期刊文献+
共找到35,515篇文章
< 1 2 250 >
每页显示 20 50 100
Optimization in Transition between Two Dynamic Systems Governed by a Class of Weakly Singular Integro-Differential Equations 预览
1
作者 Shihchung Chiang 《应用数学(英文)》 2019年第10期826-835,共10页
This study presents numerical methods for solving the minimum energies that satisfy typical optimal requirements in the transition between two dynamic systems where each system is governed by a different kind of weakl... This study presents numerical methods for solving the minimum energies that satisfy typical optimal requirements in the transition between two dynamic systems where each system is governed by a different kind of weakly singular integro-differential equation. The class of weakly singular integro-differential equations originates from mathematical models in aeroelasticity. The proposed numerical methods are based on earlier reported approximation schemes for the equations of the first kind and the second kind. The main result of this study is the development of numerical techniques for determining the stability between two dynamic systems in the minimum energy sense. 展开更多
关键词 Optimal REQUIREMENT TRANSITION WEAKLY SINGULAR Integro-Differential EQUATIONS Stability
在线阅读 免费下载
Transition Specific Risk Factors Affecting the Lifestyle Disease Progression from Diabetes to Hypertension in India 预览
2
作者 Wahengbam Bigyananda Meitei Laishram Ladusingh 《健康(英文)》 2019年第8期1055-1071,共17页
Diabetes and hypertension are common co-morbid associates and coexist in many of the cases. The study attempts to understand the two-way transition between diabetes and hypertension and the risk factors affecting the ... Diabetes and hypertension are common co-morbid associates and coexist in many of the cases. The study attempts to understand the two-way transition between diabetes and hypertension and the risk factors affecting the transition using the multistate model. The study used data from the first and second waves of IHDS. There is a significant rise in the level of diabetes and hypertension from 2004-05 to 2011-12. Except for transition from hypertension to diabetes, the probability of transition in all other transition decreases and the mean waiting time to stay in the healthy state increases after adjusting for several covariates. Increases in the level of smoking, drinking of alcohol, consumption of tobacco, body mass index, education and household income quintile are the major transition specific risk factors affecting the transition between diabetes and hypertension. And the risk of transitioning from a healthy state to hypertension is higher among females compared to males. 展开更多
关键词 DIABETES HYPERTENSION TRANSITION Disease PROGRESSION INDIA
在线阅读 免费下载
Anisotropic iron-doping patterns in two-dimensional cobalt oxide nanoislands on Au(111)
3
作者 Anthony Curto Zhaozong Sun +5 位作者 Jonathan Rodriguez-Fernandez Liang Zhang Ayush Parikh Ting Tan Jeppe V. Lauritsen Aleksandra Vojvodic 《纳米研究:英文版》 SCIE EI CAS CSCD 2019年第9期2364-2372,共9页
An in teg rated approach combi ning den sity functional theory(DFT)calculati ons and atomic resol utio n sea nning tun neling microscopy(STM)is used to study well-defined iron-doped cobalt oxide nanoislands supported ... An in teg rated approach combi ning den sity functional theory(DFT)calculati ons and atomic resol utio n sea nning tun neling microscopy(STM)is used to study well-defined iron-doped cobalt oxide nanoislands supported on Au(111).The focus is on the structure and distribution of Fe dopants within these nanoislands of CoO as a function of Fe to Co ratio.The DFT and STM results agree strongly and complement each other to allow for a more complete un dersta nding of the dopa nt structure trends on the nano scale.Using Fe as a marker,we first find that the stacki ng seque nee of the moire structure of the host cobalt oxide nano islands can be ide ntified un ambiguously through a combinati on of DFT and STM.Using