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101.
The characteristic angles and cross sections for a (\mathop 1- 0) + (\mathop 1- 1)(\mathop 1\limits^ - 0) + (\mathop 1\limits^ - 1) reaction in which H− atoms with an energy of 0.1–10 000 MeV lose electrons when scattered on C, N, or O atoms were calculated for the relativistic case of the Bethe scattering theory. The cross sections for N2, O2, and CO2 molecular targets were obtained using the additivity rule. The results presented are compared with known experimental and theoretical data. 相似文献
102.
Yaroslav V. Kudryavtsev Elena N. Govorun Arkady D. Litmanovich Hartmut R. Fischer 《Macromolecular theory and simulations》2004,13(5):392-399
Summary: The thermodynamic equilibrium in a melt of homopolymer C mixed with clay modified by a diblock copolymer AB is considered in theory. It is assumed that mixing is carried out in two stages. At first, the diblock copolymer penetrates into the interlayers formed by long clay sheets. Then, the clay with adsorbed diblock copolymer chains is added to the homopolymer melt. It is shown that the first process is thermodynamically favorable only if the interlayer width exceeds some threshold value that depends mostly on the difference in the adsorption energy of units A and B. A spontaneous mixing at the second stage is possible only if the enthalpic interactions between homopolymer and copolymer units are not very unfavorable. If so, the formation of an intercalated state is expected for a homopolymer of length comparable to the copolymer length, while for a long homopolymer the anticipated equilibrium state is exfoliation. The spatial distribution of A, B, and C units across the interlayer has been studied for different parameters of the system. The most readily adsorbing units A occupy almost all clay surface. However, the layer of block A is considerably swelled by both B and C units. The mutual distribution of units B and C may vary from almost homogeneous to having rather sharp boundary depending on the value of the Flory‐Huggins parameter χBC. The formation of a pure homopolymer layer at the center of the interlayer indicates about a tendency to exfoliate.
103.
The form of the electron distribution function in the positive column of low-pressure discharges is examined under conditions
such that the electron mean free path exceeds the vessel radius. Its formation is analyzed taking all major factors into account,
including elastic and inelastic collisions, radial and axial electric fields, and the loss of fast electrons to the wall.
It is shown that the main mechanism controlling the fast part of the distribution function is the loss of electrons to the
wall, which is determined by the scattering of electrons into a comparatively small loss cone that depends on the relationship
between the axial and radial components of the velocity. Since the elastic collision rate for all elements has a weak dependence
on the energy beyond the ionization threshold, ultimately the high-energy part of the electron energy distribution function
in the positive column of low-pressure discharges is nearly Maxwellian. The subthreshold portion of the distribution function,
in turn, is determined by the energy diffusion, in a comparatively strong field, of Maxwellian electrons which arrive after
inelastic collisions. The final electron distribution function is well approximated by an exponential with a single slope
over the entire energy range. Only within a narrow range of scattering angles is the electron distribution function strongly
depleted by the loss of electrons to the vessel walls. In the end, it is concluded that this phenomenon, like the Langmuir
paradox, may be related to aspects of the physics of the formation of the electron distribution function owing to a combination
of already known mechanisms, rather than to a hypothetical mechanism for thermalization of the electrons, as assumed up to
now in the literature. A comparison of solutions of the model kinetic equation given here with published Monte Carlo calculations
and experimental data shows that they are in good agreement.
Zh. Tekh. Fiz. 69, 34–41 (November 1999) 相似文献
104.
L. A. Pesin E. M. Baitinger I. N. Kovalev S. E. Evsyukov Yu. P. Kudryavtsev 《Journal of Structural Chemistry》1999,40(3):406-411
The influence of atomic ordering defects on the integrated characteristics of photoelectron and Auger spectra of various carbon
objects is studied. The analysis of the data indicates that there is a correlation between the type of hybridization of valence
electrons and the relative intensity of photoemission of the core electrons and Auger emission. The results obtained on a
fullerene sample support the existence of fractional types of hybridization. 相似文献
105.
