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电液3-UPS/S并联稳定平台参数振动特性分析
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作者 袁晓明 王维锜 +1 位作者 庞浩东 张立杰 《振动与冲击》 EI CSCD 北大核心 2024年第5期52-61,共10页
针对电液3-UPS/S并联稳定平台驱动液压缸的压力脉动所产生的参数振动,建立了稳定平台的参数振动方程并利用多尺度法求解了主共振响应与组合共振响应的一次近似解;分析了主共振与组合共振响应特性以及振动幅值在初始工作空间内的变化规律... 针对电液3-UPS/S并联稳定平台驱动液压缸的压力脉动所产生的参数振动,建立了稳定平台的参数振动方程并利用多尺度法求解了主共振响应与组合共振响应的一次近似解;分析了主共振与组合共振响应特性以及振动幅值在初始工作空间内的变化规律,最后采用四阶龙格库塔法与模态试验对参数振动模型进行验证。结果表明:数值解与理论解之间的最大误差为4.20%,固有频率理论值与试验值之间的最大误差为4.66%,可验证参数振动模型的正确性。 展开更多
关键词 电液3-UPS/S并联稳定平台 压力脉动 参数振动 多尺度法 振动特性
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Nominal Model-Based Sliding Mode Control with Backstepping for 3-Axis Flight Table 被引量:11
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作者 刘金琨 孙富春 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2006年第1期65-71,共7页
Based on nominal model, a novel global sliding mode controller (GSMC) with a new control scheme is proposed for a practical uncertain servo system. This control scheme consists of two combined controllers, One is th... Based on nominal model, a novel global sliding mode controller (GSMC) with a new control scheme is proposed for a practical uncertain servo system. This control scheme consists of two combined controllers, One is the global sliding mode controller for practical plant, the other is the integral backstepping controller for nominal model. Modeling error between practical plant and nominal model is used to design GSMC. The steady-state control accuracy can be guaranteed by the integral backstepping control law, and the global robustness can be obtained by GSMC. The stability of the proposed controller is proved according to the Lyapunov approach. The simulation results both of sine signal and step signal tracking for 3-axis flight table are investigated to show good position tracking performance and high robustness with respect to large and parameter changes over all the response time. 展开更多
关键词 nominal model sliding mode control backstepping control robust control 3-axis flight table
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Stiffness of Postural Alignment System Based on 3-Axis Actuators for Large Aircraft Components 被引量:4
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作者 GUO Zhimin JIANG Junxia KE Yinglin 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2010年第4期524-531,共8页
Aircraft digital flexible assembly fixture and technologies are widely used in developed countries, while the traditional jig-based assembly mode is still used in China. The application study of aircraft digital flexi... Aircraft digital flexible assembly fixture and technologies are widely used in developed countries, while the traditional jig-based assembly mode is still used in China. The application study of aircraft digital flexible assembly system is just beginning in our country recently. To meet the requirements of automated posture alignment and join in digital assembly system for large aircraft components, a novel fitting fixture called 3-axis actuator is developed. On the basis of the actuators, three kinds of posture alignment system for large aircraft components are proposed, including