the distinct con trast of the embedded Fe dopa nt atoms as observed with atom-resolved STM,we find correlatio ns betwee n Fe dopa nt positi on and the CoO/Au(111)moire patter n at varyi ng Fe dopa nt den sities.Formatio n of Fe-dopa nt clusters within the nano islands is investigated in detail through DFT and found to agree with the dopant patter ns observed in STM.We find that the structural effects of Fe dopants throughout the nanoislands with the basal planes and the two types of edges—the oxygen and metal edges—have different nature.Both DFT calculations and STM images show a strong preferenee for Fe dopants to be located directly on or near the oxygen edge of the nanoislands as opposed to being directly on or n ear the metal edge.Take n together,our results illustrate that Fe dopa nt incorporati on and distributi on within CoO nanoislands are highly an isotropic and gover ned by both the moire structure of the basal planes as well as nano-size effects present at the under-coordinated edges of different local geometry and chemistries. 展开更多
关键词 seanning TUNNELING microscopy(STM) density functional theory(DFT) cobalt oxide TRANSITION METAL OXIDES mixed TRANSITION METAL OXIDES
Urban Transition Dynamics in the Regional Rescaling of the Pearl River Delta Area:a Qualitative Approach 预览
4
作者 Yang Fu 《宏观管理与公共政策(英文)》 2019年第1期7-17,共11页
The Pearl River Delta region has been the hub of urban vibrancy and boom ever since the country’s opening up and devolution reforms.However,the political and economic institutions of the cities in this region are so ... The Pearl River Delta region has been the hub of urban vibrancy and boom ever since the country’s opening up and devolution reforms.However,the political and economic institutions of the cities in this region are so different and complicated that they pose great challenges to the integration of the whole region.This study takes one prominent experiment of urban expansion,Hengqin in Zhuhai,as a case study to investigate how institutional innovations are forged and managed to boost urban development and transitions towards sustainable growth and regional integration.We adopt a multi-level perspective framework to analyze Hengqin’s urban transition.Government archives,master plans,various documents and interviews with government officials,planners,residents,and businesses from Zhuhai,Hong Kong,and Macau are chosen as sources of the analysis,which delineates the complex interactions from a variety of stakeholders.Despite difficulties in the early days,Hengqin is now transitioning quickly,although still confronted with inter-scalar challenges.A better understanding of the governance and economic innovations that have taken place,and the investment-driven development strategies involved,will help shed light on the urban transition of other similar city regions. 展开更多
关键词 Urban transition MULTI-LEVEL Perspective Governance transition Niche management Urban rescaling
在线阅读 免费下载
SFRP4 expression correlates with epithelial mesenchymal transitionlinked genes and poor overall survival in colon cancer patients 预览
5
作者 Landry E Nfonsam Jana Jandova +2 位作者 Hunter C Jecius Pamela N Omesiete Valentine N Nfonsam 《世界胃肠肿瘤学杂志:英文版(电子版)》 CAS 2019年第8期589-598,共10页
BACKGROUND Colon cancer is among the most commonly diagnosed cancers in the United States with an estimated 97220 new cases expected by the end of 2018.It affects 1.2 million people around the world and is responsible... BACKGROUND Colon cancer is among the most commonly diagnosed cancers in the United States with an estimated 97220 new cases expected by the end of 2018.It affects 1.2 million people around the world and is responsible for about 0.6 million deaths every year.Despite decline in overall incidence and mortality over the past 30 years,there continues to be an alarming rise in early-onset colon cancer cases(<50 years).Patients are often diagnosed at late stages of the disease