Victor V. Yashin Yaroslav V. Kudryavtsev Yury A. Kriksin Arkady D. Litmanovich 《Macromolecular Symposia》2004,210(1):31-40
The influence of energetic parameters of the interchain homo- and heterocontacts on a local ordering of Bernoullian copolymers has been studied using Monte Carlo simulations and probabilistic analysis. The results of both methods are in a good agreement. Then simple Monte Carlo procedure was employed to study the ordering in products of a polymeranalogous reaction with accelerating effect of neighboring groups. When the reaction with intra- and interchain acceleration and local ordering proceed simultaneously in confined conditions, the ordering might affect the process so that the formation of certain nano-structures (in particular, not trivial strip-like ones) is possible. 相似文献
106.
Yaroslav V. Kudryavtsev Arkady D. Litmanovich Alexey G. Makeev Sergey V. Bogomolov 《Macromolecular theory and simulations》1999,8(2):161-171
A theory describing slow macromolecular reaction and interdiffusion in a compatible polymer blend is extended to consider H‐bonding. The known treatments of H‐bonding influence on the free energy of mixing and chains' mobilities are combined to calculate mutual diffusion coefficients in the framework of linear non‐equilibrium thermodynamics. Numerical calculations are performed for a blend of two random copolymers AC and BC to reveal the effect of H‐bonding (between A and B, B and B units) on the interdiffusion profiles. Then, the transformation of A units into B ones is included and the reaction‐diffusion equations are solved with the parameters corresponding to the blend of poly(tert‐butyl acrylate‐co‐styrene) with poly‐(acrylic acid‐co‐styrene) in which the thermal decomposition of tert‐butyl acrylate units takes place. The numerical calculations show that this system is suitable for the experimental verification of theoretical predictions concerning the interplay between macromolecular reaction and interdiffusion in polymer blends. 相似文献
107.
Victor Yashin Yaroslav Kudryavtsev Elena Govorun Arkady Litmanovich 《Macromolecular theory and simulations》1997,6(1):247-269
A theory describing slow macromolecular reaction and interdiffuion in a compatible polymer blend is suggested based on the linear non-equilibrium thermodynamic principles. A simple model system is considered. In a blend consisting initially of homopolymers A and B, the transformation A → B proceeds with the B units accelerating the reaction. A system of diffusive-reaction equations for relevant macroscopic variables is derived. The randomness of the reacting chains' structure gives rise to a new interdiffusion mode in addition to the reacting polymer-homopolymer B interdiffusion. Numerical calculations reveal that the diffusive intermixing of reacting chains of different composition may significantly affect the reaction rate and the local compositional heterogeneity as well. It is possible to discriminate the fast- and the slow-mode theories of interdiffusion using reaction kinetics data. Under certain conditions, the reaction may proceed in a non-trivial autowave-like regime. 相似文献
108.
109.
Yu. V. Shestakov L. M. Barkov V. F. Dmitriev R. A. Golovin V. N. Kudryavtsev B. A. Lazarenko S. I. Mishnev D. M. Nikolenko I. A. Rachek R. Sh. Sadykov V. N. Stibunov D. K. Toporkov L. I. Shekhtman S. A. Zevakov 《Physics of Particles and Nuclei》2014,45(1):338-340
At BINP the construction of the tagging system for almost-real photons (TS) is in progress. The energy of tagging photons can be up to 1.5 GeV. The projected energy resolution of TS is better then 1%. For at least a half of photons the linear polarization can be determined. The tagging system will extend the possibilities for photoreaction studying at VEPP-3 significantly. TS would allow to perform a complete kinematics reconstruction, thus permitting a reliable rejection of the background processes; to extend the measurements to higher photon energy; to enabling Σ-asymmetry measurements and double polarization experiments. 相似文献
110.
S. M. Kudryavtsev 《Doklady Physics》2017,62(7):366-370
An analytical expansion of the osculating orbital elements for all major planets of the Solar system into compact analytical series is presented. The method of spectral analysis of the numerical planetary ephemerides DE431 over the entire time interval of 30 000 years covered by them has been used. The derived series surpass considerably all of the known analogs in their compactness and accuracy of representing the planetary ephemerides over long time intervals. 相似文献