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Roller Screw and Threaded Chain Speed Reducer: An Experimental Evaluation
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作者 Filiberto Gutiérrez 《Modern Mechanical Engineering》 2024年第1期1-11,共11页
We are developing a speed reducer that can be considered a transformation of a worm gear reducer: the worm is replaced by an inverted roller screw, and the gear is replaced by a threaded chain drive. This configuratio... We are developing a speed reducer that can be considered a transformation of a worm gear reducer: the worm is replaced by an inverted roller screw, and the gear is replaced by a threaded chain drive. This configuration lessens wear, increases load capacity, and improves efficiency. The threaded chain consists of nut-shaped links. This paper presents the results of tests carried out on a prototype with a reduction ratio of 46. 展开更多
关键词 speed Reducer Inverted Roller screw chain Drive Threaded chain Drive
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D-S理论和Markov链组合的桥梁性能退化预测研究
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作者 杨国俊 田里 +2 位作者 唐光武 毛建博 杜永峰 《应用数学和力学》 CSCD 北大核心 2024年第4期416-428,共13页
为准确预测桥梁性能退化,考虑到数据随机性和微小扰动发生状态跳跃,提出了一种D-S(Dempster-Shafer)证据理论和Markov链组合的桥梁性能退化组合预测模型和性能退化率的概念.该模型基于指数平滑(exponential smoothing,ES)方法获得新的... 为准确预测桥梁性能退化,考虑到数据随机性和微小扰动发生状态跳跃,提出了一种D-S(Dempster-Shafer)证据理论和Markov链组合的桥梁性能退化组合预测模型和性能退化率的概念.该模型基于指数平滑(exponential smoothing,ES)方法获得新的预测数据序列,并利用Markov链和D-S理论不断进行优化,从而实现桥梁性能退化的组合预测.实际工程的应用结果表明:性能退化率可以直观地表征在梁性能退化的速度.其次,该模型的平均相对误差为1.54%,较于回归、灰色和模糊加权Markov链模型,精度分别提高了1.11%,0.88%和2.8%,而后验差比值为0.242,小于0.35;模型的标准差为9.021,相比其他模型分别减小了3.978,3.405和7.500,而变异系数为0.109,均小于其他模型,验证了组合预测模型在精度和稳定性方面的优越性,可为在役桥梁结构性能退化预测与维护提供理论基础. 展开更多
关键词 桥梁工程 性能退化预测 D-s证据理论 MARKOV链 组合预测模型 桥梁性能退化率
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基于改进YOLOX-S的轻量化煤矸石检测方法研究
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作者 高如新 杜亚博 常嘉浩 《河南理工大学学报(自然科学版)》 CAS 北大核心 2024年第4期133-140,共8页
目的 为了探索基于现有机器视觉煤矸石检测方法的模型参数量、计算量对检测速度和嵌入式设备的影响,方法 提出一种基于改进的无锚框YOLOX-S轻量化煤矸石检测模型。为使模型能提取更真实的煤矸石特征信息,收集分选现场煤矸石样本,保证实... 目的 为了探索基于现有机器视觉煤矸石检测方法的模型参数量、计算量对检测速度和嵌入式设备的影响,方法 提出一种基于改进的无锚框YOLOX-S轻量化煤矸石检测模型。为使模型能提取更真实的煤矸石特征信息,收集分选现场煤矸石样本,保证实际环境下的煤矸石检测效果,适应实际生产环境。结合CSPNet,将输入的特征图分割成两个分支,实现更丰富的梯度组合,同时减少模型计算量;之后在其中一条分支使用Ghost轻量化卷积,通过少量常规卷积生成一组特征图,达到初次减少计算量和参数量的效果,然后在此特征图基础上经过简单线性变化操作,生成一组新的特征图,将两组特征图进行融合,降低对计算资源需求的同时,也达到了常规卷积相同的特征提取效果;引入LeakyReLU激活函数减弱模型梯度消失的影响,提取更深更多的特征信息;最后融合两个分支特征,保证较高的检测精度,提升模型检测速度。采用CIOU Loss(complete IOU loss)优化目标边界框回归损失函数,使模型回归损失收敛更快,提高模型目标定位能力。结果 与原模型相比,本文改进模型在保证较高的平均精度均值90.51%情况下,模型参数减少47%,计算量减少49%,检测速度达到50帧/s。结论 轻量化煤矸石检测模型使智能化煤矸石检测在实际生产环境中具有一定的应用前景。 展开更多
关键词 煤矸石检测 YOLOX-s 轻量化 目标定位 检测速度
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Ultralong nitrogen/sulfur Co-doped carbon nano-hollowsphere chains with encapsulated cobalt nanoparticles for highly efficient oxygen electrocatalysis 被引量:5
