全文获取类型
收费全文 | 30868篇 |
免费 | 2611篇 |
国内免费 | 5318篇 |
专业分类
化学 | 19460篇 |
晶体学 | 758篇 |
力学 | 2294篇 |
综合类 | 406篇 |
数学 | 4542篇 |
物理学 | 11337篇 |
出版年
2022年 | 544篇 |
2021年 | 606篇 |
2020年 | 647篇 |
2019年 | 724篇 |
2018年 | 729篇 |
2017年 | 944篇 |
2016年 | 863篇 |
2015年 | 807篇 |
2014年 | 1140篇 |
2013年 | 1616篇 |
2012年 | 1507篇 |
2011年 | 1670篇 |
2010年 | 1717篇 |
2009年 | 1754篇 |
2008年 | 1843篇 |
2007年 | 1763篇 |
2006年 | 1628篇 |
2005年 | 1349篇 |
2004年 | 1151篇 |
2003年 | 970篇 |
2002年 | 1024篇 |
2001年 | 987篇 |
2000年 | 998篇 |
1999年 | 589篇 |
1998年 | 423篇 |
1997年 | 372篇 |
1996年 | 370篇 |
1995年 | 316篇 |
1994年 | 315篇 |
1993年 | 363篇 |
1992年 | 339篇 |
1991年 | 310篇 |
1990年 | 346篇 |
1989年 | 339篇 |
1987年 | 290篇 |
1985年 | 294篇 |
1984年 | 305篇 |
1983年 | 279篇 |
1982年 | 292篇 |
1979年 | 307篇 |
1978年 | 335篇 |
1977年 | 321篇 |
1976年 | 406篇 |
1975年 | 360篇 |
1974年 | 390篇 |
1973年 | 399篇 |
1972年 | 369篇 |
1971年 | 336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 15 毫秒
71.
72.
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
73.
三苯甲基自由基及其二聚体稳定性的理论研究 总被引:1,自引:1,他引:0
采用量子化学AM1 MO方法优化了三苯甲基自由基及其两种二聚体的构型,并计算了反应物和二聚物的生成焓、活化能以及它们的电荷布居,计算结果表明,三苯甲基自由基是一种较稳定的自由基,在这个自由基中存在明显的共轭效应,分子中电子云呈平均化分布.它的二聚体1,4—环己二烯衍生物分子中的5个苯基排布在环己二烯环平面的两端,明显降低了苯基之间的空间排斥力,使二聚物—环己二烯衍生物分子的稳定性大大高于六苯乙烷.因此,三苯甲基自由基的二聚体是1,4—环己二烯衍生物而不是六苯基乙烷,得到了与实验事实一致的结果。 相似文献
74.
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
75.
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
76.
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
77.
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
78.
79.
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
80.