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121.
Accurate calculation of absolute one-electron redox potentials of some para-quinone derivatives in acetonitrile 总被引:1,自引:0,他引:1
Standard ab initio molecular orbital theory and density functional theory calculations have been used to calculate absolute one-electron reduction potentials of several para-quinones in acetonitrile. The high-level composite method of G3(MP2)-RAD is used for the gas-phase calculations and a continuum model of solvation, CPCM, has been employed to calculate solvation energies. To compare the theoretical reduction potentials with experiment, the reduction potentials relative to a standard calomel electrode (SCE) have also been calculated and compared to experimental values. The average error of the calculated reduction potentials using the proposed method is 0.07 V without any additional approximation. An ONIOM method in which the core is studied at G3(MP2)-RAD and the substituent effect of the rest of the molecule is studied at R(O)MP2/6-311+G(3df,2p) provides an accurate low-cost alternative to G3(MP2)-RAD for larger molecules. 相似文献
122.
An experimental method based on confocal microscopy and particle image velocimetry (PIV) is used to characterize the flow
in a polymer solution during solvent casting. The flow inside a 200-μm-thick film of a poly(vinyl alcohol) (PVA) solution
is visualized near a vertical wall of a mold using confocal microscopy of seed particles during solvent evaporation at 25,
35, and 45°C, and the corresponding velocity vector fields are determined from projections of the confocal images. Flow toward
the vertical wall is observed inside the film as well as a slower Marangoni-type counter flow at the film surface during the
initial phase of solvent evaporation, resulting from a polymer concentration gradient along the film due to a local variation
in evaporation rate. Total volume of the polymer solution in the observation volume as well as solvent evaporation rate are
determined as a function of time, both revealing close correlation to average horizontal velocity data from PIV. The PIV measurements
show significant differences in the flow velocity fields at different temperatures. The PIV measurements correlate with the
solvent evaporation rates as well as the final polymer thicknesses on the vertical wall of the mold. Surface tension and viscosity
measurements are taken for different concentrations of PVA solution. 相似文献
123.
Ab initio molecular orbital theory has been used to calculate enthalpies of formation of the keto tautomers of 1-hydroxyisoquinoline, 5-hydroxyisoquinoline, and 1,5-dihydroxyisoquinoline. The high-level composite method G3//B3LYP has been used for this study, and the results have been compared with available experimental values. The keto tautomer is more favourable for 1-hydroxyisoquinoline and 1,5-dihydroxyisoquinoline, and the experimental enthalpies of formation are in better agreement with the theoretical enthalpies of formation of the keto forms. 相似文献
124.
125.
Mansoor Anbia Fatimah Ahmadian Marzie Rezaie 《Journal of the Iranian Chemical Society》2018,15(11):2533-2540
In this study, TiO2 nanoparticles have been obtained from low-grade ilmenite ore via two consecutive acid digestion and solvent extraction processes. The as-extracted TiO2 (Anatase phase) product was characterized using techniques such as XRD, XRF, FESEM, FTIR and BET surface area. Diluted sulfuric acid and D2EHPA (bis-(2-ethyl-hexyl) phosphoric acid) were used as digester agent and an extraction solvent, respectively. The effects of main parameters such as recycling capacities and D2EHPA concentration, as well as the extraction time and temperature on TiO2 extraction were investigated. The results demonstrated that the best performance and efficiency for titanium and total iron uptake were 99 and 3.8%, respectively, at the lowest concentration of D2EHPA. 相似文献
126.
Ab initio molecular orbital theory has been used to calculate enthalpies of formation of isoquinoline, 1-hydroxyisoquinoline, 5-hydroxyisoquinoline, and 1,5-dihydroxyisoquinoline as well as some pyridine and quinoline derivatives. The proton affinities of the four isoquinoline derivatives were also obtained. The high-level composite methods G3(MP2), G3(MP2)//B3LYP, G3//B3LYP, and CBS-QB3 have been used for this study, and the results have been compared with available experimental values. For six of the eight studied compounds, the theoretical enthalpies of formation were very close to the experimental values (to within 4.3 kJ · mol−1); where comparison was possible, the theoretical and experimental proton affinities were also in excellent agreement with one another. However, there is an extraordinary discrepancy between theory and experiment for the enthalpies of formation of 1-hydroxyisoquinoline and 1,5-dihydroxyisoquinoline, suggesting that the experimental values for these two compounds should perhaps be re-examined. We also show that popular low cost computational methods such as B3LYP and MP2 show very large deviations from the benchmark values. 相似文献
127.
Hamed Akbari Khorami Mansoor Keyanpour-RadMohammad Reza Vaezi 《Applied Surface Science》2011,257(18):7988-7992
In this paper, we report the synthesis of SnO2/ZnO composite nanofibers via electrospinning method. Polyvinyl alcohol (PVA)/zinc acetate/stannous chloride nanofibers were electrospun using a solution containing PVA, zinc acetate and stannous chloride in distilled-water followed by calcination at 650 °C for 2 h, obtaining the related composite nanofibers. The nanofibers were characterized by simultaneous thermal analysis (STA), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and Fourier Transform Infrared spectroscopy (FTIR). Ethanol sensing of the nanofibers showed a good and desirable sensing behavior such as high sensitivity, quick response and recovery times. 相似文献
128.
129.
Khalid Mohammed Khan Aneela Karim Sumayya Saied Nida Ambreen Xayale Rustamova Shagufta Naureen Sajid Mansoor Muhammad Ali Shahnaz Perveen M. Iqbal Choudhary Guillermo Antonio Morales 《Molecular diversity》2014,18(2):295-306
Twenty eight (28) derivatives 2–29 were synthesized and four analogs were found to exhibit single-digit $\hbox {IC}_{50}$ values as $\upbeta $ -glucuronidase inhibitors. Molecular modeling indicates that three factors: substituent R, lone pair on the nitrogen of azomethine part, and the interactions made by the main skeleton of the molecule, determined the enzyme inhibitory potential of these compounds. The planar conformation of the molecules allows them to fit deep inside the pocket while blocking the entry of other physiological substrates seems to play an important role in their activity. 相似文献
130.
Mansoor H. Alshehri Barry J. Cox James M. Hill 《The European Physical Journal B - Condensed Matter and Complex Systems》2014,87(9):1-11
Fullerenes have attracted considerable attention in various areas of science and technology. Owing to their exceptional physical, chemical, and biological properties, they have many applications, particularly in cosmetic and medical products. Using the Lennard-Jones 6-12 potential function and the continuum approximation, which assumes that intermolecular interactions can be approximated by average atomic surface densities, we determine the binding energies of a C60 fullerene with respect to both single-strand and double-strand DNA molecules. We assume that all configurations are in a vacuum and that the C60 fullerene is initially at rest. Double integrals are performed to determine the interaction energy of the system. We find that the C60 fullerene binds to the double-strand DNA molecule, at either the major or minor grooves, with binding energies of ?4.7 eV or ?2.3 eV, respectively, and that the C60 molecule binds to the single-strand DNA molecule with a binding energy of ?1.6 eV. Our results suggest that the C60 molecule is most likely to be linked to the major groove of the dsDNA molecule. 相似文献