The past decades have seen much plethora of publications about what makes a good teacher. Many of these have fallen into content of educational tips and advice on such guides as organizing and assessing students' ...The past decades have seen much plethora of publications about what makes a good teacher. Many of these have fallen into content of educational tips and advice on such guides as organizing and assessing students' learning and behaviour and ignored such matters as that a teacher should be an expert learner in this dramatically changing society. This paper suggests that to keep exploring good teaching and to be an expert learner as two essential strategies of getting charismatic characteristics of a good teacher in the new era.展开更多
This study based on researcher's adult oral English teaching experience,takes an adult English learner as a case study to explore the characteristics of an autonomous English learner.From analysis of data (observa...This study based on researcher's adult oral English teaching experience,takes an adult English learner as a case study to explore the characteristics of an autonomous English learner.From analysis of data (observation and teaching diary),this study elaborates three common characteristics of an autonomous learner:(1) Firstly,an autonomous learner has a high motivation;(2) Secondly,an autonomous learner is good at trying different learning strategies,especially metacognitive strategy to manage learning proceeding.(3) Lastly,an autonomous learner readily takes charge of their own learning by making plan and reflecting on it.Meanwhile,this study presents teacher's role as a facilitator and consultor and some factors that need taking into consideration,offering a precious experience for future's fostering of autonomous English learners.展开更多
In order to reflect the influence of the drivers' characteristic differences on intersection capacity under a mixed traffic flow, a driver correction coefficient for the intersection capacity calculation according to...In order to reflect the influence of the drivers' characteristic differences on intersection capacity under a mixed traffic flow, a driver correction coefficient for the intersection capacity calculation according to the driver's visual characteristics is proposed. First, the parameters of the driver's visual characteristics at some real roads, including gaze fixation distribution, mean fixation duration, visual angle distribution and some other parameters at intersections, are collected. Then, the relationship between the traffic flow rate at intersections and the parameters of driver eye movements are established. The analytical results indicate that when the traffic flow is unsaturated, the parameters of driver eye movements change relatively little; however, when the traffic flow is saturated, the parameters of driver eye movements change drastically. Finally, the saturation-flow-rate model is modified according to the parameters of driver eye movements; thus, a capacity model of intersections considering the driver's visual characteristics is obtained.展开更多
Bennett's linkage is a spatial fourlink linkage,and has an extensive application prospect in the deployable linkages.Its kinematic and dynamic characteristics analysis has a great significance in its synthesis and...Bennett's linkage is a spatial fourlink linkage,and has an extensive application prospect in the deployable linkages.Its kinematic and dynamic characteristics analysis has a great significance in its synthesis and application. According to the geometrical conditions of Bennett 's linkage,the motion equations are established,and the expressions of angular displacement,angular velocity and angular acceleration of the followers and the displacement,velocity and acceleration of mass center of link are shown. Based on Lagrange's equation,the multi-rigid-body dynamic model of Bennett's linkage is established. In order to solve the reaction forces and moments of joint,screw theory and reciprocal screw method are combined to establish the computing method.The number of equations and unknown reaction forces and moments of joint are equal through adding link deformation equations. The influence of the included angle of adjacent axes on Bennett 's linkage 's kinematic characteristics,the dynamic characteristics and the reaction forces and moments of joint are analyzed.Results show that the included angle of adjacent axes has a great effect on velocity,acceleration,the reaction forces and moments of Bennett's linkage. The change of reaction forces and moments of joint are apparent near the singularity configuration.展开更多
Water blooms have become a worldwide environmental problem. Recently, algicidal bacteria have attracted wide attention as possible agents for inhibiting algal water blooms. In this study, one strain of algicidal bacte...Water blooms have become a worldwide environmental problem. Recently, algicidal bacteria have attracted wide attention as possible agents for inhibiting algal water blooms. In this study, one strain of algicidal bacterium B5 was isolated from activated sludge. On the basis of analysis of its physiological characteristics and 16S rDNA gene sequence, it was identified as Bacillusfusiformis. Its algaelysing characteristics on Microcystis aeruginosa, Chlorella and Scenedesmus were tested. The results showed that: (1) the algicidal bacterium B5 is a Gram-negative bacterium. The 16S rDNA nucleotide sequence homology of strain B5 with 2 strains of B. fusiformis reached 99.86%, so B5 was identified as B. fusiformis; (2) the algal-lysing effects of the algicidal bacterium B5 on M. aeruginosa, Chlorella and Scenedesrnus were pronounced. The initial bacterial and algal cell densities strongly influence the removal rates of chlorophyll-a. The greater the initial bacterial cell density, the faster the degradation of chlorophyll-a. The greater the initial algal cell density, the slower the degradation of chlorophyll-a. When the bacterial cell density was 3.6 × 10^7 cells/ml, nearly 90% of chlorophyll-a was removed. When the chlorophyll-a concentration was less than 550 μg/L, about 70% was removed; (3) the strain B5 lysed algae by secreting metabolites and these metabolites could bear heat treatment.展开更多
AIM: To investigate differences of clinical characteristics and disease courses between familial and sporadic inflammatory bowel disease (IBD) patients.
