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81.
Janak Ramakrishnan 《Mathematical Logic Quarterly》2010,56(4):406-408
We prove that a function definable with parameters in an o‐minimal structure is bounded away from ∞ as its argument goes to ∞ by a function definable without parameters, and that this new function can be chosen independently of the parameters in the original function. This generalizes a result in [1]. Moreover, this remains true if the argument is taken to approach any element of the structure (or ±∞), and the function has limit any element of the structure (or ±∞) (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
82.
Seebauer EG Dev K Jung MY Vaidyanathan R Kwok CT Ager JW Haller EE Braatz RD 《Physical review letters》2006,97(5):055503
The technologically useful properties of a crystalline solid depend upon the concentration of defects it contains. Here we show that defect concentrations as deep as 0.5 microm within a semiconductor can be profoundly influenced by gas adsorption. Self-diffusion rates within silicon show that nitrogen atoms adsorbed at less than 1% of a monolayer lead to defect concentrations that vary controllably over several orders of magnitude. The results show that previous measurements of diffusion and defect thermodynamics in semiconductors may have suffered from neglect of adsorption effects. 相似文献
83.
M. Giffhorn B. Becker A. A. Menovsky J. A. Mydosh G. J. Nieuwenhuys S. Ramakrishnan 《高压研究》2013,33(1-6):159-163
Abstract An uniaxial pressure cell for low temperature use is described in detail. Then we present data of the electrical resistance of single crystals of Lu5Ir4Si10, which is known to show a charge-density-wave transition around 83 K and to become superconducting near 3.8 K, both phenomena being anticorrelated under pressure. Since the CDW in Lu5Ir4Si10 is a quasi one-dimensional phenomenon because of a chain-like structure, it responds to uniaxial pressure in a specific way. 相似文献
84.
Umadevi M Vanelle P Terme T Rajkumar BJ Ramakrishnan V 《Journal of fluorescence》2008,18(6):1139-1149
Solvatochromic and preferential solvation of 1,4-dihydroxy-2,3-dimethyl-9,10-anthraquinone (DHDMAQ) have been investigated
using optical absorption and fluorescence emission techniques. Optical absorption spectra of DHDMAQ in different solvents
show the intra molecular charge transfer band in the region 400–550nm. The observed blue shift with solvent polarity indicates
the delocalisation of the excited state, owing to reduction in quasiaromaticity of the chelate rings formed by intra molecular
hydrogen bonds, due to electrostatic or hydrogen bonding interaction. This is also confirmed by the observed low oscillator
strength and the transition dipole moment. The observed quantum yield of DHDMAQ in different solvents is due to the inter
molecular hydrogen bond in the excited state in addition to the intra molecular hydrogen bond. It also reveals from the low
oscillator strength, which indicates that the radiative decay is low. Excited state dipole moment of DHDMAQ is calculated
by solvatochromic data
and it shows a lower value than ground state dipole moment. The preferential solvation parameter shows that in dimethyl formamide
(DMF) + ethanol mixture, the DHDMAQ is preferentially solvated by ethanol in DMF rich region and by DMF in ethanol rich region.
In the case of DMF + dichloromethane mixture DHDMAQ is preferentially solvated by DMF. 相似文献
85.
86.
In this paper, the error estimation and adaptive strategy developed for the linear elastodynamic problem under transient dynamic loading based on the Z–Z criterion is utilized for 2D and plate bending problems. An automatic mesh generator based on “growth meshing” is utilized effectively for adaptive mesh refinement. Optimal meshes are obtained iteratively corresponding to the prescribed domain discretization error limit and for a chosen number of basis modes satisfying modal truncation errors. Numerous examples show the effectiveness of the integrated approach in achieving the target accuracy in finite element transient dynamic analysis. 相似文献
87.
Anti-biofouling properties of comblike block copolymers with amphiphilic side chains 总被引:1,自引:0,他引:1
Krishnan S Ayothi R Hexemer A Finlay JA Sohn KE Perry R Ober CK Kramer EJ Callow ME Callow JA Fischer DA 《Langmuir : the ACS journal of surfaces and colloids》2006,22(11):5075-5086
Surfaces of novel block copolymers with amphiphilic side chains were studied for their ability to influence the adhesion of marine organisms. The surface-active polymer, obtained by grafting fluorinated molecules with hydrophobic and hydrophilic blocks to a block copolymer precursor, showed interesting bioadhesion properties. Two different algal species, one of which adhered strongly to hydrophobic surfaces, and the other, to hydrophilic surfaces, showed notably weak adhesion to the amphiphilic surfaces. Both organisms are known to secrete adhesive macromolecules, with apparently different wetting characteristics, to attach to underwater surfaces. The ability of the amphiphilic surface to undergo an environment-dependent transformation in surface chemistry when in contact with the extracellular polymeric substances is a possible reason for its antifouling nature. Near-edge X-ray absorption fine structure spectroscopy (NEXAFS) was used, in a new approach based on angle-resolved X-ray photoelectron spectroscopy (XPS), to determine the variation in chemical composition within the top few nanometers of the surface and also to study the surface segregation of the amphiphilic block. A mathematical model to extract depth-profile information from the normalized NEXAFS partial electron yield is developed. 相似文献
88.
Jinnah MM Umadevi M Ravikumar B Ramakrishnan V 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2004,60(13):2977-2983
The infrared and Raman spectra of bis(L-threoninium) sulphate monohydrate crystal have been recorded and analysed at room temperature. The proposed assignment of normal modes is based on group theoretical analysis. There is extensive intermolecular hydrogen bonding in the crystal and this is responsible for the changes in the position and intensity of several bands. The anion fundamentals continue to be degenerated which indicates that its symmetry is unaffected in the molecule. 相似文献
89.
Spectral and photophysical properties of 1,6-naphthyridine derivatives: a new class of compounds for nonlinear optics 总被引:1,自引:0,他引:1
Indirapriyadharshini VK Ramamurthy P Raghukumar V Ramakrishnan VT 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2002,58(8):1535-1543
1,6-Naphthyridines are a class of compounds that exhibit second harmonic generation on excitation with a Nd-YAG laser (1064 nm). Solvatochromism has been used to estimate enhancement in the dipole moments on excitation and the values of first-order hyperpolarizability, beta. Photophysical studies on the title compounds show that they have a fluorescence lifetime of about 10 ns and fluorescence quantum yield of approximately 0.05-0.1 in different solvents. Kurtz powder method has been used to find the NLO efficiency of the compounds with reference to urea. 相似文献
90.
Rajkumar BJ Ramakrishnan V 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2001,57(2):247-254
The two methionine cations in the asymmetric part of the unit cell of bis(DL-methionine dihydrogen phosphate) have different conformations. This, together with the different environments seen by the two -CH2- groups in each skeleton cause several of the group wavenumbers to occur as doublets or as broad bands. The anion contains two dissimilar P-O bonds, which distorts the phosphate tetrahedron. Due to this, the stretching wavenumbers appear as doublets. There is extensive hydrogen bonding in the system in all three crystallographic directions and this is responsible for the changes in the position and intensity of several bands. Fermi resonance has also been observed. 相似文献