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作者 Wei Zhang Xingmei Guo +6 位作者 Cong Li Jiang-Yan Xue Wan-Ying Xu Zheng Niu Hongwei Gu Carl Redshaw Jian-Ping Lang 《Carbon Energy》 SCIE CSCD 2023年第8期15-30,共16页
The development of simple and effective strategies to prepare electrocatalysts,which possess unique and stable structures comprised of metal/nonmetallic atoms for oxygen reduction reaction(ORR)and oxygen evolution rea... The development of simple and effective strategies to prepare electrocatalysts,which possess unique and stable structures comprised of metal/nonmetallic atoms for oxygen reduction reaction(ORR)and oxygen evolution reaction(OER),is currently an urgent issue.Herein,an efficient bifunctional electrocatalyst featured by ultralong N,S-doped carbon nano-hollow-sphere chains about 1300 nm with encapsulated Co nanoparticles(Co-CNHSCs)is developed.The multifunctional catalytic properties of Co together with the heteroatom-induced charge redistribution(i.e.,modulating the electronic structure of the active site)result in superior catalytic activities toward OER and ORR in alkaline media.The optimized catalyst Co-CNHSC-3 displays an outstanding electrocatalytic ability for ORR and OER,a high specific capacity of 1023.6 mAh gZn^(-1),and excellent reversibility after 80 h at 10mA cm^(-2)in a Zn-air battery system.This work presents a new strategy for the design and synthesis of efficient multifunctional carbon-based catalysts for energy storage and conversion devices. 展开更多
关键词 Co nanoparticles N s co-doping oxygen electrocatalysts rechargeable Zn-air batteries ultralong carbon nano-hollow-sphere chains
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售货机升降系统S型速度控制策略
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作者 冯高明 邱文仙 金明磊 《电子科技》 2024年第5期54-61,共8页
在传统三闭环控制方式下,售货机升降接货系统易因启停过程中加速度突变产生冲击,导致系统运行不平稳。针对这一问题,文中对传统升降系统加减速控制策略进行改进,加入前馈和微分负反馈,提出一种S型速度曲线控制算法。根据路径规划判别条... 在传统三闭环控制方式下,售货机升降接货系统易因启停过程中加速度突变产生冲击,导致系统运行不平稳。针对这一问题,文中对传统升降系统加减速控制策略进行改进,加入前馈和微分负反馈,提出一种S型速度曲线控制算法。根据路径规划判别条件将S型速度曲线分为七段式、六段式和四段式3种,并给出各路径约束条件下的参数求解方法和具体执行流程。将该算法运用到升降控制系统中进行仿真和实际工况测试,实验结果表明,与传统三闭环控制相比,文中所提控制策略可以提高售货机升降系统运行的平稳性,减小冲击,使速度曲线更加柔和,并能够保持较好的跟踪性能。 展开更多
关键词 加减速控制 s型速度曲线 升降系统 加速度突变 冲击 售货机 控制策略 跟踪性能
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A novel mechanism of PHB2-mediated mitophagy participating in the development of Parkinson's disease 被引量:2
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作者 Yongjiang Zhang Shiyi Yin +4 位作者 Run Song Xiaoyi Lai Mengmeng Shen Jiannan Wu Junqiang Yan 《Neural Regeneration Research》 SCIE CAS CSCD 2024年第8期1828-1834,共7页
Endoplasmic reticulum stress and mitochondrial dysfunction play important roles in Parkinson s disease,but the regulato ry mechanism remains elusive.Prohibitin-2(PHB2)is a newly discove red autophagy receptor in the m... Endoplasmic reticulum stress and mitochondrial dysfunction play important roles in Parkinson s disease,but the regulato ry mechanism remains elusive.Prohibitin-2(PHB2)is a newly discove red autophagy receptor in the mitochondrial inner membrane,and its role