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91.
V. Ya. Grinberg T. V. Burova N. V. Grinberg A. I. Usov D. R. Tur V. S. Papkov 《Polymer Science Series A》2009,51(4):390-395
The interaction of poly(ethylaminophosphazene) hydrochloride (M SD = 3.2 × 105) with potassium ι-carrageenan (M w = 2.2 × 105), which is a linear regular anionic polysaccharide, has been studied by high-sensitivity DSC at pH 3.8 in a 0.15 mol/l solution of KCl. The dependences of temperature, enthalpy, and the cooperativity parameter of the double helix-coil transition of polysaccharide on the concentration ratio of polyphosphazene and polysaccharide have been obtained. The presence of polyphosphazene has no effect on the temperature and cooperativity of transition, whereas the enthalpy of the transition decreases linearly with the content of polyphosphazene and turns to zero at a mass polymer-to-polysaccharide ratio of approximately 1: 1, which corresponds to the equivalent concentrations of polyphosphazene and polysaccharide with respect to charges. Our data indicate that the mixing of poly(ethylaminophosphazene) hydrochloride and potassium ι-carrageenan solutions gives rise to formation of the stoichiometric interpolyelectrolyte complex, in which the polysaccharide loses its ability to form double helix typical of ι-carrageenan in saline solution (0.15 M KCl). 相似文献
92.
A. G. Bubnov E. Yu. Burova V. I. Grinevich V. V. Rybkin J.-K. Kim H.-S. Choi 《Plasma Chemistry and Plasma Processing》2007,27(2):177-187
This study examined processes of decomposing phenol and its derivatives (resorcin, pyrocatechol and hydroquinone) in aqueous
solutions under the action of an atmospheric pressure oxygen dielectric barrier discharge in the presence or absence of catalysts
in the plasma zone. Two types of catalysts were tested, NiO and TiO2. It was found that both materials exhibited catalytic properties. The action of NiO accelerated the step of phenol destruction
while the action of TiO2 catalyst resulted in a more preferable composition of decomposition products and provided a higher degree of carboxylic acid
conversion into carbon dioxide than the NiO catalyst. 相似文献
93.
T. G. Burova 《Journal of Structural Chemistry》1997,38(2):201-206
A direct method for calculating the resonance Raman and two-photon absorption spectra of polyatomic molecules is described
in detail The method is based on the adiabatic model and uses Herzberg-Teller’s approximation. Relations ruling out direct
summation over vibrational quantum numbers of excited electronic states and representing the matrix elements of the Green
function of a multidimensional oscillator as functions of vibration frequencies and Dushinsky transformation parameters are
derived. The relations are convenient for constructing algorithms.
Translated from Zhumal Struktumoi Khimii, Vol. 38, No. 2, pp. 248–255, March–April, 1997. 相似文献
94.
Hydration characterization of N-vinylcaprolactam polymers by absorption millimeter-wave measurements
Mikhail M. Vorob’ev Tatiana V. Burova Natalia V. Grinberg Alexander S. Dubovik Nikolai G. Faleev Vladimir I. Lozinsky 《Colloid and polymer science》2010,288(14-15):1457-1463
Water molecules in the polymer hydration shell known as bound water lose their mobility in comparison with unperturbed water. This effect was quantified by absorption measurements in the millimeter-wave range of microwaves (1–10 mm, 30–300 GHz). Hydration measurements were performed for poly(N-vinylcaprolactam) (PNVCL) and copolymers of N-vinylcaprolactam (NVCL) and N-vinylimidazol (NVIA). The association of hydrophobic groups in PNVCL upon coil-to-globule transition was found to cause a decrease in the relative hydration number, which is the relative amount of bound water per solute molecule as measured by microwave method at 31 GHz. Millimeter-wave hydration measurements were confirmed by the determinations of specific heat capacity (c p) with differential scanning calorimetry. Hydration determinations of NVCL/NVIA copolymers revealed that they associate via hydrophobic clustering with a decrease in hydration of hydrophobic groups. 相似文献
95.
The tautomeric composition of isolated adenine has been analyzed using computational IR spectroscopy. A comparison with experimental
data has demonstrated that, in addition to adenine-N9H, which dominates in the quantitative content, two more tautomers that have the N9H imino and N7H amino forms exist in the isolated state and in the gas phase. 相似文献
96.
This paper deals with the visualization of a domain that contains four limit cycles for quadratic dynamical systems of first-order differential equations with real coefficients. The visualization of the domain is carried out in the three-dimensional space of coefficients corresponding to the nonlinear part of the quadratic system. Theoretical and practical aspects of the numerical solution of the Cauchy problem for unstable systems are discussed. 相似文献
97.
98.
T. V. Burova 《Journal of Mathematical Sciences》1998,91(6):3380-3386
Mutual dimensional properties of basis-equivalent (b-equivalent) and weakly l-equivalent topological spaces are studied. It
is shown that the b-equivalence does not preserve bicompactness; in particular, b-equivalent topological spaces can be non-l-equivalent.
Bibliography: 18 titles.
Translated fromZapiski Nauchnykh Seminarov POMI, Vol. 231, 1995, pp. 76–87.
Translated by O. A. Ivanov. 相似文献
99.
Quantum-mechanical calculation of the intensity distribution in resonance Raman spectra of cytosine 总被引:1,自引:0,他引:1
A quantum-mechanical calculation of the relative intensities of lines in resonance Raman (RR) spectra of cytosine excited by laser radiation at 266, 218, and 200 nm was performed in different approximations of the vibronic theory. Both the Herzberg-Teller effect and the contribution from electronic states located close to the resonance state are shown to play a significant role in determining the relative intensities of lines. A satisfactory agreement between the calculated results and experimental data is obtained. The specific features of the intensity distribution in the RR spectra of cytosine are compared with those in the spectra of the previously studied thymine and uracil, which have a similar structure and also belong to the simplest nucleic acid bases. 相似文献
100.
Reaction of 2,4,5-trioxo-7-aminopyrido[2,3-d]pyrimidines with acylating agents takes place both at the amino group and at the cyclic nitrogen atom. Reaction of these compounds with formic acid, chloroacetyl chloride in pyridine, cyanoacetic acid in the presence of acetic anhydride, and oxalyl chloride leads to monoacylation at the amino group but with methyl chloroformate it is the product of acylation at the cyclic nitrogen. Refluxing in acetic anhydride gave mono-, di-, and triacetyl derivatives. The structures of these compounds were proved using spectral data.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 811–814, June, 1990. 相似文献