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Seasonal Characteristics of Forecasting Uncertainties in Surface PM_(2.5)Concentration Associated with Forecast Lead Time over the Beijing-Tianjin-Hebei Region
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作者 Qiuyan DU Chun ZHAO +6 位作者 Jiawang FENG Zining YANG Jiamin XU Jun GU Mingshuai ZHANG Mingyue XU Shengfu LIN 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2024年第5期801-816,共16页
Forecasting uncertainties among meteorological fields have long been recognized as the main limitation on the accuracy and predictability of air quality forecasts.However,the particular impact of meteorological foreca... Forecasting uncertainties among meteorological fields have long been recognized as the main limitation on the accuracy and predictability of air quality forecasts.However,the particular impact of meteorological forecasting uncertainties on air quality forecasts specific to different seasons is still not well known.In this study,a series of forecasts with different forecast lead times for January,April,July,and October of 2018 are conducted over the Beijing-Tianjin-Hebei(BTH)region and the impacts of meteorological forecasting uncertainties on surface PM_(2.5)concentration forecasts with each lead time are investigated.With increased lead time,the forecasted PM_(2.5)concentrations significantly change and demonstrate obvious seasonal variations.In general,the forecasting uncertainties in monthly mean surface PM_(2.5)concentrations in the BTH region due to lead time are the largest(80%)in spring,followed by autumn(~50%),summer(~40%),and winter(20%).In winter,the forecasting uncertainties in total surface PM_(2.5)mass due to lead time are mainly due to the uncertainties in PBL heights and hence the PBL mixing of anthropogenic primary particles.In spring,the forecasting uncertainties are mainly from the impacts of lead time on lower-tropospheric northwesterly winds,thereby further enhancing the condensation production of anthropogenic secondary particles by the long-range transport of natural dust.In summer,the forecasting uncertainties result mainly from the decrease in dry and wet deposition rates,which are associated with the reduction of near-surface wind speed and precipitation rate.In autumn,the forecasting uncertainties arise mainly from the change in the transport of remote natural dust and anthropogenic particles,which is associated with changes in the large-scale circulation. 展开更多
关键词 ........ forecasting uncertainties forecast lead time meteorological fields Beijing-Tianjin-Hebei region
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Association of daily sitting time and leisure-time physical activity with body fat among U.S.adults 被引量:1
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作者 Jingwen Liao Min Hu +4 位作者 Kellie Imm Clifton J.Holmes Jie Zhu Chao Cao Lin Yang 《Journal of Sport and Health Science》 SCIE CAS CSCD 2024年第2期195-203,共9页
Background:Prolonged sitting and reduced physical activity lead to low energy expenditures.However,little is known about the joint impact of daily sitting time and physical activity on body fat distribution.We investi... Background:Prolonged sitting and reduced physical activity lead to low energy expenditures.However,little is known about the joint impact of daily sitting time and physical activity on body fat distribution.We investigated the independent and joint associations of daily sitting time and physical activity with body fat among adults.Methods:This was a cross-sectional analysis of U.S.nationally representative data from the National Health and Nutrition Examination Survey2011-2018 among adults aged 20 years or older.Daily sitting time and leisure-time physical activity(LTPA)were self-reported using the Global Physical Activity Questionnaire.Body fat(total and trunk fat percentage)was determined via dual X-ray absorptiometry.Results:Among 10,808 adults,about 54.6%spent 6 h/day or more sitting;more than one-half reported no LTPA(inactive)or less than 150 min/week LTPA(insufficiently active)with only 43.3%reported 150 min/week or more LTPA(active)in the past week.After fully adjusting for sociodemographic data,lifestyle behaviors,and chronic conditions,prolonged sitting time and low levels of LTPA were associated with higher total and trunk fat percentages in both sexes.When stratifying by LTPA,the association between daily sitting time and body fat appeared to be stronger in those who were inactive/insuufficiently active.In the joint analyses,inactive/insuufficiently active adults who reported sitting more than 8 h/day had the highest total(female:3.99%(95%confidence interval(95%CI):3.09%-4.88%);male:3.79%(95%CI:2.75%-4.82%))and trunk body fat percentages(female:4.21%(95%CI:3.09%-5.32%);male:4.07%(95%CI:2.95%-5.19%))when compared with those who were active and sitting less than 4 h/day.Conclusion:Prolonged daily sitting time was associated with increased body fat among U.S.adults.The higher body fat associated with 6 h/day sitting may not be offset by achieving recommended levels of physical activity. 展开更多
