全文获取类型
收费全文 | 5407篇 |
免费 | 717篇 |
国内免费 | 911篇 |
专业分类
化学 | 2947篇 |
晶体学 | 37篇 |
力学 | 980篇 |
综合类 | 66篇 |
数学 | 355篇 |
物理学 | 2650篇 |
出版年
2024年 | 7篇 |
2023年 | 50篇 |
2022年 | 109篇 |
2021年 | 142篇 |
2020年 | 164篇 |
2019年 | 146篇 |
2018年 | 160篇 |
2017年 | 235篇 |
2016年 | 259篇 |
2015年 | 240篇 |
2014年 | 295篇 |
2013年 | 525篇 |
2012年 | 308篇 |
2011年 | 329篇 |
2010年 | 284篇 |
2009年 | 315篇 |
2008年 | 322篇 |
2007年 | 345篇 |
2006年 | 330篇 |
2005年 | 302篇 |
2004年 | 299篇 |
2003年 | 229篇 |
2002年 | 254篇 |
2001年 | 184篇 |
2000年 | 163篇 |
1999年 | 159篇 |
1998年 | 137篇 |
1997年 | 117篇 |
1996年 | 97篇 |
1995年 | 103篇 |
1994年 | 90篇 |
1993年 | 61篇 |
1992年 | 47篇 |
1991年 | 42篇 |
1990年 | 22篇 |
1989年 | 34篇 |
1988年 | 25篇 |
1987年 | 17篇 |
1986年 | 10篇 |
1985年 | 12篇 |
1984年 | 10篇 |
1983年 | 2篇 |
1982年 | 18篇 |
1981年 | 11篇 |
1980年 | 2篇 |
1979年 | 8篇 |
1978年 | 7篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1973年 | 2篇 |
排序方式: 共有7035条查询结果,搜索用时 15 毫秒
131.
醋酸乙烯酯在硅橡胶上的辐射接枝研究 总被引:2,自引:0,他引:2
研究了不同溶剂中的醋酸乙烯酯在硅橡胶上的辐射接技状况及接枝后硅橡胶表面结构情况.结果表明:(1)在硅橡胶-乙酸乙酯-醋酸乙烯酯体系中,接枝有自加速效应;(2)适量加入对苯二酚,接枝诱导期延长,接枝速率下降,凝胶效应消失,辐射接技经验关联式为RP=0.27×[D](-0.560)×[I](0.490)×[C](0.920),接核反应为扩散控制反应;(3)不同的溶剂对硅橡胶接枝有不同的影响,如甲醇发生敏化作用,提高接枝速率,而苯发生惰化作用,降低接枝速率;(4)在合适的甲醇和苯配比时,接枝反应几乎恒速进行,用扫描电镜(SEM)观察断面,接枝区比较均一,出现微相分离. 相似文献
132.
P. Torline G. du Plessis N. Schnautz J. C. Thompson 《Journal of separation science》1979,2(10):613-616
A detailed method for the routine preparation of glass capillary columns is presented. The method consists of coating a glass tube with quartz powder prior to pulling the tube into a capillary. The inner surface of the capillary consists of an even distribution of quartz particles fused to the walls. This surface has been found readily deactivated by standard procedures and ideal for the preparation of thick-film glass capillary columns. The method has been thoroughly tested in two independent laboratories to ensure that the procedures described are reproducible. 相似文献
133.
Tong ZHAO 《数学年刊B辑(英文版)》2022,43(2):195-208
This paper characterizes the limits of a large system of interacting particles distributed on the real line. The interaction occurring among neighbors involves two kinds of independent actions with different rates. This system is a generalization of the voter process, of which each particle is of type A or a. Under suitable scaling, the local proportion functions of A particles converge to continuous functions which solve a class of stochastic partial differential equations driven by Fisher-Wrig... 相似文献
134.