and tend to have poor survival.We previously showed that the WNT“gatekeeper”gene,secreted frizzled-related protein 4(SFRP4),is over-expressed in early-onset colon cancer.SFRP4 is speculated to play an essential role in cancer by inhibiting the epithelial mesenchymal transition(EMT).AIM To investigate the correlation between SFRP4 expression and EMT-linked genes in colon cancer and how it affects patient survival.METHODS SFRP4 expression relative to that of EMT-linked genes and survival analysis were performed using the University of California Santa Cruz Cancer Browser interface.RESULTS SFRP4 was found to be co-expressed with the EMT-linked markers CDH2,FN1,VIM,TWIST1,TWIST2,SNAI1,SNAI2,ZEB1,ZEB2,POSTN,MMP2,MMP7,MMP9,and COL1A1.SFRP4 expression negatively correlated with the EMTlinked suppressors CLDN4,CLDN7,TJP3,MUC1,and CDH1.The expression of SFRP4 and the EMT-linked markers was higher in mesenchymal-like samples compared to epithelial-like samples which potentially implicates SFRP4-EMT mechanism in colon cancer.Additionally,patients overexpressing SFRP4 presented with poor overall survival(P=0.0293).CONCLUSION Considering the implication of SFRP4 in early-onset colon cancer,particularly in the context of EMT,tumor metastasis,and invasion,and the effect of increased expression on colon cancer patient survival,SFRP4 might be a potential biomarker for early-onset colon cancer that could be targeted for diagnosis and/or disease therapy. 展开更多
关键词 SECRETED frizzled-related protein 4 Epithelial MESENCHYMAL transition COLON cancer Survival
在线阅读 免费下载
Effect of Modified Vermiculite on the Interface of a Capric Acid-expanded Vermiculite Composite Phase Change Material with Phase Transition Kinetics
6
作者 ZHANG Hongguang ZHU Jiaoqun +2 位作者 CHENG Xiaomin ZHOU Weibing LIU Fengli 《武汉理工大学学报:材料科学英文版》 SCIE EI CAS 2019年第2期345-352,共8页
A new type of capric acid(CA)-acid expanded vermiculite(AEV) composite phase change material(PCM) with improved adsorption ability and interface adhesive strength was developed. Through the analysis of non-isothermal ... A new type of capric acid(CA)-acid expanded vermiculite(AEV) composite phase change material(PCM) with improved adsorption ability and interface adhesive strength was developed. Through the analysis of non-isothermal phase transition kinetics, modified vermiculite was observed to change and affect the phase transformation mechanism of the composite. AEV was treated with hydrochloric acid to improve the specific surface area and micro-pore structure. The surface area measured by BET increased from 81.94 m2/g for expanded vermiculite(EV) to 544.13 m2/g for AEV. CA-EV and CA-AEV composite PCMs were prepared by direct impregnation. The non-isothermal phase transition isotherms of CA-EV and CA-AEV were recorded by DSC at different heating rates(1, 5, 10, 15, and 20 ℃/min), which indicated that the phase transition rate increased with the heating rate and the phase transition process changed. Kinetics parameters were analyzed by a double extrapolation method. The activation energy(E) under the original state(Eα→0) of CA-AEV and CA-EV was 1 117 kJ/mol and 937 kJ/mol, respectively, and 1 205 kJ/mol and 1 016 kJ/mol under the thermal equilibrium state(Eβ→0). The most probabilistic mechanism function of CA-AEV satisfied G(α)=α2/3, which followed the Mample special rule, and the function of CA-EV satisfied G(α)=[(1+α)1/3-1]2, which followed the anti-Jander function. 展开更多
关键词 modified VERMICULITE PHASE CHANGE material PHASE TRANSITION KINETICS thermal storage
Nonlinear optics in the electron-hole continuum in 2D semiconductors:two-photon transition, second harmonic generation and valley current injection
7
作者 Pu Gong Hongyi Yu +1 位作者 Yong Wang Wang Yao 《科学通报:英文版》 SCIE EI CSCD 2019年第15期1036-1043,共8页