关键词 ADULTS Body fat distribution Physical activity Sitting time
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Effect of sintering temperature and holding time on structure and properties of Li_(1.5)Ga_(0.5)Ti_(1.5)(PO_4)_(3)electrolyte with fast ionic conductivity
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作者 Yin-yi LUO Hao-zhang LIANG +6 位作者 Ping ZHANG Lei HAN Qian ZHANG Li-dan LIU Zhi-wei LUO Tian-xiang NING An-xian LU 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2024年第9期2959-2971,共13页
Li_(1.5)Ga_(0.5)Ti_(1.5)PO_(4))_(3)(LGTP)is recognized as a promising solid electrolyte material for lithium ions.In this work,LGTP solid electrolyte materials were prepared under different process conditions to explo... Li_(1.5)Ga_(0.5)Ti_(1.5)PO_(4))_(3)(LGTP)is recognized as a promising solid electrolyte material for lithium ions.In this work,LGTP solid electrolyte materials were prepared under different process conditions to explore the effects of sintering temperature and holding time on relative density,phase composition,microstructure,bulk conductivity,and total conductivity.In the impedance test under frequency of 1-10^(6) Hz,the bulk conductivity of the samples increased with increasing sintering temperature,and the total conductivity first increased and then decreased.SEM results showed that the average grain size in the ceramics was controlled by the sintering temperature,which increased from(0.54±0.01)μm to(1.21±0.01)μm when the temperature changed from 750 to 950°C.The relative density of the ceramics increased and then decreased with increasing temperature as the porosity increased.The holding time had little effect on the grain size growth or sample density,but an extended holding time resulted in crack generation that served to reduce the conductivity of the solid electrolyte. 展开更多
关键词 sintering temperature holding time CONDUCTIVITY cracks solid-state electrolyte
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Prevalence and Antibiotic Resistance of Urinary Tract Pathogens, with Molecular Identification of Klebsiella pneumoniae, Klebsiella oxytoca, and Acinetobacter spp., Using Multiplex Real-Time PCR
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作者 Hawa Tarnagda Djénéba Ouermi +12 位作者 Tani Sagna Wendyam Marie Christelle Nadembega Abdoul Karim Ouattara Lassina Traoré Rogomenoma Alice Ouedraogo Prosper Bado Bapio Valérie Elvira Jean Télesphore Bazie Nicole Bouda/Zongo Luc Zongo Albert Théophane Yonli Théodora Mahoukèdè Zohoncon Florencia Wendkuuni Djigma Jacques Simpore 《American Journal of Molecular Biology》 CAS 2024年第4期245-260,共16页
Urinary tract infections (UTIs) caused by uropathogens are a significant public health problem, and their treatment primarily relies on antibiotic therapy. However, the increasing global development of antibiotic resi... Urinary tract infections (UTIs) caused by uropathogens are a significant public health problem, and their treatment primarily relies on antibiotic therapy. However, the increasing global development of antibiotic resistance necessitates updating diagnostic techniques to ensure higher sensitivity and specificity, especially with advancements in science and medicine. This study aimed to evaluate the prevalence of UTIs and antibiotic resistance profiles through urine culture, as well as to identify Klebsiella pneumoniae, Klebsiella oxytoca, and Acinetobacter spp. in urine samples using a molecular approach with multiplex real-time PCR. From May 3 to July 25, 2023, at the Pietro Annigoni Biomolecular Research Center (CERBA) and Saint Camille Hospital of Ouagadougou (HOSCO), 209 urine samples collected from patients with suspected UTIs were analyzed using both urine culture and multiplex real-time PCR. Among the 209 patients, 52.15% were male and 47.85% female, with an average age of 46.87 ± 21.33 years. Urine