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Search Results: 1 - 10 of 23744 matches for " 吕双双 "
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电化学分析法快速测定粮油食品中的总植物甾醇含量
双双
- , 2015, DOI: 10.13982/j.mfst.1673-9078.2015.5.047
Abstract: 本文研究了植物甾醇在裸玻碳电极上的电化学反应过程,建立了差分脉冲法快速测定粮油食品中的总植物甾醇含量的新方法。试验表明:通过快速循环伏安法测定植物甾醇在1.72 V处出现氧化峰,无还原峰,其电极反应过程是不可逆的;并且探索了电化学法测定植物甾醇的试验条件,结果显示:乙腈-异丙醇(9:1,V/V)为最佳有机溶剂,支持电解质是50 mmol/L高氯酸锂(LiClO4),脉冲幅度50 mV、电位增量为3 mV、脉冲宽度为0.05 s、脉冲间隔为0.3 s;在此条件下,以差分脉冲伏安法测定植物甾醇的线性范围是160~800 μg/mL,检测限是8.8 μg/mL(S/N=3),线性系数r=0.998。并用该法测定了玉米胚芽油脱臭馏出物中总植物甾醇含量,回收率为97.0~101.3%;结果表明,在非水溶剂中,电化学分析法测定植物甾醇是可行的,并且操作简便,样品无需前处理,测定结果精确。
The electrochemical reaction process of plant sterols in a bare glassy carbon electrode was investigated to develop a new differential-pulse voltammetric method for rapid detection of phytosterols in cereals, oils, and other foodstuff. Cyclic voltammogram of phytosterols showed that the oxidation peak appeared at 1.72 V and no reduction peak was observed, which indicated that the electrode reaction process was irreversible. The electrochemical conditions were optimized for the detection of phytosterols. The results showed that the optimal conditions were: acetonitrile and 2-propanol (9:1,V/V) as organic solvent, 50 mmol/L LiClO4 as supporting electrolyte, pulse amplitude of 50 mV, potential increment of 3 mV, pulse width of 0.05 s, and pulse interval of 0.3 s. Under these optimized conditions, the calibration curves for determination of phytosterol demonstrated an excellent linear response within the range 160 to 800 μg/mL (r = 0.998), with the detection limit at 8.8 μg/mL (S/N = 3). The proposed method was successfully applied to the determination of phytosterol in corn germ oil deodorizer distillate and the recovery rate was 97.0% to 101.3%. The results indicate that the electrochemical analysis method is feasible for the detection of phytosterols in non-aqueous solvents, easy to perform, and does not require complicated pretreatment of samples.
A Research of Xetwork Security Architecture Based on Agent Technology under LAX Environmt
局域网环境中基于Agent的网络安全体系研究

双双,刘培玉
计算机科学 , 2000,
Abstract: 一、引言在网络技术迅速发展和普及的同时,网络的安全性问题也日益突出,越来越多的人已经意识到网络上存在着大量的安全威胁。一个用户或一个局域网络连接到Internet或其他外部网络后,虽然可方便地进行信息的共享,但是由于网络开放性的体系结构,用户或局域网络自身的信息和数据,包括某些具有不同程度
钢筋混凝土框架结构整体超强系数需求分析
双双,大刚
地震工程与工程振动 , 2015, DOI: 10.13197/j.eeev.2015.06.1.cuiss.001
Abstract: 针对我国现行抗震设计规范尚未对结构的超强性能作明确的考虑,本文考虑不同设防烈度,不同层数严格按现行抗震规范设计了17个典型RC框架结构,采用OpenSees进行有限元建模与分析,并通过结构拟静力试验数据对有限元模型进行验证。采用文中提出的动力能力谱方法,对RC框架结构在地震作用下的反应进行分析,得到结构在不同设防水准下的整体超强系数需求值,并将其分析结果与传统静力能力谱方法分析结果进行对比分析。按Ⅵ、Ⅶ、Ⅷ度设防烈度设计的不同层数的结构,设防地震作用下,超强系数需求值的变化范围分别为0.51~1.89、0.46~1.94、0.57~1.80;罕遇地震作用下,超强系数需求值的变化范围分别为1.18~4.05、1.33~3.45、1.42~2.66。采用动力能力谱方法可以有效地分析结构在地震作用下的超强系数需求值,量化结构在特定地震设防水准作用下承载力的实际需求,改善静力能力谱方法中动力需求谱与静力能力谱曲线的不和谐性。
局域网环境中基于agent的网络安全体系研究
双双 刘培玉?
