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101.
Miros?aw Meissner 《Applied Acoustics》2008,69(7):583-590
In this paper, a modal analysis was used to describe a reverberation phenomenon in a room of complex shape. A theoretical model was limited to low sound frequencies, when eigenmodes are lightly damped, thus they may be approximated by uncoupled normal acoustic modes of a hard-walled room. A utility of this method was demonstrated in a numerical example where the enclosure in a form of two coupled rooms was considered. A reverberation time was evaluated from a time decay of spatial root mean square pressure, the overall measure of room pressure. The results of calculations, performed for three different distributions of absorbing materials on room walls, showed how various location of the material can effect a dependence of the reverberation time on a frequency of sound source. 相似文献
102.
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104.
Mirosław Dors Jerzy Mizeraczyk Tadeusz Czech Jerzy Konieczka 《Czechoslovak Journal of Physics》1996,46(10):953-960
The aim of this paper is to investigate the influence of NH3 additive (540–1470 ppm) on the conversion of NO2 and the creation of NO and N2O in a mixture of N2:O2:CO2: NO2:NH3 subjected to the so-called direct current (dc) corona discharge. The dc corona discharge was generated in a needle-to-plate reactor. Seven positively polarized needles were used as one electrode and a stainless steel plate as the other. The time-averaged discharge current was varied from 0 to 7 mA. It was found that the dc corona discharge decomposed NO2 and produced NO and N2O. The reduction of NO2 was higher without NH3 additive if the residence time of the operating gas was relatively short. However, in a longer corona discharge processing the NH3 additive may be useful for reduction of NO2.Supports from the Research and Development Commitee (KBN) under Programme KBN 0889/P4/93/04 and the Polish Academy of Sciences within IMP 3.1 project are gratefully acknowledged. 相似文献
105.
Miros?aw Szafran Iwona Kowalczyk Andrzej Katrusiak 《Journal of Molecular Structure》2006,786(1):25-32
A novel betaine derivative, 3-(2-amino-pyridinium)-propionate monohydrate, has been synthesized and its structure studied by X-ray diffraction, FTIR, Raman, 1H and 13C NMR spectroscopies and by DFT calculations. The crystals are monoclinic, space group P21/c with a=8.0800(16), b=15.242(3), c=7.1698(14) Å, β=104.30(3)° and Z=4. Each oxygen atom of the carboxylate group is engaged in two intermolecular hydrogen bonds, one with water molecule and the other with amine group. The water molecules link the molecules of 3-(2-amino-pyridinium)-propionate into planar zigzag chains along the b axis. The screening constants for 1H and 13C atoms have been calculated by GIAO/B3LYP/6-31 G(d,p) and analyzed. Linear correlations between the experimental 1H and 13C chemical shifts and the computed screening constants have been obtained. Raman and FTIR spectra of the title betaine have been investigated. 相似文献
106.
The potentiometric titration with dithiooxamide applied to mercury determinations in industrial wastes is compared with cold-vapour atomic absorption spectrometry and spectrophotometry with dithizone. The potentiometric method is shown to have adequate sensitivity and selectivity as well as economic advantages. 相似文献
107.
Lorenc J Hanuza J Maczka M Kucharska E Kaminskii AA Kaino T Yaima T Yokoo A 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,61(4):685-695
Polycrystalline infrared and polarized FT-Raman spectra have been measured for 2-adamantylamino-5-nitropyridine, a novel organic material for laser Raman converters. The assignment of IR and Raman bands is given on the basis of DFT calculations. The spectroscopic studies have not indicated the presence of any significant intermolecular interactions in the crystal structure of this compound. The lines observed in the stimulated Raman spectrum of this crystal are assigned to the respective molecular vibrations. 相似文献
108.
Mirosław Lachowicz 《Annali di Matematica Pura ed Applicata》1991,160(1):41-62
Summary The asymptotic behaviour of solutions of the kinetic equations on the level of the Euler fluid dynamics is studied. In contrast to the previous studies in Sobolev spaces, the analysis is carried out in C0 (with respect to the space variable) setting. Thus, one needs to use only few Hilbert and initial layer terms, and consequently a lower smoothness is required for the solution of the Euler system.on leave from Wydzia Matematyki, Uniwersytet Warszawski, Poland. 相似文献
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Wanda Wieczorek Maria Bukowska-Strzyżewska Aleksandra Olma Zbigniew J. Kamńnski Mirosław T. Leplawy 《Journal of chemical crystallography》1991,21(2):107-112
(+)-4-Benzoylamino-4-carboxy--butyrolactone was synthesized, and its structure solved by direct methods and refined toR=0.033. The molecule adopts a skew conformation with a C7-N1-C8-C12 torsion angle of 59.6(2)°. The lactone ring has an envelope conformation, with the C(8) atom deflected from the ring plane. The absolute configuration of (+)-benzylami-no-4-carboxy--butyrolactone5 was assigned asR by the application of Hamilton's test to the unique diffraction data, and confirmed by the estimation of the Bijvoet coefficientB fromhkl and
diffraction data. This result proves theR configuration for (+) enantiomer of the parent-hydroxymethylaspartic acid. 相似文献