We investigate two-photon transitions to the electron-hole scattering continuum in monolayer transition-metal dichalcogenides, and identify two contributions to this nonlinear optical process with opposite circularly ... We investigate two-photon transitions to the electron-hole scattering continuum in monolayer transition-metal dichalcogenides, and identify two contributions to this nonlinear optical process with opposite circularly polarized valley selection rules. In the non-interacting limit, the competition between the two contributions leads to a crossover of the selection rule with the increase of the two-photon energy. With the strong Coulomb interaction between the electron and hole, the two contributions excite electron-hole scattering states in orthogonal angular momentum channels, while the strength of the transition can be substantially enhanced by the interaction. Based on this picture of the two-photon transition, the second harmonic generation(SHG) in the electron-hole continuum is analyzed, where the Coulomb interaction is shown to greatly alter the relative strength of different cross-circular polarized SHG processes. Valley current injection by the quantum interference of one-photon and two-photon transition is also investigated in the presence of the strong Coulomb interaction, which significantly enhances the injection rate. 展开更多
关键词 2D SEMICONDUCTORS Nonlinear optics Electron-hole CONTINUUM Two-photon transition Second-harmonic generation VALLEY current injection
A New Filter Collaborative State Transition Algorithm for Two-Objective Dynamic Reactive Power Optimization
8
作者 Hongli Zhang Cong Wang Wenhui Fan 《清华大学学报自然科学版(英文版)》 EI CAS CSCD 2019年第1期30-43,共14页
Dynamic Reactive Power Optimization (DRPO)is a large-scale,multi-period,and strongly coupled nonlinear mixed-integer programming problem that is difficult to solve directly.First,to handle discrete variables and switc... Dynamic Reactive Power Optimization (DRPO)is a large-scale,multi-period,and strongly coupled nonlinear mixed-integer programming problem that is difficult to solve directly.First,to handle discrete variables and switching operation constraints,DRPO is formulated as a nonlinear constrained two-objective optimization problem in this paper.The first objective is to minimize the real power loss and the Total Voltage Deviations (TVDs),and the second objective is to minimize incremental system loss.Then a Filter Collaborative State Transition Algorithm (FCSTA)is presented for solving DRPO problems.Two populations corresponding to two different objectives are employed.Moreover,the filter technique is utilized to deal with constraints.Finally,the effectiveness of the proposed method is demonstrated through the results obtained for a 24-hour test on Ward &Hale 6bus,IEEE 14bus,and IEEE 30bus test power systems.To substantiate the effectiveness of the proposed algorithms,the obtained results are compared with different approaches in the literature. 展开更多
关键词 dynamic reactive power optimization FILTER COLLABORATIVE state transition ALGORITHM WARD &Hale 6bus EEE 14bus IEEE 30bus
Seasonal Variability in the Distribution of Phytoplankton in Paracas Bay/Peru, as a Response to Environmental Conditions 预览
9
作者 Sonia Sánchez Nelly Jacobo +3 位作者 Avy Bernales Augusto Franco Jorge Quispe Georgina Flores 《环境科学与工程:B》 2019年第1期7-16,共10页
During 2013-2015, a series of bio-oceanographic surveys was carried out in Paracas bay (13°50′ S). This coastal habitat represents a transition between open ocean and continent. Changes in distribution and struc... During 2013-2015, a series of bio-oceanographic surveys was carried out in Paracas bay (13°50′ S). This coastal habitat represents a transition between open ocean and continent. Changes in distribution and structure of phytoplankton community and presence of noxious algal blooms were evaluated. The vertical stability of water column was analyzed on transects of temperature, salinity and potential density. Stratification of the water column as well as other variables presented a seasonal behavior. The