全文获取类型
收费全文 | 175篇 |
免费 | 1篇 |
专业分类
化学 | 84篇 |
力学 | 16篇 |
数学 | 9篇 |
物理学 | 67篇 |
出版年
2022年 | 6篇 |
2021年 | 2篇 |
2020年 | 4篇 |
2019年 | 9篇 |
2018年 | 1篇 |
2017年 | 2篇 |
2016年 | 1篇 |
2015年 | 1篇 |
2014年 | 6篇 |
2013年 | 11篇 |
2012年 | 10篇 |
2011年 | 11篇 |
2010年 | 5篇 |
2009年 | 5篇 |
2008年 | 7篇 |
2007年 | 12篇 |
2006年 | 9篇 |
2005年 | 11篇 |
2004年 | 9篇 |
2003年 | 11篇 |
2002年 | 7篇 |
2001年 | 3篇 |
2000年 | 5篇 |
1999年 | 4篇 |
1997年 | 1篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 1篇 |
1992年 | 3篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1982年 | 2篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1975年 | 1篇 |
1974年 | 2篇 |
1966年 | 1篇 |
排序方式: 共有176条查询结果,搜索用时 156 毫秒
101.
Intramolecular hydride transfer between 1,4-dihydronicotinamide and nicotinamidium moieties connected by a polymethylene chain ?(CH2)n? is studied by the 1H-spin saturation transfer technique. For n=3 an effective molarity EM=210 is found for the 4,4′-hydride exchange which is not accompanied by the competing 4,6′ and solvent exchange processes reported in related intermolecular reactions. 相似文献
102.
The convex feasibility problem asks to find a point in the intersection of finitely many closed convex sets in Euclidean space. This problem is of fundamental importance in the mathematical and physical sciences, and it can be solved algorithmically by the classical method of cyclic projections.In this paper, the case where one of the constraints is an obtuse cone is considered. Because the nonnegative orthant as well as the set of positive-semidefinite symmetric matrices form obtuse cones, we cover a large and substantial class of feasibility problems. Motivated by numerical experiments, the method of reflection-projection is proposed: it modifies the method of cyclic projections in that it replaces the projection onto the obtuse cone by the corresponding reflection.This new method is not covered by the standard frameworks of projection algorithms because of the reflection. The main result states that the method does converge to a solution whenever the underlying convex feasibility problem is consistent. As prototypical applications, we discuss in detail the implementation of two-set feasibility problems aiming to find a nonnegative [resp. positive semidefinite] solution to linear constraints in n [resp. in
, the space of symmetric n×n matrices] and we report on numerical experiments. The behavior of the method for two inconsistent constraints is analyzed as well. 相似文献
103.
Katalin E. Kvr Gyula Batta Jozef Kowalewski Leila Ghalebani Danuta Kruk 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2004,167(2):239
Conventional relaxation parameters (T1−1, T2−1, and NOE), obtained at different temperatures and magnetic fields, are reported for the hydroxymethyl (C6) carbon in methyl-β-
-glucopyranoside in a D2O/DMSO cryosolvent. These data are interpreted with the Lipari–Szabo model. In addition, two-field measurements of longitudinal and spin-locked relaxation rates related to the cross-correlated carbon–proton dipole–dipole interactions for the same carbon are reported. The complete data set consisting the conventional and cross-correlated relaxation parameters is interpreted using a new “hybrid” approach, in which the Lipari–Szabo model for the auto-correlated spectral densities is combined with the two-site jump model for the cross-correlated spectral densities, with the global correlation time as a common parameter. The two-site jump rates thus obtained are in reasonable agreement with the ultrasonic relaxation measurements, and have reasonable temperature dependence. 相似文献
104.
The forced nonlinear vibrations of a cylindrical shell fully filled with a fluid in instability zones of single-mode deformation are analyzed. It is shown that the deformation mode of the shell in these zones is traveling bending waves propagating in the circumference direction. The effect of the fluid on the characteristics of these waves is studied__________Translated from Prikladnaya Mekhanika, Vol. 41, No. 5, pp. 76–82, May 2005. 相似文献
105.
Forced nonlinear vibrations of cylindrical shells partially filled with a liquid are studied. The wave motions of the free liquid surface are taken into account. Regular periodic deformation modes of the shell are studied, and frequency ranges where these modes do not occur are determined 相似文献
106.
Svetlana G. Pukhovskaya Dao Tkhe Nam Yulia B. Ivanova Lizaveta S. Liulkovich Alexander S. Semeikin Sergei A. Syrbu Mikalai M. Kruk 《Journal of inclusion phenomena and macrocyclic chemistry》2017,89(3-4):325-332
Macrocycle acidity and Zn2+ ion coordination are reported for three porphyrin derivatives which differ in both steric and electronic substitution effects on the macrocycle π-conjugated system. The role of the electronic substitution effects in the macrocycle deprotonation and metal ion chelating was found to be dominating whereas the macrocycle nonplanar distortions contribute to the acidity and metal chelation rate of the studied porphyrins in less extent. The contributions of both resonance and inductive electronic substitution effects have been distinguished based on the relationship between the weighted sum of resonance and inductive Hammett constants and the acidity and metal ion chelation rate. 相似文献
107.
108.
The problem of determination of the hydrodynamic characteristics of an ideal incompressible liquid moving with constant velocity
past a spherical body in an infinite circular cylinder is considered. It is assumed that the cylinder axis passes through
the mass center of the spherical body. The total liquid potential has been constructed both in spherical and cylindrical coordinate
systems. The hydrodynamic characteristics of the flow in the cylinder were researched based upon comparison with the corresponding
characteristics of the liquid flow of a spherical body in a boundless medium.
S. P. Timoshenko Mechanics Institute, National Academy of Sciences of Ukraine, Kiev. Translated from Prikladnaya Mekhanika,
Vol. 35, No. 6, pp. 27–31, June, 1999. 相似文献
109.
110.
Kruk M. M. Pukhovskaya S. G. Ivanova Yu. B. Koifman O. I. 《Russian Chemical Bulletin》2020,69(6):1072-1075
Russian Chemical Bulletin - Enthalpy—entropy compensation upon the coordination of zinc ions by porphyrins with various structural organizations of peripheral substitution in solutions at 298... 相似文献