):4063-4074
Polybenzoxazine (PBZZ) thin films can be fabricated by the plasma‐polymerization technique with, as the energy source, plasmas of argon, oxygen, or hydrogen atoms and ions. When benzoxazine (BZZ) films are polymerized through the use of high‐energy argon atoms, electronegative oxygen atoms, or excited hydrogen atoms, the PBZZ films that form possess different properties and morphologies in their surfaces. High‐energy argon atoms provide a thermodynamic factor to initiate the ring‐opening polymerization of BZZ and result in the polymer surface having a grid‐like structure. The ring‐opening polymerization of the BZZ film that is initiated by cationic species such as oxygen atoms in plasma, is propagated around nodule structures to form the PBZZ. The excited hydrogen atom plasma initiates both polymerization and decomposition reactions simultaneously in the BZZ film and results in the formation of a porous structure on the PBZZ surface. We evaluated the surface energies of the PBZZ films polymerized by the action of these three plasmas by measuring the contact angles of diiodomethane and water droplets. The surface roughness of the films range from 0.5 to 26 nm, depending on the type of carrier gas and the plasma‐polymerization time. By estimating changes in thickness, we found that the PBZZ film synthesized by the oxygen plasma‐polymerization process undergoes the slowest rate of etching in CF4 plasma. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 4063–4074, 2004 相似文献
60.