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排序方式: 共有514条查询结果,搜索用时 265 毫秒
31.
M. Aulice Scibioh P. V. Ragini S. Rani V. R. Vijayaraghavan B. Viswanathan 《Journal of Chemical Sciences》2001,113(4):343-350
With the aim of finding a suitable electrocatalyst for the efficient reduction of carbon dioxide, the electrochemistry of
nickel (II) complex of 1,3,6,9,11,14-hexaazatricyclo [12·2·1·1] octadecane was studied using cyclic voltammetry (CV) and controlled-potential
electrolysis (CPE) techniques in the presence and absence of CO2 in 100% H2O, CH3CN-H2O mixtures (20–100%) and DMF-H2O (70–100%) mixtures. The efficiency of this process is determined using the coulometry technique. CO is the major product
in the gaseous phase and HCOOH the sole product formed in the solution phase. 相似文献
32.
The first 1,3-dipolar reaction of azomethine ylides with optically pure vinyl sulfoxide are reported. The presence of the sulfinyl group increase the reactivity of the acrylate moiety as a dipolarophile, and the reactions evolve with complete regio- and endo-selectivities. Nevertheless, mixtures of the two diastereoisomers 4 and 5 (75-88% de) resulting from the anti dipole/s-cis dipolarophile and syn dipole/s-trans dipolarophile approaches, respectively, are obtained. The stereoselectivity can be controlled by using THF or MeCN as solvents or by changing the reaction temperature in MeCN. After separation of the cycloadducts, optically pure 2,5-dihydro-1H-pyrroles are easily obtained by pyrolytic desulfinylation. 相似文献
33.
Venkatraman S Anand VG PrabhuRaja V Rath H Sankar J Chandrashekar TK Teng W Senge KR 《Chemical communications (Cambridge, England)》2002,(16):1660-1661
First successful syntheses and structural characterization of new core modified meso aryl azuliporphyrins by a simple [3 + 1] methodology are reported. 相似文献
34.
35.
K. S. Viswanathan G. S. Dwarakanath V. V. Shanbhag 《Proceedings Mathematical Sciences》1971,74(3):115-132
The structure of strong shock waves in monatomic gases is studied using the Fokker-Planck model to represent the particle collisions and the Mott-Smith distribution to describe the distribution function within the shock front. The differential equation governing the variation of the density within the shock is derived by using the variational principle. The thickness of the shock front is evaluated numerically for various monatomic gases for Mach numbers varying from 2 to 20, and besides, the variation of the shock thickness with viscosity is also studied for different gases. Several parameters of physical interest within the shock, such as density, temperature and mean velocity of flow are evaluated numerically and detailed curves showing their variation within the shock are presented for different Mach numbers. It is found that the temperature rises very steeply, reaches a maximum within a distance less than half the thickness of the shock and then diminishes slowly to attain its asymptotic downstream values. The variation of the mean velocity is slow for weak shocks, but for higher Mach numbers, the mean velocity diminishes steeply and reaches the downstream values within half the thickness of the shock. 相似文献
36.
B. Viswanathan C. V. Bhuvana M. V. C. Sastri 《Reaction Kinetics and Catalysis Letters》1979,11(2):173-177
Molecular orbital calculations of charge distributions for the -allyl complex with transition metal ions in molybdates show that the activated -allyl species is formed by transfer of charge density to the metal ion. The relative charge distributions on the three carbon atoms of the adsorbed allyl species govern the course of oxidation reaction.
- , - . .相似文献
37.
Hexagonal Se shows no indication of a transformation to a metallic, superconducting phase up to 160 kbar. Amorphous Se transforms at about 130 kbar to an unstable metallic, superconducting state which anneals slowly at room temperature toward a non-metallic, non-superconducting phase. Monoclinic Se behaves much like amorphous Se. X-ray diffraction indicates that all samples are in the hexagonal phase after release of pressure. 相似文献
38.
A theory has been given for the scattering of neutrons by anharmonic crystals, for which terms of the typeV
(3) (k
1j1; —k
1j1;o
j) which contribute to the sublattice displacements are not neglected. Using the standard perturbation theory in the interaction
picture or Green’s function method, an expression has been derived for the differential scattering cross-section which brings
in the shift and the width of the phonons in one-phonon energy exchange processes. It is shown that the sublattice displacements
will modify the phase factor arising from the scattering by any atom in the unit cell, and the Debye-Waller factor also gets
altered both by the sublattice displacements as well as by higher order terms arising from anharmonicity. It is shown that
the differential scattering cross-section contains a term linearly depending on the third order anharmonicity coefficientV
(3) (k
1j1;k
2j2;k
3j3) and neutron scattering by crystals should provide a useful method for evaluating the third order anharmonicity coefficients. 相似文献
39.
40.