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61.
D. V. Antonov G. V. Kuznetsov P. A. Strizhak 《Journal of Engineering Thermophysics》2016,25(3):337-351
Characteristic temperatures and concentrations of a vapor–gas mixture in a wake of water droplets moving through combustion products (initial temperature 1170 K) were determined using the Ansys Fluent mathematical modeling package. We investigated two variants of motion: motion of two droplets (with sizes from 1 mm to 3 mm), consecutive and parallel, and motion of five staggered droplets. The influence of the relative position of droplets and also of distances between them (varied from 0.01 mm to 5 mm) on temperatures and concentrations of water vapor was established. The distances determine the relation between the evaporation areas and the total volume occupied by a droplet aggregate in the gas medium. The results of modeling for conditions that take into account vaporization on the droplet surface at average constant values of evaporation rate and also with consideration of the change in the latter, depending on the droplet temperature field, are compared. We determined conditions under which the modeling results are comparable for the assumption of a constant vaporization rate and with regard to the dependence of the latter on temperature. The earlier hypothesis on formation of a buffer vapor layer (“thermal protection”) around a droplet, which decreases the thermal flow from the external gas medium, was validated. 相似文献
62.
E. V. Kudryashova I. M. Deygen K. V. Sukhoverkov L. Yu. Filatova N. L. Klyachko A. M. Vorobei O. I. Pokrovskiy K. B. Ustinovich O. O. Parenago E. N. Antonov A. G. Dunaev L. I. Krotova V. K. Popov A. M. Egorov 《Russian Journal of Physical Chemistry B, Focus on Physics》2016,10(8):1201-1210
The process of micronization of levofloxacin (LF, an antibacterial agent of the fluoroquinolone group) by the supercritical antisolvent precipitation technique (SAS) was investigated. It was shown that LF particles of different sizes (from 1 to 10 μm) and of various morphologies (from thin plates to elongated parallelepipeds) can be produced depending on the type of solvent used for conducting micronization. Investigation of the micronized LF preparations using the methods of IR-Fourier spectroscopy, Raman scattering, and circular dichroism showed that the LF micronization caused neither changes in its chemical structure nor racemization. Micronization of LF significantly affects the rate of its dissolution in model systems exhibiting effects dependent on the type of the solvent used for micronization. For example, the highest rate of dissolution at pH 4 was observed for LF preparations micronized with the help of chlorohydrocarbons. It was shown that the rate of dissolution of all micronized LF preparations was higher by 15–30% in comparison with the initial LF, which likely was related to the changes in the degree of crystallinity/amorphousness, as well as of morphologies of microparticles formed in the SAS process. 相似文献
63.
D. A. Antonov D. O. Filatov A. V. Zenkevich Yu. Yu. Lebedinskii 《Bulletin of the Russian Academy of Sciences: Physics》2007,71(1):56-58
The tunneling of electrons through Au nanoc lusters formed by pulsed laser deposition in a SiO2 thin film on a Si substrate has been investigated by combined scanning/atomic force microscopy (STM/AFM). Conducting Pt-coated Si cantilevers were used. The feedback was maintained via the AFM channel, and the current-voltage (I-V) characteristics of the tunnel contact between the AFM probe and the n +-Si substrate through a =4-nm-thick SiO2 film with Au nanoclusters =2 nm in diameter were measured simultaneously. The current image of the structure contained areas of increased current (tunnel-current channels) 2–15 nm in size, related to tunneling of electrons through Au nanoclusters in SiO2. The I-V characteristics recorded in the tunnel-current channels exhibit specific features related to the Coulomb blockade of electron tunneling through Au nanoclusters. 相似文献
64.
This study aims at contributing to quinine extraction using supercritical CO2 and ethanol as a co-solvent. The diffusion coefficients of quinine in supercritical CO2 are measured using the Taylor dispersion technique when quinine is pre-dissolved in ethanol. First, the diffusion coefficients of pure ethanol in the supercritical state of CO2 were investigated in order to get a basis for seeing a relative change in the diffusion coefficient with the addition of quinine. We report measurements of the diffusion coefficients of ethanol in scCO2 in the temperature range from 304.3 to 343 K and pressures of 9.5, 10 and 12 MPa. Next, the diffusion coefficients of different amounts of quinine dissolved in ethanol and injected into supercritical CO2 were measured in the same range of temperatures at p = 12 Mpa. At the pressure p = 9.5 MPa, which is close to the critical pressure, the diffusion coefficients were measured at the temperature, T = 343 K, far from the critical value. It was found that the diffusion coefficients are significantly dependent on the amount of quinine in a small range of its content, less than 0.1%. It is quite likely that this behavior is associated with a change in the spatial structure, that is, the formation of clusters or compounds, and a subsequent increase in the molecular weight of the diffusive substance. 相似文献
65.
Kholupenko E. E. Krassilchtchikov A. M. Badmaev D. V. Bogdanov A. A. Tuboltsev Yu. V. Chichagov Yu. V. Antonov A. S. Kuleshov D. O. Khil’kevich E. M. 《Technical Physics》2020,65(6):886-895
Technical Physics - Source and noise signals in a new camera of the TAIGA-IACT Cherenkov γ-ray telescope based on silicon photomultipliers (SiPM) have been simulated. It is shown that... 相似文献
66.
Vladimir V. Aristov Anatoly S. Buchelnikov Yury D. Nechipurenko 《Entropy (Basel, Switzerland)》2022,24(2)
Some problems of describing biological systems with the use of entropy as a measure of the complexity of these systems are considered. Entropy is studied both for the organism as a whole and for its parts down to the molecular level. Correlation of actions of various parts of the whole organism, intercellular interactions and control, as well as cooperativity on the microlevel lead to a more complex structure and lower statistical entropy. For a multicellular organism, entropy is much lower than entropy for the same mass of a colony of unicellular organisms. Cooperativity always reduces the entropy of the system; a simple example of ligand binding to a macromolecule carrying two reaction centers shows how entropy is consistent with the ambiguity of the result in the Bernoulli test scheme. Particular attention is paid to the qualitative and quantitative relationship between the entropy of the system and the cooperativity of ligand binding to macromolecules. A kinetic model of metabolism. corresponding to Schrödinger’s concept of the maintenance biosystems by “negentropy feeding”, is proposed. This model allows calculating the nonequilibrium local entropy and comparing it with the local equilibrium entropy inherent in non-living matter. 相似文献
67.
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69.
K. R. Karimov A. I. Anfinogenov Ya. B. Chernov V. V. Chebykin A. A. Pankratov B. D. Antonov 《Russian Journal of Applied Chemistry》2010,83(10):1804-1810
Possibility of producing zinc-aluminide coatings by thermal diffusion impregnation of steels under mechanical activation of
the surface of samples in a rotating reactor was analyzed. 相似文献
70.
It is demonstrated that laser irradiation causes formation of complicated fractal structures (classical dendrites) on a steel surface. The distribution of dendrites over the irradiated region can be controlled using variations in the profile of the incident laser beam. Electron microscopy is used to evaluate the size distributions of dendrites and the surface distribution density. 相似文献