检索结果-南通市图书馆

社保缴费与小微企业产品技术创新关系研究——基于CMES数据调查的实证分析

在线全文

学校读者我要写书评

暂无评论

中国物价 2024年第6期 58-62页

作者：张海峰张福春中共江门市委党校经济教研室中共海南省委党校经济教研部

本文基于中国小微企业调查数据,实证分析社保缴费对小微企业产品技术创新的影响。结果表明:(1)社保缴费能够促进小微企业的产品技术创新,社保缴费规模越大,小微企业的产品技术创新程度越高;(2)社保缴费对小微企业产品技术创新的作用存... 详细信息

本文基于中国小微企业调查数据,实证分析社保缴费对小微企业产品技术创新的影响。结果表明:(1)社保缴费能够促进小微企业的产品技术创新,社保缴费规模越大,小微企业的产品技术创新程度越高;(2)社保缴费对小微企业产品技术创新的作用存在地区差异,对东部地区小微企业的产品技术创新作用显著,对中西部地区的小微企业作用不显著;(3)社保缴费与规模对产品技术创新的作用存在企业主学历差异,企业主学历为低学历组的小微企业,社保缴费与规模对产品技术创新的作用显著,高学历组作用不显著。

关键词：社保缴费小微企业产品技术创新 CMES

First-principles study on electronic structures and optical properties of the single-walled (n, 0) ZnO nanotubes

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2013年第4期56卷 706-712页

作者： DONG JunTang zhang fuchun zhang WeiHu zhang ZhiYong College of Physics and Electronic Information Yanan University Information Science and Technology Institution Northwest University

Using the first-principles calculations, we studied the geometric structures, electronic structures and optical properties of the single-walled (n, 0) ZnO nanotubes (NTs). The calculated results show that all the bind energies of the single-walled (n,0) ZnO NTs are of negative values, which indicate that the ZnO NTs can exist stably as single-walled NTs. While the calculated results of electronic structure indicate that the single-walled (n,0) ZnO NTs are a type of direct wide band-gap semiconductor materials, the whole valence bands are spread and drift to low-energy direction with the increase of the NT diameter. The defect energy levels caused by quantum size and surface effects emerge on the top of the valence bands. Furthermore, the calculated results of optical properties reveal that the dielectric peaks have a blue shift and the edge of absorption band corresponds to ultraviolet band with the decrease of the NT diameter. The single-walled (n, 0) ZnO NTs can be applied to ultraviolet semiconductor systems.

关键词： ZnO first-principles nanotube properties

老年髋部骨折患者住院期间发生术后心力衰竭的列线图预测模型的构建及验证

在线全文

学校读者我要写书评

暂无评论

北京大学学报（医学版） 2024年第5期56卷 874-883页

作者：刘园梅傅义程郝靖欣张福春刘慧琳北京大学第三医院老年内科北京100191

目的:构建预测老年髋部骨折患者住院期间发生术后心力衰竭(postoperative heart failure, PHF)的列线图预测模型并验证其效能。方法:采用回顾性队列研究设计,将2015年7月至2023年12月在北京大学第三医院住院接受手术治疗的老年髋部骨折... 详细信息

目的:构建预测老年髋部骨折患者住院期间发生术后心力衰竭(postoperative heart failure, PHF)的列线图预测模型并验证其效能。方法:采用回顾性队列研究设计,将2015年7月至2023年12月在北京大学第三医院住院接受手术治疗的老年髋部骨折患者(≥65岁)纳入研究,以2015年7月至2021年12月入院的患者为开发队列,以2022年1月至2023年12月入院的患者为验证队列,通过电子病历系统收集患者的临床资料。采用单因素及多因素Logistic回归分析筛选老年髋部骨折患者PHF的预测因素,并通过R语言构建列线图预测模型,采用Bootstrap方法进行内外部验证。分别采用受试者工作特征(receiver operating characteristic, ROC)曲线下面积(area under the curve, AUC)、校准曲线、Hosmer-Lemeshow拟合优度检验、决策曲线分析(decision curve analysis, DCA)评价模型的区分度、校准度和临床适用性。结果:开发队列共944例患者,其中54例(5.7%)住院期间发生PHF;验证队列共469例患者,其中18例(3.8%)住院期间发生PHF。多因素Logistic回归分析显示,年龄(OR=1.071, 95%CI:1.019~1.127,P=0.008)、合并心脏病史(OR=5.360, 95%CI:2.808~10.234,P<0.001)、术前血红蛋白(OR=0.979, 95%CI:0.960~0.999,P=0.041)、术前血肌酐(OR=1.007, 95%CI:1.001~1.013,P=0.015)、髋关节置换术(OR=2.513, 95%CI:1.259~5.019,P=0.009)和全身麻醉(OR=2.024, 95%CI:1.053~3.890,P=0.034)是老年髋部骨折患者发生PHF的独立预测因素。基于4个术前预测因素构建列线图预测模型,模型内外部验证的AUC值分别为0.818(95%CI:0.768~0.868)、0.873(95%CI:0.805~0.929),显示其预测效能良好。校准曲线和Hosmer-Lemeshow拟合优度检验(内部验证χ^(2)=9.958,P=0.354;外部验证χ^(2)=5.477,P=0.791)显示模型的预测准确性较高。DCA表明该模型具有一定的临床适用性。结论:本研究建立了一个简单易用的术前列线图预测模型,可有效预测老年髋部骨折患者发生PHF的风险,有助于早期识别PHF高危患者,优化围手术期管理。

