检索结果-南通市图书馆

Active Vibration Isolation of Micro-Manufacturing Platform Based on Neural Network

在线全文

学校读者我要写书评

暂无评论

厦门大学学报（自然科学版） 2002年第S1期41卷 67-68页

作者： zhang chun-liang, mei De-qing, CHEN Zi-chen (Institute of Production Engineering, Zhejiang University, Hangzhou 310027, China)

The micromation and precision of the Micro-Electromechanical System demand that its manufacturing, measuring and assembling must work in a micro-manufacturing platform with good ability to isolate vibrations. This paper develops a vibration isolation system of micro-manufacturing platform. The brains of many kinds of birds can isolate vibrations well, such as woodpecker’s brain. When a woodpecker pecks the wood at the speed as 1.6 times as the velocity of sound, its brain will tolerate the wallop 1 500 times of the weight of itself without any damage. The isolation mechanics and organic texture of woodpecker’s brain that has good isolation characteristics were studied. A structure model of vibration isolation system for the micro-manufacturing platform is established based on the bionics of the bird’s brain vibration isolation mechanism. In order to isolate effectively the high frequency vibrations from the ground, a rubber layer is used to isolate vibrations passively between the micro-manufacturing platform’s pedestal and the ground. This layer corresponds to the cartilage and muscles in the outer meninges of the bird’s brain. The active vibration isolation technique is adopted to isolate vibrations between the micro-manufacturing platform and the pedestal. Air springs are used as elastic components, which correspond to the interspaces between the outer meninges and the encephala of the bird’s brain. Actuators are made of giant magnetostrictive material, and it corresponds to the nerves and neural muscles linking the meninges and the encephala. The actuators and air springs are arranged vertically in parallel to make use of the giant magnetostrictive actuators effectively. The air springs support almost all weight of the micro-manufacturing platform and the giant magnetostrictive actuators support almost no weight. In order to realize high performance to isolate complex micro-vibration, the control method using a three-layer neural network is presented. This vibra

关键词： micro-manufacturing platform active vibration isolation bionic mechanics neural network

Morphological characteristics of submandibular glands of miniature pig

在线全文

学校读者我要写书评

暂无评论

Chinese Medical Journal 2005年第16期118卷 1368-1373页

作者： zhang Xin Li Jun Liu Xiao-yong Sun Yi-lin zhang chun-mei Wang Song-ling Salivary Gland Disease Center and Molecular Laboratory for Gene Therapy Faculty of Stomatology Capital University of Medical Sciences Beijing 100050 China Uhrastructure Unit Department of Pathology Chinese Academy Medical Sciences Neuroscience Institute Beijing 100050 China

Background Miniature pig （minipig） is increasingly used as a large animal model for a variety of biomedical studies. Little information is available in the literature on anatomy, histology and sialogragh of the submandibular gland of the minipig. The purpose of this study was to characterize the morphology of a miniature pig＇s （minipig） submandibular gland as a large animal model for further biomedical studies. Methods Five minipigs were subjected to sialographic, anatomic, histologic, histochemical and uhrastructural evaluations for submandibular glands. Results Sialograms showed a long, horizontal main excretory duct and a pear-shaped gland located inferoposterior to the angle of the mandible. The submandibular glands lied superficial to the suprahyoid, and infrahyoid muscle groups, and were covered by the inferior portion of the parotid gland. The submandibular glands were characterized by a mixed parenchyma of mucous and serous secretory aeini. Alcian blue （AB） staining and periodic acid-Schiff （PAS） reactions demon-strated that minipig submandibular glands synthesized and secreted acid mucous substances by serous cells and polysaccharide, and neutral mucous substances, by mucous cells. Conclusion The submandibular gland of the minipig is considered a useful large salivary gland animal model for biomedical studies.

