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1.
G.J. Babonas A. Reza I. Simkiene M. Baran U.O. Karlsson 《Applied Surface Science》2006,252(15):5391-5394
Optical properties of Fe-doped silica films on Si were investigated by ellipsometric technique in the region 1-5 eV. Samples were produced by sol-gel method. Precursors were prepared by mixing tetraethoxysilane (TEOS) solution in ethanol and water with aqueous solution of Fe-chloride or Fe-acetate. The coating solution was deposited on Si substrates by spin on technique. The size of Fe-containing nanometric-sized particles depended on technology and varied from 20 to 100 nm. Optical response of complex hybrid samples SiO2:Fe/Si was interpreted in a multi-layer model. In the inverse problem, the Maxwell equations were solved by transfer matrix technique. Dielectric function of Fe-doped silica layers was calculated in the model of effective media. Analysis of optical data has shown that various Fe-oxides formed. Experimental data for films obtained from precursors with Fe-acetate and annealed in hydrogen were well described by the model calculations taking into account a small contribution 1-5% of metal Fe imbedded in silica. The Fe/Fe-O contribution to optical response increased for samples grown from FeCl3-precursor. Ellipsometric data for Fe-doped silica films on Si were interpreted taking into account the structural AFM studies as well as the results of magnetic measurements. 相似文献
2.
Jilly James Chidambaram Ramalechume Asit Baran Mandal 《Journal of Polymer Science.Polymer Physics》2007,45(17):2410-2420
The shape, size, aggregation, hydration, and correlation times of water insoluble PEO‐PPO‐PEO triblock copolymer micelles with sodium dodecylsulfate (SDS) micelles were investigated using transport studies and dynamic light scattering technique. From the conductance of micellar solutions of the polymer in 25 mM SDS and 5 mM NaCl, the hydration of polymer micelles were determined using the principle of obstruction of electrolyte migration by the polymer. The asymmetry of the micellar particles of polymer and polymer‐SDS mixed micellar systems in 5 mM NaCl and their average axial ratios were calculated using intrinsic viscosity and hydration data obeying Simha–Einstein equation. Hydration number and micellar sizes were variable with temperature. The shape of the polymer micelles has been ellipsoidal rather than spherical. The micellar volume, hydrodynamic radius, radius of gyration, diffusional coefficients as well as translational, rotational and effective correlation times have been calculated from the absolute values of the axes. The partial molal volume of polymer micelles has also been determined and its comparison with the molar volume of pure polymer suggested a volume contraction due to immobilization of the water phase by the hydrophilic head groups of the polymer. The thermodynamic activation parameters for viscous flow favor a more ordered water structure around polymer micelles at higher temperatures. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2410–2420, 2007 相似文献
3.
J. Baran A. J. Barnes M. K. Marchewka A. Pietraszko H. Ratajczak 《Journal of Molecular Structure》1997,416(1-3):33-42
The crystal structure of bis(betaine)-selenic acid has been determined by X-ray diffraction as orthorhombic, space group Pbca, with a = 11.591(2), b = 22.930(5), c = 12.045(2) Å and Z = 8. The crystal comprises hydrogen selenate ions, HSeO−4, and two distinct betaine molecules, which are held together into a complex by short hydrogen bonds. One of the betaine molecules is present as the zwitterion form (CH3)3N+---CH2---COO− and the second occurs as the protonated form (CH3)3N+---CH2---COOH. Powder FTIR and Raman spectra were measured. An assignment of the observed bands to vibrations of the hydrogen bonds and internal vibrations of the hydrogen selenate ion and the betaine molecules is proposed. 相似文献
4.
E. J. Baran 《Monatshefte für Chemie / Chemical Monthly》1973,104(6):1653-1659
The mean amplitudes of vibration of ICl2
–, IBr2
–, BrCl2
– and ClF2
– have been calculated, from known spectroscopic data, in the temperature range between O° and 1000°K. Also generalized mean-square amplitudes and values for theBastiansen—Morino shrinkage effect are reported. The results are briefly discussed.