the non-redundant system, the redundant actuating system, and the redundant leg system, and their constitutions and properties are introduced. Through deriving the feeding transmission stiffness model of single actuator and analyzing the inverse kinematics of these systems, the relationship between the external force and the changes of position and orientation of large aircraft component is obtained, and then the postural alignment stiffness models are established. With the method mentioned above, the postural alignment stiffness of three systems is computed by using the algebraic formulate, and the results show that redundant properties can increase system's postural alignment stiffness. As an example, a optimized layout of the assembly system for a given model of aircraft is developed, the results of application show that the layout has many advantages, such as high accuracy, stiffness, stability, reliability, efficiency and flexible, which can satisfy the requirement of aircraft digital assembly system well. The proposed study of postural alignment stiffness for different systems can supply the theoretic support for the optimization layout design of aircraft digital assembly system, and contribute to evaluate the system working performance of systems. 展开更多
关键词 3-axis actuator large aircraft component redundant postural alignment stiffness posture-holding
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QFT Robust Control Design for 3-Axis Flight Table Servo System with Large Friction 被引量:3
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作者 刘金琨 尔联洁 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2004年第1期34-38,共5页
The 3-axis flight table is an important device and a typical high performanceposition and speed servo system used in the hardware-in-the-loop simulation of flight controlsystem. Friction force and uncertainty are the ... The 3-axis flight table is an important device and a typical high performanceposition and speed servo system used in the hardware-in-the-loop simulation of flight controlsystem. Friction force and uncertainty are the main characteristics in the 3-axis flight table servosystem. Based on the description of dynamic and static model of a nonlinear Stribeck frictionmodel, and taking account of the practical uncertainties of 3-axis flight table servo system, theQFT controller is designed. Simulation and realtime results are presented. 展开更多
关键词 quantitative feedback theory 3-axis flight table friction model ROBUSTCONTROL
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Integrating stable isotopes and factor analysis to delineate the groundwater provenance and pollution sources in the northwestern part of the Amman-Al Zarqa Basin, Jordan
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作者 Mutawakil OBEIDAT Ahmad AL-AJLOUNI +2 位作者 Eman BANI-KHALED Muheeb AWAWDEH Muna ABU-DALO 《Journal of Arid Land》 SCIE CSCD 2023年第12期1490-1509,共20页
