期刊文献+
共找到3,203篇文章
< 1 2 161 >
每页显示 20 50 100
Investigating short- and long-term transfer effects of a Taiji beginner course in participants' daily life
1
作者 Agnes Maria Schitter Brigitte Ausfeld-Hafter Marko Nedeljkovic 《Journal of Integrative Medicine》 SCIE CAS CSCD 2013年第5期295-304,共10页
in recent years research investigating various health benefits of Taiji practice has markedly increased. Despite this growing scientific interest, essential questions such as to what extent a Taiji course may exert no... in recent years research investigating various health benefits of Taiji practice has markedly increased. Despite this growing scientific interest, essential questions such as to what extent a Taiji course may exert noticeable effects in participants' everyday life, what these effects are, and how and where potential transfer effects occur, have hardly been considered. The aim of our study was to explore transfer effects from a Taiji course into participants' daily lives. METHODS: We conducted a longitudinal observational study in 45 healthy participants at the end of their three-month Taiji beginner course (tpl) and at two months (tp2) as well as one year after course completion (tp3). Participants were asked to report their Taiji practice behavior at all time points, as well as to rate and describe perceived transfer effects of Taiji course contents on their daily life at tpl and tp3. RESULTS: Transfer effects were reported by 91.1% of all respondents after course completion (tpl) and persisted in 73.3% at the one-year follow-up assessment (tp3), counting "increase of self-efficacy", "improvement of stress management", and "increase of body awareness" as the most frequently mentioned effects. Transfer effects predominantly occurred in participants' work and social environments, as well as during everyday activities in public areas. While self- reliant Taiji practice frequency significantly decreased from 82.2% at tpl to 55.6% at tp3 (P 〈 0.001), the magnitude of self-reported transfer effects did not (P = 0.35). As explorative analyses revealed, regular Taiji course attendance was highly correlated with stronger transfer effects at tpl (r = 0.51; P 〈 0.001) and tp3 (r = 0.35; P = 0.020). Participants reporting high self-reliant Taiji practice frequency at tp2 were likely to maintain a regular practice routine at tp3 (r = 0.42; P 〈 0.004), whereas self-reliant practice frequency and transfer effects at tpl were positively correlated with self-reliant practice frequency at tp3 on a trend level (r 〈 0.27; P 〉 0.08). CONCLUSION: Our data underline the importance of regular course participation for pronounced and long lasting transfer effects into participants' everyday life. We discuss that several context and process-related aspects of a Taiji intervention are potentially relevant factors for enhancement of transfer effect. 展开更多
关键词 Tai Ji daily life transfer effects SELF-EFFICACY longitudinal study healthy subjects Tai Ji daily life transfer effects SELF-EFFICACY longitudinal study healthy subjects
下载PDF
Heat Transfer Effectiveness of Three-Fluid Separated Heat Pipe Exchanger 被引量:3
2
作者 Chengming Shi Yang Wang Ying Yang Quan Liao 《Journal of Thermal Science》 SCIE EI CAS CSCD 2011年第1期64-69,共6页
A heat transfer model for three-fluid separated heat pipe exchanger was analyzed,and the temperature transfer matrix for general three-fluid separated heat exchanger working in parallel-flow or counter-flow mode was o... A heat transfer model for three-fluid separated heat pipe exchanger was analyzed,and the temperature transfer matrix for general three-fluid separated heat exchanger working in parallel-flow or counter-flow mode was obtained.It was found that the forms of temperature transfer matrix are similar for heat pipe rows with equal or different heat transfer surface area.Furthermore,by using the temperature transfer matrix of the heat pipe exchanger,the relationship between heat transfer effectiveness θ 1,θ 2 and M,NTU,U,Δt i were derived for the exchanger operating in parallel-flow or counter-flow mode,and a simple special example was adopted to demonstrate the correctness of these relationships. 展开更多
关键词 heat pipes three-fluid heat exchangers heat transfer effectiveness temperature transfer matrix
原文传递
