期刊文献+
共找到8篇文章
< 1 >
每页显示 20 50 100
不同浓度镉污染土壤条件下3种常见植物富集研究
1
作者 王丽 《安徽农学通报》 2009年第24期46-46,65,共2页
以上海青小白菜、芥菜和川油Ⅲ为材料,研究了不同浓度镉污染土壤条件下蔬菜对镉的吸收、富集规律。芥菜和川油Ⅲ对镉的吸收大于上海青小白菜,富集系数呈现极显著差异。芥菜在土壤镉污染达50mg.kg-1时,吸收量系数最大,适宜做镉污染土壤... 以上海青小白菜、芥菜和川油Ⅲ为材料,研究了不同浓度镉污染土壤条件下蔬菜对镉的吸收、富集规律。芥菜和川油Ⅲ对镉的吸收大于上海青小白菜,富集系数呈现极显著差异。芥菜在土壤镉污染达50mg.kg-1时,吸收量系数最大,适宜做镉污染土壤修复研究材料。 展开更多
关键词 蔬菜 吸收量系数 芥菜
下载PDF
Linear and Nonlinear Optical Properties in Spherical Quantum Dots 被引量:1
2
作者 Yusuf Yakar Bekir Cakir Ayhan Ozmen 《Communications in Theoretical Physics》 SCIE CAS CSCD 2010年第6期1185-1189,共5页
We calculate the energy eigenvalues and the sate functions of one-electron Quantum Dot (QD) by using a combination of Quantum Genetic Algorithm (QGA) and Hartre-Fock-Roothaan (HFR) method. The linear and the thi... We calculate the energy eigenvalues and the sate functions of one-electron Quantum Dot (QD) by using a combination of Quantum Genetic Algorithm (QGA) and Hartre-Fock-Roothaan (HFR) method. The linear and the third-order nonlinear optical absorption coefficients for the 1s-1p, 1p-1d, and 1d-1f transitions are examined as a function of the incident photon energy for three different values of the stoichiometric ratio. The results show that the stoichiometric ratio, impurity, relaxation time, and dot size have great influence on the optical absorption coefficients of QDs. 展开更多
关键词 optical properties spherical quantum dot QGA and HFR method
下载PDF
Linear and Nonlinear Optical Absorptions of a Hydrogenic Donor in a Quantum Dot Under a Magnetic Field 被引量:3
3
作者 XIE Wen-Fang 《Communications in Theoretical Physics》 SCIE CAS CSCD 2009年第5期923-926,共4页
The linear and nonlinear optical properties of a hydrogenic donor in a disc-like parabolic quantum dot in the presence of an external magnetic field are studied. The calculations were performed within the effective ma... The linear and nonlinear optical properties of a hydrogenic donor in a disc-like parabolic quantum dot in the presence of an external magnetic field are studied. The calculations were performed within the effective mass approximation, using the matrix diagonalization method and the compact density-matrix approach. The linear and nonlinear optical absorption coefficients between the ground (L =0) and the first excited state (L = 1) have been examined based on the computed energies and wave functions. We find that the linear, nonlinear third-order, and total optical absorption coefficients are strongly affected by the confinement strength of QDs, the external magnetic field, and the incident optical intensity. 展开更多
关键词 quantum dot nonlinear optics
下载PDF
Study on absorption coefficients of dual-energy γ-rays in determining phase fractions of multiphase flows
4
作者 李志彪 李东晖 吴应湘 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2005年第12期1416-1419,共4页
This paper discusses the principle and mathematical method to measure the phase fractions of multiphase flows by using a dual-energy gamma-ray system. The dual-energy gamma-ray device is composed of radioactive isotop... This paper discusses the principle and mathematical method to measure the phase fractions of multiphase flows by using a dual-energy gamma-ray system. The dual-energy gamma-ray device is composed of radioactive isotopes of 241Am and 137Cs with emission energies of 59.5 keV and 662 keV respectively. A rational method to calibrate the absorption coefficient was introduced in detail. The statistical error has been analyzed on the basis of the accurate absorption coefficient which enables determination phrase fractions almost independent of the flow regime. Improvement has been achieved on the measurement accuracy of phase fractions. 展开更多
关键词 Absorption coefficient γ-rays DUAL-ENERGY Phase fraction
下载PDF
The Method of Imbedded Lagrangian Element to Estimate Wave Power Absorption by Some Submerged Devices
5
作者 Gerard C. Nihous 《Journal of Marine Science and Application》 2014年第2期134-142,共9页
A simple approach is described to estimate the wave power absorption potential of submerged devices known to cause wave focusing and flow enhancement. In particular, the presence of a flow-through power take-off (PTO... A simple approach is described to estimate the wave power absorption potential of submerged devices known to cause wave focusing and flow enhancement. In particular, the presence of a flow-through power take-off (PTO) system, such as low-head turbines, can be accounted for. The wave radiation characteristics of an appropriately selected Lagrangian element (LE) in the fluid domain are first determined. In the limit of a vanishing mass, the LE reduces to a patch of distributed normal dipoles. The hydrodynamic coefficients of this virtual object are then input in a standard equation of motion where the effect of the PTO can be represented, for example, as a dashpot damping term. The process is illustrated for a class of devices recently proposed by Carter and Ertekin (2011), although in a simplified form. Favorable wave power absorption is shown for large ratios of the LE wave radiation coefficient over the LE added mass coefficient. Under optimal conditions, the relative flow reduction from the PTO theoretically lies between 0.50 and 1 2 ≈ 0.71, with lower values corresponding to better configurations. Wave power capture widths, the sensitivity of results to PTO damping and sample spectral calculations at a typical site in Hawaiian waters are proposed to further illustrate the versatility of the method. 展开更多