Globally,groundwater contamination by nitrate is one of the most widespread environmental problems,particularly in arid and semiarid areas,which are characterized by low amounts of rainfall and groundwater recharge.Th... Globally,groundwater contamination by nitrate is one of the most widespread environmental problems,particularly in arid and semiarid areas,which are characterized by low amounts of rainfall and groundwater recharge.The stable isotope composition of groundwater(δ2H-H2O andδ18O-H2O)and dissolved nitrate(δ15N-NO3–andδ18O-NO3–)and factor analysis(FA)were applied to explore groundwater provenance,pollution,and chemistry evolution in the northwestern part of the Amman-Al Zarqa Basin,Jordan.In this study,we collected 23 samples from the Lower Ajloun aquifer in 2021,including 1 sample from a groundwater well and 22 samples from springs.These samples were tested for electrical conductivity,total dissolved solids,pH,temperature,dissolved oxygen,the concentration of major ions(Ca2+,Mg2+,Na+,K+,HCO3–,Cl–,SO42–,and NO3–),and the stable isotope composition of groundwater and dissolved nitrate.The results revealed that groundwater in the study area is mainly Ca–Mg–HCO3 type and can be classified as fresh water,hard water,and very hard water.The range and average concentration of NO3–were 3.5–230.8 and 50.9 mg/L,respectively.Approximately 33%of the sampling points showed NO3–levels above the maximum allowable concentration of 50.0 mg/L set by the World Health Organization(WHO)guidelines for drinking water quality.The values ofδ18O-H2O andδ2H-H2O showed that groundwater in the study area is part of the current water cycle,originating in the Mediterranean Sea,with significant evaporation,orographic,and amount effects.The values of the stable isotope composition of NO3–corresponded toδ15N-NO3–andδ18O-NO3–values produced by the nitrification process of manure or septic waste and soil NH4+.The FA performed on the hydrochemical parameters and isotope data resulted in three main factors,with Factor 1,Factor 2,and Factor 3,accounting for 50%,21%,and 11%of the total variance,respectively.Factor 1 was considered human-induced factor,named"pollution factor",whereas Factor 2,named"conservative fingerprint factor",and Factor 3,named"hardness factor",were considered natural factors.This study will help local researchers manage groundwater sustainably in the study area and other similar arid and semiarid areas in the world. 展开更多
关键词 stable isotope composition δ15N-NO3 δ18O-NO3 groundwater quality pollution sources JORDAN
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Influence of CaxSr1-x(0≤x≤1)Substitution for Zn on Microwave Dielectric Properties of Li2ZnTi3O8 Ceramic as Temperature Stable Materials 被引量:1
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作者 TIAN Shi LIAO Zelin +1 位作者 WANG Heng WANG Weimin 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2020年第4期686-690,共5页
A temperature stable Li2Zn0.95(SrxCa1-x)0.05Ti3O8(0≤x≤1)ceramics were fabricated using a conventional solid-state route sintered at 1100℃for 4 h.The XRD results indicate that the main phase Li2ZnTi3O8 and secondary... A temperature stable Li2Zn0.95(SrxCa1-x)0.05Ti3O8(0≤x≤1)ceramics were fabricated using a conventional solid-state route sintered at 1100℃for 4 h.The XRD results indicate that the main phase Li2ZnTi3O8 and secondary phase including SrxCa1-xTiO3(0≤x≤1)solid solution and TiO2 co-exist in composite and form a