A Brief Analysis of the Positive and Negative Effectsof the Native Language Transfer in English Study 被引量:2
3
作者 徐玲 丁琳 《科技信息》 2010年第35期I0276-I0276,I0285,共2页
As the native language transfer inevitably exerts definite influences on English study,the paper is to give a more detailed analysis to the positive and negative effects in one's L2 learning.In English teaching,th... As the native language transfer inevitably exerts definite influences on English study,the paper is to give a more detailed analysis to the positive and negative effects in one's L2 learning.In English teaching,the full use of the positive effect of the native language transfer and the utmost elimination of the negative effect of the native language transfer would bring about a great advance in English quality improvement of the learners.The learners should be taught not to avoid negative influence. 展开更多
关键词 英语学习 英语翻译 阅读 母语迁移
下载PDF
Influence of Tilted Angle on Effective Linear Energy Transfer in Single Event Effect Tests for Integrated Circuits at 130 nm Technology Node 被引量:2
4
作者 张乐情 卢健 +5 位作者 胥佳灵 刘小年 戴丽华 徐依然 毕大炜 张正选 《Chinese Physics Letters》 SCIE CAS CSCD 2017年第11期119-122,共4页
A heavy-ion irradiation experiment is studied in digital storage cells with different design approaches in 130?nm CMOS bulk Si and silicon-on-insulator (SOI) technologies. The effectiveness of linear energy transf... A heavy-ion irradiation experiment is studied in digital storage cells with different design approaches in 130?nm CMOS bulk Si and silicon-on-insulator (SOI) technologies. The effectiveness of linear energy transfer (LET) with a tilted ion beam at the 130?nm technology node is obtained. Tests of tilted angles θ=0 ° , 30 ° and 60 ° with respect to the normal direction are performed under heavy-ion Kr with certain power whose LET is about 40?MeVcm 2 /mg at normal incidence. Error numbers in D flip-flop chains are used to determine their upset sensitivity at different incidence angles. It is indicated that the effective LETs for SOI and bulk Si are not exactly in inverse proportion to cosθ , furthermore the effective LET for SOI is more closely in inverse proportion to cosθ compared to bulk Si, which are also the well known behavior. It is interesting that, if we design the sample in the dual interlocked storage cell approach, the effective LET in bulk Si will look like inversely proportional to cosθ very well, which is also specifically explained. 展开更多
关键词 SOI Influence of Tilted Angle on effective Linear Energy transfer in Single Event effect Tests for Integrated Circuits at 130 nm Tec
下载PDF
Mixed convective heat and mass transfer analysis for peristaltic transport in an asymmetric channel with Soret and Dufour effects 被引量:5
5
作者 F.M.Abbasi A.Alsaedi T.Hayat 《Journal of Central South University》 SCIE EI CAS 2014年第12期4585-4591,共7页
The present investigation addresses the simultaneous effects of heat and mass transfer in the mixed convection peristaltic flow of viscous fluid in an asymmetric channel. The channel walls exhibit the convective bound... The present investigation addresses the simultaneous effects of heat and mass transfer in the mixed convection peristaltic flow of viscous fluid in an asymmetric channel. The channel walls exhibit the convective boundary conditions. In addition, the effects due to Soret and Dufour are taken into consideration. Resulting problems are solved for the series solutions. Numerical values of heat and mass transfer rates are displayed and studied. Results indicate that the concentration and temperature of the fluid increase whereas the mass transfer rate at the wall decreases with increase of the mass transfer Biot number. Furthermore, it is observed that the temperature decreases with the increase of the heat transfer Biot number. 展开更多
关键词 peristaltic transport heat and mass transfer Soret and Dufour effects convective boundary conditions
下载PDF
Delay Effect on Coherent Transfer of Optical Frequency Based on a Triple-Pass Scheme 被引量:1
6
作者 Chao-qun Ma Li-Fei Wu +2 位作者 Jiao Gu Yan-He Chen Guo-Qing Chen 《Chinese Physics Letters》 SCIE CAS CSCD 2018年第8期9-13,共5页