cultures revealed an overall UTI prevalence of 23.44%, with a prevalence of 8.13% in men versus 15.31% in women (P = 0.023). The bacterial prevalence rates were as follows: Escherichia coli (12.92%), Klebsiella spp. (7.18%), Enterobacter cloacae (1.44%), Staphylococcus aureus (0.96%), and other bacteria. Klebsiella spp. demonstrated 100% resistance to Amoxicillin and Amoxicillin/Clavulanic Acid, while Escherichia coli showed 96.2% and 65.4% resistance to Amoxicillin and Amoxicillin/Clavulanic Acid, respectively. PCR analysis of the target bacteria revealed mono-infection prevalence rates of Klebsiella pneumoniae (10.39%), Klebsiella oxytoca (7.79%), and Acinetobacter spp. (7.79%), along with a co-infection prevalence rate of Klebsiella pneumoniae/Acinetobacter spp. (1.30%). This study demonstrated that PCR, with its high sensitivity and specificity, could effectively distinguish Klebsiella pneumoniae from Klebsiella oxytoca and detect Acinetobacter spp. in less than 24 hours—something urine culture alone could not achieve. The relative ease of automating urine PCR testing, combined with its diagnostic accuracy and rapid turnaround time, makes it a valuable addition to modern medical practice for the laboratory diagnosis of UTIs. 展开更多
关键词 Urinary Tract Infections Klebsiella pneumoniae Klebsiella oxytoca Acinetobacter .... Urine Culture Real-time PCR
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Quality-adjusted time without symptoms or toxicity analysis of haploidentical-related donor vs.identical sibling donor hematopoietic stem cell transplantation in acute myeloid leukemia
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作者 Yuewen Wang Xianli Gao +12 位作者 Ting Wang Xiaohui Zhang Lanping Xu Yu Wang Chenhua Yan Huan Chen Yuhong Chen Wei Han Fengrong Wang Jingzhi Wang Xia Yan Xiaodong Mo Xiaojun Huang 《Chinese Journal of Cancer Research》 SCIE CAS CSCD 2024年第5期530-544,共15页
Objective:We aimed to compare the quality-adjusted time without symptoms or toxicity(Q-TWiST)in acute myeloid leukemia(AML)patients who received haploidentical-related donor(HID)and identical sibling donor(ISD)hematop... Objective:We aimed to compare the quality-adjusted time without symptoms or toxicity(Q-TWiST)in acute myeloid leukemia(AML)patients who received haploidentical-related donor(HID)and identical sibling donor(ISD)hematopoietic stem cell transplantation(HSCT).Methods:Five clinical health states were defined:toxicity(TOX),acute graft-versus-host disease(GVHD),chronic GVHD(cGVHD),time without symptoms and toxicity(TWiST)and relapse(REL).The equation used in this study was as follows:Q-TWiST=UTOX×TOX+UTWiST×TWiST+UREL×REL+UaGVHD×aGVHD+UcGVHD×cGVHD.Results:A total of 239 AML patients were enrolled.We established a mathematical model,i.e.,Q-TWiST HID HSCT>Q-TWiST ISD HSCT,to explore the range of utility coefficients satisfying the inequality.Based on the raw data,the utility coefficient is equivalent to the following inequality:10.57067UTOX-46.27733UREL+105.9374+3.388078UaGVHD-210.8198UcGVHD>0.The model showed that when UTOX,UREL,and UaGVHD were within the range of 0-1,as well as when UcGVHD was within the range of 0-0.569,the inequality Q-TWiST HID HSCT>Q-TWiST ISD HSCT was valid.According to the results of the ChiCTR1800016972 study,the median coefficients of TOX,acute GVHD(aGVHD),and cGVHD were 0.56(0.41-0.76),0.56(0.47-0.72),and 0.54(0.37-0.79),respectively.We selected a series of specific examples of the coefficients,i.e.,UTOX=0.5,UREL=0.05,UaGVHD-0.5,and UcGVHD-0.5.The Q-TWiST values of ISD and HID HSCT were 896 and 900 d,respectively(P=0.470).Conclusions:We first observed that Q-TWiST was comparable between AML patients receiving HID HSCT and those receiving ISD HSCT. 展开更多
关键词 Quality-adjusted time without symptoms or toxicity acute myeloid leukemia allogeneic hematopoietic stem cell transplantation HAPLOIDENTICAL
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Effect of ageing time on corrosion behavior of Mg-10Gd-4.8Y-0.6Zr extruded-alloy 被引量:1
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作者 李慧中 刘洪挺 +3 位作者 郭菲菲 王海军 梁霄鹏 刘楚明 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2011年第7期1498-1505,共8页