stable composite system when the(CaxSr1-x)(0≤x≤1)substitutes for Zn of Li2ZnTi3O8 ceramic.As x is increased from 0 to 1,the relative permittivity(εr)increases from 26.65 to 27.12,and the quality factor(Q×f)increases from 63300 to 66600 GHz.With the increased of x,the temperature coefficient of resonant frequency(τf)increases from 0.27 to 8.23 ppm/℃,and then decreases to 3.51 ppm/℃.On the whole,the Li2Zn0.95(SrxCa1-x)0.05Ti3O8(0≤x≤1)ceramics show excellent comprehensive properties of middleεr=25-27,higher Q×f≥60000 GHz andτf≤±8.5 ppm/℃. 展开更多
关键词 Li2Zn0.95(SrxCa1-x)0.05Ti3O8(0≤x≤1) microwave dielectric properties temperature stable materials SUBSTITUTION
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关于路面基层中高平3^(#)煤矸石的试验研究
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作者 高世川 闫建兵 王秀龙 《能源与节能》 2024年第11期203-205,共3页
随着科技的不断进步和创新,公路建设行业不断涌出了各种新兴技术、材料和工艺。在以绿色环保、变废为宝为主题的背景下,探讨了将煤矸石用于路面基层的可行性,并对高平3^(#)煤矸石水稳层材料进行了详细的研究,通过验证煤矸石的无侧限抗... 随着科技的不断进步和创新,公路建设行业不断涌出了各种新兴技术、材料和工艺。在以绿色环保、变废为宝为主题的背景下,探讨了将煤矸石用于路面基层的可行性,并对高平3^(#)煤矸石水稳层材料进行了详细的研究,通过验证煤矸石的无侧限抗压强度,证明了3^(#)煤矸石可应用于实际工程中。 展开更多
关键词 公路建设 路面基层 高平3^(#)煤矸石 水稳层材料
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血清ORMDL3结合FeNO对哮喘稳定期急性发作的预测分析
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作者 韩方方 马朝阳 《齐齐哈尔医学院学报》 2024年第6期535-539,共5页
目的 分析血清类黏蛋白1样蛋白3(ORMDL3)结合呼出气一氧化氮(FeNO)对哮喘稳定期急性发作的预测价值。方法 选择2018年7月—2023年8月在本院门诊随访的120例哮喘稳定期患者作为疾病组,另同期选取120名健康体检者作为对照组,检测两组ORMDL... 目的 分析血清类黏蛋白1样蛋白3(ORMDL3)结合呼出气一氧化氮(FeNO)对哮喘稳定期急性发作的预测价值。方法 选择2018年7月—2023年8月在本院门诊随访的120例哮喘稳定期患者作为疾病组,另同期选取120名健康体检者作为对照组,检测两组ORMDL3 mRNA表达量和FeNO浓度。依据疾病组3个月内是否出现哮喘急性发作将其分为急性发作组和非急性发作组,比较两组患者ORMDL3 mRNA表达量和FeNO浓度,采用多因素Logistic回归分析哮喘稳定期急性发作的影响因素,采用受试者工作特征(ROC)曲线分析ORMDL3 mRNA、FeNO单项及联合对哮喘稳定期急性发作的预测价值。结果 疾病组ORMDL3 mRNA表达量、FeNO浓度均高于对照组(P<0.05);急性发作组ORMDL3 mRNA表达量、FeNO浓度、体质量指数(BMI)以及吸烟史占比均高于非急性发作组(P<0.05),淋巴细胞计数、用力肺活量占预计值百分比(FVC%)、第一秒用力呼气末容积占预计值百分比(FEV1%)低于非急性发作组(P<0.05);经多因素Logistic回归分析显示,高ORMDL3 mRNA、高FeNO、高BMI均为哮喘稳定期患者急性发作的危险因素(P<0.05),高FVC%、高FEVI%为其保护因素(P<0.05)。ORMDL3 mRNA、FeNO联合预测哮喘稳定期患者急性发作的灵敏度高于单独预测,联合预测的AUC高于单独预测(P<0.05),联合预测的特异度与单独预测相近。结论 ORMDL3、FeNO均在哮喘稳定期急性发作患者中存在异常高表达,均是哮喘稳定期急性发作的影响因素,且两者联合对哮喘稳定期急性发作具有较好的预测价值。 展开更多
关键词 哮喘 稳定期 急性发作 血清类黏蛋白1样蛋白3 呼出气一氧化氮 预测价值
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春用蚕品种华康3号、川山×蜀水的丰产性和稳产性分析
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作者 吴礼兵 秦友华 +4 位作者 姚程杰 谢进军 严晓鹤 张兆琴 任振霞 《北方蚕业》 2024年第3期14-18,共5页
应用非参数统计法、高稳系数法以及稳定性参数法等分析方法,对春用家蚕品种华康3号和川山×蜀水的高产稳产性及丝质性状进行水平比较与稳定性分析。试验表明,华康3号和川山×蜀水盒种产茧量、健蛹率、解舒率、茧丝长、洁净度均... 应用非参数统计法、高稳系数法以及稳定性参数法等分析方法,对春用家蚕品种华康3号和川山×蜀水的高产稳产性及丝质性状进行水平比较与稳定性分析。试验表明,华康3号和川山×蜀水盒种产茧量、健蛹率、解舒率、茧丝长、洁净度均优于菁松×皓月,具有张产高、丝质优的特点;两个品种在稳定性方面各有差异。 展开更多
关键词 华康3 川山×蜀水 丰产性 稳产性
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The establishment of a stable PC-3 cell line overexpressing micro RNA-145
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作者 熊大芾 《外科研究与新技术》 2011年第2期123-123,共1页
Objective To establish stable prostate cancer bone metastasis cell line overexpressing microRAN-145 (miR-145)for the study of the mechanism of miR-145 in bone metastasis.Methods pMSCV-miR-145 plasmids and retroviruses... Objective To establish stable prostate cancer bone metastasis cell line overexpressing microRAN-145 (miR-145)for the study of the mechanism of miR-145 in bone metastasis.Methods pMSCV-miR-145 plasmids and retroviruses of pMSCV-vector 展开更多
