全文获取类型
收费全文 | 54174篇 |
免费 | 1896篇 |
国内免费 | 167篇 |
专业分类
化学 | 35332篇 |
晶体学 | 395篇 |
力学 | 978篇 |
综合类 | 4篇 |
数学 | 8888篇 |
物理学 | 10640篇 |
出版年
2023年 | 374篇 |
2022年 | 465篇 |
2021年 | 827篇 |
2020年 | 870篇 |
2019年 | 886篇 |
2018年 | 1085篇 |
2017年 | 1029篇 |
2016年 | 1988篇 |
2015年 | 1622篇 |
2014年 | 1704篇 |
2013年 | 3473篇 |
2012年 | 3419篇 |
2011年 | 3814篇 |
2010年 | 2337篇 |
2009年 | 2059篇 |
2008年 | 3204篇 |
2007年 | 3068篇 |
2006年 | 2737篇 |
2005年 | 2463篇 |
2004年 | 2014篇 |
2003年 | 1652篇 |
2002年 | 1439篇 |
2001年 | 1105篇 |
2000年 | 979篇 |
1999年 | 772篇 |
1998年 | 590篇 |
1997年 | 525篇 |
1996年 | 662篇 |
1995年 | 480篇 |
1994年 | 491篇 |
1993年 | 512篇 |
1992年 | 484篇 |
1991年 | 374篇 |
1990年 | 347篇 |
1989年 | 287篇 |
1988年 | 298篇 |
1987年 | 308篇 |
1986年 | 295篇 |
1985年 | 383篇 |
1984年 | 358篇 |
1983年 | 291篇 |
1982年 | 280篇 |
1981年 | 252篇 |
1980年 | 243篇 |
1979年 | 231篇 |
1978年 | 212篇 |
1977年 | 215篇 |
1976年 | 188篇 |
1974年 | 159篇 |
1973年 | 193篇 |
排序方式: 共有10000条查询结果,搜索用时 406 毫秒
101.
We study condensation of ethanol-hexanol vapour by numerical solution of kinetic equations. The number of droplets formed
in unit volume is computed within self-consistent classical model. It is shown that formation of ethanol-rich droplets prevails
at the initial stage of nucleation process, but in the stationary state formation of droplets near the saddle point (on cluster
formation energy surface) plays the dominant role.
Presented at the 6th Joint Seminar “Development of Materials Science in Research and Education”, Karlštejn, Czech Republic,
17–19 September 1996.
This work was supported by Grant No. A1010615 of the Grant Agency of the Academy of Sciences of the Czech Republic. 相似文献
102.
S. Pumplün 《manuscripta mathematica》1998,97(1):93-108
For a Brauer–Severi variety X over a field k of characteristic not two, every symmetric bilinear space over X up to Witt equivalence is defined over k.
Received: 2 February 1998 相似文献
103.
P. González D. Fernández J. Pou E. García J. Serra B. León M. Pérez-Amor T. Szörényi 《Applied Physics A: Materials Science & Processing》1993,57(2):181-185
A study of the gas-phase parameters involved in ArF laser induced chemical vapour deposition of silicon-oxide thin films is presented. A complete set of experiments has been performed showing the influence of the concentration of the precursor gases, N2O and SiH4, and their influence on total and partial pressures on film growth and properties. In this paper we demonstrate the ability of this LCVD method to deposit silicon oxide films of different compositions and densities by appropriate control of gas composition and total pressure. Moreover, a material specific calibration plot comprising data obtained using different preparation techniques is presented, allowing determination of the stoichiometry of SiO
x
films by using FTIR spectroscopy independently of the deposition method. For the range of processing conditions examined, the experimental results suggest that chemical processes governing deposition take place mainly in the gas phase. 相似文献
104.
Ivo Nezbeda 《Czechoslovak Journal of Physics》1998,48(1):117-122
By transforming a realistic water-water potential separately into long-ranged and short-ranged systems and using computer
simulations it is shown that the structure of water is determined primarily by short-ranged (both repulsive and attractive)
forces. An extended primitive model of water is then shown to provide both the spatial and orientational arrangement of water
molecules in the liquid phase in semi-quantitative agreement with diffraction experiments. Practical importance of this finding
is exemplified by formulating a perturbation expansion about the primitive model reference and its individual steps are analyzed
with respect to their implementation.
This work was supported by the Grant Agency of the Czech Republic (Grant No. 203/96/0585) and by the Grant Agency of the Academy
of Sciences of the Czech Republic (Grant No. A-4072607). 相似文献
105.
Impact of the internucleotide linkage modification by inserting a methylene group to the P-O bond (—O—PO
2
—
—O— chain changed for —O—PO
2
—
—CH2—O—), on the modified oligonucleotide binding ability to the natural DNA strand was studied by molecular dynamics simulation. Complex of (dT)11 with a deoxyadenosine undecamer containing alternating modified and natural internucleotide linkage was studied as a model system. The Amber force field was completed by a set of new parameters needed to model the modified part of the nucleotide. The simulations confirmed existence of a double-helical complex the melting point of which is considerably higher than 300 K. While the thymidine (unmodified) strand possesses a B-type secondary structure, the conformation of the adenosine (modified) strand is not stable at 300 K. The -ggt conformation of the modified linkages is highly preferred, temporary jumps to the -g-gt and ggt conformations were, however, observed. 相似文献
106.
The purpose of this paper is to give the Reid ``Roundabout Theorem' for quadratic functionals with general boundary conditions.
In particular, we describe the so-called coupled point and regularity condition introduced in [16] in terms of Riccati equation
solutions.
Accepted 27 February 1996 相似文献
107.
V.I. Fernández A. Iucci C.M. Naón 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,30(1):53-56
We present an extension of the Tomonaga-Luttinger model in which left and right-moving particles have different Fermi velocities.
We derive expressions for one-particle Green's functions, momentum-distributions, density of states, charge compressibility
and conductivity as functions of both the velocity difference ε and the strength of the interaction β. This allows us to identify
a novel restricted region in the parameter space in which the system keeps the main features of a Luttinger liquid but with
an unusual behavior of the density of states and the static charge compressibility κ. In particular κ diverges on the boundary
of the restricted region, indicating the occurrence of a phase transition.
Received 20 May 2002 / Received in final form 23 August 2002 Published online 19 November 2002 相似文献
108.
109.
Ricardo García-Pelayo Iván Salazar William C. Schieve 《Journal of statistical physics》1993,72(1-2):167-187
An analytically solvable model for sand avalanches of noninteracting grains of sand, based on the Chapman-Kolmogorov equations, is presented. For a single avalanche, distributions of lifetimes, sizes of overflows and avalanches, and correlation functions are calculated. Some of these are exponentials, some are power laws. Spatially homogeneous distributions of avalanches are also studied. Computer simulations of avalanches of interacting grains of sand are compared to the solutions to the Chapman-Kolmogorov equations. We find that within the range of parameters explored in the simulation, the approximation of noninteracting grains of sand is a good one. 相似文献
110.
X-ray photoelectron and Auger spectroscopies were used to examine surface bonding and overlayer growth during palladium and copper deposition onto films of fullerene, C60 The results were consistent with metal cluster formation on C60. The observed positive core electron binding energy shifts in small metallic clusters supported on C60 were shown to originate in metal-fullerene interaction accompanied by charge transfer. Palladium-fullerene intermixing at temperatures as low as ss 50°C was observed for small Pd coverages. 相似文献