maximum values were recorded in summer and were directly related to the seasonal heat flux in surface layers of the bay, while in winter this stratification index was minimum. N/P ratios showed a seasonal variation with highest values in winter and lowest ones in summer. Silicate concentrations were minimum mainly during in spring due to high biological fixation. The dominance of diatoms was evident in winter and spring, with maximum abundances of r strategists. The diversity and equitability indexes were low (< 3 bits?cel^-1 and 0.31, respectively). During summer, there was a greater contribution of oceanic species, with high concentrations of the dinoflagellate Prorocentrum cordatum;and a higher frequency of algal blooms (Akashiwo sanguinea, Heterosigma akashiwo, Eutreptiella gymnastica and Gonyaulax polygramma) in the coastal zone. Silicates and pH presented a significant correlation with diatom abundances in spring, whilst dinoflagellates were associated to warm and salinity conditions in summer. Weak correlations were found for potentially toxic dinoflagellates with temperature and for Pseudo-nitzschia group with silicates and phosphates. 展开更多
关键词 HAB TRANSITION ZONES inshore ECOSYSTEM Paracas bay-Peru PHYTOPLANKTON
在线阅读 下载PDF
中国山区农村土地利用转型及其对土地整治的政策启示
10
作者 张佰林 孙丕苓 +2 位作者 姜广辉 张瑞娟 高江波 《地理学报:英文版》 SCIE CSCD 2019年第10期1713-1730,共18页
The cultivation of mountainous land results in water loss and soil erosion. With rapid urbanization and industrialization in China, labor emigration relieves the cultivation of mountainous areas in regions with high p... The cultivation of mountainous land results in water loss and soil erosion. With rapid urbanization and industrialization in China, labor emigration relieves the cultivation of mountainous areas in regions with high poverty and leads to a significant land use transition. This research built an analysis framework for "land use transition – driving mechanism – effects –responses" for mountainous areas of China undergoing land use transition and then proposed the direction of mountainous land consolidation. The results showed that the turning point of land use morphology was the core of rural land use transition in mountainous areas. The expansion of cropland and the contraction of forestland have transitioned to the abandonment of cropland and the expansion of forestland;this transition was the main characteristic of the dominant land use change. Land marginalization and land ecological functional recovery were the main characteristics of the recessive land use transition in mountainous areas. Socioeconomic factors were the primary driving forces during land use transition in mountainous areas, with labor emigration being the most direct force. The rising costs of farming and the challenging living conditions causing labor emigration were fundamental driving forces. Rural land use transition in mountainous areas reduced the vulnerability of the ecological function of land ecosystems. The advantages and disadvantages of the socioeconomic effects should focus on rural development of mountainous areas as well as the livelihood of farmers;this should be further supported by empirical and quantitative research. Rural land use transition of mountainous areas improves natural restoration and is related to socioeconomic development. Rural land consolidation of mountainous areas should conform to land use transition,with the goal of shifting from the increase of cultivated land to the synergies of ecological and environmental protection. 展开更多
关键词 LAND use TRANSITION driving FORCE effect LAND CONSOLIDATION mountainous area
Analysis of Transition Mechanism of Cubic Boron Nitride Single Crystals under High Pressure-High Temperature with Valence Electron Structure Calculation
11
作者 吕美哲 许斌 +2 位作者 蔡立超 贾凤 袁兴栋 《中国物理快报:英文版》 SCIE CAS CSCD 2019年第1期10-13,共4页