in Parkinson’s disease remains unclear.Protein kinase R(PKR)-like endoplasmic reticulum kinase(PERK)is a factor that regulates cell fate during endoplasmic reticulum stress.Parkin is regulated by PERK and is a target of the unfolded protein response.It is unclear whether PERK regulates PHB2-mediated mitophagy thro ugh Parkin.In this study,we established a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine(MPTP)-induced mouse model of Parkinson’s disease.We used adeno-associated virus to knockdown PHB2 expression.Our res ults showed that loss of dopaminergic neurons and motor deficits were aggravated in the MPTP-induced mouse model of Parkinson’s disease.Ove rexpression of PHB2 inhibited these abnormalities.We also established a 1-methyl-4-phenylpyridine(MPP+)-induced SH-SY5Y cell model of Parkinson’s disease.We found that ove rexpression of Parkin increased co-localization of PHB2 and microtubule-associated protein 1 light chain 3,and promoted mitophagy.In addition,MPP+regulated Parkin involvement in PHB2-mediated mitophagy through phosphorylation of PERK.These findings suggest that PHB2 participates in the development of Parkinson’s disease by intera cting with endoplasmic reticulum stress and Parkin. 展开更多
关键词 endoplasmic reticulum dopaminergic neuron microtubule-associated protein 1 light chain 3 MITOPHAGY oxidative stress PARKIN Parkinson’s disease PKR-like endoplasmic reticulum kinase reactive oxygen species prohibitin-2
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基于MCGS的刮板链螺栓自动紧固速度控制系统研究
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作者 任庆忠 周好斌 +1 位作者 徐向前 程卓 《机电工程技术》 2024年第3期50-53,共4页
针对刮板链螺栓紧固的局限性,设计了一种刮板链螺栓自动紧固设备,根据刮板链螺栓紧固的工艺流程,采用SolidWorks对刮板链螺栓自动紧固设备进行几何建模。在紧固过程中,由于步进电机转速太快时力矩不足,转速太慢时,紧固时间较长,效率太... 针对刮板链螺栓紧固的局限性,设计了一种刮板链螺栓自动紧固设备,根据刮板链螺栓紧固的工艺流程,采用SolidWorks对刮板链螺栓自动紧固设备进行几何建模。在紧固过程中,由于步进电机转速太快时力矩不足,转速太慢时,紧固时间较长,效率太差。因此设计了一种基于MCGS的刮板链螺栓自动紧固速度控制系统,通过对步进电机矩频特性和螺栓拧紧曲线进行分析,得到了步进电机转速与旋转角度的关系,从而推出步进电机速度当量与紧固时间的关系。通过对螺栓紧固时间内速度当量值进行离散,采用MCGS设计硬件和编写软件脚本,同时对人机交互界面进行组态,将设计的控制系统进行联机调试。结果表明:该速度控制系统在15 s的紧固时间内,将速度当量值从3000离散至1000,达到了螺栓紧固的力矩要求,在简化紧固过程的同时,缩短了紧固时间,实现了刮板链螺栓的自动紧固,保证了设备运行的可靠性与稳定性,提高了工作效率。 展开更多
关键词 刮板链 螺栓紧固 速度控制 控制系统 MCGs
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一种S型加减速组合的速度规划算法
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作者 李甍材 赵东标 冯胜利 《机械科学与技术》 CSCD 北大核心 2024年第1期54-63,共10页
针对传统NURBS曲线插补S型加减速的改进难以在加工柔性和加工效率上同时兼顾的问题,提出一种将多种S型加减速组合的速度规划算法。选取分别在加工柔性和加工效率上单独改进的两种S型加减速,并设计了一种兼顾柔性和效率的新改进S型加减... 针对传统NURBS曲线插补S型加减速的改进难以在加工柔性和加工效率上同时兼顾的问题,提出一种将多种S型加减速组合的速度规划算法。选取分别在加工柔性和加工效率上单独改进的两种S型加减速,并设计了一种兼顾柔性和效率的新改进S型加减速。在速度规划中,根据简化后的4种加减速形式,灵活组合这3种S型加减速,并采取合并曲线分段的速度平滑方式,减少了曲线段间的速度波动。仿真结果表明:该算法能在提高加工效率的同时满足加加速度的连续,最终实现加工柔性和加工效率的兼得。 展开更多
关键词 NURBs插补 s型加减速 速度平滑 速度规划
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Faster than the Speed of Light Is a Quantum Phenomena
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作者 Ardeshir Irani 《Journal of High Energy Physics, Gravitation and Cosmology》 CAS 2023年第2期379-382,共4页