Two Job’s tears cultivars, yy18-1 (high resistance to drought stress) and yy12-7 (susceptible to drought stress) were used to investigate the responses of seed germination, root and seedling growth, and seedling anti...Two Job’s tears cultivars, yy18-1 (high resistance to drought stress) and yy12-7 (susceptible to drought stress) were used to investigate the responses of seed germination, root and seedling growth, and seedling antioxidant characteristics to drought stress simulated by polyethylene glycol (PEG) 6000 solutions with 0, -0.05, -0.1, -0.15, and -0.2 MPa osmotic potentials. The results showed that the germination energy, germination rate, germination index, root and seedling lengths, root and seedling diameters, root and seedling fresh masses, root and seedling dry masses, and seedling relative water content (RWC) decreased with the decrease of the osmotic potential of PEG 6000 solution. The contents of hydrogen peroxide (H2O2), malondialdehyde (MDA), and proline in seedling increased with the decrease of the osmotic potential of PEG 6000 solution. The activities of peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR) in seedling increased and then decreased with the decrease of osmotic potential of PEG 6000 solution. -0.1 MPa was the optimal osmotic potential of PEG 6000 solution simulated drought stress at germination stage for Job’s tears. The proline content and activities of POD and CAT were important mechanisms for the maintenance of drought resistance in Job’s tears seedling.展开更多
The made tea quality and chemical characteristics of 4 albinos cultivars were investigated. It shows that constitutes of micro-elements, contents of polyphenols and total amino acids in 4 samples are much different du...The made tea quality and chemical characteristics of 4 albinos cultivars were investigated. It shows that constitutes of micro-elements, contents of polyphenols and total amino acids in 4 samples are much different due to the biological diversity. The DPPH free radicals scavenging ability of the 4 albinos tea is also different. The free radicals scavenging rate has a significant positive correlation to the content of total polyphenols, total catechins, as well as C, CG, GCG, EGCG, but there is no positive relationship to the content of Zn, Se.展开更多
Geochemical differentiation of soils has a series of consequences on plant and places pressure on the ecological environment.The quantitative evaluation of element migration in the Earth’s critical zone is a challeng...Geochemical differentiation of soils has a series of consequences on plant and places pressure on the ecological environment.The quantitative evaluation of element migration in the Earth’s critical zone is a challenging task.In this study,two demonstration study areas of Scutellaria baicalensis Georgi were selected,and multiple chemical weathering indexes,chemical loss fraction,mass migration coefficients and biological enrichment coefficient method were used to assess the ecological and geochemical suitability.The results show that for the element of Fe,Zn,Se,Cu,Co,Ni,Mo and Ge,the degree of weathering and soil maturation,were greater in the rhyolitic tuff area than in the Plagioclase gneiss area.In both research sites,the heavy metal level of samples in Scutellaria baicalensis Georgi did not exceed the standard limits.The plagioclase gneiss region’s surface soil environment was more alkaline,and the content of soil organic matter was lower,resulting in a higher bioenrichment intensity of Ge,Co,Cu,and Se elements in Scutellaria baicalensis Georgi than in the rhyolite-tuff area.The elements of Cd,Nb,Mo,Pb and As are considerably enriched in the soil of the plagioclase gneiss area but lost by leaching in the soil of the rhyolite tuff area,which is connected to the interplay of elemental abundance and human impact in the parent materials.This study provides a good example of how to assess growth suitability of Chinese medicinal materials in the Earth’s critical zone.展开更多
This paper investigates how the type of written feedback provided by teachers affects learners’ ability to revise essays. A total of 120 participants participated in two rounds of essay composition and feedback deliv...This paper investigates how the type of written feedback provided by teachers affects learners’ ability to revise essays. A total of 120 participants participated in two rounds of essay composition and feedback delivery. The findings indicate that learners who receive comments in the form of questions are more prone to make revisions compared to those receiving statements or imperatives. These results hold significant implications for educators and the ways they utilize written feedback to enhance learners’ writing skills.展开更多
General situation and distribution of round houses of the Hakka in south Jiangxi were introduced, such architectural styles as enclosed house with a square yard (kouzi wei, in the shape of 口), enclosed house with a y...General situation and distribution of round houses of the Hakka in south Jiangxi were introduced, such architectural styles as enclosed house with a square yard (kouzi wei, in the shape of 口), enclosed house with a yard of three transverse and one longitudinal constructions (guozi wei, in the shape of 国), and enclosed house with a round house in its yard (tao wei) were taken to analyze features of the Hakka's enclosed houses. It was highlighted that the Hakka's enclosed houses in south Jiangxi has diversified architectural styles and outstanding defensive and living functions. Construction art and religious culture shown by the enclosed houses were interpreted, and the branch of Han people with unique dialects, cultures, folk customs and emotional attitudes was proposed as a miniature of the culture in south Jiangxi. Moreover, it was stressed that more attention of the public and more efforts for the protection should be given to the Hakka's cultures in south Jiangxi, carriers of the locals' history over the past thousands of years.展开更多
