检索结果-南通市图书馆

Dynamic bivariate normal copula

在线全文

学校读者我要写书评

暂无评论

Science China Mathematics 2016年第5期59卷 955-976页

作者： LIAO Xin PENG Liang PENG ZuoXiang zheng yanting School of Mathematics and Statistics Southwest University Department of Risk Management and Insurance Georgia State University Department of Finance Beijing Technology and Business University

Normal copula with a correlation coefficient between-1 and 1 is tail independent and so it severely underestimates extreme probabilities. By letting the correlation coefficient in a normal copula depend on the sample size, H¨usler and Reiss(1989) showed that the tail can become asymptotically dependent. We extend this result by deriving the limit of the normalized maximum of n independent observations, where the i-th observation follows from a normal copula with its correlation coefficient being either a parametric or a nonparametric function of i/n. Furthermore, both parametric and nonparametric inference for this unknown function are studied, which can be employed to test the condition by H¨usler and Reiss(1989). A simulation study and real data analysis are presented too.

关键词： estimation normal copula tail dependence/independence

氯氮平联合阿戈美拉汀改善精神分裂症患者阴性症状的疗效评价

在线全文

学校读者我要写书评

暂无评论

临床心身疾病杂志 2025年第1期31卷 118-121页

作者：沈文超吴贻明宋兵福郑琰婷上海市杨浦区精神卫生中心上海200093

目的探讨氯氮平联合阿戈美拉汀改善精神分裂症患者阴性症状的疗效。方法将69例精神分裂症患者按照随机数字表法分为研究组(35例)和对照组(34例)。对照组患者给予氯氮平联合安慰剂治疗12周,研究组患者给予氯氮平联合阿戈美拉汀治疗12周... 详细信息

目的探讨氯氮平联合阿戈美拉汀改善精神分裂症患者阴性症状的疗效。方法将69例精神分裂症患者按照随机数字表法分为研究组(35例)和对照组(34例)。对照组患者给予氯氮平联合安慰剂治疗12周,研究组患者给予氯氮平联合阿戈美拉汀治疗12周。治疗前后,采用阳性和阴性症状量表(PANSS)、阴性症状量表(SANS)评估两组患者临床症状和阴性症状。结果治疗后,研究组患者PANSS总分及一般精神病理症状、阴性症状评分较治疗前降低,且阴性症状评分低于对照组(P<0.01);研究组患者SANS评分较治疗前降低(P<0.01)。结论氯氮平联合阿戈美拉汀改善精神分裂症患者阴性症状疗效显著,临床应用潜力较好。

关键词：阿戈美拉汀精神分裂症阴性症状疗效

中国城市群的空间模式——分散性区域集聚的理论背景、形成机理及最新进展

在线全文

学校读者我要写书评

暂无评论

地理科学进展 2020年第2期39卷 339-352页

作者：郑艳婷北京师范大学经济与资源管理研究院北京100875 城市绿色发展科技战略研究北京市重点实验室北京100875

从空间模式而言,城市群的本质是人口和经济活动在更大范围城市地域实体内的集聚。在这一集聚体内,原乡村地区密集参与着工业化、经济发展。在国内外经典文献分析的基础上,论文将城市群这一特征概括为分散性区域集聚,并认为分散性区域集... 详细信息

从空间模式而言,城市群的本质是人口和经济活动在更大范围城市地域实体内的集聚。在这一集聚体内,原乡村地区密集参与着工业化、经济发展。在国内外经典文献分析的基础上,论文将城市群这一特征概括为分散性区域集聚,并认为分散性区域集聚是信息技术革命以来经济全球化空间选择的结果,也是中国政策制度背景的产物。作为全球制造业生产平台和协调控制中心在空间上的独特反映,这一根本属性使得城市群区别于传统区域,在空间上并不遍在;其分散性的发展特征使得它同时代表着最为严重的资源环境约束,值得特别关注。从分散性的地域单元入手的规划策略较目前的城市群整体战略而言,可能较易实施和取得效果。同时,随着中国内需战略和"一带一路"倡议的实施,城市群发生发展的国内外背景正在发生重要转变。分散性区域集聚的空间模式并不一定适用于中国所有区域,在进行规划管理时,必须审慎对待这一客观事实。