The possibilities of hexagonal boron nitride (hBN)and lithium boron nitride (Li3BN2)transition into cubic boron nitride (cBN)under synthetic pressure 5.0 GPa and synthetic temperature 1700K are analyzed with the use o... The possibilities of hexagonal boron nitride (hBN)and lithium boron nitride (Li3BN2)transition into cubic boron nitride (cBN)under synthetic pressure 5.0 GPa and synthetic temperature 1700K are analyzed with the use of the empirical electron theory of solids and molecules.The relative differences in electron density are calculated for dozens of hi-phase interfaces hBN/cBN,Li3BN2/cBN.These relative differences of hBN/cBN are in good agreement with the first order of approximation (<10%),while those of Li3BN2/cBN are much greater than 10%. This analysis suggests that Li3BN2 is impossible to be intermediate phase but is a catalyst and cBN should be directly transformed by hBN. 展开更多
关键词 Transition Mechanism CUBIC BORON VALENCE Electron Structure Calculation
Spatial distribution and filtering efficiency of Daphnia in a deep subtropical reservoir 预览
12
作者 ZHANG Man SMYTH Rebecca Ashley +6 位作者 ZHU Weixia ZHANG Li LI Yuncong WANG Yifan LI Xuejun GU Qianhong GAO Yunni 《海洋湖沼学报(英文)》 SCIE CAS CSCD 2019年第4期1277-1288,共12页
Studies of Daphnia distribution and function could help people manage and protect water quality. We investigated how spatial distribution and filtering efficiency of Daphnia in the transition and lacustrine zones of t... Studies of Daphnia distribution and function could help people manage and protect water quality. We investigated how spatial distribution and filtering efficiency of Daphnia in the transition and lacustrine zones of the Nanwan Reservoir (China). Samplings were conducted seasonally for 2 years from six sites in the reservoir. Daphnia abundance and biomass were significantly higher in the lacustrine zone than in the transition zone. Similar composition and biomass of edible phytoplankton were found in the two zones, suggesting that food quantity could not explain high Daphnia distribution in the lacustrine zone. The variations of water velocity and food quality could help explaining Daphnia patchy distribution in the reservoir. On the one hand, rapid water velocity can cause the Daphnia decrement in the transition zone. On the other hand, the ratio of particulate organic carbon (POC) to chlorophyll a (chl a) concentration was significantly higher in the transition zone, indicating more allochthonous material constituted the food source for Daphnia. The lower quality food likely suppressed Daphnia development in the transition zone. A linear regression between Daphnia abundance and Secchi depth (SD) may suggest a cause-effect relationship where increased filtering efficiency was responsible for increased water clarity to some extent. 展开更多
关键词 DAPHNIA LACUSTRINE ZONE transition ZONE water CLARITY Nanwan RESERVOIR
在线阅读 下载PDF
双创背景下大学计算机基础实验室的适应性转型研究 预览
13
作者 孙海英 《锦州医科大学学报:社会科学版》 2019年第1期77-79,共3页
高校实验室在大学生创新创业能力提升方面发挥着重要的作用,是大学生从事创新创业训练的重要平台之一。作为高校实验室的重要组成部分,在传统的开设大学计算机基础课及部分专业课的基础上,理应从工作人员、教学方式、资源配置、管理制... 高校实验室在大学生创新创业能力提升方面发挥着重要的作用,是大学生从事创新创业训练的重要平台之一。作为高校实验室的重要组成部分,在传统的开设大学计算机基础课及部分专业课的基础上,理应从工作人员、教学方式、资源配置、管理制度等方面谋求主动转型,以期更加适应大学生从事创新创业实践活动的需要。 展开更多
关键词 创新创业 基础实验室 转型 适应性
在线阅读 下载PDF
首创会展城市缝合带——双线公园设计 预览
14
作者 林文波 叶清 +2 位作者 祝捷 王石 杨光伟 《建筑技艺》 2019年第8期84-89,共6页
结合深圳市国际会展中心设计,从会展与城市的需求出发,提出首层+8m标高公共休闲带这一线性空间模块,探讨将会展配套功能向外延伸、城市功能向内渗透的可能性,以期将会展中心对城市的侵入从过去的公共消极性转化为城市生活驱动器。在打... 结合深圳市国际会展中心设计,从会展与城市的需求出发,提出首层+8m标高公共休闲带这一线性空间模块,探讨将会展配套功能向外延伸、城市功能向内渗透的可能性,以期将会展中心对城市的侵入从过去的公共消极性转化为城市生活驱动器。在打造城市绿色系统枢纽基础上,探讨高复合公众生活、展会一体化、城市发展激活的景观设计,并以景观为核心,构建城市中不同标高的平行公共空间,打造多元双线公园。 展开更多
关键词 缝合 过渡 互补 缓冲 多元
在线阅读 下载PDF
药品零加成形势下医院药房的转型之路 预览
15
作者 沈佳燕 罗震宇 余旭奔 《医院管理论坛》 2019年第4期5-7,共3页
随着医改的深入,全面取消药品加成使得医院药房和药学人员面临着严峻挑战,为适应医疗卫生体制改革需求,研究医院药学服务模式的转型升级尤为迫切。本文分析了取消药品加成政策及对医院药房的影响,并就医院药房的转型之路进行了探讨。
关键词 药品加成 医院药房 转型
在线阅读 下载PDF
Experimental investigation of combined vibrations for a hydrofoil-rod system at low Reynold numbers 预览
16