We demonstrate a triple-pass scheme for coherent transfer of optical frequency and the delay effect on the fiber phase noise compensation. It is theoretically proved that the delay effect consists of both fiber delay ... We demonstrate a triple-pass scheme for coherent transfer of optical frequency and the delay effect on the fiber phase noise compensation. It is theoretically proved that the delay effect consists of both fiber delay and servo delay. The delay effect confines the servo bandwidth within 1/8 and induces a residual fiber phase noise after noise compensation. For a 25-km-long fiber, the servo bandwidth is found to be around 1 k Hz, and the fiber phase noise is suppressed approaching to the theoretical limitation. The triple-pass scheme enables the simultaneous transfer of optical frequency to multiple remote users. The performance of noise compensator in the triple-pass scheme can achieve a similar level result compared with that in the double-pass scheme. 展开更多
关键词 Delay effect on Coherent transfer of Optical Frequency Based on a Triple-Pass Scheme AOM
下载PDF
Numerical Analysis of Magnetic-Shielding Effectiveness for Magnetic Resonant Wireless Power Transfer System 被引量:1
7
作者 卢伟国 李惠荣 +1 位作者 陈伟铭 刘黎辉 《Chinese Physics Letters》 SCIE CAS CSCD 2017年第8期148-151,共4页
Magnetic radiation phenomena appear inevitably in the magnetic-resonance wireless power transfer (MR-WPT) system, and regarding this problem the magnetic-shielding scheme is applied to improve the electromagnetic pe... Magnetic radiation phenomena appear inevitably in the magnetic-resonance wireless power transfer (MR-WPT) system, and regarding this problem the magnetic-shielding scheme is applied to improve the electromagnetic performance in engineering. In this study, the shielding effectiveness of a two-coil MR-WPT system for different material shields is analyzed in theory using Moser's formula and Schelkunoff's formula. On this basis a candidate magnetic-shielding scheme with a double-layer structure is determined, which has better shielding effectiveness and coils coupling coefficient. Finally, some finite element simulation results validate the correctness of the theoretical analysis, and the shielding effectiveness with the double-layer shield in maximum is 30?dB larger than the one with the single-layer case. 展开更多
关键词 MR WPT Numerical Analysis of Magnetic-Shielding effectiveness for Magnetic Resonant Wireless Power transfer System
下载PDF
EFFECTS OF MASS TRANSFER ON THE THINNING AND RUPTURE OF A PLANE PARALLEL LIQUID FILM
8
作者 李佟茗 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 1994年第3期33-49,共17页
The effects of mass transfer and physical properties upon the thinning and rupture of adraining plane parallel film are investigated.An equation is derived in which the thinning rate is afunction of bulk properties.su... The effects of mass transfer and physical properties upon the thinning and rupture of adraining plane parallel film are investigated.An equation is derived in which the thinning rate is afunction of bulk properties.surface properties(surface tension,surface viscosities,and the variationof surface tension with surface concentration),intermolecular forces(London-van der Waals forcesand electrostatic double layer forces),adsorption and surface diffusion coefficients,bubble size andfilm thickness.An estimation for the critical thickness at which a film rupture is carried out and thecoalescence time is obtained by integration to the critical thickness,The coalescence time is predictedas a function of bulk and surface properties,London-van der forces,adsorption and surfacediffusion coefficients,and bubble size. 展开更多
关键词 BUBBLE COALESCENCE thin film drainage mass transfer effect on COALESCENCE
下载PDF
Theoretical Study of Impact of Side Substituent Effecton Intramolecular Proton Transfer of Perylenequinone
9
作者 Ying QIAN Yan WANG Ruo Zhuang LIU(Department of Chemical and Environmental Engineering, Beijing Polytechnic University, Beliing100022)(Department of Chemistry, Beijing Normal University, Beijing 100875) 《Chinese Chemical Letters》 SCIE CAS CSCD 1999年第4期317-320,共4页
Semi-empirical molecular orbital theory AMI method is employed to study the ortho-position substituent impact on intramolecular proton transfer reaction of perylenequinone. The calculation demonstrates that the peryle... Semi-empirical molecular orbital theory AMI method is employed to study the ortho-position substituent impact on intramolecular proton transfer reaction of perylenequinone. The calculation demonstrates that the perylenequinone molecule is of stable structure. and all substituents may cause the decrease of barriers for the hydrogen transfer reaction. 展开更多