计算机科学 , 2000,
Abstract:
基于Pushover分析的钢筋混凝土框架结构抗侧向倒塌能力评定
大刚,双双,陈志恒
工程力学 , 2013, DOI: 10.6052/j.issn.1000-4750.2011.05.0315
Abstract: 建筑物在地震作用下的倒塌是造成地震灾害的主要原因,如何合理评定建筑物的抗倒塌能力是结构抗倒塌设计的前提条件,也是对现有结构进行抗震性能鉴定与加固的基础。该文提出采用结构整体抗震性能系数作为结构整体抗侧向倒塌能力的定量评定指标,以一榀严格按我国规范设计的钢筋混凝土框架结构为例,采用Pushover分析方法对其进行侧向增量倒塌分析,通过结构的失效模式来识别结构的破坏过程,得到了结构超强系数、延性系数、延性折减系数、反应修正系数以及位移放大系数,分析中考虑了不同侧向力分布形式、梁柱线刚度比、柱端弯矩增大系数(COF)对结构抗倒塌能力的影响。研究结果表明:通过结构整体抗震性能系数可以对结构整体抗倒塌能力进行定量评估,可以实现结构延性与承载力的双重控制。
地震作用下钢筋混凝土框架结构连续倒塌极限状态可靠度分析
宋鹏彦,大刚,双双
建筑结构学报 , 2013,
Abstract: 将结构连续倒塌的全概率方法应用于地震作用下的结构整体连续倒塌极限状态可靠度分析,采用构件可靠度方法对结构进行地震作用下最可能失效构件的识别,基于改进点估计法的随机Pushdown方法和随机竖向增量动力分析(竖向IDA)方法,进行完好和损伤结构的概率抗竖向连续倒塌能力分析及参数灵敏度分析。采用整体可靠度方法,分析了损伤结构的竖向连续倒塌条件失效概率。基于系统可靠度理论和全概率方法,分析了RC框架结构发生侧向增量倒塌以及构件地震损伤引起的结构竖向连续倒塌的联合失效概率。分析结果表明,按照我国现行规范设计的钢筋混凝土框架结构具有良好的抗连续倒塌能力。
填充墙和现浇板对钢筋混凝土框架结构整体超强的影响研究
双双,大刚,宋鹏彦
建筑结构学报 , 2014,
Abstract: 为充分实现框架结构的“强柱弱梁”耗能机制,需要考虑填充墙、现浇T形截面梁及其翼缘现浇板内与梁肋平行配置的钢筋对结构整体超强系数的影响。考虑抗震设防烈度、结构层数等因素,严格按我国抗震规范设计了15个典型钢筋混凝土框架结构,对结构进行Pushover分析,得到了各种结构在非弹性阶段由于内力重分布而形成的超强性能。结果表明:结构设计考虑填充墙、现浇楼板的影响,会提高结构的整体超强能力,结构整体超强系数均随着抗震设防烈度的增高而减小,且先随结构层数的增大而减小,结构层数大于8层后,又随结构的层数的增大而增大。可以保守地认为,分别按抗震设防烈度6,7,8度设计的结构,同时考虑填充墙和现浇板影响时,结构整体超强系数分别至少要达到5.0,3.0,2.0。
血管回声跟踪技术评估兔颈动脉斑块形成后动脉弹性功能改变
双双,陈莉,仁华,王涌△
- , 2018,
Abstract:
Objective To investigate the carotid artery elasticity in rabbits with carotid artery plaques by echo tracking (ET) technique,and compare its diagnostic value with pulse-Doppler technique in assessing vascular stiffness .Methods Forty-three healthy male New Zealand rabbits were fed with high cholesterol diet.All rabbits were examined by 3 ultrasound methods at the beginning and the end of the 4th week in this experiment respectively,which were two-dimensional ultrasonography,pulse-Doppler technique and ET technique.The hemodynamic indexes were detected by pulse-Doppler technique,including pulsatility index (PI),resistance index (RI),peak systolic velocity (PSV),end diastolic velocity (EDV),and mean velocity (MnV);the elasticity parameters of carotid were measured by ET technology,including stiffness parameter (β),pressure-strain elastic modulus (Ep),arterial compliance (AC),one-point pulse wave velocity (PWVβ) and augmentation index (AI).According to the results of plaques at the end of the 4th week,the rabbits were divided into 2 groups:no plaque formation group (group A) and plaque group (group B).All datum detected at the beginning were defined accordingly as group A0 and group B0.Then,comparing all datum among these groups. Results Elasticity parameters β,Ep,and PWVβ increased significantly at the end of the 4th week compared with those at the beginning (P < 0.001).The same results were found between group B and group A,showing parameters β,Ep,and PWVβ of group B were higher than those of group A.No difference was found between AC and AI,as among the references of pulse-Doppler technique. Conclusions ET technique can be used in detecting carotid artery elasticity with or without plaque,and its diagnostic value is better than pulse-Doppler technique.
