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71.
Ionel Stavarache Ana-Maria Lepadatu Nicoleta G. Gheorghe Ruxandra M. Costescu George E. Stan Dan Marcov Adrian Slav Gheorghe Iordache Tionica F. Stoica Vladimir Iancu Valentin S. Teodorescu Cristian M. Teodorescu Magdalena Lidia Ciurea 《Journal of nanoparticle research》2011,13(1):221-232
Transmission electron microscopy and X-ray photoelectron spectroscopy analyses are performed to investigate Ge nanoparticles embedded in an amorphous SiO2 matrix. GeSiO thin films are prepared by two methods, sol?Cgel and radio frequency magnetron sputtering. After the deposition, the sol?Cgel films are annealed in either N2 (at 1 atm and 800 °C) or H2 (at 2 atm and 500 °C), and the sputtered films in H2 (at 2 atm and 500 °C), to allow Ge segregation. Amorphous Ge-rich nanoparticles (3?C7 nm size) are observed in sol?Cgel films. Crystalline Ge nanoparticles in the high pressure tetragonal phase (10?C50 nm size) are identified in the sputtered films. The size of the nanoparticles increases with Ge concentration in the volume of the film. At the film surface, the Ge concentration is much larger that in the volume for both sol?Cgel and sputtered films. At the same time, at the film surface, only oxidized Ge is observed. 相似文献
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Methods for determination of 2-amino-4-nitrophenol and 4-amino-2-nitrophenol, metabolites of 2,4-dinitrophenol, were developed using differential pulse (DP) voltammetry and HPLC with amperometric and spectrophotometric detection. The applicability of these methods was tested by the determination of the analytes in model samples of urine after preliminary separation by solid-phase extraction. Voltammetry enabled parallel determination of both analytes, but its application in real matrix was severely limited due to the interference of other compounds present in urine. HPLC allowed the determination in real urine matrix down to micromolar concentrations; amperometric detection proved to be more sensitive and selective than the spectrophotometric one. 相似文献
74.
Stefanie Schwamborn Leonard Stoica Dr. Sebastian Neugebauer Dr. Torsten Reda Dr. Hanns‐Ludwig Schmidt Prof. Dr. Wolfgang Schuhmann Prof. Dr. 《Chemphyschem》2009,10(7):1066-1070
Local redox conversion of nitro end groups of a 4‐nitrothiophenol self‐assembled monolayer on gold is achieved by direct‐mode scanning electrochemical microscopy (SECM). Potential pulses are applied to the modified gold surface leading to local reduction of nitro end groups to either hydroxylamine (?0.47 V, see picture) or amino groups (?0.6 V) exclusively beneath the positioned SECM tip.
75.
John A. Arredondo Ernesto Pérez-Chavela Cristina Stoica 《Journal of Nonlinear Science》2014,24(6):997-1032
The Schwarzschild potential, defined as \(U(r)=-A/r-B/r^3\) , where \(r\) is the relative distance between two mass points and \(A,B>0\) , models astrophysical and stellar dynamics systems in a classical context. In this paper we present a qualitative study of a three mass point system with mutual Schwarzschild interaction where the motion is restricted to isosceles configurations at all times. We retrieve the relative equilibria and provide the energy–momentum diagram. We further employ appropriate regularization transformations to analyze the behavior of the flow near triple collision. We emphasize the distinct features of the Schwarzschild model when compared to its Newtonian counterpart. We prove that, in contrast to the Newtonian case, on any level of energy the measure of the set on initial conditions leading to triple collision is positive. Further, whereas in the Newtonian problem triple collision is asymptotically reached only for zero angular momentum, in the Schwarzschild problem the triple collision is possible for nonzero total angular momenta (e.g., when two of the mass points spin infinitely many times around the center of mass). This phenomenon is known in celestial mechanics as the black-hole effect and is understood as an analog in the classical context of behavior near a Schwarzschild black hole. Also, while in the Newtonian problem all triple collision orbits are necessarily homothetic, in the Schwarzschild problem this is not necessarily true. In fact, in the Schwarzschild problem there exist triple collision orbits that are neither homothetic nor homographic. 相似文献
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Endres J Litvinova E Savran D Butler PA Harakeh MN Harissopulos S Herzberg RD Krücken R Lagoyannis A Pietralla N Ponomarev VY Popescu L Ring P Scheck M Sonnabend K Stoica VI Wörtche HJ Zilges A 《Physical review letters》2010,105(21):212503
The pygmy dipole resonance has been studied in the proton-magic nucleus 124Sn with the (α, α'γ) coincidence method at Eα=136 MeV. The comparison with results of photon-scattering experiments reveals a splitting into two components with different structure: one group of states which is excited in (α, α'γ) as well as in (γ, γ') reactions and a group of states at higher energies which is only excited in (γ, γ') reactions. Calculations with the self-consistent relativistic quasiparticle time-blocking approximation and the quasiparticle phonon model are in qualitative agreement with the experimental results and predict a low-lying isoscalar component dominated by neutron-skin oscillations and a higher-lying more isovector component on the tail of the giant dipole resonance. 相似文献
78.
79.
The rates of axion emission by nucleon–nucleon bremsstrahlung are calculated with the inclusion of the full momentum contribution from a nuclear one pion exchange (OPE) potential. The contributions of the neutron–neutron (nn), proton–proton ( pp) and neutron–proton (np) processes in both the non-degenerate and degenerate limits are explicitly given. We find that the finite-momentum corrections to the emissivities are quantitatively significant for the non-degenerate regime and temperature-dependent, and should affect the existing axion mass bounds. The trend of these nuclear effects is to diminish the emissivities. 相似文献
80.
Stoica L Ruzgas T Ludwig R Haltrich D Gorton L 《Langmuir : the ACS journal of surfaces and colloids》2006,22(25):10801-10806
This paper presents some functional differences as well as similarities observed when comparing the newly discovered cellobiose dehydrogenase (CDH) from Trametes villosa (T.v.) with the well-characterized one from Phanerochaete chrysosporium (P.c.). The enzymes were physically adsorbed on spectrographic graphite electrodes placed in an amperometric flow through cell connected to a flow system. In the case of T.v.-CDH-modified graphite electrodes, a high direct electron transfer (DET) current was registered at the polarized electrode in the presence of the enzyme substrate reflecting a very efficient internal electron transfer (IET) process between the reduced FAD-cofactor and the oxidized heme-cofactor. In the case of P.c.-CDH-modified graphite electrodes, the DET process is not as efficient, and the current will greatly increase in the presence of a mediator (mediated electron transfer, MET). As a consequence, when comparing the two types of enzyme-modified electrodes an inverted DET/MET ratio for T.v.-CDH is shown, in comparison with P.c.-CDH. The rates of the catalytic reaction were estimated to be comparable for both enzymes, by measuring the combined DET + MET currents. The inverted DET/MET ratio for T.v.-CDH-modified electrodes might suggest that probably there is a better docking between the two domains of this enzyme and that the linker region of P.c.-CDH might have an active role in modulating the rate of the IET (by changing the interdomain distance), with respect to pH. Based on the new properties of T.v.-CDH emphasized in the present study, an analytical application of a third-generation biosensor for lactose was recently published. 相似文献