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41.
在准静态隧道电离理论模型和准经典阈上电离理论模型的基础上,建立了一个描述基于光场感生电离的椭圆偏振光场电离电子能量分布的简单模型,推导出了既易于理解又相对简单适用的描述椭圆偏振光场的电子能量分布函数解析表达式.利用此式数值计算了不同偏振参量下的椭圆偏振光场中类钯氙系统的电子能量分布曲线,计算结果表明在相同的激光功率密度下,偏振参量对基于OFI电子碰撞机制的X射线辐射强度是有影响的,并与报道的实验结果一致
关键词:
椭圆偏振光场
电子能量分布
类钯氙系统
电子碰撞机制 相似文献
42.
Yingzi Wang Paul T. Inglefield Alan A. Jones 《Journal of Polymer Science.Polymer Physics》2002,40(18):1965-1974
One‐ and two‐dimensional xenon‐129 nuclear magnetic resonance (129Xe NMR) experiments were performed on a series of poly(2,6‐dimethyl‐1,4‐phenylene oxide) (PXE) samples to characterize the sorption environments and the relative mobility of xenon in the samples. Samples of PXE in sealed NMR tubes pressurized with xenon were studied as a function of temperature, pressure, and processing. In a dense cast film of PXE, the shift relative to the free gas resonance is smaller than that observed for typical glassy polymers, indicating a higher free volume environment. Solubility rises rapidly as temperature decreases. The lower shift and rapid increase in solubility with decreasing temperature are consistent with a relatively high free volume environment for gas sorption. If PXE is antiplasticized, the shift is slightly larger, the increase in signal intensity with decreasing temperature is smaller, and the line widths are greater. This sample is a better packed glass with less free volume and slower diffusion. Samples of PXE produced by rapid precipitation have broad lines and even lower shifts corresponding to a wide distribution of higher free volume environments. The appearance of two lines at low temperatures is consistent with the presence of a bimodal distribution of environments similar to what has been observed with positron annihilation lifetime spectroscopy. The resonance closest to the free gas resonance is associated with very large free volume elements relative to those of traditional glassy polymers. In two‐dimensional experiments, there is a rapid exchange of xenon by diffusion between the two environments, indicating the close spatial proximity of the environments. Two‐dimensional experiments and one‐dimensional progressive saturation experiments reflect a rapid exchange of xenon between the sorbed state and the free gas resonance for the precipitated samples. At low temperatures, the high field peak exchanges more rapidly with the free gas. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1965–1974, 2002 相似文献
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44.
Knowledge on cavitation bubble size distribution, ambient radius of bubbles is of interest for many applications that include therapeutic and diagnostic medicine. It however becomes a hard quest when increasing the ultrasonic frequency, when direct observation of bubble dynamics is no longer possible. An indirect method based on the estimation of the bubble dissolution time under pulsed ultrasound (362 kHz) is used here under optimized conditions to derive ambient radii of cavitation bubbles in water saturated with He, Ar, Xe, O2, N2 and air: 3.0 µm for Ar, 1.2 µm for He, 3.1 µm for Xe, 2.8 µm for O2, around 1 µm for N2 and air. If the pulse on-time is increased, bubble coalescence occurs, the extent of which is rather limited for Ar but extremely high for He or N2. 相似文献
45.
Michele Mauri Matteo Farina Giorgio Patriarca Roberto Simonutti K. Thomas Klasson 《International Journal of Polymer Analysis and Characterization》2015,20(2):119-129
Pecan shell-based biochar is utilized as a filtration medium, sequestrant for metallic ions, soil conditioner, and other applications. One process for creating the biochar involves the use of phosphoric acid at high temperature in a partial oxygen atmosphere to produce a highly porous carbonaceous material. In this work, we found 129Xe NMR to be an excellent technique to study micropores in biochar. Thus, the 129Xe chemical shift in biochar was found to vary linearly with the xenon pressure; from the data an estimate of about 8–9 Å could be proposed for the average pore diameter in pecan shell-based biochar. Through saturation recovery and 2-D NMR exchange experiments, information on the exchange between free versus bound xenon was obtained. Furthermore, correlations of 129Xe NMR data with the carbonization process conditions were made. 相似文献
46.
