全文获取类型
收费全文 | 277篇 |
免费 | 5篇 |
国内免费 | 9篇 |
专业分类
化学 | 146篇 |
晶体学 | 4篇 |
力学 | 13篇 |
数学 | 76篇 |
物理学 | 52篇 |
出版年
2022年 | 4篇 |
2020年 | 6篇 |
2019年 | 3篇 |
2018年 | 6篇 |
2017年 | 4篇 |
2016年 | 10篇 |
2015年 | 16篇 |
2014年 | 16篇 |
2013年 | 23篇 |
2012年 | 7篇 |
2011年 | 10篇 |
2010年 | 14篇 |
2009年 | 10篇 |
2008年 | 8篇 |
2007年 | 6篇 |
2006年 | 9篇 |
2005年 | 6篇 |
2004年 | 8篇 |
2003年 | 13篇 |
2002年 | 8篇 |
2001年 | 8篇 |
2000年 | 5篇 |
1999年 | 6篇 |
1998年 | 5篇 |
1997年 | 6篇 |
1996年 | 6篇 |
1995年 | 3篇 |
1994年 | 4篇 |
1993年 | 3篇 |
1992年 | 5篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1986年 | 4篇 |
1985年 | 3篇 |
1982年 | 5篇 |
1981年 | 3篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1972年 | 2篇 |
1971年 | 4篇 |
1970年 | 3篇 |
1968年 | 2篇 |
1966年 | 1篇 |
1937年 | 1篇 |
1921年 | 1篇 |
1902年 | 1篇 |
1900年 | 1篇 |
排序方式: 共有291条查询结果,搜索用时 0 毫秒
101.
本文从约化的角度考虑BKP方程族的Pfaffian形式的解.证明了通过施加适当的微分约束,KP方程族的格拉姆行列式的解很自然的约化为BKP方程族的解. 相似文献
102.
103.
Tobias Holck Colding William P. Minicozzi II 《Calculus of Variations and Partial Differential Equations》2014,49(3-4):1045-1059
In this paper we generalize the monotonicity formulas of “Colding (Acta Math 209:229–263, 2012)” for manifolds with nonnegative Ricci curvature. Monotone quantities play a key role in analysis and geometry; see, e.g., “Almgren (Preprint)”, “Colding and Minicozzi II (PNAS, 2012)”, “Garofalo and Lin (Indiana Univ Math 35:245–267, 1986)” for applications of monotonicity to uniqueness. Among the applications here is that level sets of Green’s function on open manifolds with nonnegative Ricci curvature are asymptotically umbilic. 相似文献
104.
105.
E. Kuchta R. J. Alvarez II Y. H. Li D. A. Krueger C. Y. She 《Applied physics. B, Lasers and optics》1990,50(2):129-132
The Doppler-free line shape of the 6s
2
1
S
0 – 6s
16p
1
1
P
1 transition at 553.5 nm in natural Ba in the presence of an argon or helium buffer gas has been measured at 744 K for gas pressures from 0.2 to 100 Torr. Using the measured data for pressures above 5 Torr, the broadening rate coefficients for the half width at half maximum (HWHM) are determined to be (4.9±0.5)10–9 and (5.0±0.5)10–9 s–1 cm–3 for helium and argon respectively. 相似文献
106.
Studies of the barium salts of bromanilic acid, nitranilic acid and polyporic acid show that they are not superior to barium chloranilate as reagents for determining sulfate. Improved syntheses of polyporic acid and atromentin are presented; two new syntheses of barium bromanilate, and one new synthesis of barium nitranilate and of barium polyporate are also presented. Ultraviolet absorption spectra show that polyporic acid forms a dimer in dimethylsulfoxide solution. 相似文献
107.
A. J. A. Aquino L. A. Soares II A. B. F. Da Silva M. Trsic 《Journal of Molecular Structure》1986,139(3-4):327-332
Semiempirical MNDO calculations are performed on various models for the polythiazyl polymer with increasing chain sizes. Population analysis, geometry optimization and the evolution of the frontier orbital energies are discussed. A low-lying broken symmetry structure with (SN)2 repeating units is detected. 相似文献
108.
K. Kuroda E. S. Wilkins Jr C. E. Willoughby E. O. Kraemer F. L. Smith II S. L. Tompsett R. F. Hanzal B. R. Burmester R. R. Roepke H. H. Green J. C. Morgan E. J. King G. E. Vladimirov J. A. Epstein L. D. Behr J. W. Palmer G. Blumenthal und H. T. Clarke 《Fresenius' Journal of Analytical Chemistry》1937,108(1-2):73-80
Ohne Zusammenfassung 相似文献
109.
G.S. Grubbs II 《Journal of Molecular Structure》2010,963(1):87-261
The pure rotational spectrum of perfluoroiodoethane between 8.0 and 11.9 GHz has been measured on a search accelerated, correct intensity Fourier transform microwave (SACI-FTMW) spectrometer. The spectra is dense with 247 measured transitions in the given region. Only the anti conformer was observed for which rotational constants are reported. Nuclear electric quadrupole coupling constants due to the iodine-127 were determined and are reported. Also, two dipole forbidden/quadrupole allowed ΔJ=2 transitions were observed in the spectra. The observation of these transitions has been rationalized on the basis of near degeneracies between energy levels connected by χab. 相似文献
110.
James J. Devery III James J. Douglas John D. Nguyen Kevin P. Cole Robert A. Flowers II Corey R. J. Stephenson 《Chemical science》2015,6(1):537-541
Knowledge of the kinetic behavior of catalysts under synthetically relevant conditions is vital for the efficient use of compounds that mediate important transformations regardless of their composition or driving force. In particular, these data are of great importance to add perspective to the growing number of applications of photoactive transition metal complexes. Here we present kinetic, synthetic, and spectroscopic evidence of the mechanistic behavior of fac-Ir(ppy)3 in a visible light-mediated radical addition to 3-methylindole, demonstrating the instability of fac-Ir(ppy)3 under these conditions. During the reaction, rapid in situ functionalization of the photocatalyst occurs, eventually leading to deactivation. These findings demonstrate a conceivable deactivation process for catalytic single electron reactions in the presence of radicophilic ligands. Attempts to inhibit photocatalyst deactivation through structural modification provide further insight into catalyst selection for a given system of interest. 相似文献