Classical Mechanics using Einstein’s theories of relativity places a limit on speed as the speed of light. Quantum Mechanics has no such limitation. To understand space accelerating faster than the speed of light and... Classical Mechanics using Einstein’s theories of relativity places a limit on speed as the speed of light. Quantum Mechanics has no such limitation. To understand space accelerating faster than the speed of light and information being exchanged instantaneously between two entangled electrons separated by huge distances, one uses Planck’s length, Planck’s time, and Planck’s mass to indicate that space and time are discrete and therefore along with masses smaller than Planck’s mass are Quantum Mechanical in nature. Faster than the speed of light c = 3 × 10<sup>8</sup> m/s is a classical effect only in dimensions of space lower than our 3-D Universe, but it is a Quantum effect in all dimensions of space. Because space can oscillate sending out ripples from the source, it is the medium used for transporting light waves and gravity waves. 展开更多
关键词 Faster than the speed of Light CLAssICAL QUANTUM Planck’s Units space as a Medium Comparison with string Theory
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基于深度学习和广义S变换协同的风速预测
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作者 朱哲萱 马汝为 +1 位作者 曹黎媛 李春祥 《太阳能学报》 EI CAS CSCD 北大核心 2024年第7期664-671,共8页
针对实测风速的非平稳性特点,提出一种基于深度学习和时频分析的风速混合预测方法。首先,采用经验模态分解(EMD)将风速分解为若干子层,由此得到趋势分量和脉动分量以降低风速的非线性。根据2个分量的时频特性,采用长短时记忆(LSTM)处理... 针对实测风速的非平稳性特点,提出一种基于深度学习和时频分析的风速混合预测方法。首先,采用经验模态分解(EMD)将风速分解为若干子层,由此得到趋势分量和脉动分量以降低风速的非线性。根据2个分量的时频特性,采用长短时记忆(LSTM)处理趋势分量,极限学习机(ELM)处理脉动分量。其次,引入广义S变换(GST)来获得预测过程中的时频特性。同时,采用改进的灰狼算法(IGWO)对GST、LSTM和ELM的参数进行优化。最后,以内蒙古某风场实测风速对所提模型进行验证,结果表明该模型具有较高的精度。 展开更多
关键词 风电场 风速 预测 长短时记忆 极限学习机 广义s变换
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Storage time affects the level and diagnostic efficacy of plasma biomarkers for neurodegenerative diseases
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作者 Lifang Zhao Mingkai Zhang +4 位作者 Qimeng Li Xuemin Wang Jie Lu Ying Han Yanning Cai 《Neural Regeneration Research》 SCIE CAS 2025年第8期2373-2381,共9页
Several promising plasma biomarker proteins,such as amyloid-β(Aβ),tau,neurofilament light chain,and glial fibrillary acidic protein,are widely used for the diagnosis of neurodegenerative diseases.However,little is k... Several promising plasma biomarker proteins,such as amyloid-β(Aβ),tau,neurofilament light chain,and glial fibrillary acidic protein,are widely used for the diagnosis of neurodegenerative diseases.However,little is known about the long-term stability of these biomarker proteins in plasma samples stored at-80°C.We aimed to explore how storage time would affect the diagnostic accuracy of these biomarkers using a large cohort.Plasma samples from 229 cognitively unimpaired individuals,encompassing healthy controls and those experiencing subjective cognitive decline,as well as 99 patients with cognitive