作者 Ren-feng Wang Ke Chen +2 位作者 Francis Nobelesse Yun-xiang You Wei Li 《水动力学研究与进展:英文版》 SCIE EI CSCD 2019年第3期512-521,共10页
A hydrodynamic tunnel experimental investigation and analysis of vibration characteristics for a hydrofoil in a transient regime is considered. Tests are performed for NACA 0017 models with a non-uniform section at an... A hydrodynamic tunnel experimental investigation and analysis of vibration characteristics for a hydrofoil in a transient regime is considered. Tests are performed for NACA 0017 models with a non-uniform section at an angle of attack AOA = 5° and Reynolds numbers up to Re = 7.0 x 106. This study is related to a project design of experiments in a complex facility that involves several parameters. The analysis focuses on the vibrations of a hydrofoil for different values of the bracing stiffness kh, the torsional stiffness ka, and the locations of the elastic axis a and of the center of gravity xa . The structural bracing response is investigated via measurements of the displacement of the free tip section of the hydrofoil using a three-axis acceleration sensor, and the torsional response of the structure is analyzed via measurements of displacements with single-axis acceleration sensors. The hydrofoil is made of reinforced plastics without flexibility, and elastic functions are performed by a spring support mechanism combined with a torsional structure. The study shows that an increase of the velocity results in different behaviors of the bracing and torsional amplitudes. Another notable result of the study is that the emergence of transition occurs simultaneously with additional peaks and changes of vibration amplitudes. 展开更多
关键词 Vibrations LIFTING BODIES transition LAMINAR separation BUBBLES
在线阅读 下载PDF
论16-17世纪英国的教育变革 预览
17
作者 谢彤 《贵州师范学院学报》 2019年第1期55-59,共5页
16—17世纪的英国处在传统社会向近代社会的转型时期,经济、政治和社会结构发生很大变化,教育领域亦发生重大变革。随着民族国家的逐步确立,王权不断扩大,社会各阶层为了适应时代的变化,做出了适应自身利益的教育调整:贵族的教育主要是... 16—17世纪的英国处在传统社会向近代社会的转型时期,经济、政治和社会结构发生很大变化,教育领域亦发生重大变革。随着民族国家的逐步确立,王权不断扩大,社会各阶层为了适应时代的变化,做出了适应自身利益的教育调整:贵族的教育主要是为了满足统治者的需要,培养治国人才;对中等阶层来说,主要是为了提升自己的社会地位,满足当时社会的需要;对于社会下层来说,是为了提高他们的识字水平,养成良好的生活习惯。这一时期英国社会各阶层教育的变革,折射出了英国教育世俗化、大众化的走向。 展开更多
关键词 英国 社会转型 教育变革 世俗化 大众化
在线阅读 下载PDF
Threshold and decay properties of transient isolated turbulent band in plane Couette flow 预览
18
作者 Jianzhou LU Jianjun TAO +1 位作者 Weitao ZHOU Xiangming XIONG 《应用数学和力学:英文版》 SCIE EI CSCD 2019年第10期1449-1456,共8页
By direct numerical simulations of the plane Couette flow (PCF) in a large computational domain, it is shown that an isolated turbulent band decays monotonically at low Reynolds numbers but experiences transient growt... By direct numerical simulations of the plane Couette flow (PCF) in a large computational domain, it is shown that an isolated turbulent band decays monotonically at low Reynolds numbers but experiences transient growth before the eventual relaminarization at moderate Reynolds numbers. The lower bound Reynolds number of the transient-growth regime is determined as 286. The width, length, and tilt angle of the iso- lated band structure are defined based on the disturbance kinetic energy in the mid-plane, and the geometric characteristics of the band can be described with a tilted rectangle. It is illustrated that before its eventual fragmentation, the isolated turbulent band decays in a style of longitudinal contraction, where the center, width, and tilt angle of the band keep almost constant but the band length contracts with a statistically constant velocity. 展开更多
关键词 plane COUETTE flow (PCF) SUBCRITICAL transition TURBULENT BAND
在线阅读 下载PDF
Rural vitalization in China:A perspective of land consolidation
19
作者 LONG Hualou ZHANG Yingnan TU Shuangshuang 《地理学报:英文版》 SCIE CSCD 2019年第4期517-530,共14页
