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81.
Illarion Dorofeyev 《Physics letters. A》2008,372(9):1341-1347
Rate of energy transfer between a small body and a sample by means of the fluctuating electromagnetic fields is studied analytically and numerically. The obtained formula for the rate of heat liberation is valid for the case of arbitrary shapes of interacting bodies. A nonmonotonic behavior of the rate of heat transfer due to the temperature dependence of dielectric function is shown for the first time. Shifts of the Froehlich and Coulomb peaks at the curve of spectral power density of the rate of heat transfer are studied using various models of the local and nonlocal response functions. 相似文献
82.
R. Conte 《Physics letters. A》2008,372(13):2269-2270
The Bianchi IX cosmological model in vacuum can be represented by several six-dimensional dynamical systems. In one of them we present a new closed form solution expressed by a third Painlevé function. 相似文献
83.
Dr. Ze-Lin Zhu Sheng-Fu Wang Li-Wen Fu Ji-Hua Tan Chen Cao Dr. Yi Yuan Shek-Man Yiu Dr. Ye-Xin Zhang Prof. Yun Chi Prof. Chun-Sing Lee 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(4):e202103202
Upon fusing the pyrazinyl pyrazole entity in giving pyrazolo[3,4-f]quinoxaline chelate, the corresponding Os(II) based NIR emitter exhibited “invisible” and efficient electroluminescence with a peak maximum at 811 nm. A maximum external quantum efficiency of 0.97 % and a suppressed efficiency roll-off till a current density of 300 mA cm−2 was also exhibited. 相似文献
84.
Two unusual one-dimensional(1-D) compounds,viz.[Co(Medpq)(QUI)·H2O]2n· 2.4nH2O 1 and [Cd(Medpq)(QUI)·H2O]n·nH2O 2,were synthesized by the combination of two different metallic salts and organic ligands,namely 2,3-pyridinedicarboxylic acid(H2QUI) and 2-methyldipyrido[3,2-f:2',3'-h]quinoxaline(Medpq) ligand.The compounds were characterized by elemental analyses,TG,fluorescent emission and single-crystal X-ray diffraction analyses. 相似文献
85.
One of the mechanisms proposed for methanol oxidation by methanol dehydrogenase (MDH) involves a hydride transfer to the quinone carbonyl carbon C5 of 2,7,9-tricarboxy-1H-pyrrolo[2,3-f]-quinoline-4,5-dione (PQQ), initiated by abstraction of a proton from the substrate methanol by a general base. Molecular dynamics studies are performed on MDH-bound to the C5 reduced intermediate (C5RI) of PQQ, for 3 ns. The structural features of the MD and X-ray structures are compared. An interesting feature observed during simulations is the strong hydrogen bond between oxyanion O5 of C5RI and Asp297-CO2H in the active site. Asp297-CO2− is suggested to be the general-base catalyst for removing the hydroxyl proton of methanol in concert with the hydride ion transfer from the putative methoxide to C5 carbonyl of PQQ. The formed Asp297-CO2H acts as the required proton source for the immediate product. Anticorreleated motions observed in the MD structure are not across the active site to influence the reaction mechanism of MDH. 相似文献
86.
Y. Jia G. Yu J. Dong 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,61(4):433-439
The binding energies and sizes of excitons, and energy splitting of
the bright-dark excitons in single-walled carbon nanotubes have been
calculated using the nonorthogonal tight-binding model, supplemented
by the long-range Coulomb interaction. It is found that the binding
energies and the sizes of excitons not only depend on tube's
diameter d, but also its chirality. However, the splitting of the
bright-dark excitons mostly depends on 1/d2. Our obtained
results show that the curvature effect is very important for the
exciton excitations in the SWNTs, especially in the smaller diameter
ones. 相似文献
87.
Absorption spectra of germanium nanocrystals 总被引:1,自引:0,他引:1
Dmitriy V. MelnikovJames R. Chelikowsky 《Solid State Communications》2003,127(5):361-365
Absorption spectra of hydrogenated germanium nanocrystals are calculated in real space using ab initio pseudopotentials constructed within the local density approximation. Nanocrystals with over 800 atoms are considered. We find the calculated spectra are essentially bulk-like for systems with ∼250 atoms or more. The energy positions for the E1 and E2 reflectivity peaks are blue-shifted with respect to their bulk values owing to quantum confinement. Comparisons with available experimental data reveal good agreement for the energies of the E1 peak, whereas the energy position of the E2 peak is underestimated by a constant shift, which is independent of the nanocrystal size. This shift is consistent with local density calculations for bulk germanium. 相似文献
88.
89.
A. M. Badr A. A. EL-Amin A. F. Al-Hossainy 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,53(4):439-448
In this investigation, the synthesis process of the apyrazole derivative for
diphenylphosphino-methane hydrazine complexes
[ Ni(Cl)2{(Ph2P)2CHC(R1R2)NHNH2}] was
reported, and the obtained crystals were analyzed by X-ray diffraction. As a
result of the growth process, a set of complexes were formed. The structures
of these complexes are discussed on the basis of Elemental analysis (EA),
IR, 1H-NMR, 31P-NMR spectroscopic data and FAB mass spectra. The
compound under investigation shows typical semiconductor behavior as a
result of delocalization of the π-electrons in the structure. The
reflectance and transmittance spectra for the crystals were measured and
analyzed in the incident photon energy range 1.29 to 3.93 eV and in the
temperature range 77 to 300 K. The optical study revealed that the optical
transition is direct allowed. Below the absorption edge, the refractive
index as a function of wavelength was determined in the low energy region of
the used incident photon energy range. From the refractive index-wavelength
variations, the oscillator and dispersion energies of the refractive index
for the obtained crystals were determined. The static refractive index and
static dielectric constant were evaluated. 相似文献
90.
We have realized an AlAs two-dimensional electron system in which electrons occupy conduction-band valleys with different Fermi contours and effective masses. In the quantum Hall regime, we observe both resistivity spikes and persistent gaps at crossings between the Landau levels originating from these two valleys. From the positions of the spikes in tilted magnetic fields and measurements of the energy gaps away from the crossings, we find that, after occupation of the minority valley, the spin susceptibility drops rapidly, and the electrons possess a single interaction-enhanced g-factor, despite the dissimilarity of the two occupied valleys. 相似文献