关键词： submandibular gland miniature pig sialography anatomy histology

在线全文

学校读者我要写书评

暂无评论

基于高光谱影像的干旱区草地光谱特征分析

光谱学与光谱分析 2012年第2期32卷 445-448页

作者：张春梅张建明兰州大学资源环境学院兰州大学干旱区水循环与水资源研究中心甘肃兰州730000

基于石羊河流域金昌地区Hyperion高光谱影像,通过FLAASH大气校正,利用纯像元指数法提取草地波谱信息,并运用光谱一阶微分法和连续统去除法进行定量化处理。结果表明,相对于生长旺盛期的草地光谱特征,衰退期草地光谱红边左移,斜率降低,... 详细信息

基于石羊河流域金昌地区Hyperion高光谱影像,通过FLAASH大气校正,利用纯像元指数法提取草地波谱信息,并运用光谱一阶微分法和连续统去除法进行定量化处理。结果表明,相对于生长旺盛期的草地光谱特征,衰退期草地光谱红边左移,斜率降低,蓝边、黄边特征减弱,可见光波段反射值较高,近红外波段反射率较低;不同覆盖度草地的红边、绿峰、蓝光和红光吸收谷位置保持一致,可见光波段的光谱吸收特征(波段深度、宽度、面积、对称性)随覆盖度的增大呈有规律的变化,可作为提取或判定植被覆盖度的依据。

关键词：高光谱遥感光谱曲线纯像元草地

Antimicrobial effect of acidified nitrate and nitrite on six common oral pathogens in vitro

在线全文

学校读者我要写书评

暂无评论

Chinese Medical Journal 2006年第22期119卷 1904-1909页

作者： XIA Deng-sheng LIU Yin zhang chun-mei YANG Sheng-hui WANG Song-lin Salivary Gland Disease Center and Molecular Laboratory for GeneTherapy Capital Medical University School of StomatologyBeijing 100050 China Beijing Institute of Dental Research Beijing 100050 China

Background Salivary nitrate is positively correlated with plasma nitrate and its level is 9 times the plasma level after nitrate loading. Nitrate in saliva is known to be reduced to nitrite by oral bacteria. Nitrate and nitrite levels in saliva are 3-5 times those in serum in physiological conditions respectively in our previous study. The biological functions of high salivary nitrate and nitrite are still not well understood. The aim of this in vitro study was to investigate the antimicrobial effects of nitrate and nitrite on main oral pathogens under acidic conditions. Methods Six common oral pathogens including Streptococcus mutans NCTC 10449, Lactobacillus acidophilus ATCC 4646, Porphyromonas gingivalis ATCC 33277, Capnocytophaga gingivalis ATCC 33624, Fusobacterium nucleatum ATCC 10953, and Candida albicans ATCC 10231 were cultured in liquid medium. Sodium nitrate or sodium nitrite was added to the medium to final concentrations of 0, 0.5, 1, 2, and 10 mmol/L. All of the microorganisms were incubated for 24 to 48 hours. The optical densities （OD） of cell suspensions were determined and the cultures were transferred to solid nutrient broth medium to observe the minimum inhibitory concentration and minimum bactericidal/fungicidal concentration for the six tested pathogens. Results Nitrite at concentrations of 0.5 to 10 mmol/L had an inhibitory effect on all tested organisms at low pH values. The antimicrobial effect of nitrite increased with the acidity of the medium. Streptococcus mutans NCTC 10449 was highly sensitive to nitrite at low pH values. Lactobacillus acidophilus ATCC 4646 and Candida albicans ATCC 10231 were relatively resistant to acidified nitrite. Nitrate at the given concentrations and under acidic conditions had no inhibitory effect on the growth of any of the tested pathogens. Conclusion Nitrite, at a concentration equal to that in human saliva, is both cytocidal and cytostatic to six principal oral pathogens in vitro, whereas nitrate at a simil

关键词： nitrite nitrate oral pathogens acidification

反式卤素钙钛矿太阳能电池光伏性能的理论研究

在线全文

学校读者我要写书评

暂无评论

物理学报 2020年第11期69卷 319-325页

作者：张翱张春秀陈云琳张春梅孟涛北京印刷学院基础部北京102600 北京交通大学理学院微纳材料及应用研究所北京100044

正式MAPbI3 (MA=CH3NH3+)太阳能电池存在明显的电滞效应现象,这严重影响其光伏性能,而反式结构的电池能有效压低电滞效应.使用AMPS-1D程序对反式MAPbI3太阳能电池进行系统理论模拟和优化,分别用Cu2O,CuSCN,NiOx作为空穴传输材料,用PC61B... 详细信息

