检索结果-南通市图书馆

在线全文

学校读者我要写书评

暂无评论

电视胸腔镜辅助NUSS手术微创治疗漏斗胸

中南大学学报（医学版） 2008年第5期33卷 443-447页

作者：刘文亮喻风雷尹邦良中南大学湘雅二医院胸外科长沙410011

目的：总结18例电视胸腔镜辅助NUSS手术的处理经验,探讨NUSS术后近期疗效和并发症的预防和治疗。方法：2006年12月至2007年9月共施行了18例电视胸腔镜下NUSS手术治疗漏斗胸,其中传统手术后复发5例。结果：18例患者手术时间30-70 min,平... 详细信息

目的：总结18例电视胸腔镜辅助NUSS手术的处理经验,探讨NUSS术后近期疗效和并发症的预防和治疗。方法：2006年12月至2007年9月共施行了18例电视胸腔镜下NUSS手术治疗漏斗胸,其中传统手术后复发5例。结果：18例患者手术时间30-70 min,平均45 min,均于术后5-7 d出院。患者胸廓畸形明显改善。其中1例术中损伤心包,1例术后出现伤口液化以及部分肺不张,经治疗后均痊愈。结论：NUSS手术具有微创、美观、手术时间短、操作简单等优点,近期效果满意,远期效果还需进一步观察。围术期正确的处理可减少并发症。

关键词：胸壁畸形漏斗胸胸腔镜 NUSS手术并发症

在线全文

学校读者我要写书评

暂无评论

凝灰岩机制砂混凝土抗低温硫酸盐侵蚀性

浙江大学学报（工学版） 2017年第3期51卷 532-537页

作者：温小栋蔡煜梁赵莉冯蕾宁波工程学院浙江宁波315016

为了研究低温环境下凝灰岩机制砂对混凝土抗硫酸盐侵蚀性的影响,结合腐蚀介质及低温环境特点,采用10±1℃的硫酸钠/硫酸镁复合溶液模拟服役环境;利用电脉冲加速腐蚀介质迁移,对比分析腐蚀前、后试样的强度变化、腐蚀产物的物相等.结果表... 详细信息

为了研究低温环境下凝灰岩机制砂对混凝土抗硫酸盐侵蚀性的影响,结合腐蚀介质及低温环境特点,采用10±1℃的硫酸钠/硫酸镁复合溶液模拟服役环境;利用电脉冲加速腐蚀介质迁移,对比分析腐蚀前、后试样的强度变化、腐蚀产物的物相等.结果表明:凝灰岩机制砂拌制试件比河砂拌制试件更容易受到低温硫酸盐侵蚀破坏;一定掺量的氢氧化钡可改善试件的抗硫酸盐侵蚀能力,但当掺量高于4%时,改善作用开始降低;低温硫酸盐侵蚀后机制砂拌制试件的腐蚀物以碳硫硅酸钙为主,河砂拌制试件的腐蚀物以钙矾石为主.从凝灰岩石粉的物相及机制砂混凝土孔结构探讨抗低温硫酸盐侵蚀能力弱化原因.该研究可以为硫酸盐区划环境下机制砂混凝土的耐久性设计提供一定参考.

关键词：硫酸盐侵蚀凝灰岩机制砂滨海土壤低温加速腐蚀

在线全文

学校读者我要写书评

暂无评论

等离激元Au纳米流体集热器性能研究

西安交通大学学报 2020年第8期54卷 44-49页

作者：张煜侯予陈良西安交通大学能源与动力工程学院西安710049

为了探究含有Au纳米流体的二维太阳能体吸收式集热器的性能,采用控制容积法数值求解了太阳能集热器内部的温度分布,将集热器出口平均温度作为温升的衡量标准,分析了影响集热器温升和效率的主要因素。研究结果表明:集热器内光谱强度在Au... 详细信息

为了探究含有Au纳米流体的二维太阳能体吸收式集热器的性能,采用控制容积法数值求解了太阳能集热器内部的温度分布,将集热器出口平均温度作为温升的衡量标准,分析了影响集热器温升和效率的主要因素。研究结果表明:集热器内光谱强度在Au等离激元共振波长(500 nm左右)处大幅衰减,证明了金属表面等离激元共振效应可大幅强化光谱吸收特性;集热器内光谱辐射吸收程度影响集热器温度分布,从而影响集热器温升和效率;采用纯水作为工作流体时集热器效率仅39.99%,添加Au纳米粒子比添加Ag纳米粒子具有更高的集热器效率,可达78.75%;流体流速主要影响集热器温升,集热器高度主要影响集热器效率;当流速为0.1 m/s时可获得最大集热器温升36.63 ℃,集热器高度为2.5 cm时可获得最高效率82.98%;粒径和集热器长度对集热器温升和效率影响均不大。

关键词：等离激元共振集热器纳米粒子光谱特性光热转换效率

Stereoselective synthesis of substituted 1,3-dienes from propargylic esters: electrophilic-metal or redox catalysis?