关键词 power take-off (PTO) Lagrangian element (LE)
下载PDF
Measurement and Modeling for the Solubility of Hydrogen Sulfide in Primene JM-T
6
作者 李杰 林晓 +3 位作者 宁朋歌 曹宏斌 张懿 John C. Crittenden 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2014年第1期89-97,共9页
The primary aliphatic amine Primene JM-T was investigated as a potential absorbent for H2S removal. The solubility of HzS in JM-T was measured at 298, 313,333,353, and 368 K with H2S partial pressures from 20 to 760 k... The primary aliphatic amine Primene JM-T was investigated as a potential absorbent for H2S removal. The solubility of HzS in JM-T was measured at 298, 313,333,353, and 368 K with H2S partial pressures from 20 to 760 kPa and HzS loading from 0.02 to 0.8 mol H2S per mol JM-T. Relevant physical properties, such as density, viscoslty and dielectric constant, ot the matenal were measured. 'The thermodynamlc model with two-suttlX Margules equation was used to correlate the experimental vapor-liquid equilibrium data. Furthermore, the absorption mechanism in non-aqueous system is suggested and the difference between non-aqueous and aqueous absorption system is pointed out. 展开更多
关键词 Primene JM-T H2S removal ABSORPTION thermodynamic model
下载PDF
Firmness measurement of peach by impact force response 被引量:2
7
作者 Yong-wei WANG Jun WANG Chong YAO Qiu-jun LU 《Journal of Zhejiang University-Science B(Biomedicine & Biotechnology)》 SCIE CAS CSCD 2009年第12期883-889,共7页
The impact force response of a peach impacting on a metal flat-surface was considered as nondestructive determination of firmness. The objectives were to analyze the effect of firmness, drop height, fruit mass, and im... The impact force response of a peach impacting on a metal flat-surface was considered as nondestructive determination of firmness. The objectives were to analyze the effect of firmness, drop height, fruit mass, and impact orientation on the impact force parameters, and to establish a relationship between the impact force parameter and firmness. The effect of fruit firmness, drop height and fruit mass on the impact force parameters (coefficient of restitution, percentage of energy absorbed, and coefficient of force-time) was evaluated. The study found that the coefficient of restitution, percentage of energy absorbed, and force-time impact coefficient were significantly affected by fruit ripeness, but not affected by drop height, impact position (fruit cheek), and mass. The percentage of absorbed energy increased with ripeness, while the force-time impact coefficient and coefficient of restitution decreased with ripeness. Relationships were obtained between the three impact characteristic parameters (force-time impact coefficient, coefficient of restitution, and percentage of energy absorbed) and peach firmness using a polynomial model (R2=0.932), S model (R2=0.910), and exponential model (R2=0.941), respectively. 展开更多
关键词 FIRMNESS PEACH Impact force Coefficient of restitution Percentage of absorbed energy
原文传递
Noninvasive photoacoustic measurement of absorption coefficient using internal light irradiation of cylindrical diffusing fiber
8
作者 彭东青 朱莉莉 +1 位作者 李志芳 李晖 《Optoelectronics Letters》 EI 2017年第5期367-371,共5页
Absorption coefficient of biological tissue is an important parameter in biomedicine, but its determination remains a challenge. In this paper, we propose a method using focusing photoacoustic imaging technique and in... Absorption coefficient of biological tissue is an important parameter in biomedicine, but its determination remains a challenge. In this paper, we propose a method using focusing photoacoustic imaging technique and internal light irradiation of cylindrical diffusing fiber(CDF) to quantify the target optical absorption coefficient. Absorption coefficients for ink absorbers are firstly determined through photoacoustic and spectrophotometric measurements at the same excitation, which demonstrates the feasibility of this method. Also, the optical absorption coefficients of ink absorbers with several concentrations are measured. Finally, the two-dimensional scanning photoacoustic image is obtained. Optical absorption coefficient measurement and simultaneous photoacoustic imaging of absorber non-invasively are the typical characteristics of the method. This method can play a significant role for non-invasive determination of blood oxygen saturation, the absorption-based imaging and therapy. 展开更多
关键词 Imaging techniques IRRADIATION Light absorption Photoacoustic effect
原文传递
上一页 1 下一页 到第
使用帮助 返回顶部