关键词 perylenequinone AM1 method proton transfer substituent effect
下载PDF
THE EFFECT OF THE TRANSFER OF LAK CELLS, COMBINED WITH ALLOIMMUNIZATION, ON THE PULMONARY METASTASES OF RAT MAMMARY CARCINOMA
10
作者 李松枝 巴德年 《Chinese Journal of Cancer Research》 SCIE CAS CSCD 1989年第1期16-19,共4页
Alloimmunization was combined with lympho-kine activated killer (LAK) cells to assess its effect on mammary carcinoma in rats. The animals were injected with both irradiated allosplenocytes and syngeneic LAK cells. Me... Alloimmunization was combined with lympho-kine activated killer (LAK) cells to assess its effect on mammary carcinoma in rats. The animals were injected with both irradiated allosplenocytes and syngeneic LAK cells. Metastatic lung nodules were markedly reduced using combined therapy when compared with the transfer of LAK cells or alloimmuni-zation alone. IL-2 activity in the serum of alloim-munized rats could be detected. This activity, maintained in vivo for one week, may be responsible for enhancing the antitumor effect of transferred LAK cells. 展开更多
关键词 LAK THE effect OF THE transfer OF LAK CELLS COMBINED WITH ALLOIMMUNIZATION ON THE PULMONARY METASTASES OF RAT MAMMARY CARCINOMA
下载PDF
Numerical Modelling of Non-similar Mixed Convection Heat and Species Transfer along an Inclined Solar Energy Collector Surface with Cross Diffusion Effects 被引量:1
11
作者 Osman Anwar Bég Ahmed Bakier +1 位作者 Ramachandra Prasad Swapan Kumar Ghosh 《World Journal of Mechanics》 2011年第4期185-196,共12页
An analysis is performed to study thermo-diffusion and diffusion-thermo effects on mixed convection heat and mass transfer boundary layer flow along an inclined (solar collector) plate. The resulting governing equatio... An analysis is performed to study thermo-diffusion and diffusion-thermo effects on mixed convection heat and mass transfer boundary layer flow along an inclined (solar collector) plate. The resulting governing equations are transformed and then solved numerically using the local nonsimilarity method and Runge-Kutta shooting quadrature. A parametric study illustrating the influence of thermal buoyancy parameter (&#950), Prandtl number (Pr), Schmidt number (Sc), Soret number (Sr), Dufour number (Du) and concentration-to- thermal-buoyancy ratio parameter, N, on the fluid velocity, temperature and concentration profiles as well as on local skin-friction, Nusselt and Sherwood numbers is conducted. For positive inclination angle of the plate (&#947 = 70 degrees), flow velocity (f') is strongly increased i.e. accelerated, with thermal buoyancy force parameter (&#950), in particular closer to the plate surface;further into the boundary layer, &#950 has a much reduced effect. Conversely temperature (&#952) and concentration (&#968) is decreased with increasing thermal buoyancy parameter, &#950. For negative plate inclination, the flow is accelerated whereas for positive inclination it is decelerated i.e. velocity is reduced. Conversely with negative plate inclination both the temperature and concentration in the boundary layer is reduced with the opposite apparent for positive inclination. Increasing Prandtl number strongly reduces temperature in the regime whereas an increase in Schmidt number boosts temperatures with temperature overshoots near the plate surface for Sc = 3 and 5 (i.e. for Sc > 1). Concentration is reduced continuously throughout the boundary layer, however, with increasing Schmidt number. A positive increase in concentration-to-thermal-buoyancy ratio parameter, N, significantly accelerates the flow in the domain, whereas negative N causes a deceleration. A velocity overshoot is also identified for N = 20, at intermediate distance from the plate surface. Negative N (thermal and concentration buoyancy forces oppose each other) induces a slight increase in both fluid temperature and concentration, with the reverse observed for positive N (thermal and concentration buoyancy forces assisting each other). Increasing Dufour number respectively causes a rise in temperature and a decrease in concentration, whereas an increase in Soret number cools the fluid i.e. reduces temperature and enhances concentration values. In the absence of Soret and Dufour effects, positive N causes a monotonic increase in local Nusselt number, NuxRex-1/2 with &#950 Cos &#947, for N = -1 the local Nusselt number remains constant for all values of parameter, &#950 Cos &#947. Local Sherwood number, ShxRex-1/2 is boosted considerably with higher Schmidt numbers and also with positive N values. The computations in the absence of Soret and Dufour effects correlate accurately with the earlier study by Chen et al. (1980). 展开更多