关键词 CELL LINE PC The establishment of a stable PC-3 cell line overexpressing micro RNA-145
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Optimization of efficient stable reagent of alkaline thiourea solution for gold leaching 被引量:5
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作者 王云燕 柴立元 +2 位作者 闵小波 何德文 彭兵 《Journal of Central South University of Technology》 EI 2003年第4期292-296,共5页
Na2SiO3 and Na2SeO3 were chosen as stable reagents of alkaline thiourea solution substituting Na2SO3, according to the structure-property relationship between the stability of alkaline thiourea and the structure of th... Na2SiO3 and Na2SeO3 were chosen as stable reagents of alkaline thiourea solution substituting Na2SO3, according to the structure-property relationship between the stability of alkaline thiourea and the structure of thiourea and sulfite ion, and the effect of the stable reagents on stability of alkaline thiourea was investigated. The results show that contrary to Na2SeO3, Na2SO3 and Na2SiO3 affect the stability of alkaline thiourea solution remarkably. The stable effect of Na2SiO3 on alkaline thiourea is obviously better than that of Na2SO3. The stable reagents Na2SO3 and Na2SiO3 decrease the decomposition rate of alkaline thiourea solution greatly, and the decomposition rate of alkaline thiourea reduces from (72.5%) to (33.8%) with addition of (0.3 mol·L-1) Na2SiO3. Dissolution currents of gold in the alkaline thiourea solution containing Na2SO3 and Na2SiO3 are (2.0) (mA·cm-2) and (3.5) (mA·cm-2) at the potential of 0.42 V, respectively, and Na2SO3 is consumed excessively due to the oxidation reaction of Na2SO3 occurring in the studied potential range. Na2SiO3 is an efficient stable reagent of alkaline thiourea solution, and gold dissolution is accelerated much more obviously by Na2SiO3 than by Na2SO3. 展开更多
关键词 ALKALINE THIOUREA gold LEACHING stable REAGENT NA2SIO3 Na2SO3 Na2SeO3
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Li4-xSbxSn1-xS4 solid solutions for air-stable solid electrolytes 被引量:5
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作者 Zhuoran Zhang Jianxing Zhang +4 位作者 Yulong Sun Huanhuan Jia Linfeng Peng Yunyang Zhang Jia Xie 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2020年第2期171-176,共6页
The sulfide solid electrolytes have the characteristics of high ionic conductivity and low grain boundary resistance, which make them suitable for bulk-type all-solid-state batteries. However, most of them suffer from... The sulfide solid electrolytes have the characteristics of high ionic conductivity and low grain boundary resistance, which make them suitable for bulk-type all-solid-state batteries. However, most of them suffer from poor stability in air. Here, we explore the air stable sulfide solid electrolytes in Li4-xSbxSn1-xS4 system. The solid solutions of Li4-xSbxSn1-xS4(0 ≤ x ≤ 0.5) can be formed in Li4-xSbxSn1-xS4 system. Li3.8 Sb0.2 Sn0.8 S4 achieves the highest ionic conductivity of 3.5 × 10-4 S cm-1 in this system,which is 5 times as that of Li4 Sn S4 and 3 orders of magnitude higher than that of Li3 Sb S4, respectively. Li3.8 Sb0.2 Sn0.8 S4 crystallizes into the same structure with high ionic conductivity phase of β-Li3 PS4. Moreover, Li3.8 Sb0.2 Sn0.8 S4 owns good stability in humid air. Matching with LiCoO2 and Li4 Ti5 O12,Li3.8 Sb0.2 Sn0.8 S4 exhibits the potential to be applied in all-solid-state batteries. 展开更多