The corrosion behaviors of Mg-10Gd-4.8Y-0.6Zr extruded-alloys with various ageing time were investigated by immersion test and electrochemical measurements.The results show that the corrosion rate of the experimental ... The corrosion behaviors of Mg-10Gd-4.8Y-0.6Zr extruded-alloys with various ageing time were investigated by immersion test and electrochemical measurements.The results show that the corrosion rate of the experimental alloy decreases with the increase of ageing time from 0 to 108 h.The corrosion resistance of the experimental alloy was found to increase with the increase of the size of the precipitate phases.The open circuit potential of the experimental alloy increases with the increase of the ageing time.The potentiodynamic polarization curves show that the cathodic over-potential increases with the increase of ageing time,leading to a decrease in the current density of anodic current plateau with the increase of ageing time. 展开更多
关键词 .................. alloy corrosion behavior ageing time
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Relationship between Storage Environment and Fruit Quality of a Pear Cultivar Xinli No.7 at Different Picking Time 被引量:2
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作者 张琦 段黄金 姜喜 《Agricultural Science & Technology》 CAS 2017年第9期1675-1679,1690,共6页
[Objective] This study aimed to study the effects of different picking time and storage environment on fruit quality of a pear cultivar Xinlin No.7 and the relationship between storage environment and fruit quality, s... [Objective] This study aimed to study the effects of different picking time and storage environment on fruit quality of a pear cultivar Xinlin No.7 and the relationship between storage environment and fruit quality, so as to provide a theoretical basis for storage and preservation of Xinli No.7. [Method] The fruits of Xinli NO.7 were picked up in August (optimal) and September respectively and then stored in room, cellar and freezer, respectively. The dynamics in temperature, humidity, CO2 concentration, fruit weight loss rate, pericarp chlorophyll content and fruit interior quality were determined. [Result] The environment differed significantly among different storage methods. In room and cellar, the temperature showed a downward trend, and the humidity decreased after early-mid October. The CO2 concentration changed steadily, and increased rapidly in cellar after December. In freezer, the temperature and humidity changed steadily, and the CO2 concentration increased after October. The changes in quality of the fruits harvested in August and September were similar. There was a certain correlation between storage environment and fruit quality of Xinli No.7. In room and cellar, the variation trends of tem- perature and humidity were consistent with those of chlorophyll content, fruit hardness and titratable acid content with positive correlations, but were opposite from those of fruit weight loss rate, soluble solids content and soluble sugar content with negative correlations. In freezer, the CO2 concentration was closely related to the changes in fruit quality. Its variation trend was consistent with those of fruit weight loss rate and soluble solids content, but was opposite from those of pericarp chlorophyll content, fruit firmness, soluble sugar content and titratable acid content. The differences in some of the traits reached significant levels (P〈0.05, P〈0.01). [Conclusion] With the extension of storage time, the temperature, humidity and CO2 concentration changed according to different patterns among different storage methods. The changes in fruit quality of Xinli NO.7 were related to the storage environment, especially to the temperature, to a certain extent. 展开更多
关键词 Xinli .... Harvest time Storage environment Correlation
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Effect of milling time on microstructure of Ti35Nb2.5Sn/10HA biocomposite fabricated by powder metallurgy and sintering 被引量:1
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作者 王晓鹏 徐丽娟 +4 位作者 陈玉勇 禹基道 肖树龙 孔凡涛 刘志光 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2012年第3期608-612,共5页
A new β-Ti based Ti35Nb2.5Sn/10 hydroxyapitite(HA) biocompatible composite was fabricated by mechanical milling and pulsed current activated sintering(PCAS).The microstructures of Ti35Nb2.5Sn/10HA powder particle... A new β-Ti based Ti35Nb2.5Sn/10 hydroxyapitite(HA) biocompatible composite was fabricated by mechanical milling and pulsed current activated sintering(PCAS).The microstructures of Ti35Nb2.5Sn/10HA powder particles and composites sintered from the milled powders were studied.Results indicated that α-Ti phase began to transform into β-Ti phase after the powders were mechanically milled for 8 h.After mechanical milling for 12 h,α-Ti completely transformed into β-Ti phase,and the ultra fine Ti35Nb2.5Sn/10HA composite powders were obtained.And ultra fine grain sized Ti35Nb2.5Sn/10HA sintered composites were obtained by PCAS.The hardness and relative density of the sintered composites both increased with increasing the ball milling time. 展开更多