关键词 HEAT and Mass transfer Inclined Plate Soret/Dufour effectS BUOYANCY Numerical Solar Energy
下载PDF
Analysis of Hidden Danger in Farmer's Rights and Interests during Farmland Transfer——An Evaluation of Rights Safeguarding Effect of Farmland Transfer Contract 被引量:2
12
作者 WANG Shu-han WU Xiu-min 《Asian Agricultural Research》 2010年第8期61-64,共4页
Taking Shuangliu County,Chengdu City,China as an example,evaluation index system for the rights protection effects of farmland transfer is established contract from three aspects of basic information,transfer agreemen... Taking Shuangliu County,Chengdu City,China as an example,evaluation index system for the rights protection effects of farmland transfer is established contract from three aspects of basic information,transfer agreement and legal safeguards in the contracts.According to the investigation data,weight of evaluation index is determined by both entropy weight and Analytic Hierarchy Process.Comprehensive index method is used to evaluate the rights protection effects of farmland transfer contract in the flat dam,high hill and low hill in Shuangliu County,Chengdu,China.Result shows that the transfer agreement of farmland and the basic information of contract greatly affect the rights protection effects of farmland transfer contract.There are differences in the five indices of the information of the signature of contract,pricing for payment,time limit for farmland transfer,transfer mode of farmland,and use range of farmland transfer.During the farmland transfer in reality,there are three hidden dangers in farmer's land rights and interests,which are the ill-formed transfer behavior,the relatively low income of farmers from farmland transfer,and the quality decline of farmland and difficult full reclamation in transfer period.Based on the evaluation result and investigation data,countermeasures are put forward to improve the rights protection effects of farmland transfer contract. 展开更多
关键词 Farmland transfer Farmer's rights and interests Rights safeguarding effect AHP China
下载PDF
Hall Effect on Peristaltic Flow of Third Order Fluid in a Porous Medium with Heat and Mass Transfer
13
作者 Nabil T. M. Eldabe Ahmed Y. Ghaly +2 位作者 Sallam N. Sallam Khaled Elagamy Yasmeen M. Younis 《Journal of Applied Mathematics and Physics》 2015年第9期1138-1150,共13页
We investigated the influence of hall, heat and mass transfer on the peristaltic flow of MHD third order fluid under long-wavelength and low Reynolds number approximation. The governing equations are solved analytical... We investigated the influence of hall, heat and mass transfer on the peristaltic flow of MHD third order fluid under long-wavelength and low Reynolds number approximation. The governing equations are solved analytically with the appropriate boundary conditions by using perturbation technique. The formula of velocity with temperature and concentration is obtained analytically as a function of the physical parameters of the problem. 展开更多
关键词 Peristaltic Flow THIRD Order FLUID HALL effect Heat Mass transfer
下载PDF
Fading Effects on the Performance of OFDM-Based Systems Using Channel Transfer Function
14
作者 Chie Dou 《通讯和计算机(中英文版)》 2012年第12期1404-1411,共8页
关键词 OFDM系统 信道增益 性能比较 衰落信道 传递函数 无线局域网 概率分布 信号噪声比
下载PDF
Chemical Reaction and Thermal Diffusion Effects on Mass Transfer Flow through an Inclined Plate
15
作者 Farjana Akter Md. Manjiul Islam +2 位作者 Ariful Islam Md. Shakhaoath Khan Md. Saddam Hossain 《Open Journal of Fluid Dynamics》 2016年第1期62-74,共13页
