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351.
ABSTRACTThe rapid development of consumer electronics and portable devices imposes a great demand for energy efficient information display systems. Among the information display devices, liquid crystal display (LCD) devices stands in the front. The fabrication of energy-efficient LCD systems demands new material and techniques. In this work, the conventional polyimide alignment layer of twisted nematic liquid crystal device (TNLCD) was replaced with ferroelectric polymer nanoparticle doped alignment layer. Morphology of the alignment layer was analysed using field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM). The ferroelectric nature of the polymer alignment layer was studied using dynamic contact electrostatic force microscopy (DC-EFM). TNLCD cells are fabricated with this modified alignment layer and the switching characteristics are compared with the conventional TNLCD devices. The TNLCD with modified alignment layer has shown a reduction of 50% in threshold (Vthr) and 47% reduction in saturation voltage (Vsat). 相似文献
352.
T. Varghese K. M. Balakrishna 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,57(1):9-11
The electron momentum distribution and Compton profiles of the rare earth
element Eu was measured using HPGe photon detector. The target atoms were
excited by means of 59.54 keV gamma rays from Am-241 radioactive source of
strength 300 mCi. Elemental foil of uniform aerial density, and purity
better than 99.9% was used as target. The data were recorded and analyzed
using a 4 K multichannel analyzer. These data duly corrected for instrumental
resolution effects, sample absorption, energy dependence of the differential
Compton cross-section and double scattering, and compared with theoretical
renormalized free atom (RFA) values. 相似文献
353.
Data reduction is an important issue in the field of data mining. The goal of data reduction techniques is to extract a subset of data from a massive dataset while maintaining the properties and characteristics of the original data in the reduced set. This allows an otherwise difficult or impossible data mining task to be carried out efficiently and effectively. This paper describes a new method for selecting a subset of data that closely represents the original data in terms of its joint and univariate distributions. A pair of distance criteria, motivated by the χ2-statistic, are used for measuring the goodness-of-fit between the distributions of the reduced and full datasets. Under these criteria, the data reduction problem can be formulated as a bi-objective quadratic program. A genetic algorithm technique is used in the search/optimization process. Experiments conducted on several real-world data sets demonstrate the effectiveness of the proposed method. 相似文献
354.
Bhavana Purushothaman Babu Varghese Puttaiah Bhyrappa 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(3):252-253
In the title complex, [Zn(C36H20N4S4)], the ZnII ion occupies a special position on an inversion centre with four-coordinate geometry. The porphyrin ring shows a wave-like conformation, with the closest interporphyrin plane separation being 3.60 (6) Å. The two disordered thienyl groups are inclined with respect to the porphyrin plane at angles of 70 (4) and 67 (2)°. 相似文献
355.
Vinayakrishnan Rajan Babu Varghese Ton G. van Leeuwen Wiendelt Steenbergen 《Optics Communications》2008,281(6):1755-1760
We report on the dependence of the decorrelation time on the spatial intensity correlation of speckles generated in the far-field by back-scattered photons from turbid media. The effects contribute to an explanation of an earlier observation that the average Doppler width of the power spectrum of detector current fluctuations depends on the size of the illuminating laser beam. The space-time correlation of the speckles generated by a particle suspension illuminated by a collimated laser beam is analyzed from serial images taken by a high speed camera. It was found that larger spatial correlation distances, associated with large speckles, exhibit a slower temporal decorrelation. 相似文献
356.
A molecular salt with formula [BmIm]3[PMo12O40]3? has been prepared using room temperature ionic liquid and phosphomolybdic acid. The material is characterized by single-crystal X-ray diffraction. The compound crystallizes in orthorhombic system with space group Pca21. It is also characterized by CHN analysis, 31P MAS NMR, UV–vis DRS and near-IR methods. Thermal stability of the compound is investigated by TGA, IR and PXRD methods. Near-IR shows the loss of water of crystallization by the Keggin ions of phosphomolybdic acid bonded with ionic liquid. 相似文献
357.