关键词 ................ ultrafine grain powder metallurgy milling time
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Effects of dwell time during sintering on electrical properties of 0.98(K_(0.5)Na_(0.5))NbO_3-0.02LaFeO_3 ceramics 被引量:1
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作者 程花蕾 周万城 +2 位作者 杜红亮 罗发 朱冬梅 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2013年第10期2984-2988,共5页
The effects of dwell time on the phase structure, microstructure, and electrical properties were investigated for the 0.98(K0.sNa0.5)NbO3-0.02LaFeO3 ceramics (abbreviated as 0.98KNN-0.02LF). All the ceramics sinte... The effects of dwell time on the phase structure, microstructure, and electrical properties were investigated for the 0.98(K0.sNa0.5)NbO3-0.02LaFeO3 ceramics (abbreviated as 0.98KNN-0.02LF). All the ceramics sintered for different dwell time are of pure phase and the peak intensity of the 0.98KNN-0.02LF ceramics becomes stronger with a longer dwell time. Denser microstructures with larger grain size are developed for the sample with a longer dwell time. The maximum dielectric permittivity decreases with increasing the dwell time, and the deteriorative dielectric properties are due to the increasing grain size and the domain wall motion. Ferroelectric properties results indicate that 2Pr value slightly decreases with increasing the dwell time, while the 2Ec value increases. Consequently, the 0.98KNN-0.02LF ceramic sintered at 1150 ℃ for 2 h shows optimum dielectric properties (er=2253 and tan fi〈5%) and ferroelectric properties (2Pr=34.51 gC/cm2 and 2Ec=5.07 kV/mm). 展开更多
关键词 ............... dwell time dielectric properties ferroelectric property lead-free ceramics
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Time Delay Characteristic of Industrial Wireless Networks Based on IEEE 802.15.4a 被引量:2
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作者 Tong-Tao Li Ting-Gang Jia +1 位作者 Min-Rui Fei Huo-Sheng Hu 《International Journal of Automation and computing》 EI 2011年第2期170-176,共7页
The IEEE 802.15.4a standard provides a framework for low-data-rate communication systems,typically sensor networks.In this paper,we established a realistic environment for the time delay characteristic of industrial n... The IEEE 802.15.4a standard provides a framework for low-data-rate communication systems,typically sensor networks.In this paper,we established a realistic environment for the time delay characteristic of industrial network based on IEEE 802.15.4a.Several sets of practical experiments are conducted to study its various features,including the effects of 1) numeral wireless nodes,2) numeral data packets,3) data transmissions with different upper-layer protocols,4) physical distance between nodes,and 5) adding and reducing the number of the wireless nodes.The results show that IEEE 802.15.4a is suitable for some industrial applications that have more relaxed throughput requirements and time-delay.Some issues that could degrade the network performance are also discussed. 展开更多
关键词 time delay characteristic IEEE ......... industrial wireless network performance test sensor .........
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Projected Regional 1.50℃and 2.00℃Warming Threshold-crossing Time Worldwide Using the CMIP6 Models
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作者 MENG Yali DUAN Keqin +5 位作者 SHANG Wei SHI Peihong LI Shuangshuang CHENG Ying CHEN Rong ZHANG Zhaopeng 《Chinese Geographical Science》 SCIE CSCD 2023年第6期1095-1108,共14页