A numerical investigation of boundary layer mass transfer flow through an inclined plate with the effect of chemical reaction and thermal diffusion is presented in this study. The governing partial differential equati... A numerical investigation of boundary layer mass transfer flow through an inclined plate with the effect of chemical reaction and thermal diffusion is presented in this study. The governing partial differential equations (PDE) are transformed to a system of dimensionless non-similar coupled PDEs. The transformed, non-similar conservations equations (momentum balance equation, energy balance equation and concentration balance equation) are then solved using a numerical approach known as explicit finite difference method (EFDM). Basically EFDM introduced for the unsteadiness in the momentum, temperature, and concentration fluid fields is based on the time dependent fluid velocity, temperature and concentration of the boundary surface. During the course of discussion, it is found that the various parameters related to the problem influence the calculated resultant expressions. The computed numerical solution results for the velocity, temperature, and concentration distribution with the effect of various important dimensionless parameters (Grashof number, Modified Grashof number, Prandtl number, Schmidt number, Soret number, Dufour number, chemical reaction parameter and inclination parameter) entering into the problems are critically analyzed and discussed graphically. It can be seen that two physical phenomena chemical reaction and thermal diffusion can greatly effect on the boundary layer fluid flows through an inclined plate. 展开更多
关键词 Chemical Reaction Mass transfer Inclined Plate Soret effects Dufour effects
下载PDF
The water resource transfer in Datong river valley and its effects on ecological environment
16
《Global Geology》 1998年第1期54-54,共1页
关键词 The water resource transfer in Datong river valley and its effects on ecological environment
下载PDF
Numerical Study on Heat Transfer Characteristics of Heated/Cooled Rods Having a Composite Board in between: Effect of Thermal Vias
17
作者 Yasushi Koito Toshio Tomimura 《Journal of Electronics Cooling and Thermal Control》 2017年第4期91-102,共12页
By placing a sample between a heated and a cooled rod, a thermal conductivity of the sample can be evaluated easily with the assumption of a one-dimensional heat flow. However, a three-dimensional constriction/spreadi... By placing a sample between a heated and a cooled rod, a thermal conductivity of the sample can be evaluated easily with the assumption of a one-dimensional heat flow. However, a three-dimensional constriction/spreading heat flow may occur inside the rods when the sample is a composite having different thermal conductivities. In order to investigate the thermal resistance due to the constriction/spreading heat flow, the three-dimensional numerical analyses were conducted on the heat transfer characteristics of the rods. In the present analyses, a polymer-based composite board having thermal vias was sandwiched between the rods. From the numerical results, it was confirmed that the constriction/spreading resistance of the rods was strongly affected by the thermal conductivity of the rods as well as the number and size of the thermal vias. A simple equation was also proposed to evaluate the constriction/spreading resistance of the rods. Fairly good agreements were obtained between the numerical results and the calculated ones by the simple equation. Moreover, the discussion was also made on an effective thermal conductivity of the composite board evaluated with the heated and the cooled rod. 展开更多
关键词 Heat transfer Enhancement THERMAL Via Constriction/Spreading Resistance STEADY-STATE Method effective THERMAL Conductivity
下载PDF
Defect-rich Mg-Al MMOs supported TEPA with enhanced charge transfer for highly efficient and stable direct air capture 被引量:2
18
作者 Meng Zhao Jiewen Xiao +1 位作者 Wanlin Gao Qiang Wang 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2022年第5期401-410,共10页