The core objective of rural vitalization is to systemically establish a coupling pattern of various rural development elements including population,land and industry.As one of the prerequisites,land resources is requi... The core objective of rural vitalization is to systemically establish a coupling pattern of various rural development elements including population,land and industry.As one of the prerequisites,land resources is required to be optimally allocated via land consolidation.Con seque ntly,la nd con solidati on con tributes greatly to population agglomeration,industrial developme nt and resources support under the con text of combati ng rural decline.Based on the key eleme nts affecting rural development,this paper elaborates the con no tation of rural vitalization and land consolidation in the new era as well as their relationships.Furthermore,the paper analyzes the alternative paths for achieving rural vitalization via land consolidation,and discusses the future directions of land consolidation and rural vitalization.The conclusions are drawn as follows:(1)To cope with the loss and decline of the intrinsic elements in rural areas,rural vitalization is a development strategy aimed at realizing economic,political,cultural and ecological rejuvenation in rural area by reshaping socio?economic morphology and spatial pattern in rural territory.(2)From the perspective of rural vitalization,land consolidation is endowed with new connotation,which should not only target at activating the key elements of rural development,but also place emphasis on coordimating material space and spirit core as well as integrating the restructuring of the physical space and the rural gov?ernance system.(3)Land consolidation should be compatible with regional natural conditions and the current stage of socio-economic development.According to the principle of regional planning and classification strategy,the appropriate models and paths should be adopted to promote the benign interactions of population,land and industry based on engineering techniques and ecological means.(4)Under the background of national strategy of rural vitaliza?tion,it is n ecessary to reshape the value orientati on of la nd con solidation based on a scie tific understandi 展开更多
关键词 RURAL TRANSFORMATION DEVELOPMENT RURAL vitalization LAND CONSOLIDATION LAND use transition DEVELOPMENT elements REGIONAL mode
Ultrafast Form II to I Transition of Isotactic Polybutene-1
20
作者 Xing Qiu Umair Azhar +2 位作者 Jing-Qing Li Ding-Hai Huang Shi-Chun Jiang 《高分子科学:英文版》 SCIE CAS CSCD 2019年第7期633-636,共4页
Isotactic polybutene-1 (iPB-1) is a semi-crystalline polymer with polymorph and puzzled structural transitions. The stable form I of iPB-1 with excellent physical and mechanical properties can hardly be obtained direc... Isotactic polybutene-1 (iPB-1) is a semi-crystalline polymer with polymorph and puzzled structural transitions. The stable form I of iPB-1 with excellent physical and mechanical properties can hardly be obtained directly from the melt;instead, metastable form II will spontaneously and slowly transform into form I. Bypassing the unstable form II formation is of great significance in polymer processing, which inspires extensive research on seeking the pathways to direct formation of form I. Methods for accelerating form II to I transition are another main focus in terms of practical approach for directly obtaining form I. Taking advantage of the solvent, an ultrafast transition of iPB-1 from form II to I within minutes has been achieved at room temperature. Such an ultrafast transition is detected after treating with dichloromethane (DCM) at 30 ℃, though the framework of isothermally crystalized iPB-1 spherulite morphology could not be fully modified. The ultrafast II-I transition of iPB-1 is attributed to the solvent-induced packed-mesophase and temperature-selected chain conformation adjustment.This ultrafast transition would shed light on understanding the mechanisms of polymorphic transitions in iPB-1. 展开更多
关键词 POLYBUTENE-1 ULTRAFAST TRANSITION MESOPHASE CONFORMATION
上一页 1 2 250 下一页 到第
使用帮助 返回顶部 意见反馈