Objectives: This study empirically assesses the impact of the changes in women’s characteristics, empowerment, availability and quality of health services on woman’s decision to use antenatal care (ANC) and the freq...Objectives: This study empirically assesses the impact of the changes in women’s characteristics, empowerment, availability and quality of health services on woman’s decision to use antenatal care (ANC) and the frequency of that use during the period 2000-2008. Study Design: The study is a cross-sectional analytical study using 2000 and 2008 Egypt Demographic and Health Surveys. Methods: The assessment of the studied impact is conducted using the Zero-inflated Negative Binomial Regression. In addition, Factor Analysis technique is used to construct some of the explanatory variables such as women’s empowerment, the availability and quality of health services indicators. Results: Utilization of antenatal health care services is greatly improved from 2000 to 2008. Availability of health services is one of the main determinants that affect the number of antenatal care visits in 2008. Wealth index and quality of health services play an important role in raising the level of antenatal care utilization in 2000 and 2008. However, the impact of the terminated pregnancy on receiving ANC increased over time. Conclusions: Further research of the determinants of antenatal health care utilization is needed, using more updated measures of women’s empowerment, availability and quality of health services. In order to improve the provision of antenatal health care services, it is important to understand barriers to antenatal health care utilization. Therefore, it is advisable to collect information from women about the reasons for not receiving antenatal care.展开更多
Current research on pump-turbine units is focused on the unstable operation at off-design conditions, with the characteristic curves in generating mode being S-shaped. Unlike in the traditional water turbines, pump-tu...Current research on pump-turbine units is focused on the unstable operation at off-design conditions, with the characteristic curves in generating mode being S-shaped. Unlike in the traditional water turbines, pump-turbine operation along the S-shaped curve can lead to difficulties during load rejection with unusual increases in the water pressure, which leads to machine vibrations. This paper describes both model tests and numerical simulations. A reduced scale model of a low specific speed pump-turbine was used for the performance tests, with comparisons to computational fluid dynamics(CFD) results. Predictions using the detached eddy simulation(DES) turbulence model, which is a combined Reynolds averaged Naviers-Stokes(RANS) and large eddy simulation(LES) model, are compared with the two-equation turbulence mode results. The external characteristics as well as the internal flow are for various guide vane openings to understand the unsteady flow along the so called S characteristics of a pump-turbine. Comparison of the experimental data with the CFD results for various conditions and times shows that DES model gives better agreement with experimental data than the two-equation turbulence model. For low flow conditions, the centrifugal forces and the large incident angle create large vortices between the guide vanes and the runner inlet in the runner passage, which is the main factor leading to the S-shaped characteristics. The turbulence model used here gives more accurate simulations of the internal flow characteristics of the pump-turbine and a more detailed force analysis which shows the mechanisms controlling of the S characteristics.展开更多
In this study,on the basis of absolute first-arrival times of 84756 P-and S-waves from 6085 earthquakes recorded at 56 fixed stations in Yibin and surrounding areas in China from January 2009 to January 2019,focal par...In this study,on the basis of absolute first-arrival times of 84756 P-and S-waves from 6085 earthquakes recorded at 56 fixed stations in Yibin and surrounding areas in China from January 2009 to January 2019,focal parameters and three-dimensional(3 D)body-wave high-resolution velocity structures at depths of 0–30 km were retrieved by double-difference tomography.Results show that there is a good correspondence between the spatial distribution of the relocated earthquakes and velocity structures,which were concentrated mainly in the high-velocity-anomaly region or edge of high-velocity region.Velocity structure of P-and S-waves in the Yibin area clearly shows lateral inhomogeneity.The distribution characteristics of the P-and S-waves near the surface are closely related to the geomorphology and geologic structure.The low-velocity anomaly appears at the depth of 15–25 km,which is affected by the lower crust current.The Junlian–Gongxian and Gongxian–Changning earthquake areas,which are the two most earthquake-prone areas in the Yibin region,clearly differ in earthquake distribution and tectonic characteristics.We analyzed the structural characteristics of the Junlian–Gongxian and Gongxian–Changning earthquake areas on the basis of the 3 D bodywave velocity structures in the Yibin region.We found that although most seismicity in the Yibin area is caused by fluid injection,the spatial position of seismicity is controlled by the velocity structures of the middle and upper crust and local geologic structure.Fine-scale 3 D velocity structures in the Yibin area provide important local reference information for further understanding the crustal medium,seismogenic structure,and seismicity.展开更多