关键词：老年人髋部骨折心力衰竭列线图

Exact solution to a class of generalized Kitaev spin-1/2 models in arbitrary dimensions

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2020年第4期63卷 125-135页

作者： JianJian Miao HuiKe Jin fuchun zhang Yi Zhou Kavli Institute for Theoretical Sciences University of Chinese Academy of SciencesBeijing 100190China Department of Physics Zhejiang UniversityHangzhou 310027China CAS Center for Excellence in Topological Quantum Computation University of Chinese Academy of SciencesBeijing 100190China Collaborative Innovation Center of Advanced Microstructures Nanjing UniversityNanjing 210093China Beijing National Laboratory for Condensed Matter Physics&Institute of Physics Chinese Academy of SciencesBeijing 100190China

We construct a class of exactly solvable generalized Kitaev spin-1/2 models in arbitrary dimensions, which is beyond the category of quantum compass models. The Jordan-Wigner transformation is employed to prove the exact solvability. An exactly solvable quantum spin-1/2 model can be mapped to a gas of free Majorana fermions coupled to static Z2 gauge fields. We classify these exactly solvable models according to their parent models. Any model belonging to this class can be generated by one of the parent models. For illustration, a two dimensional(2D) tetragon-octagon model and a three dimensional(3D) xy bond model are studied.

关键词： exactly solvable models Kitaev honeycomb model quantum spin liquid

A first-principles study of the size-dependent electronic properties of SiC nanotubes

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2010年第7期53卷 1333-1338页

作者： zhang WeiHu zhang fuchun zhang ZhiYong LU ShuYuan YANG YanNing Xi’an Institute of Optics and Precision Mechanics Chinese Academy of SciencesXi’an 710068China Graduate University of Chinese Academy of Sciences Beijing 100049China College of Physics and Electronic Information Yan’an UniversityYan’an 716000China College of Information Science and Technology Northwest UniversityXi’an 710127China Department of Telecommunications Xi’an Institute of Posts and TelecommunicationsXi’an 710121China

We investigate the structural and electronic properties of SiC nanotubes(NTs) with hexagonal cross sections by a first-principles calculation using plane-wave ultra-soft pseudo-potential technology based on the density-functional *** results reveal that surface-layer C and Si atoms relax significantly upon decreasing the tube-wall thickness because of surface-size and quantum-size *** also find that all relaxed SiC NTs stay stably on the nanoscale because of an admixture of sp2 and sp3 hybridization between C and Si atoms and a strong covalent,and that the band gap tends to decrease with increasing tube-wall *** calculations further indicate that both C and Si atoms on the inner and outer surface of SiC NTs contribute to defect states at the top of the valence band and at the bottom of the conduction *** results provide reference information for a thorough understanding of the properties of SiC nanostructures and also enable more precise monitoring and control of the growth of SiC nanostructures.

关键词： density function theory SiC nanotube electronic properties quantum-size effects

Computational exploration and screening of novel Janus MA2Z4 (M = Sc–Zn, Y–Ag, Hf–Au;A=Si, Ge;Z=N, P) monolayers and potential application as a photocatalyst

在线全文

学校读者我要写书评

暂无评论

Frontiers of physics 2022年第6期17卷 51-61页

作者： Weibin zhang Woochul Yang Yingkai Liu Zhiyong Liu fuchun zhang College of Physics and Electronics Information Yunnan Key Laboratory of Opto-Electronic Information TechnologyKey Laboratory of Advanced Technique&Preparation for Renewable Energy Materials-Ministry of EducationYunnan Normal UniversityKunming 650500China College of Physics and Electronic Information Yan’an UniversityYan’an 716000China Department of Physics Dongguk UniversitySeoul 04620Republic of Korea

By high-throughput calculations,13 thermally and environmentally stable Janus MA_(2)Z_(4) monolayers were screened from 104 types of *** 13 stable monolayers have very high charge carrier concentrations(×10^(15) cm^(–2)),which are better than those of the well-known graphene and TaS_(2).Because of their excellent conductivity,the 6 monolayers with band gaps less than 0.5 eV are identified as potential electrode materials for hydrogen evolution reaction *** potential applications as photoelectric or photocatalytic materials,bandgaps(Eg-HSE)higher than 0.5 eV remained,which resulted in 7 potential *** on optical absorption analysis in the visible-light range,H-HfSiGeP_(4) and HMoSiGeP_(4) have higher absorption ability and optical conductivity,which is quite impressive for optoelectronic,solar cell device,and photocatalysis ***,the transmittance coefficient of Janus MA_(2)Z_(4) monolayers is approximately 70%–80%in the visible-light range,which implies that these monolayers show good light *** potential applications as photocatalysts,the redox potential and charge effective mass analysis indicate that H-HfSiGeP_(4),HMoSiGeP_(4),T-ScSiGeN_(4),and T-ZrSiGeN_(4) are suitable photocatalysts for CO_(2) reduction *** high-throughput identification,13 types of new and stable Janus MA2Z4 monolayers were explored,and the basic properties and potential applications were investigated,which can reduce the time for experiments and provide basic data for the material genome initiative.