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2024年第5期67卷 1384-1396页

作者： Mengfu Dai liangliang Song liang-An Chen Jiangsu Collaborative Innovation Center of Biomedical Functional Materials Jiangsu Key Laboratory of New Power BatteriesSchool of Chemistry and Materials ScienceNanjing Normal UniversityNanjing 210023China Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources International Innovation Center for Forest Chemicals and MaterialsCollege of Chemical EngineeringNanjing Forestry UniversityNanjing 210037China

1,3-Diene architectures are not only widely present in natural products, pharmaceuticals, and functional organic materials but also serve as versatile building blocks to furnish important functionalized molecules in synthetic chemistry due to conjugated repeating C=C units. Accordingly, various strategies to access substituted 1,3-dienes in a stereoselective manner have been developed. However, chemo-, regio-and stereoselective synthesis of highly substituted 1,3-dienes still remains elusive and challenging. Readily available propargylic esters have emerged as an appealing class of synthetic intermediates for accessing functionalized 1,3-dienes, especially challenging tri-or tetrasubstituted variants, via transition-metal catalysis, including electrophilic metal and redox neutral catalysis. This review, for the first time, systematically highlights recent advances in transitionmetal catalyzed synthesis of substituted 1,3-dienes from propargylic esters, discusses the mechanisms and synthetic utilities, and gives the remaining challenges and potential opportunities in this field.

关键词： 1 3-diene propargylic ester Lewis acid redox catalysis transition metal

Highly efficient ultraviolet high-harmonic generation from epsilon-near-zero indium tin oxide films

在线全文

学校读者我要写书评

暂无评论

Photonics Research 2021年第3期9卷 317-323页

作者： Wendong Tian Fei liang Dazhi Lu Haohai yu Huaijin Zhang State Key Laboratory of Crystal Materials and Institute of Crystal Materials Shandong UniversityJinan 250100China

High-harmonic generation in the ultraviolet region is promising for wireless technology used for communications and sensing. However, small high-order nonlinear coefficients prevent us from obtaining high conversion efficiency and functional photonic devices. Here, we show highly efficient ultraviolet harmonic generation extending to the fifth order directly from an epsilon-near-zero indium tin oxide(ITO) film. The real part of the annealed ITO films was designed to reach zero around 1050 nm, matching with the central wavelength of an Yb-based fiber laser, and the internal driving electric field was extremely enhanced. A high energy conversion efficiency of 10-4 and 10-6 for 257.5 nm(fourth-order) and 206 nm(fifth-order) ultraviolet harmonic generation was obtained,which is at least 2 orders of magnitude higher than early reports. Our results demonstrate a new route for overcoming the inefficiency problem and open up the possibilities of compact solid-state high-harmonic generation sources at nanoscale.

关键词： film. harmonic ultraviolet

Comparative chemical characters of Pseudostellaria heterophylla from geographical origins of China

在线全文

学校读者我要写书评

暂无评论

Chinese Herbal Medicines 2023年第3期15卷 439-446页

作者： Miao Sha Xiaohuan Li yu Liu Hongyue Tian Xu liang Xia Li Wenyuan Gao Tianjin Key Laboratory for Modern Drug Delivery&High-Efficiency School of Pharmaceutical Science and TechnologyTianjin UniversityTianjin 300193China

Objective:Pseudostellaria heterophylla has been paid more attention in recent years,mainly as a medicine food homology *** content determination of *** is not specified in the Chinese Pharmacopoeia(version 2020).The environmental conditions in different production areas could exert an influence on the quality of *** purpose of this study is to discriminate *** collected from different geographical origins of ***:In this study,the content of polysaccharide in 28 batches of *** was determined using phenol–sulfuric *** fingerprints were established under optimised HPLC-PDA ***,the similarity analysis(SA)and the quantification of heterophyllin B were *** metabolites of *** were identified and evaluated using UHPLC-Q Exactive HF orbitrap MS *** component analysis(PCA),partial least squares discriminant analysis(PLS-DA),hierarchical cluster analysis(HCA)and orthogonal PLS-DA(OPLS-DA)were performed based on all peak ***:The polysaccharide content in Guizhou and Jiangsu was higher than that of other production areas,which varied significant from different *** the content of heterophyllin B in Anhui and Jiangsu was *** correlation coefficients of HPLC fingerprints for 28 batches samples ranged from 0.877 to 0.990,and the characteristic map can be used to identify and evaluate the quality of *** samples from Fujian,Guizhou,Jiangsu provinces can be relatively separated using multivariate statistical analysis including PCA,PLS-DA,HCA,OPLS-DA,indicating that their metabolic compositions were significantly ***,a total of 15 metabolites which were filtrated by a VIPvalue>1 and a P-value<0.05 associated with the separation of different origins were ***:HPLC fingerprint was established to evaluate the quality and authenticity of *** present work showed that the difference of g

