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31.
Summary The formation of ternary complexes of the MAL3– type [where M = CuII, NiII and ZnII ; A = nitrilotriacetic acid (NTA); L = 1-hydroxy-2-naphthoic acid (1,2 HNA) and 2-hydroxy-1-naphthoic acid (2,1 HNA)] have been studied potentiometrically in 50% v/v aqueous — ethanol (25° and µ = 0.1). Under identical conditions the binary complexes of the 1,2- and 2,1-HNA ligands have also been examined. The values of mixed ligand formation constants KMAL have been found to be lower than KML (first step formation constant of binary complexes) and even less than
(second step formation constant of binary complexes). 相似文献
32.
Virendra Singh Anita Rampal S. N. Biswas K. Datta 《Letters in Mathematical Physics》1980,4(2):131-134
The solution of a difference equation in the form of an infinite continued fraction is used to obtain a class of exact solutions for the eigenfunctions and eigenvalues of doubly anharmonic oscillators described by potentials of the type (1/2)2x2+(1/4)x4+(1/6)x6, n>0, provided certain constraints on the couplings are satisfied. The class is denumerably infinite but not complete. 相似文献
33.
Datta S Kumar K 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,62(1-3):473-477
The isotropic component of Raman band for C=O stretching mode of acetophenone in solution was analyzed by estimating the correlation coefficient with reference to Lorentzian lineshape. In the intermediate region of solute/solvent concentration there is a sharp decrease in the correlation coefficient and there appears to be a transition from non-Lorentzian to Lorentzian lineshape. The vibrational relaxation rates have been estimated from the isotropic component of Raman band in different solvents. The rate is shown to be dependent on several macroscopic as well as microscopic properties of the solute-solvent system and intermolecular interactions. The hydrodynamic and dispersion forces appear to play a major role in determining the vibrational relaxation rate and the broadening of the bands. 相似文献
34.
The stepwise acid dissociation constants for p-benzohydroquinone (QH2) in aqueous media have been explicitly calculated for the first time, with the INDO parametrized SCF –MO method. We have optimized the geometries of QH2, QH?, and Q2? and of the QH2 · 6H2O, QH? · (H3O+) · 5H2O, and Q2? · (H3O+)2 · 4H2O systems that model the solvated species. The presence of the associated water molecules (and hydronium ions) account for the stabilization due to hydrogen bonding as well as for a part of the effect of interaction of these molecules with the respective reaction fields in an aqueous medium. To simulate the first solvation shell in a more complete manner, four more water molecules have been considered to be placed above and below the quinonoid ring and the optimized geometries of the resulting hydrated species, QH2 · 10H2O, QH? · (H3O+) · 9H2O, and QH? · (H3O+) · 8H2O, have been determined. The standard free-energy changes calculated for the dissociation of QH2 into QH? and H+ is 0.0251 Hartree (65.9 kJ mol?1) and that of QH? into Q2? and H+ is 0.0285 Hartree (74.8 kJ mol?1). Experimentally observed dissociation constants for these two steps correspond to free-energy changes of 0.0214 Hartree (56.2 kJ mol?1) and 0.0248 Hartree (65.1 kJ mol?1), respectively. © 1995 John Wiley & Sons, Inc. 相似文献
35.
36.
Datta K Mukherjee AK 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,62(1-3):66-70
By UV-vis spectrophotometric method it has been shown that 1,3,5-tribromobenzene (TBB) forms molecular complexes of 1:2 stoichiometry with [60]- and [70]fullerenes. An isosbestic point could be detected in case of the [70]fullerene complex. The formation constant of the [60]fullerene complex is higher than that of the [70]fullerene complex at each of the four temperatures under study. This is in opposite order of the electron affinities of the two fullerenes; moreover, no charge transfer band was observed in the spectra of either complex in solution. This indicates that van der Waals forces, rather than CT interactions, are responsible for complexation. The results reveal that the C-atoms at the pentagon vertices of [60]fullerene have greater polarizing power than those in [70]fullerene. 相似文献
37.
The racemization of an optically active sulfilimine and optically active aminosulfonium salts was kinetically measured. The mechanism of the racemization of optically active sulfilimine (?)-1 has been established. The activation parameters for the racemization of (?)-1 and (?)-7 were calculated. A plausible pathway for the decomposition of (?)-6, (?)-7 and (?)-8 with tetra-n-butylammonium bromide in the presence of methyl ethyl ketone to provide 3-p-tolylthio-2-butanone 22 is proposed. 相似文献
38.
K. L. Baluja Anju Gupta Savita M. Datta 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1993,28(2):105-108
Configuration interaction wavefunctions, transition energies, line strengths and transition probabilities for allowed transitions within then=2 complex of C-like Fe XXI have been calculated in the LS coupling scheme. We included internal, semi-internal, and all-external types of correlations. We compare our non-relativistic line strengths values with those of relativistic calculations in the Breit-Pauli approximation. The relativistic effects on line strengths are negligible for all transitions except for the transition1 D e →1 D 0. Experimental wavelengths are used in the calculation of transition probabilities. 相似文献
39.
Sachindra Kumar Datta 《Fresenius' Journal of Analytical Chemistry》1959,168(6):418-424
Summary Eighteen anilic acids have been prepared from maleic anhydride and various aromatic amines and their properties and analytical reactions with various metal ions have been studied. The acid prepared from benzidine was insoluble in all common solvents and, hence, its application could not be studied. Most of these reagents, except those obtained from aniline, o- and p-chloroanilines, nitranilines, p-amino-acetanilide and o-phenylenediamine, produced more or less quantitative precipitations with both thorium and zirconium. Their actions towards thorium and zirconium were very much alike. They also gave precipitations with mercury(I), lead and cerium(IV), but such precipitations were not complete. Ferrous iron showed greyish turbidity with most of the reagents, but ferric iron produced colourations varying from brown to violet, such colours were, however, found to be unstable either on standing for a while or on heating. Gold and platinum underwent reduction in presence of these reagents.Part VIII: See Z. analyt. Chem. 163, 403 (1958).The work has been carried out in the chemical laboratories of Darjeeling Government College, Darjeeling. The author is grateful to the authorities of the College for the laboratory facilities. 相似文献
40.