The Paris Agreement aims to limit global warming to well below 2.00℃and pursue efforts to limit the temperature increase to 1.50℃.However,the response of climate change to unbalanced global warming is affected by sp... The Paris Agreement aims to limit global warming to well below 2.00℃and pursue efforts to limit the temperature increase to 1.50℃.However,the response of climate change to unbalanced global warming is affected by spatial and temporal sensitivities.To better understand the regional warming response to global warming at 1.50℃and 2.00℃,we detected the 1.50℃and 2.00℃warming threshold-crossing time(WTT)above pre-industrial levels globally using the Coupled Model Intercomparison Project phase 6(CMIP6)models.Our findings indicate that the 1.50℃or 2.00℃WTT differs substantially worldwide.The warming rate of land would be approximately 1.35–1.46 times that of the ocean between 60°N–60°S in 2015–2100.Consequently,the land would experience a 1.50℃(2.00℃)warming at least 10–20 yr earlier than the time when the global mean near-surface air temperature reaches 1.50℃(2.00℃)WTT.Meanwhile,the Southern Ocean between 0°and 60°S considerably slows down the global 1.50℃and 2.00℃WTT.In 2040–2060,over 98.70%(77.50%),99.70%(89.30%),99.80%(93.40%),and 100.00%(98.00%)of the land will have warmed by over 1.50℃(2.00℃)under SSP(Shared Socioeconomic Pathway)1–2.6,SSP2-4.5,SSP3-7.0,and SSP5-8.5,respectively.We conclude that regional 1.50℃(2.00℃)WTT should be fully considered,especially in vulnerable high-latitude and high-altitude regions. 展开更多
关键词 CMIP6(Coupled Model Intercomparison Project phase 6) global warming ............ time ............ time regional differences
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转基因番茄植株Mi1.2表达水平的Real Time PCR检测体系的建立 被引量:3
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作者 魏振林 田志环 +1 位作者 焦传珍 董玲 《安徽农业科学》 CAS 北大核心 2008年第18期7589-7590,共2页
[目的]为转基因番茄植株的高通量筛选奠定基础。[方法]利用CTAB法提取番茄叶片总RNA进行Real Time PCR扩增,分析转MI1、2基因的番茄植株表达水平的检测体系。[结果]提取RNA的A260/A280为1.78~1.88,RNA无明显降解。在严谨扩增条件... [目的]为转基因番茄植株的高通量筛选奠定基础。[方法]利用CTAB法提取番茄叶片总RNA进行Real Time PCR扩增,分析转MI1、2基因的番茄植株表达水平的检测体系。[结果]提取RNA的A260/A280为1.78~1.88,RNA无明显降解。在严谨扩增条件下,引物SYBR2的扩增效率高于SYBR1。Mg^2+的适宜浓度为2.0mg/L。Real Time PCR扩增产物具有良好的特异性,熔解曲线特异峰出现在84.5℃附近,在熔解曲线略低于83℃附近有极微弱的非特异峰。因此在定量反应中信号检测步骤应放在84℃。以4种不同模板分子数条件下扩增曲线Ct值得到的回归方程为Y=-3.78×log(copynumber)+39.50,相关系数为0.998。[结论]该试验获得的Real Time PCR体系可用于转基因植株表达水平的检测。 展开更多
关键词 REAL time PCR 检测体系 转基因番茄植株 熔解曲线
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基于TrueTime2.0的网络控制系统的仿真研究 被引量:3
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作者 刘川来 郭蓝天 朱孔阳 《微计算机信息》 2011年第12期109-110,143,共3页
介绍一种基于Matlab/Simulink环境的网络控制系统实时仿真工具箱TrueTime2.0。它能够对网络控制系统的网络延时、网络调度、网络参数、控制方法等进行综合的仿真研究,而且与较旧版本的TrueTime工具箱相比有了一定的改进。本文利用TrueTi... 介绍一种基于Matlab/Simulink环境的网络控制系统实时仿真工具箱TrueTime2.0。它能够对网络控制系统的网络延时、网络调度、网络参数、控制方法等进行综合的仿真研究,而且与较旧版本的TrueTime工具箱相比有了一定的改进。本文利用TrueTime2.0工具箱搭建网络控制系统仿真平台,结合具体的仿真模型对两种常用的控制网络——以太网和令牌网进行实时仿真研究。通过仿真结果可以看出TrueTime2.0工具箱能够较好地较、方便地实现网络控制系统的仿真,并验证了两种控制网络各自的特点。 展开更多
关键词 网络控制系统 Truetime2.0工具箱 网络延时 实时仿真
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Traffic Data: Bluetooth Sensors vs. Crowdsourcing——A Comparative Study to Calculate Travel Time Reliability in Calgary, Alberta, Canada 被引量:1
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作者 Shahram Tahmasseby 《Journal of Traffic and Transportation Engineering》 2015年第2期63-79,共17页
The City of Calgary did a comparative study between two techniques of traffic data collection: Bluetooth sensors and crowdsourcing, for measuring travel time reliability on two goods movement corridors in Calgary, Al... The City of Calgary did a comparative study between two techniques of traffic data collection: Bluetooth sensors and crowdsourcing, for measuring travel time reliability on two goods movement corridors in Calgary, Alberta. To estimate travel time and speed, we used the output of BIuFAX sensors, which were operated by monitoring Bluetooth signals at several points along a roadway. On the other hand, TomTom historical traffic data were extracted from the TomTom Traffic Stats portal. To calculate travel time reliability, we applied the buffer index, and the planning time index recommended by FHWA (Federal Highway Administration). The Bluetooth traffic data were presumed as the benchmark in this study. Unlike the TomTom traffic data, the data provided by the Bluetooth technology met the minimum recommended sample size requirement, although data processing was time consuming and impractical for long study periods. Our study results showed that crowdsourcing technique can be a viable alternative and provide travel time reliability estimates with a reasonable accuracy, when there are adequate numbers of records registered. However, the TomTom sample sizes in Calgary were not large enough to provide a statistically reliable method of providing travel time indices. Further researches may verify the accuracy of crowdsourcing technologies for travel time studies. 展开更多
关键词 BLUETOOTH BIuFAX travel time reliability TomTom buffer time index GPS (global positioning system) based trafficdata crowdsourced traffic .....