远志-石菖蒲药对配伍前后远志化学成分定性定量分析
广云,双双,杭太俊,宋敏
- , 2016,
Abstract: 研究药对远志-石菖蒲配伍对远志药材化学成分的影响。采用HPLC-Q-TOF-MS/MS法对远志-石菖蒲配伍前后远志化学成分进行定性,并用HPLC-UV法进行定量分析。采用C18色谱柱(250 mm×4.6 mm,5 μm),以乙腈-0.1%甲酸水溶液为流动相梯度洗脱;质谱使用电喷雾离子源,在正离子模式下扫描;通过对照品对照、质谱数据和对比文献对远志化学成分的各色谱峰进行归属,并比较远志-石菖蒲配伍前后远志各化学成分的含量变化。从远志中鉴定出8个化学成分:3,4,5-三甲氧基肉桂酸、对甲氧基肉桂酸、细叶远志皂苷、西伯利亚远志糖A5、远志??GFEA9?M?Ⅲ、细叶远志苷B、3,6′-二芥子酰基蔗糖和细叶远志苷A;经石菖蒲配伍后,远志的8个化学成分含量明显变化。远志-石菖蒲配伍后的化学成分定性定量研究可为该药对的体内配伍作用探索提供方法依据。
The purpose of this research was to explore the differences of the components of Radix Polygalae in herbal pair of Radix Polygalae and Rhizoma Acori Tatarinowii. An HPLC-Q-TOF-MS/MS method and an HPLC-UV method were established for the identification and determination of the components of Radix Polygalae, respectively. HPLC separation was carried out on a C18 column(250 mm×4. 6 mm, 5 μm)with linear gradient elution using a mobile phase consisting of acetonitrile and 0. 1% formic acid aqueous solution. Mass spectrometry with ESI source was performed in the positive ion mode to scan MS data including total ion chromatograms and ion peaks of Radix Polygalae. Eight components including 3, 4, 5-trimethoxycinnamic acid, p-methoxycinnamic acid, tenuifolin, sibiricose A5, polygalaxanthone III, tenuifoliside B, 3, 6′-disinapoly sucrose, and tenuifoliside A were identified according to the reference substance retention time, MS data and literatures. There was no significant variation found in the contents of eight chemical constituents of Radix Polygalae. The qualification and quantitation study of the components in herbal pair of Radix Polygalae and Rhizoma Acori Tatarinowii provide the methodological basis for compatibility mechanism exploration in vivo
结构鲁棒性及其评价指标
大刚,宋鹏彦,双双,王闽雄
建筑结构学报 , 2011,
Abstract: 基于“偶然事件”、“局部损伤”、“不成比例破坏”和“失效后果”四个方面给出了结构鲁棒性的新定义,将结构鲁棒性的定量测度划分为四类,分别从结构的属性、结构的确定性性能、结构的可靠度以及结构的风险等方面详细阐述了目前已经提出的各种鲁棒性指标;分别采用基于承载力的鲁棒性指标、基于可靠度的鲁棒性指标以及基于风险的鲁棒性指标,对按照我国现行规范设计的钢筋混凝土框架结构的抗震鲁棒性进行了定量评价。结果表明:采用三类指标的鲁棒性评价结果一致,按照我国现行规范设计的钢筋混凝土框架结构具有良好的抗震鲁棒性。
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