关键词 Solid ELECTROLYTE AIR stable SULFIDE Li4SnS4 β-Li3PS4 ALL-SOLID-STATE BATTERY
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Dynamics of soil organic carbon following land-use change:insights from stable C-isotope analysis in black soil of Northeast China 被引量:3
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作者 Chenglong Tu Congqiang Liu +4 位作者 Timothy A.Quine Matthew William Jones Taoze Liu Longbo Li Wenjing Liu 《Acta Geochimica》 EI CAS CSCD 2018年第5期746-757,共12页
Intensive soil tillage is a significant factor in soil organic matter decline in cultivated soils. Both cultivation abandonment and foregoing tillage have been encouraged in the past 30 years to reduce greenhouse gas ... Intensive soil tillage is a significant factor in soil organic matter decline in cultivated soils. Both cultivation abandonment and foregoing tillage have been encouraged in the past 30 years to reduce greenhouse gas emissions and soil erosion. However, the dynamic processes of soil organic carbon (SOC) in areas of either continuous cultivation or abandonment remain unclear and inconsistent.Our aims were to assess and model the dynamic processes of SOC under continuous tillage and after cultivation abandonment in the black soil of Northeast China. Soil profiles were collected of cultivated or abandoned land with cultivation history of 0–100 years. An isotope mass balance equation was used to calculate the proportion of SOC derived from corn debris (C_4) and from natural vegetation (C_3) to deduce the dynamic process. Approximately 40% of SOC in the natural surface soil (0–10 cm) was eroded in the first 5 years of cultivation, increasing to about 75% within 40 years, before a slow recovery. C_4 above 30 cm soil depth increased by 4.5%–5% or 0.11–0.12 g·kg^(-1) on average per year under continuous cultivation, while it decreased by approximately 0.34% annually in the surface soil after cultivation abandonment.The increase in the percentage of C_4 was fitted to a linear equation with given intercepts in the upper 30 cm of soil in cultivated land. A significant relationship between the change of C_4 and time was found only in the surface soil after abandonment of cultivation. These results demonstrate the loss and accumulation of corn-derived SOC in surface black soil of Northeast China under continuous tillage or cultivation abandonment. 展开更多
关键词 C3 photosynthesis C4 photosynthesis Land-use change stable carbon isotopes Black soil of Northeast China
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细胞色素P450 3A4基因C239S突变体稳定表达Flp-In^(TM)CHO细胞系的建立
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作者 何俊奇 陆定艳 +4 位作者 陈帅帅 李勇军 王永林 郑江 刘亭 《贵州医科大学学报》 CAS 2023年第12期1454-1458,共5页