正式MAPbI3 (MA=CH3NH3+)太阳能电池存在明显的电滞效应现象,这严重影响其光伏性能,而反式结构的电池能有效压低电滞效应.使用AMPS-1D程序对反式MAPbI3太阳能电池进行系统理论模拟和优化,分别用Cu2O,CuSCN,NiOx作为空穴传输材料,用PC61BM,TiO2,ZnO作为电子传输材料.数值模拟反式电池光伏性能随MAPbI3材料厚度变化的情况,结果显示ITO/NiOx/MAPbI3/ZnO(或TiO2)/Al太阳能电池的光伏性能最好.ITO的功函数从4.6 eV增加到5.0 eV能显著地提高Cu2O-基和CuSCN-基反式MAPbI3太阳能电池的光伏性能,但对NiOx-基电池光伏性能的提升却很小.实验上ITO功函数更合理范围为4.6-4.8 eV,当ITO功函数达到4.8 eV时NiOx-基反式MAPbI3太阳能电池达到最高效率29.588%.空穴传输材料中空穴迁移率增加能极大地提高反式MAPbI3太阳能电池的光伏性能,而增加电子传输材料TiO2中电子迁移率几乎不能提高电池的性能.这些模拟结果将有助于实验上设计更高性能的反式MAPbI3太阳能电池.

关键词：反式结构卤素钙钛矿太阳能电池光伏性能数值模拟

CH_(3)NH_(3)多聚体的形成对有机-无机杂化钙钛矿太阳能电池性能的影响

在线全文

学校读者我要写书评

暂无评论

物理学报 2021年第16期70卷 356-362页

作者：张翱张春秀张春梅田益民闫君孟涛北京印刷学院基础部北京102600 北京交通大学理学院微纳材料及应用研究所北京100044

采用第一性原理在MP2/aug-cc-PVTZ水平下优化得到CH_(3)NH_(3)多聚体的几何构型,发现多聚体中CH_(3)NH_(3)沿C-N轴取向,多聚体随着CH_(3)NH_(3)数量增加有收缩趋势,这有利于无机框架的结构稳定,多聚体的总偶极矩随着CH_(3)NH_(3)数量线... 详细信息

采用第一性原理在MP2/aug-cc-PVTZ水平下优化得到CH_(3)NH_(3)多聚体的几何构型,发现多聚体中CH_(3)NH_(3)沿C-N轴取向,多聚体随着CH_(3)NH_(3)数量增加有收缩趋势,这有利于无机框架的结构稳定,多聚体的总偶极矩随着CH_(3)NH_(3)数量线性增加,这导致了CH_(3)NH_(3)PbI_(3)异质结的强极化.CH_(3)NH_(3)多聚体中未配对电子分布在每个CH_(3)NH_(3)的NH_(3-)端,轨道能量在-4.4—-3.2 eV之间.计算静电势矢量场发现CH_(3)NH_(3)~+具有强亲电性,NH_(3-)端比CH_(3-)端有更强的亲电性,CH_(3)NH_(3)单体和CH_(3)NH_(3)多聚体具有弱亲电性和亲核性,CH_(3)NH_(3)多聚体的形成有效地减少CH_(3)NH_(3)与无机[PbI_(3)]-框架之间的非谐振声子振动模式,这有利于提高CH_(3)NH_(3)PbI_(3)异质结中载流子传输.电场作用下CH_(3)NH_(3)五聚体中未配对电子通过量子跃迁机制沿着C-N轴发生转移,施加不同方向电场电子的转移效率是不一样的,转移电子数量随着电场强度增加而增加,通过这样的跃迁机制在外电场作用下电子很容易注入CH_(3)NH_(3)PbI_(3)形成CH_(3)NH_(3)多聚体.这些计算结果将有助于更深刻地理解有机-无机杂化钙钛矿太阳能电池高光电转换效率的根源.