Quantum theory accepts the point-like indivisible (classical) character of a particle as a mere product of a measuring process, or what has become known as a collapse. Following the notion of empty waves, which accepts the particle as a real existent entity without regard to the measurement process, we propose an experiment that may shed some light on the reality of the particle and the consequences of that reality. 相似文献
135.
We present new results for the current as a function of transmission rate in the one-dimensional totally asymmetric simple exclusion process (TASEP) with a blockage that lowers the jump rate at one site from one tor<1. Exact finitevolume results serve to bound the allowed values for the current in the infinite system. This proves the existence of a nonequilibrium phase transition, corresponding to an immiscibility gap in the allowed values of the asymptotic densities which the infinite system can have in a stationary state. A series expansion inr, derived from the finite systems, is proven to be asymptotic for all sufficiently large systems. Padé approximants based on this series, which make specific assumptions about the nature of the singularity atr=1, match numerical data for the infinite system to 1 part in 104. 相似文献
136.
We consider a Hamiltonian paticle system interacting by means of a pair potetial. We look at the behavior of the system on a space scale of order -1, times of order -2 and mean velocities of order , with a scale parameter. Assuming that the phase space density of the particles is give by a series in (the analog of the Chapman-Enskog expansion), the behavior of the system under this rescaling is described, to the lowest order in , by the incompressible Navier-Stokes equations. The viscosity is given in terms of microscopic correlations, and its expression agrees with the Green-Kubo formula. 相似文献
137.
Laurent Serlet 《Journal of Theoretical Probability》1996,9(3):561-578
We study super-Brownian motion inR
d
starting from a nontrivial finite measure and conditioned to nonextinction as defined by Evans. If (Y
t
)
t0
denotes this process, we provide a new approach to the immortal particle representation of (Y
t
)
t0
. We then show that the measureZ onR
d
defined byZ(B)=
o
1
Y
t
(B) dt is almost surely finite on compact sets whend5 and almost surely infinite on every ball whend4. 相似文献
138.
L. Domka 《Colloid and polymer science》1993,271(11):1091-1099
Calcium carbonates of different degrees of surface hydrophobicity were obtained when sorbic acid or polyoxyethylene glycol were present during the precipitation. In the presence of trace amounts of divalent cations carbonates with high surface hydrophilicity and improved monodisperse character are obtained. Surface modification of the calcium carbonates by several proadhesive compounds can markedly improve the chemical affinity of the carbonates to polymers. Very effective are isostearoyl titanate and two polyoxyethylene compounds. Precipitated calcium carbonates modified with 2 to 3 percent (wt/wt) of isostearoyl titanate increased the tensile strenght of butadiene-styrene rubber by approximately 100%. Polyurethane is only strengthened when 30 wt/wt of a filler are introduced independently of the type proadhesive compounds. The best strength and hysteresis of polyurethanes are obtained with calcium carbonate modified with 2 percent (wt/wt) of polyoxyethylene glycol. 相似文献
140.
Three-Dimensional Modeling of the Turbulent Plasma Jet Impinging upon a Flat Plate and with Transverse Particle and Carrier-Gas Injection 总被引:4,自引:0,他引:4
Modeling results are presented concerning the turbulent thermal plasma jet impinging normally on a substrate and with transverse injection of feedstock particles and their carrier gas from a single injection tube. The k- two-equation model is employed to model the turbulence, and particle dispersion is studied considering the interaction between the moving particles and turbulent eddies and considering the effect on particle trajectories of the random variation of the turbulent fluctuating velocities in their magnitude and direction. A well-validated three-dimensional (3-D) computer code is used in the modeling. The 3-D effects due to the carrier gas injection on the jet flow field and thus on the particle trajectories and heating histories are shown to be appreciable. The radial location of the injection tube with respect to the plasma jet is shown to be a critical parameter for the study of 3-D effects, besides the carrier-gas/plasma stream mass flux ratio. Particle dispersion considerably widens the distribution of the particle trajectories and heating histories. In addition, although pertinent swirl number is often rather small, swirling may also affect the modeling results. 相似文献