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1.
Using the DFT/B3LYP method with a 6-31G(d) basis set, the structure, normal vibration frequencies, and the absolute band intensities in the IR spectra of the chlorin molecule and its four symmetric isotopomers have been calculated. Scaling of the force field by the Pulay method in independent and natural coordinates has been carried out. A method for obtaining effective force fields without using experimental data on the fundamental vibration frequencies is proposed. By comparing the vibration modes and constructing special matrices, complete assignment of the fundamental frequencies of porphin and chlorin has been carried out. It has been shown that the majority of porphin macroring vibrations upon pyrrolenine ring hydrogenation are frequency-characteristic and only 12 vibrations change considerably. A frequency correlation with regard for the mode transition between chlorin and all its isotopomers under consideration has been established. Comparative analysis of the force fields of porphin and chlorin in dependent natural coordinates has revealed the unique nonlocal character of the change in force constants of the macroring upon hydrogenation of one pyrrolenine ring. Modeling of the IR spectra of chlorin and its isotopomers has been performed. Assignment and interpretation of the normal vibrations of the molecules under consideration have been carried out. 相似文献
2.
S. N. Vorob'ev Yu. B. Nechaev S. L. Prosvirnin 《Radiophysics and Quantum Electronics》1992,35(8):440-451
The mutual coupling of the radiating elements in microstrip antennas is studied using a rigorous electrodynamic approach in which the field singularities at the radiator edges are taken into account with analytic accuracy. A spectral method is employed in combination with a method of semi-inversion by extraction of the Green-function singularity. The degree of interaction of the elements of microstrip structures at the fundamental and higher current harmonicsis determined, and the applicability of various approximations is assessed.Radio-Astronomy Institute, Academy of Sciences of Ukraine. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 35, No. 8, pp. 688–701, August, 1992. 相似文献
3.
On the basis of the model “polymer chain in an array of obstacles” the influence of the topology effects on the dynamics of concentrated polymer systems is investigated theoretically. The 1/z-expansion (where z is the coordinational number of the lattice of obstacles) is proposed for this problem. By means of this expansion the diffusion coefficient of a linear unclosed polymer chain is calculated. The equilibrium properties of linear closed chain (i.e. ring) unentangled with either of the edges of the lattice are investigated in detail. In particular, it is shown that the diffusion coefficient D of the center of mass of closed chain consisting of N links is proportional to N−5/2. 相似文献
4.
V. I. Berezin N. V. Bogachev V. V. Ganin V. V. Nechaev 《Chemistry of Heterocyclic Compounds》1993,29(5):556-559
For the molecules of pyrrole and its symmetric deuterated derivatives, vibrational spectra have been analyzed, and the force field has been defined in natural coordinates.Translated from Khimiya Geterotsiklicheskikh Soedinenii, Vol. 29, No. 5, pp. 651–655, May, 1993. 相似文献
5.
Burakov VS Lobazov AF Nechaev SV Raikov SN 《Analytical and bioanalytical chemistry》1996,355(3-4):364-366
A polarization variant of an intracavity laser spectrometer based on the competition of beams in an argon ion laser, radiating a number of narrow lines in the 275 to 529 nm spectral range, is proposed and described for the spectral analysis of liquid samples, having broad absorption bands, mainly biomolecules in solutions. By careful optimization of the operating conditions, a procedure has been established that results in a minimal measurable absorbance decreased up to 10(-5) units of optical density. The examined spectrometer provides a wide dynamic range of analysis. A determination of trace contents of amino acids in methanol were carried out. 相似文献
6.
Fluorescence, whose spectral and magnetic properties permit its assignment to the luminescence of a triplex exciplex, has been discovered at times 3 sec after photoexcitation in the luminescence spectrum of the pyrene+N,N-diethylaniline system in methanol at 600 nm by the method of nanosecond stroboscopic fluorometry.Translated from Teoreticheskaya i Eksperimental'naya Khimiya, Vol. 25, No. 5, pp. 623–626, September–October, 1989. 相似文献
7.
8.
N. G. Zarakhan E. N. Borisova P. P. Nechaev G. E. Zaikov 《Russian Chemical Bulletin》1981,30(11):2044-2046
Conclusions A mechanism is proposed for the acid-catalyzed hydrolysis of benzoylhydrazine; the limiting step in this mechanism is the interaction of the solvated proton with the reactant in ion pair form.Deceased.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2476–2478, November, 1981. 相似文献
9.
Nechaev A. P. Sultanovich Yu. A. Geiko N. S. Gramolin S. L. Zaitseva L. V. 《Chemistry of Natural Compounds》1985,21(3):307-309
The basic possibility of lowering the concentration of pancreatic lipase in the hydrolysis of triacylglycerols (TAGs) deposited on a solid sorbent has been shown. The method of preparing the initial TAGs for hydrolysis that has been developed permits not only a 10-fold reduction in the amount of ligase but also the retention of a short time of hydrolysis with a high yield of reaction products.Moscow Technological Institute of the Food Industry. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 329–332, May–June, 1985. 相似文献
10.
Borisova I. V. Nechaev M. S. Khrustalev V. N. Zemlyanskii N. N. Ustynyuk Yu. A. 《Russian Chemical Bulletin》2002,51(5):721-753
The review surveys the data on the reactions of phosphorus and arsenic ylides with compounds containing E=X bonds (E = C, Si, Ge, or Sn; X = C or S), cyclic oligomers (R2ES)n (n = 2 or 3), and heavier analogs of carbenes. These reactions give rise to two new classes of heteroorganic betaines containing the (+)E15—C—E14—X(–) (I) and (+)E15—C—E14(–) (II) (E15 = P or As; E14 = Si, Ge, or Sn; X = C or S) structural fragments. Procedures for the synthesis of these compounds, their reactivities, the X-ray diffraction structures, and the electronic structures established by high-level quantum-chemical calculations are considered in detail. The carbon analogs of betaines of type I, viz., compounds bearing the (+)P—C—C—X(–) fragment (III), are also discussed. The latter were long considered as possible intermediates in the reactions of compounds containing the polar C=X bond (X = C, O, S, NR, etc.) with phosphorus ylides (classical Wittig and Corey—Chaykovsky reactions and related processes). 相似文献