关键词：有机-无机杂化钙钛矿太阳能电池第一性原理计算

Evaluation of 3-day smoking cessation training course for doctors from 38 cities in China

在线全文

学校读者我要写书评

暂无评论

Chinese Medical Journal 2012年第7期125卷 1338-1340页

作者： zhang chun-mei XIAO Dan Robea West Susan Michie Ronald Troughton Peter Hajek WANG Chen Department of Respiratory Medicine Beijing Chao-Yang HospitalCapital Medical UniversityBeijing 100020China Beijing Hospital Ministry of HealthBeijing 100730China

Background The World Health Organization＇s ＂Framework Convention on Tobacco Control＂ came into effect in China in 2006. Since then, a series of tobacco control measures has been undertaken, including the first step to establish a coordinated network of stop-smoking clinics in Chinese hospitals. Training for stop-smoking specialists has been traditionally provided via printed materials. This study evaluated the outcomes of the first two intensive 3-day courses in smoking cessation in China run in collaboration with experts who provide training to UK Specialist Stop Smoking Service. Methods Eighty-four doctors from 38 cities in China responsible for stop-smoking treatment in 20 provinces and four autonomous regions participated in the training courses. Participants＇ knowledge competencies and self-efficacy were assessed before and after the authentication training. Results The training significantly improved participants＇ knowledge, skills and self-efficacy across different domains. Forty-eight participants were finally certified as ＂smoking cessation specialist＂. Conclusions The UK model of face-to-face training was acceptable and effective in China. A relatively brief intensive training program can generate significant improvements in skills, knowledge, and readiness to engage in smoking cessation activities.

关键词： smoking cessation certification continuing medical education self-efficacy

生命伦理的公共论坛:美国国家生命伦理委员会的历史发展及启示

在线全文

学校读者我要写书评

暂无评论

自然辩证法通讯 2008年第5期30卷 1-7页

作者：张春美上海市行政学院哲学部上海200233

本文探讨不同时期美国国家生命伦理委员会的作用。初创时期,关注人体实验伦理,构建生命伦理准则;发展时期,规范生命伦理议题,提倡科学家责任意识;完善时期,体现公共利益,建立公众参与技术决策的平台。发挥国家生命伦理委员会的公共论坛... 详细信息

本文探讨不同时期美国国家生命伦理委员会的作用。初创时期,关注人体实验伦理,构建生命伦理准则;发展时期,规范生命伦理议题,提倡科学家责任意识;完善时期,体现公共利益,建立公众参与技术决策的平台。发挥国家生命伦理委员会的公共论坛、伦理评估和伦理教育等作用,有助于我国生命科技的和谐发展。

关键词：生命伦理生命伦理委员生命伦理原则美国国家生命伦理委员会

健身跑步与穴位按摩对城市中年女性身体形态和功能的影响

在线全文

学校读者我要写书评

暂无评论

中国临床康复 2005年第8期9卷 140-141页

作者：张春美青岛大学医学院体育教研室山东省青岛市266021

目的:探讨健身跑与穴位按摩对城市中年女性身体形态和功能的影响,旨在改善中年妇女身体外形结构,提高健康水平。方法:2003-04/06对30名持续参加1个月健身跑,并配以穴位按摩的部分中年女性锻炼前后身体形态指标、技能指标进行测试。结果... 详细信息

目的:探讨健身跑与穴位按摩对城市中年女性身体形态和功能的影响,旨在改善中年妇女身体外形结构,提高健康水平。方法:2003-04/06对30名持续参加1个月健身跑,并配以穴位按摩的部分中年女性锻炼前后身体形态指标、技能指标进行测试。结果:健身跑、按摩后的身体围度指标(上臂围、腰围、臀围、大腿围、小腿围)比锻炼前降低,差异有显著性意义(t=8.06～21.60,P<0.01);健身跑、按摩后体成分指标中体质量、三头肌位皮褶厚度、肩胛下位皮褶厚度、髂前上棘位皮褶厚度、体脂百分比、体脂重比锻炼前降低,差异有显著性意义(t=13.56～26.91,P<0.01)、瘦体质量比锻炼前增高,差异有显著意义(t=-4.56,P<0.01);功能指标中锻炼后安静心率犤锻炼前:(72.70±1.51)次/min,锻炼后:(68.70±1.53)次/min犦比锻炼前降低、锻炼后肺活量犤锻炼前:(2610±83)mL,锻炼后:(3190±105)mL犦比锻炼前增高,差异有显著性意义(t=83.43,-43.04,P<0.01)。结论:健身跑配以穴位按摩可消除体内多余脂肪,降低体脂,增强体力,使外形更加健美和谐;同时,有效改善心肺功能,提高人体的有氧耐力;对预防心血管疾病亦具有重要作用。

关键词：穴位按压运动疗法身体素质