Absorption and fluorescence studies on novel Schiff bases (E)-4-(4-(4-nitro benzylideneamino)benzyl)oxazolidin-2-one (NBOA) and (E)-4-(4-(4-chlorobenzylidene amino)benzyl)oxazolidin-2-one (CBOA) were recorded in a series of twelve solvents upon increasing polarity at room temperature. Large Stokes shift indicates bathochromic fluorescence band for both the molecules. The photoluminescence properties of Schiff bases containing electron withdrawing and donating substituents were analyzed. Intramolecular charge transfer behavior can be studied based on the influence of different substituents in Schiff bases. Changes in position and intensity of absorption and fluorescence spectra are responsible for the stabilization of singlet excited-states of Schiff base molecules with different substituents, in polar solvents. This is attributed to the Intramolecular charge transfer (ICT) mechanism. In case of electron donating (?Cl) substituent, ICT contributes largely to positive solvatochromism when compared to electron withdrawing (?NO2) substituent. Ground-state and singlet excited-state dipole moments of NBOA and CBOA were calculated experimentally using solvent polarity function approaches given by Lippert–Mataga, Bakhshiev, Kawskii-Chamma-Viallet and Reichardt. Due to considerable π- electron density redistribution, singlet excited-state dipole moment was found to be greater than ground-state dipole moment. Ground-state dipole moment value which was determined by quantum chemical method was used to estimate excited-state dipole moment using solvatochromic correlations. Kamlet-Abboud-Taft and Catalan multiple linear regression approaches were used to study non-specific solute-solvent interaction and hydrogen bonding interactions in detail. Optimized geometry and HOMO-LUMO energies of NBOA and CBOA have been determined by DFT and TD-DFT/PCM (B3LYP/6-311G (d, p)). Mulliken charges and molecular electrostatic potential have also been evaluated from DFT calculations. 相似文献
358.
Hema Tresa Varghese C. Yohannan Panicker V.S. Madhavan Samuel Mathew Jarmila Vinsova Christian Van Alsenoy 《Journal of Raman spectroscopy : JRS》2009,40(9):1211-1223
FT‐IR and FT‐Raman spectra of 4‐chloro‐2‐(4‐bromophenylcarbamoyl)phenyl acetate were recorded and analyzed. The vibrational wavenumbers and corresponding vibrational assignments were examined theoretically using the Gaussian03 set of quantum chemistry codes. The red shift of the NH stretching wavenumber in the infrared (IR) spectrum from the computed wavenumber indicates the weakening of the NH bond resulting in proton transfer to the neighbouring oxygen atom. The simultaneous IR and Raman activations of the CO stretching mode give the charge transfer interaction through a π‐conjugated path. Optimized geometrical parameters of the title compound are in agreement with similar reported structures. From the optimized structure, it is clear that the hydrogen bonding decreases the double bond character of CO bond and increases the double bond character of the C N bonds. The first hyperpolarizability, predicted infrared intensities and Raman activities are reported. The calculated first hyperpolarizability is comparable with the reported values of similar derivatives and is an attractive object for future studies of non‐linear optics. The assignments of the normal modes are done by potential energy distribution (PED) calculations. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
359.
Gnana Sutha Siluvai Babu Varghese Narasimha N. Murthy 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(6):o380-o382
In the title salt, 1,3‐bis{[2‐(2‐pyridinio)ethyl][2‐(2‐pyridyl)ethyl]amino}benzene diperchlorate dihydrate, C34H38N62+·2ClO4−·2H2O, the cation contains two ethylpyridyl and two ethylpyridinium pendant pairs anchored to the two N atoms of 1,3‐phenylenediamine. The pyridyl and pyridinium N atoms are flanked by a molecule of water through strong hydrogen‐bonding interactions [N—H⋯O = 2.762 (6) and 2.758 (6) Å, and O—H⋯N = 2.834 (6) and 2.839 (6) Å]. The water molecules have weak hydrogen‐bonding interactions with the perchlorate anions as well. One of the perchlorate anions is severely disordered. 相似文献
360.
Effect of post thermal annealing on the structural and optical properties of ZnO thin films prepared from polymer precursor
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ZnO thin films were synthesised by a new method which uses polyvinyl alcohol (PVA) as polymer precursor. The films are annealed at different temperatures and for different annealing times. The structural parameters, like grain size, lattice constants, optical band gap, and Urbach energy, depend on the annealing temperature and annealing time. All the films possess tensile strain which relaxes as the annealing temperature and the annealing time increases. The photoluminescence (PL) spectra contain only ultraviolet (UV) peaks at low temperature, but as the annealing temperature and time increase we observe peaks at blue and green regions with variation of the intensities of these peaks with annealing temperature and annealing time. 相似文献