检索结果-南通市图书馆

Chinese Journal of Polymer Science 2007年第6期25卷 545-553页

作者： Li-ming tang Ji feng yu Wang Advanced Materials Laboratory Department of Chemical Engineering Tsinghua University Beijing 100084 China

Five secondary amine terminated poly（ester-amine）s （defined as PEA） with controlled molecular structures were synthesized through reacting excessive piperazine with phthalicdiglycol diacrylate （PDDA） and 1,1,1-trimethylolpropane triacrylate （TMPTA） at a constant secondary amine/acrylate group ratio of 1.5/1 and at different PDDA/TMPTA molar ratios. Both IR and ^1H-NMR spectra indicated that all acrylate groups were consumed in the reaction, based on which the structural parameters were calculated from the ^1H-NMR spectra. With decreasing PDDA/TMPTA ratio, the content of secondary amine, degree of branching, molecular weight, Tg and Td increased accordingly. These polymers were further used as both crosslinkers and flexibilizers for a linear epoxy resin E51 to form cured films under ambient condition. The gel content, relative hardness and Tg of the resulting films increased as PEA molecules changed from linear to highly branching structures. Due to the flexibility of PEA molecules, all the films possessed excellent mechanical performance.

关键词： Poly(ester-amine) Molecular structure Epoxy resin Cured film.

PIV EXPERIMENTAL RESEARCH OF FLOW STRUCTURE IN RECtangULAR CHANNEL WITH TRANSVERSELY PLACED SPIRAL COIL INSERT

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2012年第4期24卷 518-525页

作者： tang yu-feng TIAN Mao-cheng ZHANG Guan-min School of Energy Source and Power Engineering Shandong UniversityJinan 250061China

The flow field in a rectangular channel with a transversely placed spiral coil insert is investigated by Particle Image Velocimetry （PIV） measurements in both transverse and longitudinal sections. The experimental results show that multi-longitudinal vortices are induced downstream of the spiral coil and are distributed as a symmetrical vortex array along the horizontal central line of the transverse section. Along the mainstream, due to the spiral motion of the longitudinal vortices, the velocity fluctuates in a manner of the damped sinusoidal curve and the velocity component in the wall normal direction is improved in the channel. Com- pared with the flow field in a smooth channel it is found that the movement of the longitudinal vortices can cause a continuous dis- turbance near the channel walls and thus enhances the fluid velocity in the near wall region, which consequently leads to the redu- ction of the velocity gradient and a more uniform velocity distribution. With the increase of the Reynolds number, the induced longitudinal vortices gain strength and become straighter and closer to the channel walls, thus the turbulence intensity is further enha- nced in this area.

关键词： Particle Image Velocimetry (PIV) spiral coil longitudinal vortices flow disturbance

NUMERICAL SIMULATION OF FLOW AND HEAT TRANSFER CHARA-CTERISTICS OUTSIDE A PERIODICALLY VIBRATING TUBE

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2008年第5期20卷 629-636页

作者： JIANG Bo TIAN Mao-cheng LENG Xue-li tang yu-feng PAN Ji-hong School of Energy Source and Power Engineering Shandong University Jinan 250061 China

Fluid flow and heat transfer characteristics outside a vibrating tube were numerically simulated by the dynamic mesh method. The mechanism of heat transfer enhancement via periodic vibration of the tube was explored by using the field synergy principle. It is found that the field synergy angle between fluid velocity vector and temperature gradient vector for a periodically vibrating tube is significantly smaller than that for a stationary tube, and it changes approximately according to the sinusoidal law in a vibration period. The effect of time phase of the vibration on the field synergy angle and convective heat transfer coefficient were also discussed. Results indicate that the vibration can enhance heat transfer and this effect is more remarkable when time phase angle ranges between 50° and 1400 in a half period. Especially when the time phase angle is 90°, the average field synergy angle outside the tube reaches the minimum, which leads to the best heat transfer performance.

关键词： heat transfer enhancement dynamic mesh vibration field synergy Computational Fluid Dynamics (CFD)

在线全文

学校读者我要写书评

暂无评论

论诽谤罪成立之宪法限制

甘肃政法学院学报 2006年第2期 110-115页

作者：唐煜枫武汉大学法学院湖北武汉430072

诽谤罪是侵犯名誉权的犯罪,其基本行为方式就是以书面或者口头的形式表达一定的言论,因此诽谤罪的刑法适用必然对作为宪法权利的言论自由权形成一定的限制。同时,言论自由权对于公共权力之监督和民主政治之正常运作具有重要意义,为保障... 详细信息

诽谤罪是侵犯名誉权的犯罪,其基本行为方式就是以书面或者口头的形式表达一定的言论,因此诽谤罪的刑法适用必然对作为宪法权利的言论自由权形成一定的限制。同时,言论自由权对于公共权力之监督和民主政治之正常运作具有重要意义,为保障其充分实现,必须对诽谤罪的成立进行合理限制。这种限制是在引入宪法规范和理念的基础上通过对犯罪构成要件作限制解释来实现的。