关键词：城市群分散性区域集聚大都市带巨型城市区域全球城市区域全球化

In situ seed layer bandgap engineering leading to the conduction band offset reversion and efficient Sb2Se3 solar cells with high open-circuit voltage

在线全文

学校读者我要写书评

暂无评论

Journal of Energy Chemistry 2025年第2期101卷 201-212页

作者： yanting Jiang Weiyu Wang Zhirong Chen Zhenyu Fang Qiqiang Zhu Qiao zheng Jionghua Wu Hui Deng Weihuang Wang Shuying Cheng Fuzhou University Institute of Micronano Devices & Solar Cells College of Physics & Information Engineering Jiangsu Collaborative Innovation Center for Photovoltaic Science and Engineering

Sb2Se3solar cells have achieved a power conversion efficiency（PCE） of over 10%.However,the serious open-circuit voltage deficit(VOC-deificit),induced by the hard-to-control crystal orientation and heterojunction interface reaction,limits the PCE of vapor transport deposition（VTD） processed Sb2Se3solar *** overcome the VOC-deficit problem of VTD processed Sb2Se3solar cells,herein,an in-situ bandgap regulation strategy is innovatively proposed to prepare a wide band gap Sb2（S,Se）3seed layer（WBSL） at CdS/Sb2Se3heterojunction interface to improve the PCE of Sb2Se3solar *** analysis results show that the introduced Sb2（S,Se）3seed layer can enhance the [001] orientation of Sb2Se3thin films,broaden the band gap of heterojunction interface,and realize a "Spike-like" conduction band alignment withΔEc=0.11 *** addition,thanks to the suppressed CdS/Sb2Se3interface reaction after WBSL application,the depletion region width of Sb2Se3solar cells is widened,and the quality of CdS/Sb2Se3interface and the carrier transporting performance of Sb2Se3solar cells are significantly improved as ***,the harmful Se vacancy defects near the front interface of Sb2Se3solar cells can be greatly diminished by ***,the PCE of Sb2Se3solar cells is improved from 7.0% to 7.6%;meanwhile the VOCis increased to 466 mV which is the highest value for the VTD derived Sb2Se3solar *** work will provide a valuable reference for the interface and orientation regulation of antimony-based chalcogenide solar cells.

关键词： Band gap alignment Carrier transport Crystal orientation Open circuit voltage deficit Seed-layer

Multi-interface structure design of bamboo-based carbon/Co/CoO composite electromagnetic wave absorber based on biomimetic honeycomb-shaped superstructure

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2025年第3期32卷 631-644页

作者： yanting Wang He Han Huiyang Bian Yanjun Li Zhichao Lou Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources College of Materials Science and EngineeringNanjing Forestry UniversityNanjing 210037China College of Light Industry and Food Engineering Nanjing Forestry UniversityNanjing 210037China

The rapid development of 5G communication technology and smart electronic and electrical equipment will inevitably lead to electromagnetic radiation *** heterointerface polarization relaxation through nanostructure design and interface modifica-tion has proven to be an effective strategy to obtain efficient electromagnetic wave ***,this work implements an innovative method that combines biomimetic honeycomb superstructure to constrain hierarchical porous heterostructure composed of Co/CoO nano-particles to improve the interfacial polarization *** method effectively controlled the absorption efficiency of Co^(2+)through de-lignification modification of bamboo,and combined with the bionic carbon-based natural hierarchical porous structure to achieve uniform dispersion of nanoparticles,which is conducive to the in-depth construction of heterogeneous *** addition,the multiphase struc-ture brought about by high-temperature pyrolysis provides the best dielectric loss and impedance matching for the ***,the obtained bamboo-based Co/CoO multiphase composite showed excellent electromagnetic wave absorption performance,achieving excel-lent reflection loss(RL)of-79 dB and effective absorption band width of 4.12 GHz(6.84-10.96 GHz)at low load of 15wt%.Among them,the material’s optimal radar cross-section(RCS)reduction value can reach 31.9 dB·m^(2).This work provides a new approach to the micro-control and comprehensive optimization of macro-design of microwave absorbers,and offers new ideas for the high-value utiliza-tion of biomass materials.