impairment,comprising those with mild cognitive impairment and dementia,were acquired from the Sino Longitudinal Study on Cognitive Decline project.These samples were stored at-80°C for up to 6 years before being used in this study.Our results showed that plasma levels of Aβ42,Aβ40,neurofilament light chain,and glial fibrillary acidic protein were not significantly correlated with sample storage time.However,the level of total tau showed a negative correlation with sample storage time.Notably,in individuals without cognitive impairment,plasma levels of total protein and tau phosphorylated protein threonine 181(p-tau181)also showed a negative correlation with sample storage time.This was not observed in individuals with cognitive impairment.Consequently,we speculate that the diagnostic accuracy of plasma p-tau181 and the p-tau181 to total tau ratio may be influenced by sample storage time.Therefore,caution is advised when using these plasma biomarkers for the identification of neurodegenerative diseases,such as Alzheimer's disease.Furthermore,in cohort studies,it is important to consider the impact of storage time on the overall results. 展开更多
关键词 Alzheimer’s disease amyloid-β diagnostic ability glial fibrillary acidic protein NEURODEGENERATION neurofilament light chain plasma biomarkers single molecule array storage time tau
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基于S形速度曲线的键合头运动控制系统研究与分析
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作者 高岳 《电子工业专用设备》 2024年第2期52-57,共6页
根据用户工艺需求,针对全自动芯片键合设备的运动控制模块以及键合头子模块开展需求分析,结合典型试验,设计出基于S形速度曲线的键合头运动控制系统,根据S形速度曲线重新规划了键合头的运动轨迹,使其对芯片键合周期缩短的同时也保证了... 根据用户工艺需求,针对全自动芯片键合设备的运动控制模块以及键合头子模块开展需求分析,结合典型试验,设计出基于S形速度曲线的键合头运动控制系统,根据S形速度曲线重新规划了键合头的运动轨迹,使其对芯片键合周期缩短的同时也保证了键合精度。 展开更多
关键词 运动控制模块 键合头 s形速度曲线
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速度作用下SnAgCu-Al_(2)O_(3)/TiNi的摩擦学性能与磨损机理
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作者 唐俊 林海波 +1 位作者 熊邦英 杨慷 《功能材料》 CAS CSCD 北大核心 2024年第6期6174-6184,共11页
高镍钛基合金(TiNi)具有密度低、比强度高等优点,广泛应用于机械工程等领域。由于TiNi合金的耐磨性较差,限制了TiNi合金在相关领域的开发和应用。为了提高TiNi合金的减磨抗磨性能,使用激光打标机在其表面设计制备鱼鳞状表面纹理并填充... 高镍钛基合金(TiNi)具有密度低、比强度高等优点,广泛应用于机械工程等领域。由于TiNi合金的耐磨性较差,限制了TiNi合金在相关领域的开发和应用。为了提高TiNi合金的减磨抗磨性能,使用激光打标机在其表面设计制备鱼鳞状表面纹理并填充复合固体润滑剂SnAgCu-Al_(2)O_(3)(S-A/TiNi)。在表面纹理角度参数为70°的条件下,研究了不同速度对S-A/TiNi复合材料摩擦学性能的影响。结果表明,当速度为0.037 m/s时,S-A/TiNi-70°的磨痕表面产生温升,提高了固体润滑剂的塑形性能。固体润滑剂在应力的作用下固体润滑剂被挤出织构,促进润滑膜产生,获得最佳的摩擦学性能。当速度较高时(>0.037 m/s),摩擦表面温升快,使得固体润滑剂塑性性能增强。润滑膜在应力的作用下产生破坏,导致摩擦学性能降低。当速度较低(<0.037 m/s)时,摩擦表面产生较多的热量,使得固体润滑剂塑性形变过大。在循环应力作用下润滑膜容易发生剥落,导致基体摩擦学性能降低。 展开更多
关键词 s-A/TiNi 固体润滑剂 速度 摩擦磨损 润滑机理
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级间分离S形分离钢索高速分离敏感因素分析
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作者 董瑞涛 林三春 +2 位作者 荀飞 刘金峰 付继伟 《导弹与航天运载技术(中英文)》 CSCD 北大核心 2024年第2期7-10,共4页
级间分离S形分离钢索结构复杂,高速分离过程涉及大变形、复杂非线性接触等问题,其动态变形及力学特性分析是工程设计的难点之一。基于Abaqus建立S形分离钢索动态分离仿真模型,分析了S形分离钢索高速分离动态变形过程及力学特性,并通过... 级间分离S形分离钢索结构复杂,高速分离过程涉及大变形、复杂非线性接触等问题,其动态变形及力学特性分析是工程设计的难点之一。基于Abaqus建立S形分离钢索动态分离仿真模型,分析了S形分离钢索高速分离动态变形过程及力学特性,并通过地面试验进一步验证建模方法的正确性。研究了S形分离钢索长度、截面直径、拖尾长度、分离速度等多种敏感因素的影响,对工程实际具有一定的指导意义。 展开更多