关键词： HPLC fingerprint metabolites Pseudostellaria heterophylla(Miq.)Pax ex Pax et Hoffm polysaccharide UHPLC-Q Exactive HF orbitrap MS system

Enhancement of laminar flow heat transfer with single/doubleinclined ribs for unilaterally-heated channel

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2023年第7期66卷 2108-2118页

作者： WANG Xiangyu XU XiangHua liang XinGang School of Aerospace Engineering Key Laboratory for Thermal Science and Power Engineering of Ministry of EducationTsinghua UniversityBeijing 100084China

To deal with the aerodynamic heating on the aircraft surface,a potential solution is to utilize liquid cooling via the channels in part of the *** is a typical problem of flow and heat transfer in channels with unilaterally-heated *** enhancement of heat transfer in the channel is significant due to the high heating *** optimal velocity and temperature fields are obtained first based on the field synergy optimization *** rib configurations are proposed to produce the longitudinal vortices suggested by the optimal velocity *** flow and heat transfer characteristics of different rib configurations are obtained by numerical *** numerical simulations show that the heat transfer enhancement of the rib configurations are quite different,but the pressure drop increases similarly in the laminar flow range of Re = 500–*** mechanism of heat transfer enhancement with the single/double-inclined ribs for the unilaterally-heated channel is *** best enhancement of geometric parameter among the investigated parameters such as the angle,length,radius and the spacing of the ribs is obtained.

关键词： heat transfer enhancement field synergy optimization inclined ribs unilaterally-heated channel

Research on Credit Default Swaps Pricing Considering Moral Hazard Incentive under Reduce-Form Model

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Science and Systems Engineering 2024年第3期33卷 311-329页

作者： liang Wu Kangjie He Zhe Guo School of Mathematical Science Henan Institute of Science and TechnologyXinxiang453003China Public Front Office Department Industrial and Commercial Bank of ChinaZhengzhou450000China

Equilibrium pricing of credit default swaps(CDS)promotes efficient identification of credit risk in the market,which in turn leads to efficient allocation of ***,even when CDS have been priced in equilibrium,i.e.,when premiums are equal to anticipated payments,the moral hazard incentives of CDS buyers increase with CDS ***,it becomes an interesting research direction to study the impact of moral hazard incentives on the trading mechanism or pricing of derivatives(CDS).Most of the existing literature on the impact of moral hazard incentives in CDS pricing on derivatives trading mechanisms takes a macro perspective and focuses on the agreement risk *** literature exploring the analysis of the impact of moral hazard on the probability of agreement default from a micro perspective is not yet *** this in mind,this paper focuses on the mechanisms by which“fraud”,an extreme manifestation of micro-moral hazard incentives,affects the probability of *** paper introduces for the first time the concept of“claiming fraud”by credit protection buyers,which is different from the macro perspective of moral hazard incentives,and thus defines a specific extreme form of moral hazard ***,to address the intrinsic feature of the lack of economic explanatory power of the reduce-form model,this paper introduces a moral hazard incentive factor into the reduce-form model,and proposes a moral hazard state variable as a function of the asset value of the reference entity,which gives the reduce-form model strong economic explanatory power,and the default predictability is reduced by the description of the reduce-form *** terms of the object of study,this paper considers the issue of moral hazard incentives in the presence of claiming fraud in two reference entities to further explore the impact of moral hazard incentives on default protection at the micro level in terms of cyclic ***,based on the

关键词： Financial engineering moral hazard incentive claiming fraud reduce-form model probability of default calculation CDS pricing

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

具有异构分簇的粒子群优化算法研究

电子学报 2012年第11期40卷 2194-2199页

作者：李文锋梁晓磊张煜武汉理工大学物流工程学院湖北武汉430063

粒子群优化(Particle Swarm Optimization,PSO)算法在复杂多峰函数可行域空间搜索时极易陷入局部极值点.研究表明改变种群拓扑结构和调整算法参数有助于改善种群的多样性,但是目前研究中少有同时考虑种群全局拓扑结构和局部粒子个体能力... 详细信息

粒子群优化(Particle Swarm Optimization,PSO)算法在复杂多峰函数可行域空间搜索时极易陷入局部极值点.研究表明改变种群拓扑结构和调整算法参数有助于改善种群的多样性,但是目前研究中少有同时考虑种群全局拓扑结构和局部粒子个体能力.本文提出一种具有异构分簇特性的自适应PSO算法.该算法采用K-均值聚类算法对种群进行动态分簇,形成多异构子群,并采用Ring型拓扑结构进行子群间信息流通.而后采用基于寻解水平评价的粒子自适应参数调整策略进行个体调整.通过实验分析表明该算法能够提高粒子群优化的种群的多样性、粒子活性、搜索能力和收敛性能,同时也降低了算法对参数初值的依赖性.

关键词：粒子群算法自适应异构聚类函数优化