关键词： biomass honeycomb porous heterojunction structure interfacial polarization electromagnetic wave absorption

钠离子电池正极材料MoF_6的第一性原理研究

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） 2017年第5期56卷 698-703页

作者：郑炎亭郑锋吴顺情厦门大学物理科学与技术学院福建厦门361005

基于键价力场模型构造相互作用势,勘探材料结构中势能曲面以寻找适合钠离子嵌入的空间位置;并结合第一性原理进行计算,探究了MoF_6材料在钠离子嵌入过程中的结构演变及其内在机制.预测了不同钠离子含量下NaxMoF_6-Im-3 m和NaxMoF_6-Pnm... 详细信息

基于键价力场模型构造相互作用势,勘探材料结构中势能曲面以寻找适合钠离子嵌入的空间位置;并结合第一性原理进行计算,探究了MoF_6材料在钠离子嵌入过程中的结构演变及其内在机制.预测了不同钠离子含量下NaxMoF_6-Im-3 m和NaxMoF_6-Pnma的晶体结构,并研究了不同钠离子含量下的中间相稳定性;通过分析键长和键角的变化,揭示MoF_6八面体形变、钠含量及结构稳定性等方面的关系.研究结果表明,MoF_6八面体扭曲程度对结构稳定性有明显影响,扭曲程度越低,结构的能量也越低,稳定性越好;MoF_6在嵌钠过程中体积变化程度小于15%,电压高于2.9V,表明其具有成为钠离子电池正极材料的潜力.

关键词：键价力场 MoF6 钠离子电池正极材料结构预测

中美股票市场风险传染效应分析——基于相关性结构分解

在线全文

学校读者我要写书评

暂无评论

北京工商大学学报（社会科学版） 2022年第3期37卷 85-97页

作者：郑延婷栾昕黄凤北京工商大学国际经管学院北京100048 中信期货北京分公司北京100010 北京工商大学经济学院北京100048

股票市场的“溢出效应”是学术界持续关注的热点问题。在全球政治经济格局日益复杂的当下,研究中美两国股市之间的传染效应也具有现实意义。基于2001年1月—2020年7月上证综合指数和标普500指数的日收盘价数据,运用分块混合Copula模型,... 详细信息

股票市场的“溢出效应”是学术界持续关注的热点问题。在全球政治经济格局日益复杂的当下,研究中美两国股市之间的传染效应也具有现实意义。基于2001年1月—2020年7月上证综合指数和标普500指数的日收盘价数据,运用分块混合Copula模型,对不同市场行情下中美股市之间的相关性结构进行分解并识别了风险传染方向。研究发现:中美股市之间风险传染效应在低迷与繁荣两种极端市场行情下具有非对称性;在两种极端市场行情的更迭过程中,风险传染效应以较大概率伴随出现。传染强度上,2005年以后能够检测到中美股市之间存在显著的风险传染效应,而2012—2019年传染效应达到最强。传染方向上,次贷危机之前,美国股市对中国股市存在单向风险传染;次贷危机之后,美国股市的主导地位有所减弱,中国A股一度表现出对美股的单向传染效应。因此,挖掘更多的相关性结构信息,有助于全球投资者制定精细化的风险管理方案。

关键词：中美股市相关性结构分解分块混合Copula 风险传染效应传染方向

Tuning up of chromism,luminescence in cadmium-viologen complexes through polymorphism strategy:Inkless erasable printing application