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Comparison of Agrimophol Content in Agrimonia pilosa Ledeb. from Luzhou at Different Harvest Time
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作者 Xin YU Lilan OU +1 位作者 Ye ZHU Dan ZHANG 《Agricultural Biotechnology》 CAS 2017年第2期55-57,共3页
[ Objectives] This study was conducted to compare agrimophol contentsin Agrimonia pilosa Ledeb. at different harvest time, so as to select its best harvest time. [Methods] High performance liquid chromatography was us... [ Objectives] This study was conducted to compare agrimophol contentsin Agrimonia pilosa Ledeb. at different harvest time, so as to select its best harvest time. [Methods] High performance liquid chromatography was used for the determination of agfmophol in A. pilosa Ledeb. at different harvest time in Luzhou. [ Results ] The content of agrimophol could be detected by HPLC. Agrimophol had good linearity in 0.01 - 0.1 mg/ml ( r = 0.999 9 ), the average recov- ery was 101.5%, and RSD was 1.10%. The content of agrimophol in A. pilosa Ledeb. in Luzhou was 0.010 8% in June, and 0.013 1% in July, much higher than any other months. [ Conclusions] This experiment established a method for detecting the content of agrimophol by HPLC, which is simple, with high precision, high accuracy, good repeatability and recovery. The reasonable harvest time of A. pilosa Ledeb. in Luzhou is June and July. 展开更多
关键词 Agrimonia pilosa ...... AGRIMOPHOL DETERMINATION Harvest time
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Improved Radio Network Dimensioning for Real-Time Polling Service on IEEE 802.16 Wireless Networks with QoS Consideration
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作者 Thiaw Seng Ng Teong Chee Chuah Yi Fei Tan 《International Journal of Communications, Network and System Sciences》 2012年第3期192-205,共14页
Recently, applications of real-time polling service (rtPS) in IEEE 802.16 wireless networks have gained considerable popularity. These applications generate large amounts of real time traffic in the network and thus m... Recently, applications of real-time polling service (rtPS) in IEEE 802.16 wireless networks have gained considerable popularity. These applications generate large amounts of real time traffic in the network and thus maintaining the quality of service (QoS) such as packet delay requirement in rtPS dominant networks is critical. Existing dimensioning methodology does not consider QoS parameters of rtPS in network dimensioning. Moreover, exhaustive and time-consuming simulations are required to evaluate the performance and QoS of rtPS. To overcome this problem, we propose an improved radio network dimensioning framework which considers QoS parameters of rtPS in network dimensioning. In this framework, an analytical model is developed to evaluate the capacity and performance of rtPS in IEEE 802.16 wireless networks. The proposed framework provides a fast and accurate means of finding the trade-off between system load and packet delay, thus providing network operators with an analytical tool that jointly considers coverage, capacity and QoS requirements for obtaining the minimum number of sites required. The accuracy of the proposed model is validated through simulations. 展开更多
关键词 .......... DIMENSIONING Analytical Model Real time POLLING SERVICE QOS
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The Effect of Ageing Time on Some Mechanical Properties of Aluminum/0.5% Glass Reinforced Particulate Composite
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作者 Aondona .P. Ihom Nyior .G. Bem +1 位作者 Emmanuel E. Anbua Joy N. Ogbodo 《Journal of Minerals and Materials Characterization and Engineering》 2012年第9期919-923,共5页
A particulate-hardened composite usually known as cermets with aluminum matrix and reinforced with ceramic particles from broken bottles was used to investigate the effect of ageing time on hardness and tensile streng... A particulate-hardened composite usually known as cermets with aluminum matrix and reinforced with ceramic particles from broken bottles was used to investigate the effect of ageing time on hardness and tensile strength. The samples used for the work were produced using stir-cast method and the samples were cast in metal moulds to improve on the surface finish and to obtain good cooling rate. The composite composition used was Al/0.5% glass particles. The samples were treated at 500?C and quenched in water at 65?C. They were then aged at various temperatures ranging from 150?C - 210?C. The result of the hardness test showed that within the range of the ageing time selected the hardness increased with the ageing for all the ageing temperatures used. Variations were observed but this is normal in ageing, particularly when coherent and incoherent precipitates are formed at a point in time, or when over-ageing occurs. The plot of the tensile strength tests and the hardness tests, with ageing time showed the trend as observed. The highest hardness value of 37.3 HRB occurred after 5 hours of ageing likewise the highest tensile strength value of 398.36 N/mm2 occurred after 5 hours of ageing at the same ageing temperature of 190?C. The aged composite showed improved hardness and tensile strength when compared to as-cast value of 23.7 HRB for hardness and 253.12 N/mm2 for tensile strength respectively. 展开更多
