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41.
Reaction of methyl radicals with hydroxyl radicals, CH(3) + OH → products (1) was studied using pulsed laser photolysis coupled to transient UV-vis absorption spectroscopy over the 294-714 K temperature and 1-100 bar pressure ranges (bath gas He). Methyl radicals were produced by photolysis of acetone at 193.3 nm. Hydroxyl radicals were generated in reaction of electronically excited oxygen atoms O((1)D), produced in the photolysis of N(2)O at 193.3 nm, with H(2)O. Temporal profiles of CH(3) were recorded via absorption at 216.4 nm using xenon arc lamp and a spectrograph; OH radicals were monitored via transient absorption of light from a dc discharge H(2)O/Ar low pressure resonance lamp at ca. 308 nm. The absolute intensity of the photolysis light inside the reactor was determined by an accurate in situ actinometry based on the ozone formation in the presence of molecular oxygen. The results of this study indicate that the rate constant of reaction 1 is pressure independent within the studied pressure and temperature ranges and has slight negative temperature dependence, k(1) = (1.20 ± 0.20) × 10(-10)(T/300)(-0.49) cm(3) molecule(-1) s(-1). 相似文献
42.
Nikolay Banichuk Alexander Barsuk Svetlana Ivanova Evgeni Makeev Pekka Neittaanmäki 《基于设计的结构力学与机械力学》2018,46(5):615-633
We consider an infinite continuous elastic beam that interacts with linearly elastic foundation and is under compression. The problem of the beam buckling is formulated and analyzed. Then the optimization of beam against buckling is investigated. As a design variable (control function) we take the parameters of cross-section distribution of the beam from the set of periodic functions and transform the original problem of optimization of infinite beam to the corresponding problem defined at the finite interval. All investigations are on the whole founded on the analytical variational approaches and the optimal solutions are studied as a function of problems parameters. 相似文献
43.
We consider dynamics of phase boundaries in a bistable one-dimensional lattice with harmonic long-range interactions. Using Fourier transform and Wiener–Hopf technique, we construct traveling wave solutions that represent both subsonic phase boundaries (kinks) and intersonic ones (shocks). We derive the kinetic relation for kinks that provides a needed closure for the continuum theory. We show that the different structure of the roots of the dispersion relation in the case of shocks introduces an additional free parameter in these solutions, which thus do not require a kinetic relation on the macroscopic level. The case of ferromagnetic second-neighbor interactions is analyzed in detail. We show that the model parameters have a significant effect on the existence, structure, and stability of the traveling waves, as well as their behavior near the sonic limit. 相似文献
44.
The strongly correlated regime of the crossover from Bardeen-Cooper-Schrieffer pairing to Bose-Einstein condensation can be realized by diluting a system of two-component fermions with a short-range attractive interaction. We investigate this system via a novel continuous-space-time diagrammatic determinant Monte Carlo method and determine the universal curve Tc/epsilonF for the transition temperature between the normal and the superfluid states as a function of the scattering length with the maximum on the Bose-Einstein condensation side. At unitarity, we confirm that Tc/epsilonF=0.152(7). 相似文献
45.
Gianluca Geloni Evgeni Saldin Evgeni Schneidmiller Mikhail Yurkov 《Optics Communications》2008,281(14):3762-3770
We propose a technique for timing an X-ray free-electron laser (XFEL) to a high-power conventional laser with femtosecond accuracy, yielding the relative jitter between pump and X-ray probe, and allowing sorting of experimental results over a certain time window. The same electron bunch is used to produce both an XFEL pulse and an ultrashort optical pulse by means of an optical radiator downstream of the X-ray undulator. Being produced by the same electron bunch, these pulses are perfectly synchronized. Cross-correlation techniques will allow to determine relative jitter between the optical pulse (and, thus, the XFEL pulse) and a pulse from an external pump-laser. Technical realization of the proposed timing scheme uses an optical-replica synthesizer setup to be installed after the final bunch-compression stage of the XFEL for electron bunch diagnostics purposes. A number of critical issues are quantitatively analyzed. 相似文献
46.
Alexander M. Moiseenkov Evgeni V. Polunin Alexei V. Semenovsky 《Tetrahedron letters》1981,22(34):3309-3312
Nine-step synthesis of the title triterpenol from (E,E)-farnesol using a two-stage cis-C5-homologation procedure is descrilaed. 相似文献
47.
Stanev Evgeni Dencheva Maria Lyapina Maya Forghani Payam 《Journal of Thermal Analysis and Calorimetry》2020,139(1):225-236
Journal of Thermal Analysis and Calorimetry - The objective of this work was to examine the thermal conductivity of a stable nano-antifreeze containing cetyltrimethylammonium bromide coated cerium... 相似文献
48.
Cyrill Lubenov Naydenov Evgeni Penev Kirazov Vanio Ivanov Mitev 《Chromatographia》2014,77(7-8):591-602
In this paper we present a generalized physicochemical model for carrier ampholyte isoelectric focusing techniques. Accurate analysis of electrokinetic phenomena can only be performed when the physicochemical interactions of the carrier matrix with the electrode solutions are taken into consideration. It should also be taken into account that the majority of the constituents of electrolyte systems are weak, multivalent acids and bases, which have complex stoichiometric behavior, intricately linked with local transport phenomena. A generalized formulation to couple the migration/diffusion of weak electrolytes with transport phenomena is presented along with a broad treatment of macroscopic transport, which leads ultimately to the creation of an ampholyte pH gradient. These formulations and a novel scheme for the mechanism of mass transport constitute the core of the present paper. 相似文献
49.
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