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71.
72.
We measure surface recombination velocities (SRVs) below 10 cm/s on p‐type crystalline silicon wafers passivated by atomic–layer–deposited (ALD) aluminium oxide (Al2O3) films of thickness ≥10 nm. For films thinner than 10 nm the SRV increases with decreasing Al2O3 thickness. For ultrathin Al2O3 layers of 3.6 nm we still attain a SRV < 22 cm/s on 1.5 Ω cm p‐Si and an exceptionally low SRV of 1.8 cm/s on high‐resistivity (200 Ω cm) p‐Si. Ultrathin Al2O3 films are particularly relevant for the implementation into solar cells, as the deposition rate of the ALD process is extremely low compared to the frequently used plasma‐enhanced chemical vapour deposition of silicon nitride (SiNx). Our experiments on silicon wafers passivated with stacks composed of ultrathin Al2O3 and SiNx show that a substantially improved thermal stability during high‐temperature firing at 830 °C is obtained for the Al2O3/SiNx stacks compared to the single‐layer Al2O3 passivation. Al2O3/SiNx stacks are hence ideally suited for the implementation into industrial‐type silicon solar cells where the metal contacts are made by screen‐printing and high‐temperature firing of metal pastes. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
73.
Huixue LAO 《数学年刊B辑(英文版)》2010,31(3):385-392
The author uses analytic methods to study the distribution of integral ideals and Hecke Grossencharacters in algebraic number fields. Nowak's results on the distribution of integral ideals, and Chandrasekharan and Good's results on the distribution of Hecke GrSssencharacters are improved. 相似文献
74.
MgO nanoparticles (NPs) and Gr/MgO nanocomposite (NC) have been synthesized by hydrothermal route. X-ray diffraction (XRD) analysis confirmed the crystalline cubic phase of MgO and Gr/MgO NC. Raman spectroscopy was used to study the defects in the NCs. Electron microscopy study display spherical NPs of MgO on graphene sheets. UV-visible spectroscopy shows a red shift in the absorption band and a significant reduction in the bandgap for Gr/MgO NC. The improvements in dielectric properties of NC can be ascribed to interfacial polarization between rGO and MgO. The rGO in the NCs supports the electron transfer and improves the electrical conductivity. 相似文献
75.
S. Kuwata 《International Journal of Theoretical Physics》2009,48(6):1813-1832
We calculate the minimum polynomial φ(x,y) of parasupercharge Q and Hamiltonian H for single-mode parabose parasupersymmetry (P-PSUSY). Suppose that φ(x,y) satisfies the homogeneity ∀
λ∈ℝ,φ(λ
x,λ
2
y)=λ
n
φ(x,y), then the parafermionic order p
f
is restricted to either 1, 2, or 4. Under the P-PSUSY, the homogeneity of the φ(x,y) is equivalent to the parasuperconformality of Q and H. The physical meaning of the parasuperconformality is discussed, in connection with the spin of the elementary particle. 相似文献
76.
Felipe A. Asenjo 《Physics letters. A》2009,373(48):4460-4463
The effect of spin of particles is studied using a semi-classical kinetic theory for a magnetized plasma. No other quantum effects are included. We focus in the simple damping effects for the electrostatic wave modes. Besides Landau damping, we show that spin produces two new different effects of damping or instability which are proportional to ?. These corrections depend on the electromagnetic part of the wave that is coupled with the spin vector. 相似文献
77.
We fit the volatility fluctuations of the S&P 500 index well by a Chi distribution, and the distribution of log-returns by a corresponding superposition of Gaussian distributions. The Fourier transform of this is, remarkably, of the Tsallis type. An option pricing formula is derived from the same superposition of Black-Scholes expressions. An explicit analytic formula is deduced from a perturbation expansion around a Black-Scholes formula with the mean volatility. The expansion has two parts. The first takes into account the non-Gaussian character of the stock-fluctuations and is organized by powers of the excess kurtosis, the second is contract based, and is organized by the moments of moneyness of the option. With this expansion we show that for the Dow Jones Euro Stoxx 50 option data, a -hedging strategy is close to being optimal. 相似文献
78.
H. L. Kwok 《Applied physics. B, Lasers and optics》2009,94(2):279-282
Organic field-effect transistors (OFETs) have received significant attention recently because of the potential application
in low-cost flexible electronics. The physics behind their operation are relatively complex and require careful consideration
particularly with respect to the effect of charge trapping at the insulator–semiconductor interface and field effect in a
region with a thickness of a few molecular layers. Recent studies have shown that the so-called “onset” voltage (V
onset) in the rubrene OFET can vary significantly depending on past illumination and bias history. It is therefore important to
define the role of the interface trap states in more concrete terms and show how they may affect device performance. In this
work, we propose an equivalent-circuit model for the OFET to include mechanism(s) linked to trapping. This includes the existence
of a light-sensitive “resistor” controlling charge flow into/out of the interface trap states. Based on the proposed equivalent-circuit
model, an analytical expression of V
onset is derived showing how it can depend on gate bias and illumination. Using data from the literature, we analyzed the I–V characteristics of a rubrene OFET after pulsed illumination and a tetracene OFET during steady-state illumination. 相似文献
79.
Zhenlian An Min Zhao Junlan Yao Yewen Zhang Zhongfu Xia 《Applied Physics A: Materials Science & Processing》2009,95(3):801-806
To improve the thermal stability of piezoelectricity of polypropylene (PP) ferroelectrets, chemical modification of the cellular
PP film was performed via chromic acid oxidation and then hydrofluoric acid treatment. Deep chemical modification is achieved
as indicated by the energy-dispersive X-ray analyses on the cross-section of the modified cellular PP film. The results of
the isothermal decay for piezoelectric d
33-coefficient at 70°C indicate the improved thermal stability of piezoelectricity and the enhanced piezoelectric activity of
the modified PP ferroelectrets. The former is attributed to the improvement of thermal stability of the charges trapped in
the internal void surface layers as indicated by the thermally stimulated discharge measurements, while the latter results
not only from the improved thermal stability of the charges but also from the reduction in Young’s modulus of the PP ferroelectrets
due to the chemical modification as revealed by the dielectric resonance analyses. 相似文献
80.
F. V. Di Girolamo C. Aruta M. Barra P. D’Angelo A. Cassinese 《Applied Physics A: Materials Science & Processing》2009,96(2):481-487
In this paper, the dynamics of bias stress phenomenon in Sexithiophene (T6) Field Effect Transistors (FETs) has been investigated.
T6 FETs have been fabricated by vacuum depositing films with thickness from 10 to 130 nm on Si/SiO2 substrates. After the T6 film structural analysis by X-ray diffraction and the FET electrical investigation focused on carrier
mobility evaluation, bias stress instability parameters have been estimated and discussed in the context of existing models.
By increasing the film thickness, a clear correlation between the stress parameters and the structural properties of the organic
layer has been highlighted. Conversely, the mobility values as a result are found to be almost thickness independent. 相似文献