The aerodynamic and aeroacoustic characteristics of a scissor tail-rotor in a forward flight are numerically calculated.A novel computational fluid dynamics(CFD)model based on Navier-Stokes(N-S)equations is presented ...The aerodynamic and aeroacoustic characteristics of a scissor tail-rotor in a forward flight are numerically calculated.A novel computational fluid dynamics(CFD)model based on Navier-Stokes(N-S)equations is presented to simulate the unsteady flowfield and the aerodynamic characteristics of a scissor tail-rotor in the forward flight.Then the Farassat Formulation 1 Aderived from the FW-H equation is coupled into the CFD model in order to compute the aeroacoustic characteristics of the scissor tail-rotor.In addition,two different scissor tail-rotor configurations,i.e.,the L-and U-configuration,are analyzed in details and compared with a conventional one.The influence of scissor angles on the aerodynamic and aeroacoustic characteristics of the scissor tail-rotor is also investigated.The simulation results demonstrate that the flowfield,aerodynamic force and aeroacoustic characteristics of a scissor tail-rotor are significantly different from the conventional one,and the aerodynamic interaction decreases with the increase of scissor angle,which leads to a reduction of amplitude variation of the tail-rotor thrust in the forward flight.The scissor angle has an important effect on the aerodynamics and aeroacoustics of the scissor tail-rotor.展开更多
Infectious bronchitis virus was isolated from swollen proventriculi of clinically ill chicken. The suspected virus samples (2/97, 3/97, 1/98) were adapted in SPF chicken embryos for virus isolation and identification....Infectious bronchitis virus was isolated from swollen proventriculi of clinically ill chicken. The suspected virus samples (2/97, 3/97, 1/98) were adapted in SPF chicken embryos for virus isolation and identification. All the virus isolates were able to agglutinate chicken erythrocytes after treatment with trypsin, and interfer with the reproduction of Newcastle disease virus in chicken embryos, and have low antigenic relat-edness values with reference positive IBV. The isolates 2/97, 3/97, 1/98 RNAs extracted from the allantoic fluid of inoculated embryonated eggs were converted to cDNA by reverse transcription with 3'-primer of S1 gene of (IBV). Polymerase chain reaction (PCR) was performed with two primers which span the S1 gene. Amplified product of 1. 93 kb was subjected to EcoR I and BamH I digestion and the fragments obtained were the same as expected size. The PCR product was ligated to pBlueScript-SK ( + ) vector, and its nucleotide sequence was determined by the dideoxy-mediated chain termination method. Nucleotide sequence analysis showed 73. 6 - 99. 7% homology between the isolated IBV and the IBV strains in GenBank. The homology of amino acid was 71. 4 - 99.4%.展开更多
According to the theory of crystal field, the existing state of chromium ions in β-C_2S was studied with optical spectra and EPR. The energy levels of chromium ions were calculated. Chromium ions exist in form of Cr^...According to the theory of crystal field, the existing state of chromium ions in β-C_2S was studied with optical spectra and EPR. The energy levels of chromium ions were calculated. Chromium ions exist in form of Cr^(4+) and Cr^(5+) coordinated with distorted octahedra. The reason of fading of β-C_2S hydrate is that the strength of light absorption declines be- cause of the valence change of chromium ions and chroninm dissolves out and loses in water.展开更多
XI Jinping's thought on socialism with Chinese characteristics for a new era contains Chinesewisdom for the development of socialism in the world,Chinese experience of realizing modernization in adeveloping country...XI Jinping's thought on socialism with Chinese characteristics for a new era contains Chinesewisdom for the development of socialism in the world,Chinese experience of realizing modernization in adeveloping country,and Chinese solution to the global governing. It clarifies the theoretical puzzlement of "theend of history","the clash of civilizations"and "Western centrism",so that it plays an important role inhuman intellectual history. Therefore,one should adopt an international vision and a global perspective tounderstand and evaluate the theoretical significance and practical value of XI Jinpings thought on socialismwith Chinese characteristics for a new era.展开更多