关键词 级间分离 s形分离钢索 高速分离 变形过程 力学特性
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基于三次S型速度控制算法的移动机械臂末端振动研究
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作者 刘益军 李正强 +1 位作者 赖建防 吕伟宏 《机械制造与自动化》 2024年第1期232-237,共6页
移动机械臂在实际工作环境中,受其自身柔性特征和外部因素的影响而引起机械臂末端的振动,而速度控制是实现机械臂末端抑振的有效手段之一。以UR10机械臂和Husky移动平台组成的移动机械臂为研究对象,针对梯形和S型速度控制算法的不足,提... 移动机械臂在实际工作环境中,受其自身柔性特征和外部因素的影响而引起机械臂末端的振动,而速度控制是实现机械臂末端抑振的有效手段之一。以UR10机械臂和Husky移动平台组成的移动机械臂为研究对象,针对梯形和S型速度控制算法的不足,提出一种三次S型速度控制算法,通过建立移动机械臂刚柔耦合动力学的理论和仿真模型得到移动机械臂末端的振动位移曲线和加速度变化曲线,验证了三次S型速度控制算法的正确性和抑振效果的有效性。 展开更多
关键词 移动机械臂 刚柔耦合 三次s型速度控制算法
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Preliminary research on myosin light chain kinase in rabbit liver 被引量:6
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作者 Bin Ren~1 Hua-Qing Zhu~2 Zhao-Feng Luo~1 Qing Zhou~2 Yuan Wang~2 Yu-Zhen Wang~1 1 Department of Biochemistry and Molecular Biology,University of Science and Technology of China,Hefei 230027,Anhui Province,China2 Laboratory of Molecular Biology,Anhui Medical University,Hefei 230032,Anhui Province,China 《World Journal of Gastroenterology》 SCIE CAS CSCD 2001年第6期868-871,共4页
AIM: To study preliminarily the properties of myosin light chain kinase (MLCK) in rabbit liver. METHODS: The expression of MLCK was detected by reverse transcription-polymerase chain reaction(RT-PCR); the MLCK was obt... AIM: To study preliminarily the properties of myosin light chain kinase (MLCK) in rabbit liver. METHODS: The expression of MLCK was detected by reverse transcription-polymerase chain reaction(RT-PCR); the MLCK was obtained from rabbit liver, and its activity was analyzed by gamma-(32)P incorporation technique to detect the phosphorylation of myosin light chain. RESULTS: MLCK was expressed in rabbit liver, and the activity of the enzyme was similar to rabbit smooth muscle MLCK, and calmodulin-dependent. When the concentration was 0.65 mg x L(-1), the activity was at the highest level. CONCLUSION: MLCK expressed in rabbit liver may catalyze the phosphorylation of myosin light chain, which may play important roles in the regulation of hepatic cell functions. 展开更多
关键词 ANIMALs HEPATOCYTEs Liver Myosin Light chains Myosin-Light-chain Kinase PHOsPHORYLATION RABBITs Research support Non-U.s. Gov't
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Comparisons between Movement Speed of Main Types of Dunes:A Case Study of Desert Areas in Hexi Region of Gansu Province 被引量:2
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作者 CHANG Zhaofeng ZHU Shujuan +5 位作者 SHI Xuegang ZHANG Jinhu LI Ya WANG Qi ZHANG Dekui DUAN Xiaofeng 《Journal of Landscape Research》 2016年第6期36-40,共5页