关键词：诽谤罪言论自由权宪法限制限制解释

在线全文

学校读者我要写书评

暂无评论

论民意与死刑实践——一个互动关系的视角

辽宁大学学报（哲学社会科学版） 2006年第2期34卷 156-160页

作者：唐煜枫武汉大学法学院湖北武汉430072

在我国,死刑的立法和司法适用有着广泛的民意基础,司法实践中死刑大量适用的现实又在不断强化这种群体意识。在民意与死刑的适用间存在某种互动关系。应当通过制度设计在民意与具体的死刑判决之间拉开距离,以限制死刑的适用,并进而削弱... 详细信息

在我国,死刑的立法和司法适用有着广泛的民意基础,司法实践中死刑大量适用的现实又在不断强化这种群体意识。在民意与死刑的适用间存在某种互动关系。应当通过制度设计在民意与具体的死刑判决之间拉开距离,以限制死刑的适用,并进而削弱死刑的民众心理基础。

关键词：死刑民意限制死刑

在线全文

学校读者我要写书评

暂无评论

基于SPH的边坡稳定性计算中失稳判据研究

岩土工程学报 2016年第5期38卷 904-908页

作者：唐宇峰施富强廖学燕西南交通大学机械工程学院四川成都610031 四川省安全科学技术研究院四川成都610045

在用强度折减法进行边坡稳定性分析时,失稳判据的选择对安全系数有着直接的关系。光滑粒子流体动力学法(SPH)是一种新型的无网格法,由于其在大变形等领域的优势而逐渐发展起来,并扩展至边坡稳定性分析领域。然而,目前对于该方法在边坡... 详细信息

在用强度折减法进行边坡稳定性分析时,失稳判据的选择对安全系数有着直接的关系。光滑粒子流体动力学法(SPH)是一种新型的无网格法,由于其在大变形等领域的优势而逐渐发展起来,并扩展至边坡稳定性分析领域。然而,目前对于该方法在边坡稳定性分析中失稳判据的研究尚未见报道。首先通过Fortan语言编写了基于SPH强度折减法的边坡稳定性分析程序,然后通过一个经典边坡案例,讨论了不同失稳判据对安全系数的影响,并提出了一种新的位移变化失稳判定方法。结果表明,在基于SPH的边坡稳定性分析中,以塑性区贯通或以位移变化为判定准则时各有优劣,但得到的安全系数均与极限平衡法及有限元法得到的安全系数十分接近,均可作为失稳判据。而当采用位移变化准则进行分析时,采用"两步走"的方法即可以减小计算量,又可以得到较准确的安全系数,是一种值得推荐的方法。

关键词：光滑粒子流体动力学 SPH 稳定性分析失稳判据强度折减法

在线全文

学校读者我要写书评

暂无评论

包装设计对饮料畅销的重要性研究

包装工程 2020年第16期41卷 305-310页

作者：唐钰沣唐丽春海南大学海口570228

目的从包装设计的角度入手,对畅销饮料之所以畅销进行探究与分析。方法从饮料包装的设计现状、表现手法及价值三个方面进行分析,并结合实际案例分析论证包装设计与产品畅销的必然联系,和畅销饮料畅销的原因。其中,表现手法尤为重要,它... 详细信息

目的从包装设计的角度入手,对畅销饮料之所以畅销进行探究与分析。方法从饮料包装的设计现状、表现手法及价值三个方面进行分析,并结合实际案例分析论证包装设计与产品畅销的必然联系,和畅销饮料畅销的原因。其中,表现手法尤为重要,它包括了插画运用、AR互动创新、符号表现和色彩的运用,近几年插画运用逐渐在饮料包装中占据主要地位,在设计过程中,恰当地运用这四点表现手法,充分体现该产品的视觉效果,给消费者以视觉美感与吸引力,从而促进消费者的购买欲。结论一款优秀的饮料包装,除了可以直观表达饮料的特点,更能够体现饮料企业的文化内涵,塑造良好的品牌形象,加大品牌的市场影响力,从而成为畅销饮料。

关键词：包装设计饮料销量表现手法插画

基于光滑粒子流体动力学的流动法则对土体滑坡大变形的影响探讨

在线全文

学校读者我要写书评

暂无评论

岩土力学 2018年第4期39卷 1509-1516页

作者：唐宇峰施富强廖学燕周帅四川理工学院机械工程学院四川成都643000 西南交通大学机械工程学院四川成都610031 四川省安全科学技术研究院四川成都610045

光滑粒子流体动力学(SPH)是近年来发展起来的一种纯拉格朗日无网格法,并因其在大变形领域内的优势而受到广泛关注。在进行滑坡大变形分析时,流动法则及剪胀角的选取对于边坡失稳后的运动特性有重要的影响。采用Fortran自行编写了基于SP... 详细信息

