全文获取类型
收费全文 | 429372篇 |
免费 | 3082篇 |
国内免费 | 1193篇 |
专业分类
化学 | 201053篇 |
晶体学 | 6181篇 |
力学 | 24319篇 |
综合类 | 11篇 |
数学 | 72636篇 |
物理学 | 129447篇 |
出版年
2020年 | 3247篇 |
2019年 | 3806篇 |
2018年 | 15401篇 |
2017年 | 15228篇 |
2016年 | 12964篇 |
2015年 | 4622篇 |
2014年 | 6812篇 |
2013年 | 15270篇 |
2012年 | 15307篇 |
2011年 | 24008篇 |
2010年 | 15938篇 |
2009年 | 16342篇 |
2008年 | 19352篇 |
2007年 | 21491篇 |
2006年 | 12466篇 |
2005年 | 12173篇 |
2004年 | 11780篇 |
2003年 | 11158篇 |
2002年 | 10230篇 |
2001年 | 10805篇 |
2000年 | 8278篇 |
1999年 | 6265篇 |
1998年 | 5416篇 |
1997年 | 5225篇 |
1996年 | 4890篇 |
1995年 | 4486篇 |
1994年 | 4294篇 |
1993年 | 4204篇 |
1992年 | 4537篇 |
1991年 | 4804篇 |
1990年 | 4647篇 |
1989年 | 4545篇 |
1988年 | 4512篇 |
1987年 | 4498篇 |
1986年 | 4186篇 |
1985年 | 5328篇 |
1984年 | 5598篇 |
1983年 | 4701篇 |
1982年 | 4952篇 |
1981年 | 4833篇 |
1980年 | 4512篇 |
1979年 | 4862篇 |
1978年 | 5086篇 |
1977年 | 5165篇 |
1976年 | 5301篇 |
1975年 | 4892篇 |
1974年 | 4842篇 |
1973年 | 5116篇 |
1972年 | 3684篇 |
1971年 | 3139篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
971.
Jerzy Paczkowski D. C. Neckers 《Journal of polymer science. Part A, Polymer chemistry》1993,31(3):841-846
Several new fluorescence probes useful for following photopolymerization have been characterized. Among these are probes which can be used in rapidly gelling monomer mixtures and for photochemical polymerization initiated by very high laser powers. Systems which can be used with polyolacrylates and either with visible initiators or with UV initiators are reported. © 1993 John Wiley & Sons, Inc. 相似文献
972.
973.
974.
The possibilities and the limitations of 2D NMR for the structural characterization of paramagnetic metalloproteins are reviewed. We survey the general strategies for 2D1H NMR investigations of hyperfine shifted signals. Careful adaptation of classical 2D NMR experiments to fast relaxing systems results in the detection of previously not observed scalar and dipolar connectivities, thus leading to the specific assignment of selected resonances. The approach is of general applicability for paramagnetic metalloproteins. We report here on the application of the application of the method to an iron sulfur protein and a heme protein. In both cases specific assignment of several hyperfine shifted signals, corresponding to active site protons, were obtained; this allowed significant insight into the structure-function relationships of these metalloproteins. 相似文献
975.
I. Yu. Chudinovich 《Mathematical Methods in the Applied Sciences》1993,16(3):217-227
This work considers the methods for solving approximately the four types of boundary equations arising when the third initial boundary value problem of the theory of elasticity is solved with the help of retarded elastic potentials. The convergence of these methods is proved. 相似文献
976.
A. I. Podgorny 《Radiophysics and Quantum Electronics》1996,39(11-12):912-915
We have developed the Peresvet program for numerical simulation of energy accumulation above active regions. This program solves 3D MHD equations for the compressible plasma with allowance for the dissipative terms. It is shown that the energy can be stored in a layer of current by focusing the photospheric disturbances. 相似文献
977.
M. U. Belyi N. E. Bartnitskaya I. F. Mel'nik B. A. Okhrimenko S. M. Yablochkov 《Journal of Applied Spectroscopy》1995,62(3):564-567
T. Shevchenko Kiev University, 252022 Kiev, Pr. Akad. Glushakova, 6, Ukraine. Translated from Zhurnal Prikladnoi Spektroskopii,
Vol. 62, No. 3, pp. 192–196, May–June, 1995. 相似文献
978.
979.
Methods are proposed for determining the diffusion coefficients of adsorbed molecules and the adsorption isotherms from given concentrations of the solutes in the external solution. The methods are based on a comparison of experimental data with the numerical results produced by a mathematical model of internal-diffusion kinetics of adsorption from a constant bounded volume.Translated from Vychislitel'naya i Prikladnaya Matematika, No. 66, pp. 41–46, 1988. 相似文献
980.
Ingrid Lukkari Jaromir Ruzicka Gary D. Christian 《Fresenius' Journal of Analytical Chemistry》1993,346(6-9):813-818
Summary Automated methods for the determination of ammonium and ammonia are reviewed, and techniques based on gas diffusion using a semi-permeable membrane were selected for the determination of both total ammonium-nitrogen and free ammonia in fermentation samples. A simple and robust instrument based on sequential injection analysis (SIA) consisting of a piston pump and two selector valves was used. Two different methods of ammonia detection, the Berthelot method and detection using pH-indicators, have been evaluated and compared. The indicator method showed higher reproducibility and the range of determination could easily be adjusted to match the concentrations of the samples. The range of determination could be adjusted from 0.05 mmol/l to 350 mmol/l, depending on choice of acceptor solution. This method has been evaluated with fermentation medium samples and tested on-line in a yeast fermentation process.Dedicated to Professor Dr. Wilhelm Fresenius on the occasion of his 80th birthday 相似文献