全文获取类型
收费全文 | 6613篇 |
免费 | 1129篇 |
国内免费 | 656篇 |
专业分类
化学 | 1422篇 |
晶体学 | 79篇 |
力学 | 696篇 |
综合类 | 105篇 |
数学 | 1330篇 |
物理学 | 2223篇 |
无线电 | 2543篇 |
出版年
2024年 | 22篇 |
2023年 | 74篇 |
2022年 | 131篇 |
2021年 | 143篇 |
2020年 | 190篇 |
2019年 | 146篇 |
2018年 | 156篇 |
2017年 | 240篇 |
2016年 | 265篇 |
2015年 | 265篇 |
2014年 | 370篇 |
2013年 | 568篇 |
2012年 | 436篇 |
2011年 | 500篇 |
2010年 | 392篇 |
2009年 | 434篇 |
2008年 | 421篇 |
2007年 | 445篇 |
2006年 | 398篇 |
2005年 | 319篇 |
2004年 | 320篇 |
2003年 | 304篇 |
2002年 | 266篇 |
2001年 | 193篇 |
2000年 | 187篇 |
1999年 | 181篇 |
1998年 | 149篇 |
1997年 | 104篇 |
1996年 | 123篇 |
1995年 | 103篇 |
1994年 | 95篇 |
1993年 | 81篇 |
1992年 | 55篇 |
1991年 | 49篇 |
1990年 | 42篇 |
1989年 | 37篇 |
1988年 | 27篇 |
1987年 | 26篇 |
1986年 | 16篇 |
1985年 | 23篇 |
1984年 | 16篇 |
1983年 | 9篇 |
1982年 | 15篇 |
1981年 | 9篇 |
1980年 | 8篇 |
1979年 | 11篇 |
1978年 | 6篇 |
1977年 | 6篇 |
1976年 | 10篇 |
1957年 | 3篇 |
排序方式: 共有8398条查询结果,搜索用时 15 毫秒
11.
本文提出生种新的带限信号的外推方法,该方法能够很好地抑制噪声干扰,且计算复杂性较低,本文给出算法,证明了收敛性,最后给出了误差计算机实验结果。 相似文献
12.
A. B. Vasil’eva A. A. Plotnikov 《Computational Mathematics and Mathematical Physics》2006,46(5):762-767
A singularly perturbed parabolic equation with a nonlinear right-hand side of a special form is examined. A numerical analytical study of such equations is performed. 相似文献
13.
Djamel Meraghni Abdelhakim Necir 《Methodology and Computing in Applied Probability》2007,9(4):557-572
The characteristic exponent α of a Lévy-stable law S
α
(σ, β, μ) was thoroughly studied as the extreme value index of a heavy tailed distribution. For 1 < α < 2, Peng (Statist. Probab. Lett. 52: 255–264, 2001) has proposed, via the extreme value approach, an asymptotically normal estimator for the location parameter μ. In this paper, we derive by the same approach, an estimator for the scale parameter σ and we discuss its limiting behavior.
相似文献
14.
H. P. Gunnlaugsson 《Hyperfine Interactions》2006,167(1-3):851-854
The general problem of finding a distribution in hyperfine interaction parameters from experimental Mössbauer spectra is outlined. Existing methods may lack flexibility to be easily applicable to simple problems. A line shape for hyperfine parameter distributions is given, which is based on linear segments in the probability function. This method is applied in the analysis of samples containing iron in a silicate glass. 相似文献
15.
In this paper, the possibility of using the gradients of the temperature and of the internal parameters as additional state variables in Continuum Thermodynamics is considered. The expressions of the two principles are discussed and Clausius–Duhem inequality is derived under an appropriate statement of the internal entropy production. Several formulations are proposed and compared to existing results in the literature. To cite this article: P. Ireman, Q.S. Nguyen, C. R. Mecanique 332 (2004). 相似文献
16.
A detailed study of the generalized M2 factor of hard-edged diffracted beams based on the truncated second-order moments method, asymptotic analysis and self-convergent beam width approach is performed. The dependence of the generalized M2 factor on the parameters characterizing the spatial profile, and beam truncation, etc. is analyzed. 相似文献
17.
18.
Summary The solubility parameters of cationic surfactants were obtained using the inverse gas chromatographic technique. The surfactants
didodecyl dimethyl ammonium bromide, dioctadecyl dimethyl ammonium bromide and dodecyl pyridinium chloride were used as stationary
phase and retention data of different probe solutes were measured at different temperatures. The results were analysed by
the combination of Flory-Huggins and Hildebrand theories, and the solubility parameters of the surfactants were obtained in
a range of temperatures between 80–120°C. 相似文献
19.
In this paper a predictive control strategy is applied to a periodic-review dynamic inventory system with deteriorating items.
Given the current inventory level, we determine the optimal production rates to be implemented at the beginning of each of
the following periods over the control horizon. The effectiveness of this approach is the use of future information of the
inventory target level and the desired production rate, which are available, along the fixed horizon. The deterioration coefficient
may be known or unknown and both cases are considered. In the case where it is unknown, the self-tuning predictive control
is applied. The proposed control algorithms are illustrated by simulations. 相似文献
20.
The influence of the parameter of amplitude-phase coupling for nonlinear amplification on the phase-frequency characteristics of an injection laser in the regime of pumping current modulation has been investigated theoretically. The parameter is defined as the coefficient of proportionality between changes in the real and imaginary parts of the refractive index during variation of the density of photons in the cavity. The substantial dependence of the coefficient of phase modulation on the parameter of the amplitude-phase coupling for nonlinear amplification at small modulation frequencies is shown. A technique to determine the indicated parameter based on the frequency dependence of the ratio between the coefficients of phase and amplitude modulation is suggested. 相似文献