In desert areas in Hexi region,11 barchan dunes,6 chains of barchan dunes,6 pyramid dunes,6 parabolic dunes and 6 accumulated sand-belts were chosen to study their movement speed based on images obtained by Google Ear... In desert areas in Hexi region,11 barchan dunes,6 chains of barchan dunes,6 pyramid dunes,6 parabolic dunes and 6 accumulated sand-belts were chosen to study their movement speed based on images obtained by Google Earth in various periods.The results show that among the dunes,the movement of the barchan dunes was the fastest,followed by the chains of barchan dunes,and only the tops of the pyramid dunes swayed,while the parabolic dunes and accumulated sand-belts hardly moved forward.The higher the barchan dunes(or the chains of barchan dunes) were,the slower the movement was.On the contrary,the higher the pyramid dunes were,the faster the swing was.There was a positive correlation between the movement speed of the barchan dunes and the average wind speed of sandstorms. 展开更多
关键词 Barchan dunes chains of barchan dunes Pyramid dunes Movement speed Desert areas in Hexi region
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Hepatitis C virus in human B lymphocytes transformed by Epstein-Barr virus in vitro by in situ reverse transcriptase-polymerase chain reaction 被引量:11
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作者 Ji Lin Cheng Bao Ling Liu Yi Zhang Wen Bin Tong Zheng Yan Bai Fang Feng Institute of Hepatology,Peoples Hospital,Medical Center of Beijing University,Beijing 10(X)44,China 《World Journal of Gastroenterology》 SCIE CAS CSCD 2001年第3期370-375,共6页
AIM: To study persistence and replication of hepatitis C virus (HCV) in patients' peripheral blood mononuclear cells (PBMC) cultured in vitro. METHODS: Epstein Barr virus (EBV) was used to transform the hepatitis ... AIM: To study persistence and replication of hepatitis C virus (HCV) in patients' peripheral blood mononuclear cells (PBMC) cultured in vitro. METHODS: Epstein Barr virus (EBV) was used to transform the hepatitis C virus from a HCV positive patient to permanent lymphoblastoid cell lines (LCL). Positive and negative HCV RNA strands of the cultured cells and growth media were detected by reverse transcriptase-polymerase chain reaction (RT-PCR) each month. Core and NS5 proteins of HCV were further tested using immunohistochemical SP method and in situ RT-PCR. RESULTS: HCV RNA positive strands were consistently detected the cultured cells for one year. The negative-strand RNA in LCL cells and the positive-strand RNA in supernatants were observed intermittently. Immunohistochemical results medicated expression of HCV NS3 and C proteins in LCL cytoplasm mostly. The positive signal of PCR product was dark blue and mainly localized to the LCL cytoplasm. The RT-PCR signal was eliminated by overnight RNase digestion but not DNase digestion. CONCLUSION: HCV may exist and remain functional in a cultured cell line for a long period. 展开更多
关键词 B-LYMPHOCYTEs Cells Cultured Female HEPACIVIRUs development purification Herpesvirus 4 Human Humans Immunohistochemistry In Vitro Polymerase chain Reaction RNA Viral Research support Non-U.s. Gov't Reverse Transcriptase Polymerase chain Reaction Transformation Genetic Viral Core Proteins Viral Nonstructural Proteins Virus Replication