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2025年第1期36卷 322-325页

作者： yanting Yang Guorong Wang Kangjing Li Wen Yang Jing Zhang Jian Zhang Shili Li Xianming Zhang Key Laboratory of Magnetic Molecules&Magnetic Information Materials of Ministry of Education School of Chemistry and Materials ScienceShanxi Normal UniversityTaiyuan 030032China School of Chemistry Taiyuan University of TechnologyTaiyuan 030024China

In our work,polymorphism strategy has been successfully applied to tune up chromism and luminescence properties of viologen-based *** polymorphs of viologen-based complexes ofα-CdBr_(2)(PHSQ)_(2)(H_(2)O)_(2)(1)andβ-CdBr_(2)(PHSQ)_(2)(H_(2)O)_(2)(2)(PHSQ=N-(4-sulfophenyl)-4,4-bipyridinium)were synthesized by changing the *** can both respond to UV light and electricity in the manner of chromism visible to the naked eye and the coloration states have good reversibility,through which an inkless erasable printing model has been *** the coloration contrast of 1 is higher compared to ***,they both exhibit photoluminescence properties and the intensity of 1 is twice that of 2,which is accompanied by photoquenching upon continuous UV light *** only divergence of disordered/ordered O atoms in the two crystalline compounds leads to significantly different chromic and luminescent *** explorations simultaneously demonstrate that the different chromic performance between 1 and 2 should attribute to the alteration of stimulus-induced(light/electricity)electron transfer channels caused by the ordered/disordered O atoms in the complexes,which is achieved through C-H···O and O-H···O interactions to change crystal arrangement and structural rigidity,thus affect luminescent properties.

关键词： Polymorphs Photochromism Electrochromism Photoluminescence

Difference of the gut microbiota of premature ovarian insufficiency in two traditional Chinese syndromes

在线全文

学校读者我要写书评

暂无评论

Journal of Traditional Chinese Medicine 2025年第1期45卷 132-139页

作者： WU Jiaman NING Yan TAN Liya MA Fei LIN yanting ZHUO Yuanyuan Department of Traditional Chinese Medicine Shenzhen Maternity and Child Healthcare Hospital Guangzhou University of Traditional Chinese Medicine Department of Acupuncture and Moxibustion Shenzhen Traditional Chinese Medicine Hospital

PURPOSE: To investigate the differences in gut microbial characteristics between two traditional Chinese syndromes of premature ovarian insufficiency(POI). METHODS: Forty women with POI were recruited from the Department of Traditional Chinese Medicine at Shenzhen Maternity and Child Healthcare Hospital between June and December 2020. Women with POI were divided into the kidney deficiency and blood stasis syndrome(SDBS) and Qi and blood deficiency syndrome(QBDS) groups. Gut microbial community profiles were analyzed by 16S rRNA gene sequencing using an Illumina Mi Seq system. A retrospective study comparing hormone levels and gut microbiota information was performed between the SDBS and QBDS groups. RESULTS: Compared with the QBDS group, the serum levels of estradiol(E2) and anti-Müllerian hormone(AMH) were significantly decreased in the SDBS group. The quantities of Adlercreutzia, Eggerthella, Klebsiella, and Paraprevotella significantly increased in the SDBS group, whereas Lactobacillus decreased significantly. Moreover, alterations in the microbiome in the SDBS and QBDS groups were closely related to the levels of E2 and AMH. The area under the receiver operating characteristic curve for the classification of the two syndromes by the gut microbiome was 0.71. CONCLUSIONS: There were significant differences in the dominant microbiota between the SDBS and QBDS groups, and the change in Proteobacteria in the QBDS group was more significant. The characteristics of gut microbiota help us differentiate between the SDBS and QBDS groups, which may provide a basis for the objectification of TCM syndrome types.

关键词： RNA, ribosomal, 16S gastrointestinal microbiome gonadal steroid hormones primary ovarian insufficiency traditional Chinese syndromes