光滑粒子流体动力学(SPH)是近年来发展起来的一种纯拉格朗日无网格法,并因其在大变形领域内的优势而受到广泛关注。在进行滑坡大变形分析时,流动法则及剪胀角的选取对于边坡失稳后的运动特性有重要的影响。采用Fortran自行编写了基于SPH的边坡稳定性及失稳后大变形分析程序,然后通过2个经典的算例,讨论了不同流动法则及剪胀角的选取对滑坡大变形分析精度的影响。结果表明:(1)剪胀角的选取对土体失稳后的滑动距离有显著影响,随着剪胀角的增大,土体的滑动速度与距离呈明显增大趋势;(2)在关联性流动法则及非关联性流动法则ψ=1/2φ(ψ为剪胀角,φ为摩擦角)条件下,土体在大变形过程中会产生过度膨胀,且运动速度与距离要大于实际情况,而采用关联性流动法ψ=0时,对于非膨胀土可以得到比较令人满意的结果,但对于膨胀土体会使得运动速度和运动距离过小,不符合实际情况。建议在计算膨胀土大变形时,采用非关联性流动法则且适当考虑膨胀性(ψ=(0.1~0.2)φ),可以得到较好的结果。

关键词：光滑粒子流体动力学滑坡大变形流动法则剪胀角

在线全文

学校读者我要写书评

暂无评论

刑事一体化视域中专利权保护问题研究

河北法学 2023年第9期41卷 2-18页

作者：储槐植唐风玉北京大学法学院北京100871 西北师范大学法学院甘肃兰州730070

刑法对专利权保护存在明显的“不足”:体现在刑事立法层面,假冒专利罪的刑法规范被评价是象征性立法,是“附而不属”的影子刑法;成立假冒专利罪要求有“情节严重”的罪量限制,模糊专利违法与专利犯罪的界限,极大地限缩了侵犯专利权犯罪... 详细信息

刑法对专利权保护存在明显的“不足”:体现在刑事立法层面,假冒专利罪的刑法规范被评价是象征性立法,是“附而不属”的影子刑法;成立假冒专利罪要求有“情节严重”的罪量限制,模糊专利违法与专利犯罪的界限,极大地限缩了侵犯专利权犯罪的成立范围;刑事司法层面,专利执法行刑衔接机制不畅,导致“以罚代刑”,造成侵犯专利权刑罚的处罚范围极窄。国家通过犯罪化的直接方式保护专利权的目的落空。刑法对专利权的保护应当根据刑事一体化思想进行调整,更新刑法观,调整侵犯专利权犯罪的定罪结构和刑罚结构向刑法现代化转变;构建企业“合规自治”与刑法“法治”的共治制度架构。这是新时期我国建设知识产权强国新目标的需要,也是完善刑法体系对知识产权保护、维护公平竞争的市场秩序和良好的营商环境之最佳路径。

关键词：刑事一体化专利权假冒专利罪刑法现代化

Hypoxia-preconditioned bone marrow-derived mesenchymal stem cells protect neurons from cardiac arrest-induced pyroptosis

在线全文

学校读者我要写书评

暂无评论

Neural Regeneration Research 2025年第4期20卷 1103-1123页

作者： Xiahong tang Nan Zheng Qingming Lin Yan You Zheng Gong Yangping Zhuang Jiali Wu yu Wang Hanlin Huang Jun Ke feng Chen Shengli Clinical Medical College of Fujian Medical University Fujian Medical UniversityFuzhouFujian ProvinceChina Department of Emergency Fujian Provincial HospitalFuzhouFujian ProvinceChina Fujian Provincial Key Laboratory of Emergency Medicine FuzhouFujian ProvinceChina The Second Department of Intensive Care Unit Fujian Provincial Hospital South BranchFuzhouFujian ProvinceChina

Cardiac arrest can lead to severe neurological impairment as a result of inflammation,mitochondrial dysfunction,and post-cardiopulmonary resuscitation neurological *** preconditioning has been shown to improve migration and survival of bone marrow–derived mesenchymal stem cells and reduce pyroptosis after cardiac arrest,but the specific mechanisms by which hypoxia-preconditioned bone marrow–derived mesenchymal stem cells protect against brain injury after cardiac arrest are *** this end,we established an in vitro co-culture model of bone marrow–derived mesenchymal stem cells and oxygen–glucose deprived primary neurons and found that hypoxic preconditioning enhanced the protective effect of bone marrow stromal stem cells against neuronal pyroptosis,possibly through inhibition of the MAPK and nuclear factor κB ***,we transplanted hypoxia-preconditioned bone marrow–derived mesenchymal stem cells into the lateral ventricle after the return of spontaneous circulation in an 8-minute cardiac arrest rat model induced by *** results showed that hypoxia-preconditioned bone marrow–derived mesenchymal stem cells significantly reduced cardiac arrest–induced neuronal pyroptosis,oxidative stress,and mitochondrial damage,whereas knockdown of the liver isoform of phosphofructokinase in bone marrow–derived mesenchymal stem cells inhibited these *** conclude,hypoxia-preconditioned bone marrow–derived mesenchymal stem cells offer a promising therapeutic approach for neuronal injury following cardiac arrest,and their beneficial effects are potentially associated with increased expression of the liver isoform of phosphofructokinase following hypoxic preconditioning.

关键词： bone marrow–derived mesenchymal stem cells cardiac arrest cardiac resuscitation hypoxic preconditioning liver isoform of phosphofructokinase mitochondria neuroinflammation oxidative stress pyroptosis reactive oxygen species