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Syntheses, Crystal Structures and Properties of Two New W-Ag 1D Chain Complexes: [W_2Ag_2S_8·Ca(DMF)_6]_n and [WAgS_4·Na(DMF)_3]_n 被引量:1
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作者 LIYa-Min XIASheng-Qing ZHANGJian-Jun WUXin-Tao WANGLong-Sheng DUWen-Xin HUSheng-Min 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 北大核心 2005年第6期716-722,共7页
Two new complexes, [W2Ag2S8?Ca(DMF)6]n 1 and [WAgS4?Na(DMF)3]n 2, have been synthesized and characterized. Single-crystal X-ray analyses show both 1 and 2 have {WAgS4}n anion linear chains, but 1 has a discrete [Ca(DM... Two new complexes, [W2Ag2S8?Ca(DMF)6]n 1 and [WAgS4?Na(DMF)3]n 2, have been synthesized and characterized. Single-crystal X-ray analyses show both 1 and 2 have {WAgS4}n anion linear chains, but 1 has a discrete [Ca(DMF)6]2+ cation while 2 is a linear chain. UV-Visible-Near-IR spectroscopy data show that the bandgaps of the two complexes are 1.86 and 1.99 eV, respectively. Electrical conductivity measurements reveal the conductivities of 1 and 2 are 10?7 and 10?8 Scm?1, respectively and they exhibit thermally activated temperature depen- dence, which may be attributed to semiconductors. 展开更多
关键词 W/Ag/s complexes linear chain conductivity
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Rapid detection of sepsis complicating acute necrotizing pancreatitis using polymerase chain reaction 被引量:7
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作者 Wei Zhong Zhang1 Tian Quan Han2 +2 位作者 Yao Qing Tang2 Sheng Dao Zhang2 1Department of Surgery. Huangyan First Hospital, Huangyan 318020, Zhejiang Province. China 2Department of Surgery. Ruijin Hospital. Shanghai Second Medical University. Shanghai 200025. ChinaDr. Wei Zhong Zhang, graduated from Shanghai Second MedicalUniversity receiving master degree of surgery in 1999 he is devoted to basic and clinical investigation on severe acute pancreatitis and has one paper published. 《World Journal of Gastroenterology》 SCIE CAS CSCD 2001年第2期289-292,共4页
INTRODUCTIONAcute narcotizing pancreatitis usually takes a severe clinical course and is associated with multiple organ dysfunction .With the further understanding of pathophysiological events of acute pancreatisis an... INTRODUCTIONAcute narcotizing pancreatitis usually takes a severe clinical course and is associated with multiple organ dysfunction .With the further understanding of pathophysiological events of acute pancreatisis and the therapeutic measuses taken by the clinicians ,the patients can pass through the critical carry stages ,and then the septic complication caused by rtanslocated bacteria, mostly gram-negative microbes from the intestines ensues[1]. 展开更多
关键词 Polymerase chain Reaction Adult Aged Bacterial Proteins DNA Bacterial Female Humans Male Middle Aged Pancreatitis Acute Necrotizing RNA Ribosomal 16s sEPTICEMIA
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