Considering the effect of planet's number on the dynamic characteristics of the planetary gear system, a translationtorsion lumped-parameter model of 2K-H spur planetary gear system was established. Through the an...Considering the effect of planet's number on the dynamic characteristics of the planetary gear system, a translationtorsion lumped-parameter model of 2K-H spur planetary gear system was established. Through the analysis of numerical solution, the results show that 1) When the planet's number is more than 3, the order of the natural frequency will become the same; 2) When the planet's number increases, the natural frequencies of planet mode remain invariant, but when it comes to rotational mode and translational mode, the higher order natural frequencies increase and the lower order natural frequencies decrease; 3) The planet's number has a great impact on the higher order natural frequencies and a little impact on the lower order natural frequencies; and 4) To avoid the resonance, we can appropriately increase or decrease the number of the planet.展开更多
Elect roencephalographic signals can act as an indicator of abnormal discharge during epileptic seizures, providing important evidence for diagnosing epilepsy. Abnormal electroencephalographic activity was detected du...Elect roencephalographic signals can act as an indicator of abnormal discharge during epileptic seizures, providing important evidence for diagnosing epilepsy. Abnormal electroencephalographic activity was detected during seizures, and high-amplitude epileptic discharge waveforms were observed during intermission in approximately 50% of patients.展开更多
文摘The past decades have seen much plethora of publications about what makes a good teacher. Many of these have fallen into content of educational tips and advice on such guides as organizing and assessing students' learning and behaviour and ignored such matters as that a teacher should be an expert learner in this dramatically changing society. This paper suggests that to keep exploring good teaching and to be an expert learner as two essential strategies of getting charismatic characteristics of a good teacher in the new era.
文摘This study based on researcher's adult oral English teaching experience,takes an adult English learner as a case study to explore the characteristics of an autonomous English learner.From analysis of data (observation and teaching diary),this study elaborates three common characteristics of an autonomous learner:(1) Firstly,an autonomous learner has a high motivation;(2) Secondly,an autonomous learner is good at trying different learning strategies,especially metacognitive strategy to manage learning proceeding.(3) Lastly,an autonomous learner readily takes charge of their own learning by making plan and reflecting on it.Meanwhile,this study presents teacher's role as a facilitator and consultor and some factors that need taking into consideration,offering a precious experience for future's fostering of autonomous English learners.
基金The National Natural Science Foundation of China (No.50708019)Huo Yingdong Education Foundation(No.104010)Jiangsu Qing Lan Project
文摘In order to reflect the influence of the drivers' characteristic differences on intersection capacity under a mixed traffic flow, a driver correction coefficient for the intersection capacity calculation according to the driver's visual characteristics is proposed. First, the parameters of the driver's visual characteristics at some real roads, including gaze fixation distribution, mean fixation duration, visual angle distribution and some other parameters at intersections, are collected. Then, the relationship between the traffic flow rate at intersections and the parameters of driver eye movements are established. The analytical results indicate that when the traffic flow is unsaturated, the parameters of driver eye movements change relatively little; however, when the traffic flow is saturated, the parameters of driver eye movements change drastically. Finally, the saturation-flow-rate model is modified according to the parameters of driver eye movements; thus, a capacity model of intersections considering the driver's visual characteristics is obtained.
基金Sponsored by the National Natural Science Foundation of China(Grant No.51175422)
文摘Bennett's linkage is a spatial fourlink linkage,and has an extensive application prospect in the deployable linkages.Its kinematic and dynamic characteristics analysis has a great significance in its synthesis and application. According to the geometrical conditions of Bennett 's linkage,the motion equations are established,and the expressions of angular displacement,angular velocity and angular acceleration of the followers and the displacement,velocity and acceleration of mass center of link are shown. Based on Lagrange's equation,the multi-rigid-body dynamic model of Bennett's linkage is established. In order to solve the reaction forces and moments of joint,screw theory and reciprocal screw method are combined to establish the computing method.The number of equations and unknown reaction forces and moments of joint are equal through adding link deformation equations. The influence of the included angle of adjacent axes on Bennett 's linkage 's kinematic characteristics,the dynamic characteristics and the reaction forces and moments of joint are analyzed.Results show that the included angle of adjacent axes has a great effect on velocity,acceleration,the reaction forces and moments of Bennett's linkage. The change of reaction forces and moments of joint are apparent near the singularity configuration.