Mit 1 Abbildung 相似文献
Mit 1 Abbildung 相似文献
5.
Adcock W Baran Y Filippi A Speranza M Trout NA 《The Journal of organic chemistry》2005,70(3):1029-1034
Experimental gas-phase acidities are reported for a series of 3-substituted (X) bicyclo [1.1.1]pent-1-yl carboxylic acids (1, Y = COOH). A comparison with available calculated data (MP2/6-311++G**// B3LYP/6-311+G**) reveals good agreement. The relative substituent effects are shown to be adequately described by a much lower level of theory (B3LYP/6-31+G*). Various correlations are presented which clearly point to polar field effects as being the origin of the relative acidities. 相似文献
6.
Baran EJ Weil M 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,61(4):707-710
The infrared and Raman spectra of the crystalline hexaoxotellurates Hg3TeO6 and Hg2TeO5 were recorded and discussed on the basis of a site symmetry analysis derived from known structural data. Approximate values for the Te-O bond force constants are reported and some comparisons with related species are made. 相似文献
7.
I NQR and spectroscopic investigation of impurity-doped and mixed lithium iodate Li1−xHxIO3 crystals
A. Barabash T. Gavrilko K. Eshimov J. Baran H. Ratajczak 《Journal of Molecular Structure》2004,708(1-3):113-116
The 127I NQR, IR absorption and Raman spectra of impurity-doped and mixed lithium iodate Li1−xHxIO3 crystals grown from water solutions with different LiIO3/HIO3 ratios were investigated depending on the content of the impurity hydrogen x. The NQR results suggested that, at small concentration of doping iodic acid x<0.22, the lattice dynamics of the crystal grown from water solution changes significantly though the crystal retains hexagonal symmetry. Spectroscopic studies are compatible with average hexagonal symmetry of the grown doped crystals. From the results of Raman studies at room temperature and 100 K, the concentration range of hydrogen dopant 0.22<x<0.36 was found where disordered solid solution crystals Li1−xHxIO3 are formed. 相似文献
8.
I.R. Spectra of the Phases A B Te3O8 (A = Fe, In, Sc; B = Nb, Ta) and UTe3O9 The infrared spectra of the title compounds have been recorded and discussed in comparison to formerly investigated MIVTe3O8 phases. The spectrum of UTe3O9 (synthetic cliffordite) confirms the presence of uranyl groups and the structural relation of this compound to the fluorite. 相似文献
9.
Nicolaou KC Baran PS Zhong YL Barluenga S Hunt KW Kranich R Vega JA 《Journal of the American Chemical Society》2002,124(10):2233-2244
The discovery and development of the o-iodoxybenzoic acid (IBX) reaction with certain unsaturated N-aryl amides (anilides) to form heterocycles are described. The application of the method to the synthesis of delta-lactams, cyclic urethanes, hydroxy amines, and amino sugars among other important building blocks and intermediates is detailed. In addition to the generality and scope of this cyclization reaction, this article describes a number of mechanistic investigations suggesting a single electron transfer from the anilide functionality to IBX and implicating a radical-based mechanism for the reaction. 相似文献
10.
We have been studying the problem of heterogeneity of OH groups in zeolites HY for a long time. The heterogeneity was suggested by the shift of the IR band of OH groups restoring upon ammonia desorption and also by the fact that the band of OH groups forming hydrogen bonds was relatively broad (broader than for homogeneous acidic OH). In the present study we present another important argument for heterogeneity: the splitting of the IR band of free OH and OD groups in a zeolite of Si/Al=8.3 dealuminated by (NH4)2SiF6 treatment. Such a splitting is the best seen in low temperature spectra of OD groups. We found less acidic 3640 cm−1 (AlO)(SiO)2SiO1HAl(OSi)3 and more acidic 3625 cm−1 (SiO)3SiO1HAl(OSi)3 groups. The presence of these two kinds of hydroxyls corresponds to the presence of Si(2Al) and Si(1Al), respectively, detected in 29Si MAS NMR spectra. We also found a small amount of strongly acidic 3599 cm−1 hydroxyls interacting with extraframework Al species. 相似文献