关键词 ....... GLASS Ageing time PARTICULATE Composite MECHANICAL Properties
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Time and Consciousness in T.S Eliot's The Love Song of J.Alfred Prufrock
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作者 王抒飞 《海外英语》 2012年第1X期221-221,223,共2页
The relationship between time and consciousness is what T.S.Eliot concerns much in his early modernist poem The love song of J.Alfred Prufrock.This paper is an analysis of the way Eliot employs the stream of conscious... The relationship between time and consciousness is what T.S.Eliot concerns much in his early modernist poem The love song of J.Alfred Prufrock.This paper is an analysis of the way Eliot employs the stream of consciousness technique to create a typical Western modern man who suffers greatly from meaningless life and spiritual crisis. 展开更多
关键词 time CONSCIOUSNESS PRUFROCK
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An IEEE 802.3 Compatible Real Time Medium Access Control with Length-based Priority
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作者 尹汝泼 蔡云泽 张卫东 《Journal of Donghua University(English Edition)》 EI CAS 2006年第1期89-93,共5页
A new medium access control method is proposed over the predominant Ethernet broadcast channel. Taking advantages of intrinsic variable length characteristic of standard Ethemet frame, message-oriented dynamic priorit... A new medium access control method is proposed over the predominant Ethernet broadcast channel. Taking advantages of intrinsic variable length characteristic of standard Ethemet frame, message-oriented dynamic priority mechanism is established. Prioritized medium access control operates under a so-called block mode in event of collisions. High priority messages have a chance to preempt block status incurred by low priority ones. By this means, the new MAC provides a conditional detrministic real time performance beyond a statistical one. Experiments effectiveness and attractiveness of the proposed scheme.Moreover,this new MAC is completely compatible with IEEE802.3 . 展开更多
关键词 real time Ethernet medium access control dynamic priority channel blocking ...........
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Effect of holding time on microstructure and mechanical properties of Al-40 wt.%Si alloys fabricated by combination of gas atomization and spark plasma sintering
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作者 AN Yu-jiao NIU Li-bin +3 位作者 GAO Chong HU Yu-yang LI Yu-hua LIU Jin-song 《Journal of Central South University》 SCIE EI CAS CSCD 2022年第3期860-870,共11页
Hypereutectic Al-40 wt.%Si alloys were fabricated by the combination of gas atomization and spark plasma sintering(SPS) technology. The effects of holding time(15-60 min) on phase composition, microstructure, density,... Hypereutectic Al-40 wt.%Si alloys were fabricated by the combination of gas atomization and spark plasma sintering(SPS) technology. The effects of holding time(15-60 min) on phase composition, microstructure, density,mechanical properties of Al-Si alloys were investigated by XRD, SEM, a hydrostatic balance, an automatic micro hardness tester and a universal tensile testing machine. The results showed that homogenous distribution of ultrafine primary Si and high density of alloys can be obtained at holding time of 30 min. Compared with primary Si(3.7 μm)fabricated by gas atomization, the average size increased from 5.17 to 7.72 μm with the increase of holding time during SPS process. Overall, the relative density, maximum tensile strength and Vickers hardness of 94.9%, 205 MPa and HV;196.86 were achieved at holding time of 30 min, respectively. In addition, all the diffraction peaks were corresponded to α-Al or β-Si and no other phase can be detected. Finally, the densification process of SPS was also discussed. 展开更多
关键词 Al-40 ...... spark plasma sintering primary Si holding time gas atomization
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