关键词： Janus MA2Z4 high-throughput identification charge carrier concentration electronic structure optical properties

在线全文

学校读者我要写书评

暂无评论

企业家创新精神与小微企业创新关系研究

新乡学院学报 2024年第7期41卷 28-36,48页

作者：张海峰张福春董法尧中共江门市委党校经济教研室广东江门529000 中共海南省委党校经济教研部海南海口571101 中共成都市委党校马克思主义学院四川成都610110

小微企业创新能力的提升对于促进就业、科技进步、增强经济活力具有不可替代的作用。以中国小微企业调查数据(CMES)为研究样本,通过构建二元Logistic模型,实证分析企业家创新精神对小微企业创新的多维度影响,并进一步探究企业地区、品... 详细信息

小微企业创新能力的提升对于促进就业、科技进步、增强经济活力具有不可替代的作用。以中国小微企业调查数据(CMES)为研究样本,通过构建二元Logistic模型,实证分析企业家创新精神对小微企业创新的多维度影响,并进一步探究企业地区、品牌及创新程度异质性对小微企业创新促进效应的影响差异。研究结果表明:企业家创新精神对小微企业的产品技术创新、其他类型创新、专利申请均有显著促进作用,但是从匹配估计结果看促进效应存在高估的情况;企业家创新精神对小微企业创新的促进影响并不存在显著地区差异,与有自有品牌的小微企业相比,无自有品牌小微企业企业家创新精神对产品技术创新、其他创新的促进效应更大,但对专利申请的促进效应并不显著;创新投入对不同程度的企业创新均产生正向影响,而且随着创新程度的提高,创新投入的积极促进效应也相应增大。研究结果为精准解决小微企业创新面临的问题和困境提供证据,同时也为制定小微企业创新发展政策,因地制宜、分类施策提供理论依据。

关键词：企业家创新精神小微企业企业创新

在线全文

学校读者我要写书评

暂无评论

基于YOLOv7的交通目标检测算法研究

计算机测量与控制 2024年第4期32卷 74-80页

作者：王沛雪张富春董晨乐延安大学物理与电子信息学院陕西延安716000

针对交通场景中,由于光照、遮挡、目标小以及背景复杂等因素导致目标检测精度低,易出现漏检和误检问题的情况,提出了一种基于YOLOv7的交通目标检测算法;该算法在主干网络中融入多头注意力机制,以增强网络特征学习能力,从而更好地捕获数... 详细信息

针对交通场景中,由于光照、遮挡、目标小以及背景复杂等因素导致目标检测精度低,易出现漏检和误检问题的情况,提出了一种基于YOLOv7的交通目标检测算法;该算法在主干网络中融入多头注意力机制,以增强网络特征学习能力,从而更好地捕获数据和特征内部的相关性;在YOLOv7颈部网络引入协调注意力模块(CA),将位置信息嵌入到注意力机制中,忽略无关信息的干扰,以增强网络的特征提取能力;增加一个多尺度检测网络,以增强模型对不同尺度目标的检测能力;将CIoU损失函数更改为SIoU函数,以减少模型收敛不稳定问题,提高模型的鲁棒性;实验结果表明,改进的算法在BDD100K公开数据集上的检测精度和速度分别达到了59.8%mAP和96.2 FPS,相比原算法检测精度提高了2.5%;这表明改进的算法在满足实时性要求的同时,具备良好的检测精度,适用于复杂情况下的交通目标检测任务。

关键词：交通目标检测 YOLOv7网络注意力机制浅层网络检测层 SIoU损失函数

The Motion Planets Detection and Tracking Algorithm Based on Gestalt Principle

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Electronics 2018年第4期27卷 808-812页

作者： QIU Shi TANG Ying zhang Wenbo FENG Jun zhang fuchun LI Chen Xi'an Institute of Optics and Precision Mechanics of CAS Chengdu University of Technology College of Information Science & Technology School of Electronic Engineering Xidian University School of Information Science and Technology Engineering Northwestern University Department of Aviation Theory Aviation University of Air Force Institute of Deep-sea Science and Engineering Chinese Academy of Sciences

The moving planets have a few of pixels which can lead to lacking enough image characteristics when tracking them. So we propose the motion planets detection and tracking algorithm based on gestalt principle. We structure Gaussian mixture model to detect the motion area from the visual cognition perspective, and use astronomy images graphics characteristics to confirm the planet position. Then we propose space-time fusion model for tracking planet. All the experiments use 1000 16-bitframe images of wide view CCD camera which contain 5684 motion planets in total. The results show that our algorithm reaches an accuracy of 94% and has robustness.

关键词： The moving planets Gestalt principle Tracking