Lukáš Bučinský Stanislav Biskupič Michal Ilčin Vladimír Lukeš Viliam Laurinc 《Journal of computational chemistry》2011,32(2):356-367
The comparison of coupled cluster with single and double excitations and with perturbative correction of triple excitations [CCSD(T)] ground state potential curves of mercury with rare gases (RG): HgHe and HgXe, at several levels of theory is presented. The scalar relativistic (REL) effects and spin‐orbit coupling effects in the ground state potential curves of these weakly bounded dimers are considered. The CCSD(T) ground state potential curves at the level of the Dirac‐Coulomb Hamiltonian (DCH) are compared with CCSD(T) curves at the level of 4‐component spin‐free modified DCH, the scalar 2nd order Douglas‐Kroll‐Hess (DKH2) and the nonrelativistic (NR‐LL) (Lévy‐Leblond) Hamiltonian. In addition, London‐Drude formula and SCF interaction energy curves are employed in the analysis of different contributions of REL effects in dissociation energies of HgRG and Hg2 dimers. Moreover, the large anharmonicity of the HgHe ground state potential curve is highlighted. The computationally less demanding scalar DKH2 Hamiltonian is employed to calculate the HgXe, Hg2, and Xe2 all electron CCSD(T) ground state potential curves in highly augmented quadruple zeta basis sets. These potential curves are used to simulate the shear viscosity of mercury, xenon, and mercury‐xenon (Hg:Xe) mixture. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2011 相似文献
47.
We have investigated the structure evolution of the124-134Xe isotopic chain in the framework of the proton-neutron interacting model IBM2. The positive parity spectra of the ground state, quasi-β and quasi-γ bands are reproduced well. The staggering in124-130Xe are almost completely removed and the γ band agree well with the experiment data, even for the high-spin quasi-γ states. The key quantities of the collective structure evolution, including level energies, the B(E2) transition branching ratios, and the M1 excitations to 1+1mixer-symmetry states are analyzed by comparing with the experimental data. The parameters for representation of the Oπν(6) and SU πν(3) features in isotopes are examined. Both experimental data and theoretical results show that the shape phase transition of124 134Xe isotopic chain is from the SU πν(3)(triaxial rotation) to the Uπν(5)(vibration motion) with a considerable constituent of the Oπν(6) symmetry(γ-unstable rotation), where the shape phase transition rapidly takes place between the neutron number N = 76 and N = 78. 相似文献
48.
49.
Michael J. Hughes David S. Brock Helene P. A. Mercier Gary J. Schrobilgen 《ChemInform》2011,42(47):no-no
The interaction of XeF2 with excess XeOF4 leads to the formation of a mixture of α‐XeOF4·XeF2 and β‐XeOF4·XeF2. 相似文献
50.
以中子诱发235U裂变产生的135Xe 的累积产额数据为例, 利用了所有可利用的实验数据, 介绍了裂变产物产额数据的评价方法, 包括数据的收集、 修正、 评价、 误差调整和数据处理, 特别是协方差数据的评价、 半经验模型理论计算数据的应用和相关数据的处理, 给出了135Xe热能点产额的推荐值以及0~20 MeV产额-能量关系曲线。 Takeing 135Xe produced by neutron induced fission of 235U as an example, the evaluation method for fission yield was introduced using the all experimental data available. The evaluation procedure includes the experimental data collection, correction, evaluation, error assessment and data analysis. The study of the uncertainty covariance, application of semi empirical theoretical calculation and the yield energy dependence of 135Xe in the incident energy range 0~20 MeV were emphasized in this work. 相似文献