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排序方式: 共有214条查询结果,搜索用时 125 毫秒
1.
Radiophysics and Quantum Electronics - Wind-related weather hazards remain difficult to recognize targets for weather radars. Methods that use estimates of the width of the reflected-signal... 相似文献
2.
The steady motion of a spheroidal aerosol particle with inner nonuniformly distributed heat sources (sinks) that is placed
in an external temperature gradient is theoretically studied in the Stokes approximation. The mean temperature of the particle
surface is assumed to differ slightly from that of the gaseous environment. An analytic expression for the force and rate
of thermophoresis are found by solving the gas-dynamic equations in view of the motion of the environment. 相似文献
3.
R. F. Klevtsova L. A. Glinskaya V. G. Shchukin S. V. Larionov 《Journal of Structural Chemistry》2002,43(1):133-141
Single crystals of the mixed-ligand complex compounds of Cd(i-Bu2PS2)2 with Phen and 2,2-Bipy have been obtained. The crystal structures of the complexes [CdPhen{(i-C4H9)2PS2}2] (I) and [Cd(2,2-Bipy){(i-C4H9)2PS2}2] (II) were determined by X-ray diffraction (CAD-4 diffractometer, MoK
radiation, 1739 F
F
hkl
, R = 0.0417 for I and 2612 F
hkl
, R = 0.0442 for II). Monoclinic crystals with unit cell parameters a = 15.640(3), b = 20.797(4), c = 11.559(2) , = 111.21(3)°, V = 3505(1) 3, Z = 4, d
calc = 1.348 g/cm3, space group
(I); a = 14.737(3), b = 20.918(4), c = 11.517(2) , = 105.53(3)°, V = 3421(1) 3, Z = 4, d
calc = 1.334 g/cm3, space group
(II). The structures consist of discrete monomer molecules. The coordination polyhedra of the Cd atoms are distorted octahedra formed by four S atoms of two cyclic bidentate ligands i-Bu2
and two N atoms of the cyclic bidentate ligands — Phen or 2,
-Bipy molecules. The interaction between molecules I and II in the structures and the packing modes are considered. 相似文献
4.
R. F. Klevtsova L. A. Glinskaya V. G. Shchukin S. V. Larionov 《Journal of Structural Chemistry》2001,42(3):446-453
Volatile mixed-ligand complexes of Zn(i-Bu2PS2)2 with Phen and 2,2-Bipy have been synthesized. The crystal structures of the complexes ZnPhen{(i-C4H9)2PS2}2 and Zn(2,2-Bipy){(i-C4H9)2PS2}2 were determined by single crystal X-ray diffractometry (CAD-4 diffractometer, MoK radiation, 2100 Fhkl, R = 0.0423 for the first complex and 2003 Fhkl, R = 0.0486 for the second). The crystals are monoclinic with cell dimensions a = 17.580(4), b = 9.969(2), c = 19.175(4) , = 90.33(3)°, V = 3360(1) 3, Z = 4, d
calc = 1.313 g/cm3, space group P2/n (for the Phen complex); a = 24.219(5), b = 11.386(2), c = 24.916(5) , = 97.70(3)°, V = 6809(2) 3, Z = 8, d
calc = 1.249 g/cm3, space group C2/c (for the 2,2-Bipy complex). The complexes are constructed from discrete monomer molecules. The coordination polyhedra of the Zn atoms are distorted tetrahedra formed by two S atoms of the two monodentate i-Bu2PS
2
-
ligands and two N atoms of the cyclic bidentate Phen or 2,2-Bipy molecules. Intermolecular interactions and packings in the structures are analyzed. 相似文献
5.
