全文获取类型
收费全文 | 39041篇 |
免费 | 1322篇 |
国内免费 | 3051篇 |
专业分类
化学 | 20037篇 |
晶体学 | 483篇 |
力学 | 1990篇 |
综合类 | 322篇 |
数学 | 5738篇 |
物理学 | 14844篇 |
出版年
2024年 | 22篇 |
2023年 | 118篇 |
2022年 | 375篇 |
2021年 | 594篇 |
2020年 | 613篇 |
2019年 | 814篇 |
2018年 | 1221篇 |
2017年 | 1335篇 |
2016年 | 1630篇 |
2015年 | 887篇 |
2014年 | 1458篇 |
2013年 | 2264篇 |
2012年 | 2107篇 |
2011年 | 3454篇 |
2010年 | 2918篇 |
2009年 | 2804篇 |
2008年 | 2250篇 |
2007年 | 2139篇 |
2006年 | 1948篇 |
2005年 | 1627篇 |
2004年 | 2165篇 |
2003年 | 1302篇 |
2002年 | 1292篇 |
2001年 | 1103篇 |
2000年 | 1018篇 |
1999年 | 731篇 |
1998年 | 847篇 |
1997年 | 723篇 |
1996年 | 303篇 |
1995年 | 230篇 |
1994年 | 211篇 |
1993年 | 546篇 |
1992年 | 585篇 |
1991年 | 388篇 |
1990年 | 394篇 |
1989年 | 358篇 |
1988年 | 163篇 |
1987年 | 36篇 |
1986年 | 101篇 |
1985年 | 46篇 |
1984年 | 47篇 |
1983年 | 41篇 |
1982年 | 25篇 |
1981年 | 21篇 |
1980年 | 13篇 |
1978年 | 11篇 |
1977年 | 15篇 |
1976年 | 9篇 |
1975年 | 9篇 |
1968年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
In this paper we prove existence results for semilinear neutral functional differential inclusions with finite or infinite
delay in Banach spaces. Our theory makes use of analytic semigroups and fractional powers of closed operators, integrated
semigroups and cosine families.
相似文献
72.
73.
A. P. Solov’ev M. I. Perchenko Yu. P. Sinichkin O. V. Zyuryukina 《Technical Physics》2002,47(8):996-1001
An expression for a signal at the ultrasonic frequency from a photodetector arising when diffraction waves at the cathode
mix is obtained for the case when the optical and acoustic beams are space-limited and Bragg angles are small. The alternating
current generated when the scattering medium is crossed by a focused 3-MHz ultrasonic beam and illuminated by a cw He-Ne laser
is measured. Satisfactory agreement between experimental results and those calculated from the formulas obtained indicates
that our model treating acoustooptical interaction in the medium in terms of Raman-Nath diffraction is valid. Conditions for
measuring the alternating current (which is a parameter of acoustooptical imaging) that are optimal from the viewpoint of
maximizing the signal and signal-to-noise ratio are predicted theoretically and corroborated experimentally. 相似文献
74.
R. A. Kotel’nikova G. N. Bogdanov G. V. Zotina V. S. Romanova Z. N. Parnes 《Physics of the Solid State》2002,44(3):576-577
Efficient quenching of eosin phosphorescence by amino-acid derivatives of fullerene (AADFs) such as C60-alanine and C60-glycine in aqueous solutions indicates the possibility of transferring electrons from eosin to fullerene upon collisions or in the exciplex state. To investigate electron transfer in the protein structure, we studied the process of incorporation of C60-alanine and C60-glycine into the heme pocket of myoglobin by controlling Förster quenching. The dissociation constant for the protein-AADF complex was estimated. 相似文献
75.
An electrostatic interaction between two separate, grounded, uncharged, perfectly conducting spheres of different radii in a uniform electrostatic field is investigated. It is shown that at a small center-to-center distance of the spheres, the force of the polarization interaction between the spheres depends appreciably more weakly on that distance in comparison to the force of the electrostatic interaction of two elementary dipoles as it should be in view of the interaction between two like polarization charges. 相似文献
76.
对于任意秩有限总体,在二次损失下,有关文献已给出了线性可预测变量在齐次线性预测类中的唯一线性Minimax预测.本文在正态假设下,证明了这个线性Minimax预测也是线性可预测变量在一切预测类中的唯一Minimax预测. 相似文献
77.
The atomic structure and magnetic and electric properties of the Cr0.5TiSe2-Cr0.5TiTe2 system of intercalated phases were studied in detail by gradually replacing selenium by tellurium. It was revealed that this replacement changes the crystalline structure from monoclinic in the initial compounds to hexagonal in the compounds containing various types of chalcogen atoms; this is accompanied by disordering of chromium atoms in the van der Waals gaps. The electrical resistance and magnetic characteristics vary nonmonotonically on replacement of selenium by tellurium, which is associated with a change in the degree of atomic disordering during the transition from Cr0.5TiSe2 to Cr0.5TiTe2. 相似文献
78.
I. P. Dobrovol’skaya M. V. Mokeev Yu. N. Sazanov A. V. Gribanov T. E. Sukhanova 《Russian Journal of Applied Chemistry》2006,79(8):1312-1315
Variation of the supramolecular structure of heat-resistant polymide films in the course of high-temperature treatment was studied by X-ray diffraction analysis and NMR spectroscopy in solids. 相似文献
79.
Experimental data on the equilibrium and dynamics of chemisorption of vapors of organic substances on a silica gel modified with color reagents are presented. 相似文献
80.
Bernardo Lafuerza-Guillén Donal O’regan Reza Saadati 《Proceedings Mathematical Sciences》2007,117(1):61-70
We introduce the concept of quotient in PN spaces and give some examples. We prove some theorems with regard to the completeness
of a quotient. 相似文献