目的构建稳定表达细胞色素P450家族3亚家族A成员4(CYP3A4)的C239S突变体(CYP3A4-C239S)的Flp-In^(TM)CHO细胞系。方法使用Lipofectamine2000转染试剂将pcDNA5/FRT-CYP3A4-C239S突变型重组质粒和pcDNA5/FRT-空质粒转染至Flp-In TM CHO细... 目的构建稳定表达细胞色素P450家族3亚家族A成员4(CYP3A4)的C239S突变体(CYP3A4-C239S)的Flp-In^(TM)CHO细胞系。方法使用Lipofectamine2000转染试剂将pcDNA5/FRT-CYP3A4-C239S突变型重组质粒和pcDNA5/FRT-空质粒转染至Flp-In TM CHO细胞,潮霉素B(500 g/L)进行稳定筛选,采用实时荧光定量PCR(qRT-PCR)、蛋白质免疫印迹(Western blot)检测细胞中CYP3A4-C239S的mRNA和蛋白表达,采用黄曲霉素B1(AFB1)细胞毒性实验检测细胞活性。结果与Flp-In^(TM)CHO-空质粒组相比,Flp-In^(TM)CHO-3A4-C239S组的CYP3A4-C239S mRNA和蛋白表达水平均显著增加(P<0.001),AFB1细胞毒性实验显示,CYP3A4-C239S细胞组对AFB1的毒性敏感度显著增加(P<0.001)。结论成功构建了稳定表达CYP3A4-C239S的Flp-In^(TM)CHO细胞系,且为后续研究CYP3A4突变对药物代谢的影响支撑基础。 展开更多
关键词 细胞色素P4503A4 黄曲霉毒素B1 突变体 稳定表达 Flp-In^(TM)CHO细胞
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稳定同位素氘标记左氧氟沙星-D_(3)的合成 被引量:1
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作者 徐仲杰 张立 +2 位作者 孙雯 张鹏帅 雷雯 《同位素》 CAS 2023年第2期144-149,I0002,共7页
为了提高稳定同位素利用率,建立简便、成本低廉的合成方法,本研究以哌嗪为起始原料,和氯甲酸苄酯(CBZ-Cl)反应得到CBZ-哌嗪,然后与碘甲烷-D_(3)反应得到CBZ-哌嗪-CD_(3),之后脱去CBZ保护得到甲基哌嗪-D_(3),最后和左氧氟沙星羧酸反应得... 为了提高稳定同位素利用率,建立简便、成本低廉的合成方法,本研究以哌嗪为起始原料,和氯甲酸苄酯(CBZ-Cl)反应得到CBZ-哌嗪,然后与碘甲烷-D_(3)反应得到CBZ-哌嗪-CD_(3),之后脱去CBZ保护得到甲基哌嗪-D_(3),最后和左氧氟沙星羧酸反应得到左氧氟沙星-D_(3)。以投入的碘甲烷-D_(3)物质的量计算,左氧氟沙星-D_(3)产率为37.0%。所合成的左氧氟沙星-D_(3)产品经核磁共振波谱、高效液相色谱和质谱等表征确认,化学纯度为98.5%,同位素丰度为99.5atom%D,以上结果表明,合成的左氧氟沙星-D_(3)可作为同位素内标用于动物源食品中左氧氟沙星残留的定量检测。 展开更多
关键词 稳定同位素标记 左氧氟沙星-D_(3) 内标试剂
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TRANSFERABILITY OF TOUGHNESS RESULT TO FRACTURE PERFORMANCE EVALUATION OF WELDED JOINTS CONSIDERING STABLE CRACK GROWTH
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作者 Jing Hongyang (College of Material Science and Engineering, Tianjin University) Minami Fumiyoshi (Osaka University, Japan) 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2000年第2期122-125,共5页
The transferability of the toughness results in ductile-brittle transition region for welded cracked specimens is conducted by 3D FE analysis. The fracture toughness Values for the double edge notched tension specimen... The transferability of the toughness results in ductile-brittle transition region for welded cracked specimens is conducted by 3D FE analysis. The fracture toughness Values for the double edge notched tension specimens are predicted effectively from the bend test results based on the local approach considering stable crack growth. It is found that the cell model gives a good description of the stable crack growth behavior, and the local approach is useful for the transferability analysis of fracture toughness results in ductile-brittle transition region. 展开更多
关键词 Flacture toughness stable crack growth 3D FE analysis
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高效稳定的CsPbBr_(3)-Cs_(4)PbBr_(6)混合相钙钛矿纳米晶的制备及形成过程 被引量:1
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作者 陈雪莲 焦琥珀 +1 位作者 申岩冰 潘喜强 《物理学报》 SCIE EI CAS CSCD 北大核心 2023年第9期307-317,共11页
通过配体后处理法向CsPbBr_(3)钙钛矿纳米晶中加入油胺-十四烷基膦酸(OLA-TDPA)的混合配体获得了CsPbBr_(3)-Cs_(4)PbBr_(6)混合材料.在最佳比例下(CsPbBr_(3), TDPA与OLA的物质的量的比为1∶1∶15)制备的CsPbBr_(3)-Cs_(4)PbBr_(6)钙... 通过配体后处理法向CsPbBr_(3)钙钛矿纳米晶中加入油胺-十四烷基膦酸(OLA-TDPA)的混合配体获得了CsPbBr_(3)-Cs_(4)PbBr_(6)混合材料.在最佳比例下(CsPbBr_(3), TDPA与OLA的物质的量的比为1∶1∶15)制备的CsPbBr_(3)-Cs_(4)PbBr_(6)钙钛矿纳米晶混合相的光致发光量子产率可达78%,荧光寿命长达476 ns,且其在室温环境下保持稳定性至少25 d,在293 K和328 K之间的5个加热-冷却循环中具有良好的热稳定性.混合纳米晶的形成经历了表面钝化/溶解和重结晶两个阶段:在第1阶段(t≤1 h), OLA-TDPA混合配体形成了(RNH3)2PO3X型配体与纳米晶表面发生配体交换,交换后的新配体能与纳米晶表面的Pb^(2+)紧密的结合且含量较高,降低了纳米晶表面的缺陷态密度,提高了CsPbBr_(3)类球形钙钛矿纳米晶的量子产率和荧光寿命;在第2阶段,由于部分PbBr2脱离CsPbBr_(3)NCs而使其发生了重结晶,生成了少量六方相Cs_(4)PbBr_(6)纳米晶,最终获得CsPbBr_(3)和Cs_(4)PbBr_(6)双相共存的纳米晶,从而提高了纳米晶的稳定性.本工作对推动高效稳定的钙钛矿纳米晶的应用具有一定参考价值. 展开更多
