全文获取类型
收费全文 | 4567篇 |
免费 | 550篇 |
国内免费 | 530篇 |
专业分类
化学 | 816篇 |
晶体学 | 26篇 |
力学 | 448篇 |
综合类 | 123篇 |
数学 | 3066篇 |
物理学 | 1168篇 |
出版年
2024年 | 15篇 |
2023年 | 48篇 |
2022年 | 61篇 |
2021年 | 102篇 |
2020年 | 106篇 |
2019年 | 111篇 |
2018年 | 106篇 |
2017年 | 171篇 |
2016年 | 183篇 |
2015年 | 129篇 |
2014年 | 251篇 |
2013年 | 389篇 |
2012年 | 273篇 |
2011年 | 299篇 |
2010年 | 220篇 |
2009年 | 309篇 |
2008年 | 302篇 |
2007年 | 294篇 |
2006年 | 279篇 |
2005年 | 247篇 |
2004年 | 191篇 |
2003年 | 195篇 |
2002年 | 204篇 |
2001年 | 164篇 |
2000年 | 136篇 |
1999年 | 135篇 |
1998年 | 115篇 |
1997年 | 102篇 |
1996年 | 71篇 |
1995年 | 58篇 |
1994年 | 67篇 |
1993年 | 35篇 |
1992年 | 38篇 |
1991年 | 30篇 |
1990年 | 26篇 |
1989年 | 15篇 |
1988年 | 25篇 |
1987年 | 16篇 |
1986年 | 18篇 |
1985年 | 24篇 |
1984年 | 22篇 |
1983年 | 7篇 |
1982年 | 15篇 |
1981年 | 11篇 |
1979年 | 4篇 |
1978年 | 5篇 |
1977年 | 6篇 |
1976年 | 3篇 |
1975年 | 3篇 |
1936年 | 3篇 |
排序方式: 共有5647条查询结果,搜索用时 15 毫秒
71.
72.
交流示波极谱法中if~E曲线的研究(Ⅱ):if~E曲线的理论公式 总被引:4,自引:0,他引:4
提出利用i_f~E曲线代替常用的dE/dt~E曲线的新的交流示波极谱法,并研究了该法的基本理论,推导出i_f~E曲线的理论公式。 相似文献
73.
An approach to analysis of pigment release from microcapsules with size distribution 总被引:2,自引:0,他引:2
Takao Yamamoto Toshiaki Dobashi Miho Kimura Chih Pong Chang 《Colloids and surfaces. B, Biointerfaces》2002,25(4):305-311
We have studied the release curve for microcapsules with size distribution. On the basis of an analogy to the relaxation phenomena with multiple characteristic times, we propose a stretched exponential release curve for the system with size distribution and relate the release curve to the size distribution function of the microcapsule. This method was successfully applied to the transfer of azo-pigments from inner medium of dioctyl phthalate to dispersing medium of methanol through poly(ureaurethane) microcapsule membrane. 相似文献
74.
A multireference configurational interaction method based on the separated electron pair (SEP) wave functions, SEP‐CI approach, has been developed as an approximation to the traditional CASSCF method. It differs from the CASSCF method in that active orbitals are obtained from the SEP wave function without further optimization in the subsequent CI calculations, and the active space is automatically constructed according to the occupation coefficients of SEP natural orbitals. These features make the present SEP‐CI method computationally much less demanding than the CASSCF method. The applicability of the SEP‐CI method is illustrated with sample calculations on the insertion reaction of BeH2 and dissociation energies of LiH, BH, FH, H2O, and N2. © 2005 Wiley Periodicals, Inc. J Comput Chem 27: 39–47, 2006 相似文献
75.
An equation for a polarization curve of a hydrophobized electrode is proposed for electrosynthesis of a soluble electroactive product in an inner-kinetic mode. The equation contains the concentration of the target product (TP) in an explicit form. The shape of the curve depends on the biquadratic root of the TP concentration and the square root of the ratio between exchange currents of the side and target reactions. 相似文献
76.
77.
不确定金融是不确定理论在现代金融领域的一种应用,在解决金融问题中发挥着越来越重要的作用。而利率是一个重要的经济指标,经常受到一些不确定因素的影响,在研究期权定价时,有必要考虑浮动利率。本文提出了一种新的不确定指数Ornstein-Uhlenbeck过程模型,假设利率服从不确定均值回复过程,研究了期权定价问题,运用α-轨道方法,分别推导了亚式看涨期权和看跌期权定价公式。最后,设计了计算期权价格的数值算法,并给出数值算例。 相似文献
78.
In this paper we investigate two-point algebraic-geometry codes (AG codes) coming from the Beelen-Montanucci (BM) maximal curve. We study properties of certain two-point Weierstrass semigroups of the curve and use them for determining a lower bound on the minimum distance of such codes. AG codes with better parameters with respect to comparable two-point codes from the Garcia-Güneri-Stichtenoth (GGS) curve are discovered. 相似文献
79.
In this paper, we are interested in the regularity estimates of the nonnegative viscosity super solution of the $β$−biased infinity Laplacian equation $$∆^β_∞u = 0,$$ where $β ∈ \mathbb{R}$ is a fixed constant and $∆^β_∞u := ∆^N_∞u + β|Du|,$ which arises from the random game named biased tug-of-war. By studying directly the $β$−biased infinity Laplacian equation, we construct the appropriate exponential cones as barrier functions to establish a key estimate. Based on this estimate, we obtain the Harnack inequality, Hopf boundary point lemma, Lipschitz estimate and the Liouville property etc. 相似文献
80.
The diluted-field Ising model, a random nonnegative field ferromagnetic model, is shown to have a unique Gibbs measure with probability I when the field mean is positive. Our methods involve comparisons with ordinary uniform field Ising models. They yield as a corollary a way of obtaining spontaneous magnetization through the application of a vanishing random magnetic field. The correlation lengths of this model defined as (lim
n-(1/n) log 0;
n)-1, wheren is the site on the first coordinate axis at distancen from the origin and 0;
n
is the origin ton two-point truncated correlation function, is non-random. We derive an upper bound for it in terms of the correlation length of an ordinary nonrandom model with uniform field related to the field distribution of the diluted model. 相似文献