基金Project supported by the Special Funds for Doctor's Station of University(No.20060246024)Young Fund of Fudan University,and the Shanghai Tongji Gao Tingyao Environmental Science and Technology Developmem Fundation
文摘Water blooms have become a worldwide environmental problem. Recently, algicidal bacteria have attracted wide attention as possible agents for inhibiting algal water blooms. In this study, one strain of algicidal bacterium B5 was isolated from activated sludge. On the basis of analysis of its physiological characteristics and 16S rDNA gene sequence, it was identified as Bacillusfusiformis. Its algaelysing characteristics on Microcystis aeruginosa, Chlorella and Scenedesmus were tested. The results showed that: (1) the algicidal bacterium B5 is a Gram-negative bacterium. The 16S rDNA nucleotide sequence homology of strain B5 with 2 strains of B. fusiformis reached 99.86%, so B5 was identified as B. fusiformis; (2) the algal-lysing effects of the algicidal bacterium B5 on M. aeruginosa, Chlorella and Scenedesrnus were pronounced. The initial bacterial and algal cell densities strongly influence the removal rates of chlorophyll-a. The greater the initial bacterial cell density, the faster the degradation of chlorophyll-a. The greater the initial algal cell density, the slower the degradation of chlorophyll-a. When the bacterial cell density was 3.6 × 10^7 cells/ml, nearly 90% of chlorophyll-a was removed. When the chlorophyll-a concentration was less than 550 μg/L, about 70% was removed; (3) the strain B5 lysed algae by secreting metabolites and these metabolites could bear heat treatment.
文摘AIM: To investigate differences of clinical characteristics and disease courses between familial and sporadic inflammatory bowel disease (IBD) patients.
文摘Two Job’s tears cultivars, yy18-1 (high resistance to drought stress) and yy12-7 (susceptible to drought stress) were used to investigate the responses of seed germination, root and seedling growth, and seedling antioxidant characteristics to drought stress simulated by polyethylene glycol (PEG) 6000 solutions with 0, -0.05, -0.1, -0.15, and -0.2 MPa osmotic potentials. The results showed that the germination energy, germination rate, germination index, root and seedling lengths, root and seedling diameters, root and seedling fresh masses, root and seedling dry masses, and seedling relative water content (RWC) decreased with the decrease of the osmotic potential of PEG 6000 solution. The contents of hydrogen peroxide (H2O2), malondialdehyde (MDA), and proline in seedling increased with the decrease of the osmotic potential of PEG 6000 solution. The activities of peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR) in seedling increased and then decreased with the decrease of osmotic potential of PEG 6000 solution. -0.1 MPa was the optimal osmotic potential of PEG 6000 solution simulated drought stress at germination stage for Job’s tears. The proline content and activities of POD and CAT were important mechanisms for the maintenance of drought resistance in Job’s tears seedling.
文摘The made tea quality and chemical characteristics of 4 albinos cultivars were investigated. It shows that constitutes of micro-elements, contents of polyphenols and total amino acids in 4 samples are much different due to the biological diversity. The DPPH free radicals scavenging ability of the 4 albinos tea is also different. The free radicals scavenging rate has a significant positive correlation to the content of total polyphenols, total catechins, as well as C, CG, GCG, EGCG, but there is no positive relationship to the content of Zn, Se.
基金funded by the China Geological Survey,grant number DD20190822。
文摘Geochemical differentiation of soils has a series of consequences on plant and places pressure on the ecological environment.The quantitative evaluation of element migration in the Earth’s critical zone is a challenging task.In this study,two demonstration study areas of Scutellaria baicalensis Georgi were selected,and multiple chemical weathering indexes,chemical loss fraction,mass migration coefficients and biological enrichment coefficient method were used to assess the ecological and geochemical suitability.The results show that for the element of Fe,Zn,Se,Cu,Co,Ni,Mo and Ge,the degree of weathering and soil maturation,were greater in the rhyolitic tuff area than in the Plagioclase gneiss area.In both research sites,the heavy metal level of samples in Scutellaria baicalensis Georgi did not exceed the standard limits.The plagioclase gneiss region’s surface soil environment was more alkaline,and the content of soil organic matter was lower,resulting in a higher bioenrichment intensity of Ge,Co,Cu,and Se elements in Scutellaria baicalensis Georgi than in the rhyolite-tuff area.The elements of Cd,Nb,Mo,Pb and As are considerably enriched in the soil of the plagioclase gneiss area but lost by leaching in the soil of the rhyolite tuff area,which is connected to the interplay of elemental abundance and human impact in the parent materials.This study provides a good example of how to assess growth suitability of Chinese medicinal materials in the Earth’s critical zone.
文摘This paper investigates how the type of written feedback provided by teachers affects learners’ ability to revise essays. A total of 120 participants participated in two rounds of essay composition and feedback delivery. The findings indicate that learners who receive comments in the form of questions are more prone to make revisions compared to those receiving statements or imperatives. These results hold significant implications for educators and the ways they utilize written feedback to enhance learners’ writing skills.