Due to the advantages of low energy consumption and high CO_(2) selectivity, the development of solid amine-based materials has been regarded as a hot research topic in the field of DAC for the past decades.The adsorp... Due to the advantages of low energy consumption and high CO_(2) selectivity, the development of solid amine-based materials has been regarded as a hot research topic in the field of DAC for the past decades.The adsorption capacity and stability over multiple cycles have been the top priorities for evaluation of practical application value. Herein, we synthesized a novel DAC material by loading TEPA onto defect-rich Mg_(0.55)Al-O MMOs with enhanced charge transfer effect. The optimal Mg_(0.55)Al-O-TEPA67% demonstrates the highest CO_(2)uptake of(3.0 mmol g^(-1)) and excellent regenerability, maintaining ~90% of the initial adsorption amount after 80 adsorption/desorption cycles. The in situ DRIFTS experiments suggested the formation of bicarbonate species under wet conditions. DFT calculations indicated that the stronger bonding between Mg_(0.55)Al-O support and solid amine was caused by the abundance of oxygen defects on MMOs confirmed by XPS and ESR, which favors the charge transfer between the support and amine,resulting in intense interaction and excellent regenerability. This work for the first time conducted comprehensive and systematic investigation on the stabilization mechanism for MMOs supported solid amine adsorbents with highest uptake and superior cyclic stability in depth, which is different from the most popular SiO_(2)-support, thus providing facile strategy and comprehensive theoretical mechanism support for future research about DAC materials. 展开更多
关键词 Direct air capture Solid amine-based materials Mixed metal oxides Oxygen defects Charge transfer effect
下载PDF
High-Temperature Superconductivity—An Electron Transfer Phenomenon
19
作者 Joachim Sonntag 《World Journal of Condensed Matter Physics》 CAS 2024年第4期67-76,共10页
The increase of the critical temperature Tc for superconductivity in Al1−x(SiO2)x cermets with increasing x correlates with a decrease of the electron density n due to electron transfer, expressed by Tc/Tc,max=1−γ⋅n2... The increase of the critical temperature Tc for superconductivity in Al1−x(SiO2)x cermets with increasing x correlates with a decrease of the electron density n due to electron transfer, expressed by Tc/Tc,max=1−γ⋅n2(*). Behind the formula (*) and Tc/Tc,max=1−82.6(P−0.16)2, which is characteristic of hole-doped cuprat high-temperature superconductors, lies a general phenomenon, namely electron transfer, which equalizes potential differences in the material and leads to a strong reduction of n. P is the fraction of holes filled by the transferred electrons. A quantitative consideration gives Tc(x)/Tc,max=1−(1−x1−x0)2(**), where x is the doping concentration and x0 is the concentration at which superconductivity begins. At x=xmax=1the electron source is completely depleted and with further growth of x the hole density p starts to increase and Tc decreases until superconductivity disappears completely at x=2−x0. Taking into account the formula (**), the hypothesis arose that for x>xmaxTc/Tc,max=1−γ⋅p2(***), an analogue of the formula (*), and that superconductivity is possible not only by electron-Cooper pairs but also by paired holes. The mechanisms described here for HTSC suggest an analogy to the physics of semiconductors and that of nanocomposites: Electron-hole duality. The “P=1/8” anomaly in YBa2Cu3O6+x is caused by the simultaneous presence of electrons and holes, a consequence of incomplete electron transfer. 展开更多
关键词 High-Tc Superconductor Electron transfer Electron Density Hole Density “P = 1/8” Anomaly Jahn-Teller effect
下载PDF
The Mathematical Analysis on the Risk Management Effect of Crop Insurance Plan
20
作者 Youzhi Liu 《Chinese Business Review》 2003年第2期68-71,共4页
As a variant index, variation has an inherent shortcoming that it can only reflect the static fluctuation of the crop. This paper makes complementary analysis about it on the basis of the comment on Miranda's approac... As a variant index, variation has an inherent shortcoming that it can only reflect the static fluctuation of the crop. This paper makes complementary analysis about it on the basis of the comment on Miranda's approach of β index and goes on to analyze the β index approach under the condition of three kinds of crop insurance plans, β index approach has the advantage that it can dynamically reflect the risk transfer effect of crop insurance plan. At the same insurance level, the smaller the β index is, the better the corresponding risk transfer effect of crop insurance plan is; And vice versa. 展开更多
关键词 crop insurance plan β index approach risk transfer effect
下载PDF
上一页 1 2 161 下一页 到第
使用帮助 返回顶部