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21.
Monica Averna Alessandro A. Casazza Antonino Martines Marco Pedrazzi Alice Franchi Roberta De Tullio 《Natural product research》2019,33(10):1449-1455
We are reporting in the present study that molecules extracted from olive pomace prevent cell death induced by Ca2+-overloading in different cell types. Exposure of cells to these molecules counteracts the Ca2+-induced cell damages by reducing the activation of the Ca2+-dependent protease calpain, acting possibly through the modification of the permeability to Ca2+ of the plasma membrane. The purification step by RP-HPLC suggests that effective compound(s), differing from the main biophenols known to be present in the olive pomace extract, could be responsible for this effect. Our observations suggest that bioactive molecules present in the olive pomace could be potential candidates for therapeutic applications in pathologies characterised by alterations of intracellular Ca2+ homeostasis. 相似文献
22.
Gentilini C Evangelista F Rudolf P Franchi P Lucarini M Pasquato L 《Journal of the American Chemical Society》2008,130(46):15678-15682
The preparation and the properties of gold nanoparticles (Au NPs) protected by perfluorinated amphiphiles are described. The thiols were devised to form a perfluorinated region close to the gold surface and to have a hydrophilic portion in contact with the bulk solvent to impart solubility in water. The monolayer protected clusters were prepared, in an homogeneous phase using sodium thiolates because of the low nucleophilicity of the alpha-perfluorinated thiols, and fully characterized with (1)H, (19)F NMR spectrometry, IR and UV-vis absorption spectroscopies, transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS). Au NPs with core diameters ranging from 1.6 to 2.9 nm, depending on the reaction conditions, were obtained. Water-soluble NPs (MPC-F8-PEGs) were obtained with the thiol HS-F8-PEG ending with a short poly(ethylene glycol) unit (PEG-OMe 550), whereas thiols with shorter PEG chains give rise to NPs insoluble in water. MPC-F8-PEGs undergo an exchange reaction with amphiphilic alkyl thiols. ESR investigations, using a hydrophobic radical probe, indicate that the MPC-F8-PEG monolayer shows a greater hydrophobicity compared to the analogous hydrogenated monolayer. 相似文献
23.
Valentina Bleve Christian Schäfer Dr. Paola Franchi Dr. Serena Silvi Prof. Dr. Elisabetta Mezzina Prof. Dr. Alberto Credi Prof. Marco Lucarini 《ChemistryOpen》2015,4(1):2-21
An acid–base switchable molecular shuttle based on a [2]rotaxane, incorporating stable radical units in both the ring and dumbbell components, is reported. The [2]rotaxane comprises a dibenzo[24]crown-8 ring (DB24C8) interlocked with a dumbbell component that possesses a dialkylammonium (NH2+) and a 4,4′-bipyridinium (BPY2+) recognition site. Deprotonation of the rotaxane NH2+ centers effects a quantitative displacement of the DB24C8 macroring to the BPY2+ recognition site, a process that can be reversed by acid treatment. Interaction between stable 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) radicals connected to the ring and dumbbell components could be switched between noncoupled (three-line electron paramagnetic resonance (EPR) spectrum) and coupled (five-line EPR spectrum) upon displacement of the spin-labelled DB24C8 macroring. The complete base- and acid-induced switching cycle of the EPR pattern was repeated six times without an appreciable loss of signal, highlighting the reversibility of the process. Hence, this molecular machine is capable of switching on/off magnetic interactions by chemically driven reversible mechanical effects. A system of this kind represents an initial step towards a new generation of nanoscale magnetic switches that may be of interest for a variety of applications. 相似文献
24.
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26.
In this paper we prove existence and interior regularity of convex solutions of the Dirichlet problem for a class of Monge-Ampère
type equations with right hand side vanishing on the boundary, by means of the fixed point index theory for Bakelman's weak
solutions. The regularity in the interior follows from recent results of Caffarelli.
Partially supported by M.U.R.S.T., Italy
Partially supported by G.N.A.F.A. of C.N.R., Italy.
This work was accomplished during a Humbold research stay at Karlsruhe and Heidelberg Universities. 相似文献
27.
M. Airoldi E. Grilli M. Guzzi A. Bignazzi A. Bosacchi S. Franchi 《physica status solidi (a)》1994,144(2):401-413
The stability of the hydrogen-shallow acceptor complex in hydrogenated silicon-doped direct-gap AlxGa1−xAs is studied by low-temperature photoluminescence measurements. The shallow acceptors are passivated by hydrogen diffusion and the hydrogen-passivated acceptors are reactivated by a prolonged illumination with above-band-gap photons. The light-induced reactivation is virtually athermal (it is observed at cryogenic temperatures) and reversible (the minority acceptors recover their initial passivated state by heating the sample to temperatures close to room temperature). A model describing the radiative recombination processes observed in the studied samples is presented and the relative concentration of shallow acceptors is deduced from the intensity of the photoluminescence bands. The light-induced reactivation process of CAs acceptors follows a first-order kinetics with a dissociation frequency linearly dependent on the illumination intensity. 相似文献
28.
We report a reflectance study from 0.6 to 1.5 eV and at temperatures from 6 to 300 K on a series of Al0.4Ga0.6Sb/GaSb single quantum wells with different well thicknesses (tw = 4, 6, 8 and 11.7 nm), grown by Molecular beam Epitaxy on (001) GaSb substrates. R spectra show clear evidence of the structures associated to the allowed transitions from the n-th heavy- and light-hole to the n-th conduction subband level for n = 1, 2. The comparison between the experimental transition energies and those calculated in the framework of the envelope-function scheme showed a good agreement, thus confirming the reliability of the values for relevant QW parameters as band-offset, effective masses and band non-parabolicity. 相似文献
29.
A. Baraldi S. Franchi C. Chezzi R. Magnanini A. Parisini L. Tarricone 《physica status solidi b》1998,210(2):759-763
The effects on the electrical properties of AlxGa1—xSb of a level of the Te impurity (D level) coexisting with the DX center were investigated through an extensive analysis of Hall data. The experiments were performed in MBE samples in a wide range of alloy compositions (0 ≤ x ≤ 0.50) and Te doping densities (1016 to 1018 cm−3). The possibility of observing carrier freeze-out to a D level, without competition with the DX center, is restricted to lightly doped samples and to a narrow range of alloy fractions close to the Γ–L crossing of conduction band edges. Within this range the D level is most likely coupled to the L minima. At higher alloy fractions, freeze-out to a D level can be observed only at a low temperature where the DX center occupancy is frozen. An example of this procedure is given for x = 0.40. 相似文献
30.
Ottani V Martini D Franchi M Ruggeri A Raspanti M 《Micron (Oxford, England : 1993)》2002,33(7-8):587-596