全文获取类型
收费全文 | 610631篇 |
免费 | 4642篇 |
国内免费 | 1479篇 |
专业分类
化学 | 307164篇 |
晶体学 | 8731篇 |
力学 | 31532篇 |
综合类 | 24篇 |
数学 | 81737篇 |
物理学 | 187564篇 |
出版年
2021年 | 5644篇 |
2020年 | 6102篇 |
2019年 | 6970篇 |
2018年 | 9450篇 |
2017年 | 9604篇 |
2016年 | 13050篇 |
2015年 | 6945篇 |
2014年 | 11784篇 |
2013年 | 26610篇 |
2012年 | 20660篇 |
2011年 | 24664篇 |
2010年 | 18659篇 |
2009年 | 18657篇 |
2008年 | 23405篇 |
2007年 | 23187篇 |
2006年 | 21060篇 |
2005年 | 18803篇 |
2004年 | 17629篇 |
2003年 | 15900篇 |
2002年 | 15887篇 |
2001年 | 17107篇 |
2000年 | 13141篇 |
1999年 | 10152篇 |
1998年 | 8844篇 |
1997年 | 8666篇 |
1996年 | 8059篇 |
1995年 | 7292篇 |
1994年 | 7250篇 |
1993年 | 7058篇 |
1992年 | 7435篇 |
1991年 | 8032篇 |
1990年 | 7662篇 |
1989年 | 7628篇 |
1988年 | 7393篇 |
1987年 | 7208篇 |
1986年 | 6889篇 |
1985年 | 8798篇 |
1984年 | 9113篇 |
1983年 | 7718篇 |
1982年 | 8003篇 |
1981年 | 7516篇 |
1980年 | 7074篇 |
1979年 | 7735篇 |
1978年 | 8051篇 |
1977年 | 7974篇 |
1976年 | 7962篇 |
1975年 | 7642篇 |
1974年 | 7431篇 |
1973年 | 7786篇 |
1972年 | 5806篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
A. A. Slavnov 《Theoretical and Mathematical Physics》1989,79(3):579-587
V. A. Steklov Mathematics Institute, USSR Academy of Sciences. Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 79, No. 3, pp. 347–358, June, 1989. 相似文献
13.
A. D. Smirnov 《Journal of Applied Spectroscopy》1991,54(1):33-38
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 54, No. 1, pp. 46–50, January, 1991. 相似文献
14.
15.
A systematic study on the electrochemical behavior of diosmin in Britton-Robinson buffer (pH 2.0-10.0) at a glassy carbon electrode (GCE) was made. The oxidation process of the drug was found to be quasi-reversible with an adsorption-controlled step. The adsorption stripping response was evaluated with respect to various experimental conditions, such as the pH of the supporting electrolyte, the accumulation potential and the accumulation time. The observed anodic peak current at +0.73 V vs. Ag/AgCl reference electrode increased linearly over two orders of magnitude from 5.0x10(-8) M to 9.0x10(-6) M. A limit of detection down to 3.5x10(-8) M of diosmin at the GCE was achieved with a mean recovery of 97+/-2.1%. Based on the electrochemical data, an open-circuit accumulation step in a stirred sample solution of BR at pH 3.0 was developed. The proposed method was successfully applied to the determination of the drug in pharmaceutical formulations. The results compared favorably with the data obtained via spectrophotometric and HPLC methods. 相似文献
16.
A. Bozkurt 《Journal of Physics and Chemistry of Solids》2002,63(4):685-690
Ionic conductivity of dry quaternary ammonium polymer, polydiallyldimethylammonium with Cl− and H2PO4− counter ions was studied in a wide range of frequencies (10−2-107 Hz) and temperatures (300-470 K). The data were analysed within the formalism of permittivity. WAXS, and thermal properties of this polymer were investigated prior to conductivity measurements. 相似文献
17.
18.
I. A. Bol'shakov 《Journal of Mathematical Sciences》1991,56(1):2263-2279
Systems for automatic detection and correction of spelling errors in natural language texts are considered. The development of such systems for both English and Russian (and for inflected languages in general, including all Slavic languages) is discussed. An approach associated with morphological analysis of the wordforms in the given text is described. The topics considered in the paper include the main methods of automatic spelling correction, levels of automation of the spelling error correction process, the effect of the type of computer used, the use of spelling error correctors in a stand-alone mode and in combination with word-processing software, and the maintenance of auxiliary dictionaries.Translated from Itogi Nauki i Tekhniki, Seriya Teoriya Veroyatnostei, Matematicheskaya Statistika, Teoreticheskaya Kibernetika, Vol. 28, pp. 111–139, 1988. 相似文献
19.
A. L. Chistov 《Journal of Mathematical Sciences》2006,138(3):5733-5752
Consider a projective algebraic variety W which is an irreducible component of the set of all common zeros of a family of
homogeneous polynomials of degrees less than d in n + 1 variables over a field of zero characteristic. Consider a dominant
rational morphism from W to W′ given by homogeneous polynomials of degree d′. We suggest algorithms for constructing objects
in general position related to this morphism. They generalize some algorithms from the first part of the paper to the case
dim W > dim W′. These algorithms are deterministic and polynomial in (dd′)n and the size of the input. Bibliography: 12 titles.
__________
Translated from Zapiski Nauchnykh Seminarov POMI, Vol. 325, 2005, pp. 181–224. 相似文献
20.
I. J. Lozada J. C. Osorio D. V. Griffiths M. Cerrolaza 《Numerical Methods for Partial Differential Equations》2006,22(2):296-316
The semi‐analytical integration of an 8‐node plane strain finite element stiffness matrix is presented in this work. The element is assumed to be super‐parametric, having straight sides. Before carrying out the integration, the integral expressions are classified into several groups, thus avoiding duplication of calculations. Symbolic manipulation and integration is used to obtain the basic formulae to evaluate the stiffness matrix. Then, the resulting expressions are postprocessed, optimized, and simplified in order to reduce the computation time. Maple symbolic‐manipulation software was used to generate the closed expressions and to develop the corresponding Fortran code. Comparisons between semi‐analytical integration and numerical integration were made. It was demonstrated that semi‐analytical integration required less CPU time than conventional numerical integration (using Gaussian‐Legendre quadrature) to obtain the stiffness matrix. © 2005 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2006 相似文献