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共焦显微拉曼光谱在界面研究中的应用   总被引:4,自引:0,他引:4  
本研究的重点是拓宽共焦显微拉曼光谱技术在液/气、液/固界面研究中的应用。通过合理地设计实验,利用共焦显微拉曼光谱技术高的纵向分辨率研究了液/气界面水溶性的卟啉(TSPP)的聚集行为,发现TSPP在本体中和在界面上的行为有着显著的区别。同时,对甲醇电化学氧化过程中电极表面附近的溶液成分进行了剖层分析。利用其高的横向分辨率,借助表面增强效应对沉积在玻碳上的金薄层进行拉曼成像研究,发现光学成像和拉曼成像  相似文献
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The study of the interaction between collisionless plasma flow and stagnant plasma revealed the presence of an outer boundary layer at the border of a geomagnetic trap, where the super-Alfvén subsonic laminar flow changes over to the dynamic regime characterized by the formation of accelerated magnetosonic jets and decelerated Alfvén flows with characteristic relaxation times of 10–20 min. The nonlinear interaction of fluctuations in the initial flow with the waves reflected from an obstacle explains the observed flow chaotization. The Cherenkov resonance of the magnetosonic jet with the fluctuation beats between the boundary layer and the incoming flow is the possible mechanism of its formation. In the flow reference system, the incoming particles are accelerated by the electric fields at the border of boundary layer that arise self-consistently as a result of the preceding wave-particle interactions; the inertial drift of the incoming ions in a transverse electric field increasing toward the border explains quantitatively the observed ion acceleration. The magnetosonic jets may carry away downstream up to a half of the unperturbed flow momentum, and their dynamic pressure is an order of magnitude higher than the magnetic pressure at the obstacle border. The appearance of nonequilibrium jets and the boundary-layer fluctuations are synchronized by the magnetosonic oscillations of the incoming flow at frequencies of 1–2 mHz.  相似文献
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A new phenomenon was discovered on the basis of analysis of the Interball project data. A hot plasma flow is thermalized through the formation of “long-operating” vortex streets and local discontinuities and solitons in a distributed region over polar cusps. Plasma percolation through the structured boundary and secondary reconnection of fluctuating magnetic fields in a high-latitude turbulent boundary layer account for the main part of solar wind plasma inflow into the magnetospheric trap. Unlike local shocks, the ion thermalization is accompanied by the generation of coherent Alfvén waves on the scales ranging from ion gyroradius to the radius of curvature of the averaged magnetic field, as well as by the generation of diamagnetic bubbles with a demagnetized heated plasma inside. This “boiling” plasma has a frequency region where the spectrum is different from the Kolmogorov law (with slopes 1.2 and 2.4 instead of 5/3 or 3/2). The fluctuation self-organization in the boundary layer (synchronization of three-wave decays) was observed on certain frequency scales.  相似文献
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用分子动力学模拟方法结合核磁共振化学位移和红外光谱结果,研究二甲基亚砜DMSO水溶液在全浓度范围内的结构和弱相互作用. 表明径向分布函数分析,DMSO水溶液中既存在着传统的强氢键又存在C—H…O弱相互作用. 氢键网络分析发现DMSO水溶液体系在水富集区域,水分子倾向于自身缔合形成稳定的分子簇结构,而随着DMSO浓度的逐渐增加,水的有序结构受到破坏. DMSO的摩尔分数为0.35是一个特殊点,多种性质偏离理想混合最远. 水分子和DMSO分子发生了交叉缔合作用形成稳定的分子聚集体. 分子动力学统计的平均氢键数与核磁共振化学位移和红外波数变化数据结果进行比较,结果吻合很好.  相似文献
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采用分子动力学模拟方法结合核磁共振化学位移和粘度对尿素水溶液在稀浓度范围内的结构和弱相互作用进行研究. 从径向分布函数(RDF)分析看出,尿素水溶液中存在着几种不同类型、不同氢键形成能力的传统氢键. 氢键网络分析发现尿素水溶液体系在水富集区域,水分子倾向于自身缔合形成稳定的分子簇结构,而随着尿素浓度的逐渐增加,水的有序结构受到破坏,水分子和尿素分子发生了交叉缔合作用形成氢键,尿素分子有形成自身缔合的趋势. 分子动力学统计的平均氢键数与核磁共振化学位移和粘度数据结果进行比较,发现它们的变化趋势一致,证明了实验和理论结果有很强的可靠性.  相似文献
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We report the surface-enhanced Raman (SERS) spectra of morphine in silver colloid, and study the silver colloid enhanced effects on the Raman scattering of morphine. The Raman bands of morphine are assigned to certain molecule vibrations. The broad band in the long-wavelength region of the electronic absorption spectra of the sol with added adsorbent at certain concentrations has been explained in terms of the ag- gregation of the colloidal silver particles. The potential applications of SERS in quantitative measurement of the morphine samples are demonstrated. By using a proper Raman band of morphine, the detection limit of morphine in silver sol is found to be 1.5 ng/ml. The result suggests that it is of great significance to use SERS in illicit drug morphine inspection.  相似文献
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采用分子动力学模拟方法结合核磁共振化学位移系统研究了N,N-二甲基乙酰胺(DMA)水溶液体系全浓度范围的弱相互作用. 并对动力学模拟结果和核磁共振化学位移进行了比较. 径向分布函数表明体系中强氢键和C-H···O弱相互作用并存. 氢键网络分析体现了DMA水溶液结构中存在着不同的溶液结构区域. 随浓度和温度变化核磁共振化学位移值用于研究形成氢键的变化情况,并和模拟得到的结果进行比较,模拟和实验结果得到了较好的吻合.  相似文献
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Carbon-coated olivine-structured LiFe0.5Co0.5PO4 solid solution was synthesized by a facile rheological phase method and applied as cathode materials of lithium-ion batteries. The nanostructure’s properties, such as morphology, component, and crystal structure for the samples, characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer, Emmett, and Teller (BET) determination, X-ray photoelectron spectroscopy (XPS), and the electrochemical performances were evaluated using constant current charge/discharge tests and electrochemical impedance spectroscopy (EIS). The results indicate that nanoplatelet- and nanorod-structured LiFe0.5Co0.5PO4/C composites were separately obtained using stearic acid or polyethylene glycol 400 (PEG400) as carbon source, and the surfaces of particles for the two samples are ideally covered by full and uniform carbon layer, which is beneficial to improving the electrochemical behaviors. Electrochemical tests verify that the nanoplatelet LiFe0.5Co0.5PO4/C shows a better capacity capability, delivering a discharge specific capacity of 133.8, 112.1, 98.3, and 74.4 mAh g−1 at 0.1, 0.5, 1, and 5 C rate (1 C = 150 mA g−1); the corresponding cycle number is 5th, 11th, 15th, 20th, and 30th, respectively, whereas the nanorod one possesses more excellent cycling ability, with a discharge capacity of 83.3 mAh g−1 and capacity retention of 86.9% still maintained after cycling for 100 cycles at 0.5 C. Results from the present study demonstrate that the LiFe0.5Co0.5PO4 solid solution nanomaterials with favorable carbon coating effect combine the characteristics and advantage of LiFePO4 and LiCoPO4, thus displaying a tremendous potential as cathode of lithium-ion battery.  相似文献
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