关键词 钙钛矿纳米晶 CsPbBr_(3)-Cs_(4)PbBr_(6)混合相 高效稳定 配体交换 溶解重结晶
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3D Fractals, Axiom of Algebra (Δn)n = +1
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作者 Emmanuel Cadier Anaxhaoza 《Advances in Pure Mathematics》 2023年第7期473-481,共9页
After having laid down the Axiom of Algebra, bringing the creation of the square root of -1 by Euler to the entire circle and thus authorizing a simple notation of the nth roots of unity, the author uses it to organiz... After having laid down the Axiom of Algebra, bringing the creation of the square root of -1 by Euler to the entire circle and thus authorizing a simple notation of the nth roots of unity, the author uses it to organize homogeneous divisions of the limited development of the exponential function, that is opening the way to the use of a whole bunch of new primary functions in Differential Calculus. He then shows how new supercomplex products in dimension 3 make it possible to calculate fractals whose connexity depends on the product considered. We recall the geometry of convex polygons and regular polygons. 展开更多
关键词 PSYCHEDELIC Axiom of Algebra (AA) Generalization of the Sign Quantum Physics Self-Derivative Exponential Cosinus SINUS stable Groups for Derivation Operation Differential Calculation Theory Supercomplex Products Regular Polygons 3D Fractals Mathematical Imagery Geometry of Regular Polygons
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基于开源大模型的短视频与直播AI实训系统的设计与实现
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作者 史永恒 《信息技术与信息化》 2024年第8期195-198,共4页
提出了一种基于开源大模型的短视频与直播AI实训系统设计方案,旨在通过集成Llama-3、Stable Diff usion、Stable Video Diff usion等先进技术,构建一个集教学与实践于一体的智能化平台,促进新媒体人才的培养。系统设计覆盖账号定位分析... 提出了一种基于开源大模型的短视频与直播AI实训系统设计方案,旨在通过集成Llama-3、Stable Diff usion、Stable Video Diff usion等先进技术,构建一个集教学与实践于一体的智能化平台,促进新媒体人才的培养。系统设计覆盖账号定位分析、剧本策划、分镜头生成至视频合成的全链路,利用ComfyUI提供用户友好的操作界面,NestJS实现高效的服务器管理,以及MySQL和MongoDB支持数据存储。经过功能测试与用户体验评估,所设计的系统有效提升了学生的实践技能与内容创作水平,具有良好的应用前景。未来发展方向包括模型的持续优化、技术升级,以及加强与产业界的合作,以更好地适配行业需求,开拓新媒体教育的未来空间。 展开更多
关键词 短视频直播 AI实训系统 开源大模型 Llama-3 stable Diff usion stable Video Diff usion ComfyUI SORA
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阜康典型荒漠C_3植物稳定碳同位素值的环境分析 被引量:38
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作者 陈拓 马健 +4 位作者 冯虎元 何元庆 徐世健 强维亚 安黎哲 《干旱区地理》 CSCD 北大核心 2002年第4期342-345,共4页
通过对阜康典型荒漠C3 植物稳定碳同位素值的分析。叶片碳同位素值在 - 2 3‰和 - 2 9‰之间变化 ,其中主要在 - 2 7‰附近波动。这与前人报道的世界上其他地区荒漠植物碳同位素值的变化非常一致。降水可以改变叶片碳同位素值的大小 ,... 通过对阜康典型荒漠C3 植物稳定碳同位素值的分析。叶片碳同位素值在 - 2 3‰和 - 2 9‰之间变化 ,其中主要在 - 2 7‰附近波动。这与前人报道的世界上其他地区荒漠植物碳同位素值的变化非常一致。降水可以改变叶片碳同位素值的大小 ,降水越多 ,叶片碳同位素值越负 ,它们的变化幅度有物种的依赖性。叶片碳同位素值也受植物生长形式或期望寿命的影响 ,木本植物或寿命长的植物叶片碳同位素值要高。分析表明 ,利用该区土壤或陆相沉积中有机质碳同位素值可以判断气候的干湿变化 :土壤或陆相沉积中有机质碳同位素值越高 。 展开更多
关键词 荒漠C3植物 稳定碳同位素值 降水 环境信息 土壤 气候 干湿变化 红砂荒漠 梭梭荒漠
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