E. A. Amelina I. V. Videnskii N. I. Ivanova A. M. Parfenova V. V. Pelekh N. V. Altukhova E. D. Shchukin 《Colloid Journal》2001,63(5):527-531
The effect of cationic surfactants (cetyltrimethylammonium bromide and tetrabutylammonium iodide) and cationic polyelectrolyte polyethylenimine on the coefficient of friction and adhesion force p(during shear and tensile testing, respectively) at the point contacts between the individual fibers of cellulose, viscose, and cellulose acetate was studied. The comparison of these data with the results of -potential and adsorption measurements enabled us to relate the nonmonotonic dependence of parameters and pon the surfactant concentration to the changes in electrosurface properties and the hydrophilicity or hydrophobicity of the fibers. The specific free energy of interaction U[mJ/m2] was estimated for cellulose acetate fibers. 相似文献
6.
Yu. M. Atroshchenko N. K. Melekhina I. V. Shakhkel’dyan I. E. Yakunina A. N. Shchukin E. V. Shuvalova V. A. Subbotin 《Russian Journal of Organic Chemistry》2006,42(8):1220-1224
The electrophilic chlorine addition to 3-substituted 1,5-dinitro-3-azabicyclo[3.3.1]-non-6-enes in the tetrachloromethane is accompanied at an intramolecular 3,7-cyclization giving 6-chloro-3-R-1,5-dinitro-3-azoniatricyclo[3.3.1.03,7]nonane chlorides. The reaction of the tricyclic quaternary ammonium salts with sodium methoxide leads to the formation of dealkylated and dehydrohalogenated products, 3-substituted 8-chloro-1,5-dinitro-3-azabicyclo[3.3.1]non-6-enes, bicyclic products with a halogen atom in an allyl position with respect to the double bond. 相似文献
7.
Carbon-carbon bond deformation curves for fluorinated ethylene molecules and the corresponding carbocations were calculated
by the ab initio self-consistent field method in the 5-31G basis set. The maximum force required for bond cleavage was taken
as a criterion for bond strength. It has been found that for ethylene, replacement of hydrogen by fluorine insignificantly
strengthens the C=C bonds in symmetric molecules. However, in molecules with an asymmetric arrangement of fluorine atoms,
the bond is slightly weakened due to different charges on the carbon atoms. The configuration of the corresponding carbocations
also depends on the bond polarity: an assymmetric distribution of electron density in the C=C bond region leads to the formation
of σ-complexes, while a symmetric distribution of electron density (pure covalent bonding) gives π-complexes. Since the carbon-carbon
bond in the σ-complexes is essentially weaker, one should expect significant weakening of the bond in high-acidity media if
the bond exhibits any kind of asymmetry (chain branching, defects, etc.). For the considered molecules, an antibatic correlation
has been established between the strength criterion Fmax (unlike the dissociation energy) and the bond length.
Institute of Physical Chemistry, Russian Academy of Sciences, Moscow. Translated fromZhurnal Strukturnoi Khimii, Vol. 36, No. 1, pp. 34–41, January–February, 1995.
Translated by I. Izvekova 相似文献
8.
V. B. Zakharov M. G. Mal’kovskii V. Yu. Shchukin 《Moscow University Computational Mathematics and Cybernetics》2016,40(1):47-52
Block compression algorithms used for solving the problem of 7-piece chess endings are presented. The algorithms are based on data reordering before compression, the RE-PAIR compression algorithm, and use of the so-called underdetermined value method. 相似文献
9.
A.?F.?Belikova S.?N.?BuravovaEmail author E.?V.?Petrov N.?V.?Sachkova A.?S.?Shchukin 《Russian Journal of Physical Chemistry B, Focus on Physics》2016,10(3):444-450
Under conditions of high-rate loading, plastic strain localization is a result of tension in the zone of interference of unloading waves rather than of thermal softening. At stresses close to the dynamic strength of the material, the microstructure of localized strain bands consists of strongly deformed material, with a large number of incipient microdiscontinuities. At stresses below the Hugoniot elastic limit, the microstructure looks as a set of barely visible stripes. The finely striped structure at the edges of the bands of a spall damage arises as a result of the stretching of initially rounded damage centers attached to the matrix material during dynamic deformation. 相似文献
10.