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101.
根据Pegg-Barnett位相定义, 计算了一种新的奇偶非线性相干态的位相概率分布函数, 利用数值计算方法研究了它们的位相统计性质. 数值计算结果表明:新的奇偶非线性相干态的位相特性与通常奇偶相干态的位相特性截然不同. 相似文献
102.
本文从历史发展的和几何的角度说明规范变换,相位因子和规范场等物理概念的关系。它是作者一组关于规范场理论记述[1~6]的后续和补充,特别是从规范的历史发展和相位因子几何概念初步去理解杨—米尔斯规范理论的渊源。本文只是从初等水平去说明,不去触及纤维丛等数学,以避免需要拓扑学的预备知识。 相似文献
103.
为了进一步研究纳米导线阵列的排列形状以及阵列数目对其场发射行为的影响,利用镜像悬浮球模型对正方形以及六边形排列的纳米导线阵列的场发射行为进行计算与模拟,近似的得到纳米导线阵列的场发射增强因子满足如下的变化趋势:β=h/ρ(1/1+W)+1/2(1/1+W)2+3,其中h为纳米导线的高度,ρ为纳米导线的半径,W是以R为自变量的函数,R为纳米导线阵列的间距.结果显示纳米导线阵列的排列形状对其场发射性能的影响较小,而阵列间距则是影响场发射性能的关键因素:当R<R0时,场发射增强因子随着阵列间距的减小而急剧减小;当R>R0时,场发射增强因子基本不变,其中R0为导线阵列场发射的最佳间距.进一步研究表明改变纳米导线阵列的数目基本不会改变阵列的场发射性能随间距的变化趋势,但是随着阵列数目的增加,R0会有一定程度的减小,场发射增强因子也会降低.
关键词:
纳米导线
场发射
增强因子
阵列数目 相似文献
104.
The Wigner function and the symplectic tomogram of an entangled quantum state, which is a superposition of the photon’s coherent
states (even and odd coherent states), is studied. Photon statistics and violation of Bell’s inequality for the photon state
are discussed. 相似文献
105.
Transient saturation absorption spectroscopy excited near the band gap at high excitation carrier density in GaAs 下载免费PDF全文
Transient saturation absorption spectroscopy in GaAs thin films was investigated using femtosecond pump and supercontinuum probe technique at excitation densities higher than 1×10^{19}cm^{-3}. The Coulomb enhancement factor of the electron-hole plasma results in a spectrum hole at the pump wavelength. Two distinct transmission peaks at two sides of the pump wavelength are observed, arising from the bleaching of transitions from the heavy- and light-hole bands to the conduction band. The dynamic process of the transient saturation absorption is fitted using a bi-exponential function. The fast decay process is dominated by the carrier-phonon scattering and the slow process may be attributed to the electron-hole recombination. 相似文献
106.
In this study,we compared the effect of the isospin asymmetry of proton and neutron density distributions in the neutron skin-type(NST) case and in the Hartree-Fock formalism(HF) on the half-life of alpha emitters with the atomic number in the range of 82≤Z≤92.The NST case and HF formalism based on the Skyrme-SLy4 effective interaction reveal different isospin asymmetries for selected alpha emitters.Furthermore,the obtained results reveal an increase in the α-decay widths of about 30% for the NST case in comparison with the equivalent values obtained by HF formalism.The standard deviations for calculated half-lives within the NST case and HF formalism are about 0.438 and 0.391,respectively. 相似文献
107.
108.
本文提出了一种测试激光拉曼分光计中超低杂散光的新方法.实验结果表明,本方法的杂散光测量限可达10~(-14)量级. 相似文献
109.
J. Peter H. Pabon 《Journal of voice》1991,5(3)
A phonetogram is a plot of the dynamic range of the voice as a function of fundamental frequency. Traditionally, the phonetogram only records the sound-pressure level (SPL) of the threshold of phonation and the upper limit in SPL the voice can reach with sustained phonation as a function of the fundamental frequency (F0). In this study, the phonetogram is extended by including acoustic voice-quality parameters. Three additional parameters are tested: jitter, shimmer, and crest factor. For each individual voice, the variation in the three parameters is evaluated over the entire phonetogram area. By averaging individual phonetograms, standard or norm phonetograms are obtained revealing general patterns in voice-quality variation. These patterns reflect the complex relations between F0, SPL, and the acoustic voice-quality parameters just mentioned. Jitter and shimmer distributions over the phonetogram show that large variations in perturbation values can be expected when production conditions are altered. Highest perturbation values are found for the low F0 and low SPL phonations. For all voices, a gradual decrease of the crest factor is found with increasing F0, reflecting the degrading of spectral complexity with F0. The crest-factor parameter can also be used to mark those areas in the phonetogram where the fundamental dominates the waveform and where flow control is the main SPL regulating mechanism in voice production. The strong quality variations within the phonetogram stress the need for accurate control of F0 and SPL in objective voice-quality measurement. 相似文献
110.
Recently GaN-based high electron mobility transistors (HEMTs) have
revealed the superior properties of a high breakdown field and high
electron saturation velocity. Reduction of the gate leakage current
is one of the key issues to be solved for their further improvement.
This paper reports that an Al layer as thin as 3 nm was inserted
between the conventional Ni/Au Schottky contact and n-GaN epilayers,
and the Schottky behaviour of Al/Ni/Au contact was investigated
under various annealing conditions by current--voltage (I--V)
measurements. A non-linear fitting method was used to extract the
contact parameters from the I--V characteristic curves.
Experimental results indicate that reduction of the gate leakage
current by as much as four orders of magnitude was successfully
recorded by thermal annealing. And high quality Schottky contact
with a barrier height of 0.875 eV and the lowest reverse-bias
leakage current, respectively, can be obtained under 12 min
annealing at 450°C in N2 ambience. 相似文献