文摘General situation and distribution of round houses of the Hakka in south Jiangxi were introduced, such architectural styles as enclosed house with a square yard (kouzi wei, in the shape of 口), enclosed house with a yard of three transverse and one longitudinal constructions (guozi wei, in the shape of 国), and enclosed house with a round house in its yard (tao wei) were taken to analyze features of the Hakka's enclosed houses. It was highlighted that the Hakka's enclosed houses in south Jiangxi has diversified architectural styles and outstanding defensive and living functions. Construction art and religious culture shown by the enclosed houses were interpreted, and the branch of Han people with unique dialects, cultures, folk customs and emotional attitudes was proposed as a miniature of the culture in south Jiangxi. Moreover, it was stressed that more attention of the public and more efforts for the protection should be given to the Hakka's cultures in south Jiangxi, carriers of the locals' history over the past thousands of years.
文摘Objectives: This study empirically assesses the impact of the changes in women’s characteristics, empowerment, availability and quality of health services on woman’s decision to use antenatal care (ANC) and the frequency of that use during the period 2000-2008. Study Design: The study is a cross-sectional analytical study using 2000 and 2008 Egypt Demographic and Health Surveys. Methods: The assessment of the studied impact is conducted using the Zero-inflated Negative Binomial Regression. In addition, Factor Analysis technique is used to construct some of the explanatory variables such as women’s empowerment, the availability and quality of health services indicators. Results: Utilization of antenatal health care services is greatly improved from 2000 to 2008. Availability of health services is one of the main determinants that affect the number of antenatal care visits in 2008. Wealth index and quality of health services play an important role in raising the level of antenatal care utilization in 2000 and 2008. However, the impact of the terminated pregnancy on receiving ANC increased over time. Conclusions: Further research of the determinants of antenatal health care utilization is needed, using more updated measures of women’s empowerment, availability and quality of health services. In order to improve the provision of antenatal health care services, it is important to understand barriers to antenatal health care utilization. Therefore, it is advisable to collect information from women about the reasons for not receiving antenatal care.
基金Supported by National Natural Science Foundation of China(Grant No.51139007)State Key Laboratory of Hydroscience and Engineering Open Foundation of China(Grant No.2014-KY-05)
文摘Current research on pump-turbine units is focused on the unstable operation at off-design conditions, with the characteristic curves in generating mode being S-shaped. Unlike in the traditional water turbines, pump-turbine operation along the S-shaped curve can lead to difficulties during load rejection with unusual increases in the water pressure, which leads to machine vibrations. This paper describes both model tests and numerical simulations. A reduced scale model of a low specific speed pump-turbine was used for the performance tests, with comparisons to computational fluid dynamics(CFD) results. Predictions using the detached eddy simulation(DES) turbulence model, which is a combined Reynolds averaged Naviers-Stokes(RANS) and large eddy simulation(LES) model, are compared with the two-equation turbulence mode results. The external characteristics as well as the internal flow are for various guide vane openings to understand the unsteady flow along the so called S characteristics of a pump-turbine. Comparison of the experimental data with the CFD results for various conditions and times shows that DES model gives better agreement with experimental data than the two-equation turbulence model. For low flow conditions, the centrifugal forces and the large incident angle create large vortices between the guide vanes and the runner inlet in the runner passage, which is the main factor leading to the S-shaped characteristics. The turbulence model used here gives more accurate simulations of the internal flow characteristics of the pump-turbine and a more detailed force analysis which shows the mechanisms controlling of the S characteristics.
基金supported by the Research Project of Tianjin Earthquake Agency(No.yb201901)Seismic Regime Tracking Project of CEA(No.2019010127)Combination Project with Monitoring,Prediction and Scientific Research of Earthquake Technology,CEA(No.3JH-201901006)
文摘In this study,on the basis of absolute first-arrival times of 84756 P-and S-waves from 6085 earthquakes recorded at 56 fixed stations in Yibin and surrounding areas in China from January 2009 to January 2019,focal parameters and three-dimensional(3 D)body-wave high-resolution velocity structures at depths of 0–30 km were retrieved by double-difference tomography.Results show that there is a good correspondence between the spatial distribution of the relocated earthquakes and velocity structures,which were concentrated mainly in the high-velocity-anomaly region or edge of high-velocity region.Velocity structure of P-and S-waves in the Yibin area clearly shows lateral inhomogeneity.The distribution characteristics of the P-and S-waves near the surface are closely related to the geomorphology and geologic structure.The low-velocity anomaly appears at the depth of 15–25 km,which is affected by the lower crust current.The Junlian–Gongxian and Gongxian–Changning earthquake areas,which are the two most earthquake-prone areas in the Yibin region,clearly differ in earthquake distribution and tectonic characteristics.We analyzed the structural characteristics of the Junlian–Gongxian and Gongxian–Changning earthquake areas on the basis of the 3 D bodywave velocity structures in the Yibin region.We found that although most seismicity in the Yibin area is caused by fluid injection,the spatial position of seismicity is controlled by the velocity structures of the middle and upper crust and local geologic structure.Fine-scale 3 D velocity structures in the Yibin area provide important local reference information for further understanding the crustal medium,seismogenic structure,and seismicity.
