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41.
Experimental results on convective heat transfer from a single cube on a flat surface are presented for different attack angles
to the incident flow and Reynolds numbers. The character of vortex formation and the effect of flow structure on heat transfer
at detached flow around a cube were studied by visualization. Local heat transfer and heat transfer averaged over the separate
faces and the whole lateral surface of the cube were studied. Contribution of separate cube faces to total heat transfer depending
on the attack angle was estimated. Data obtained were compared with those published in literature. The reasons for observed
differences caused by the effect of many factors: boundary layer thickness, turbulence level of the incident flow, channel
constraint, etc., are analysed. 相似文献
42.
N. I. Mukhurov S. P. Zhvavyi I. V. Gasenkova S. N. Terekhov P. P. Pershukevich V. A. Orlovich 《Journal of Applied Spectroscopy》2010,77(4):549-555
Results are reported from a study of the optical properties of porous alumina films obtained by anodizing in a water solution
of sulfuric acid and modified by thermal annealing in air at T ≥ 850°C. A comparative analysis of the data shows that the
near-UV and visible photoluminescence of alumina anodized in a sulfuric acid solution is caused primarily by oxygen divacancies
(F2, F2+ _2^{+} , and F22 + _2^{2 + } centers), while sulfate ions have little effect on the luminescence properties of anodic alumina in this spectral range. 相似文献
43.
é. P. Domashevskaya S. A. Storozhilov S. Yu. Turishchev V. M. Kashkarov V. A. Terekhov O. V. Stogne Yu. E. Kalinin A. V. Sitnikov S. L. Molodtsov 《Physics of the Solid State》2008,50(1):139-145
The electronic structure and phase composition of (Co41Fe39B20)
x
(SiO2)1 − x
nanocomposites are studied by x-ray absorption near-edge spectroscopy, which is extremely sensitive to the chemical environment
of elements in multicomponent compounds. An analysis of the recorded Fe L
2, 3, Co L
2, 3, B K, Si L
2, 3, and O K absorption spectra demonstrates interatomic interactions between the elements of the metallic and dielectric components of
the nanocomposites. As a result of these interatomic interactions, a complex multiphase system, whose electronic structure
should determine the transport and magnetic properties of the nanocomposites, forms. In particular, the transformation of
the fine structure of the iron L
2, 3 spectra reflects a change in the ratio of divalent to trivalent iron in its oxides and/or silicates. CoO and complex boron
oxides are found to exist in the nanocomposites. The electrical conductivity of a FeO · F2O3 · CoO grain embedded in the silicate-oxide medium of the nanocomposites is controlled by electron exchange between Co2+, Fe2+, and Fe3+ ions. The dielectric component consists of a mixture of silicon oxide and the silicates/borosilicates of transition metals.
Original Russian Text ? é.P. Domashevskaya, S.A. Storozhilov, S.Yu. Turishchev, V.M. Kashkarov, V.A. Terekhov, O.V. Stogneĭ,
Yu.E. Kalinin, A.V. Sitnikov, S.L. Molodtsov, 2008, published in Fizika Tverdogo Tela, 2008, Vol. 50, No. 1, pp. 135–141. 相似文献
44.
We calculate exactly the vacuum polarization charge density in the field of a subcritical Coulomb impurity, Z|e|/r, in graphene. Our analysis is based on the exact electron Green's function, obtained by using the operator method, and leads to results that are exact in the parameter Zalpha, where alpha is the "fine-structure constant" of graphene. Taking into account also electron-electron interactions in the Hartree approximation, we solve the problem self-consistently in the subcritical regime, where the impurity has an effective charge Z(eff), determined by the localized induced charge. We find that an impurity with bare charge Z=1 remains subcritical, Z(eff)alpha<1/2, for any alpha, while impurities with Z=2, 3 and higher can become supercritical at certain values of alpha. 相似文献
45.
Lestinsky M Lindroth E Orlov DA Schmidt EW Schippers S Böhm S Brandau C Sprenger F Terekhov AS Müller A Wolf A 《Physical review letters》2008,100(3):033001
Term energies for dielectronic-recombination Rydberg resonances below 0.07 eV are determined for Sc18+ with absolute accuracies below 0.0002 eV by electron collision spectroscopy in an ion storage ring, using the twin-electron-beam technique and a cryogenic photocathode. The lithiumlike 2s_{1/2}-2p_{3/2} transition energy for Z=21 is determined to 4.6 ppm, less than 1% of the few-body effects on radiative corrections. Features from the hyperfine structure of the 2s state could be resolved in the dielectronic-recombination spectrum. 相似文献
46.
The results of numerical simulation of the structure of non-isothermal polydisperse bubbly turbulent flow and heat transfer behind a sudden tube expansion are presented. The study was carried out at a change in the initial diameter of the air bubbles within d m1 = 1–5 mm and their volumetric void fraction β = 0–10 %. Small bubbles are available in almost the entire cross section of the tube, while the large bubbles pass mainly through the flow core. An increase in the size of dispersed phase causes the growth of turbulence in the liquid phase due to flow turbulization, when there is a separated flow of liquid past the large bubbles. Adding the air bubbles causes a significant reduction in the length of the separation zone and heat transfer enhancement, and these effects increase with increasing bubble size and their gas volumetric flow rate ratio. 相似文献
47.
M. A. Pakhomov V. I. Terekhov 《Journal of Applied Mechanics and Technical Physics》2013,54(4):596-607
The Eulerian and Lagrangian approaches are used to perform a numerical study of the disperse phase dynamics, turbulence, and heat transfer in a turbulent gas-droplet flow in a tube with sudden expansion with the following ranges of two-phase flow parameters: initial droplet size d 1 = 0–200 µm and mass fraction of droplets M L1 = 0–0.1. The main difference between the Eulerian and Lagrangian approaches is the difference in the predictions of the droplet mass fraction: the Eulerian approach predicts a smaller value of M L both in the recirculation region and in the flow core (the difference reaches 15–20%). It is demonstrated that the disperse phase mass fraction calculated by the Lagrangian approach agrees better with measured data than the corresponding value predicted by the Eulerian approach. 相似文献
48.
The results of the numerical modeling of flow structure, turbulence, and heat transfer in a gas-droplet stream after sudden tube expansion on the basis of the Eulerian approach are presented. The gas phase turbulence was modeled using the Reynolds stress transfer model modified to allow for the presence of particles. The results are compared with those obtained using the two-equation k-ε model. The latter results overestimate the heat transfer in the separation flow as compared with the Reynolds stress transfer model. The heat transfer is shown to considerably increase, when evaporating droplets are incorporated in the separation flow (by a factor of more than 1.5 compared with the case of a single-phase flow at a small mass concentration of the droplets M L1 ≤ 0.05). The addition of the disperse phase in the turbulent gas flow leads a slight increase in the recirculation zone length. Good agreement with the experimental data indicates the adequacy of the numerical model developed. 相似文献
49.
Antonov N. N. Viktorov V. A. Gapienko V. A. Gapienko G. S. Gres’ V. N. Prudkoglyad A. F. Romanovskii V. A. Semak A. A. Solodovnikov I. P. Terekhov V. I. Ukhanov M. N. Shimanskii S. S. 《Physics of Atomic Nuclei》2022,85(3):282-288
Physics of Atomic Nuclei - Data on the production of positively charged particles emitted at an angle of 40 $${}^{\circ}$$ (in the laboratory frame) with transverse momenta of up to 2.7 GeV $$/c$$... 相似文献
50.