文摘The aerodynamic and aeroacoustic characteristics of a scissor tail-rotor in a forward flight are numerically calculated.A novel computational fluid dynamics(CFD)model based on Navier-Stokes(N-S)equations is presented to simulate the unsteady flowfield and the aerodynamic characteristics of a scissor tail-rotor in the forward flight.Then the Farassat Formulation 1 Aderived from the FW-H equation is coupled into the CFD model in order to compute the aeroacoustic characteristics of the scissor tail-rotor.In addition,two different scissor tail-rotor configurations,i.e.,the L-and U-configuration,are analyzed in details and compared with a conventional one.The influence of scissor angles on the aerodynamic and aeroacoustic characteristics of the scissor tail-rotor is also investigated.The simulation results demonstrate that the flowfield,aerodynamic force and aeroacoustic characteristics of a scissor tail-rotor are significantly different from the conventional one,and the aerodynamic interaction decreases with the increase of scissor angle,which leads to a reduction of amplitude variation of the tail-rotor thrust in the forward flight.The scissor angle has an important effect on the aerodynamics and aeroacoustics of the scissor tail-rotor.
文摘Infectious bronchitis virus was isolated from swollen proventriculi of clinically ill chicken. The suspected virus samples (2/97, 3/97, 1/98) were adapted in SPF chicken embryos for virus isolation and identification. All the virus isolates were able to agglutinate chicken erythrocytes after treatment with trypsin, and interfer with the reproduction of Newcastle disease virus in chicken embryos, and have low antigenic relat-edness values with reference positive IBV. The isolates 2/97, 3/97, 1/98 RNAs extracted from the allantoic fluid of inoculated embryonated eggs were converted to cDNA by reverse transcription with 3'-primer of S1 gene of (IBV). Polymerase chain reaction (PCR) was performed with two primers which span the S1 gene. Amplified product of 1. 93 kb was subjected to EcoR I and BamH I digestion and the fragments obtained were the same as expected size. The PCR product was ligated to pBlueScript-SK ( + ) vector, and its nucleotide sequence was determined by the dideoxy-mediated chain termination method. Nucleotide sequence analysis showed 73. 6 - 99. 7% homology between the isolated IBV and the IBV strains in GenBank. The homology of amino acid was 71. 4 - 99.4%.
文摘According to the theory of crystal field, the existing state of chromium ions in β-C_2S was studied with optical spectra and EPR. The energy levels of chromium ions were calculated. Chromium ions exist in form of Cr^(4+) and Cr^(5+) coordinated with distorted octahedra. The reason of fading of β-C_2S hydrate is that the strength of light absorption declines be- cause of the valence change of chromium ions and chroninm dissolves out and loses in water.
文摘XI Jinping's thought on socialism with Chinese characteristics for a new era contains Chinesewisdom for the development of socialism in the world,Chinese experience of realizing modernization in adeveloping country,and Chinese solution to the global governing. It clarifies the theoretical puzzlement of "theend of history","the clash of civilizations"and "Western centrism",so that it plays an important role inhuman intellectual history. Therefore,one should adopt an international vision and a global perspective tounderstand and evaluate the theoretical significance and practical value of XI Jinpings thought on socialismwith Chinese characteristics for a new era.
基金Funded by the Key Research and Development Project in Henan Province(No.142102210067)
文摘Considering the effect of planet's number on the dynamic characteristics of the planetary gear system, a translationtorsion lumped-parameter model of 2K-H spur planetary gear system was established. Through the analysis of numerical solution, the results show that 1) When the planet's number is more than 3, the order of the natural frequency will become the same; 2) When the planet's number increases, the natural frequencies of planet mode remain invariant, but when it comes to rotational mode and translational mode, the higher order natural frequencies increase and the lower order natural frequencies decrease; 3) The planet's number has a great impact on the higher order natural frequencies and a little impact on the lower order natural frequencies; and 4) To avoid the resonance, we can appropriately increase or decrease the number of the planet.
文摘Elect roencephalographic signals can act as an indicator of abnormal discharge during epileptic seizures, providing important evidence for diagnosing epilepsy. Abnormal electroencephalographic activity was detected during seizures, and high-amplitude epileptic discharge waveforms were observed during intermission in approximately 50% of patients.