检索结果-南通市图书馆

骨髓脂肪对骨转移的影响及磁共振成像定量评估

在线全文

学校读者我要写书评

暂无评论

中国组织工程研究 2025年第1期29卷 128-135页

作者：谢青霖张晓东南方医科大学第三附属医院(广东省骨科研究院)影像科广东省广州市510630

背景:早期骨转移的准确诊断对治疗方案和预后有着至关重要的作用。骨活检是骨转移诊断的金标准,但由于有创且标本尺寸小等缺点,在实际临床工作中难以落实。近年来,随着MRI技术的不断发展,磁共振定量成像技术如磁共振波谱成像、基于化学... 详细信息

背景:早期骨转移的准确诊断对治疗方案和预后有着至关重要的作用。骨活检是骨转移诊断的金标准,但由于有创且标本尺寸小等缺点,在实际临床工作中难以落实。近年来,随着MRI技术的不断发展,磁共振定量成像技术如磁共振波谱成像、基于化学移位编码的水脂肪成像等被广泛应用于骨转移的诊断,衍生的标志物包括表信号脂肪分数和质子密度脂肪分数,均能反映骨髓脂肪含量。目前,对于骨髓脂肪在骨转移瘤发生中的作用已经成为了人们关注的新焦点。目的:现就骨髓脂肪对骨转移的影响及磁共振成像定量评估技术进行综述,归纳比较不同磁共振脂肪定量技术评估骨转移的优劣势以及临床应用情况。方法:应用计算机在PubMed和中国知网数据库检索相关文献,英文检索词为“bone metastases,bone marrow adipocytes,magnetic resonance imaging,quantitative MRI,fat fraction,magnetic resonance spectrum,chemical shift encoding-based water–fat imaging”,中文检索词为“骨转移,骨髓脂肪,磁共振成像,定量磁共振成像,脂肪分数,磁共振波谱成像,基于化学移位编码的水脂肪成像”,根据纳入和排除标准共获得相关文献67篇。结果与结论:(1)骨髓脂肪细胞能通过分泌多种相关激素及细胞因子、为肿瘤细胞提供能量、诱导破骨细胞分化等多种途径协助骨转移的发生;(2)磁共振定量技术能够精确地定量脂肪组织,测量骨髓中脂肪含量的变化有助于骨转移的诊断;(3)磁共振波谱成像能够通过不同质子的进动频率反映不同的代谢产物,因此可用于脂肪定量,是目前用于评估转移性骨折的一种辅助检查手段;(4)基于化学移位编码的水脂肪成像可以使水和脂肪信号得以在正相位和反相位相分离,从而测量脂肪组织的信号,在鉴别椎体良恶性骨折方面具有较高的敏感性、特异性和准确性。

关键词：骨转移骨髓脂肪磁共振成像磁共振波谱成像基于化学移位编码的水脂肪成像综述

在线全文

学校读者我要写书评

暂无评论

红皮洋葱新品种红鼎936 F_(1)

长江蔬菜 2025年第1期 22-23页

作者：谢彬张家口市张北县农业农村局河北张家口076150

红鼎936F_(1)是长日照中早熟杂交一代红皮洋葱品种,由荷兰安莎种子集团公司(ENZAZADEN)选育。成熟期110~115天。鳞茎近圆球形,较紧实,整齐度较好,外皮深红至浅紫红色,光泽度好,外皮不易脱落,耐贮藏,较耐枯萎病,适合鲜食及加工出口。其... 详细信息

红鼎936F_(1)是长日照中早熟杂交一代红皮洋葱品种,由荷兰安莎种子集团公司(ENZAZADEN)选育。成熟期110~115天。鳞茎近圆球形,较紧实,整齐度较好,外皮深红至浅紫红色,光泽度好,外皮不易脱落,耐贮藏,较耐枯萎病,适合鲜食及加工出口。其主要栽培措施包括育苗及苗期管理、适时移栽、田间管理、病虫害防治和收获等。

关键词：洋葱红鼎936F_(1) 红皮杂交种

在线全文

学校读者我要写书评

暂无评论

基于最大影响力集合的主动学习方法

计算机科学 2025年第1期52卷 289-297页

作者：李雅和谢志鹏复旦大学计算机科学技术学院上海200438

随着深度学习技术的不断进步,其已经在许多领域广泛应用。但深度模型的训练需要消耗大量标注数据,时间与资源成本高,如何利用尽可能少的标注数据达到最佳模型效果成为一个重要的研究课题。主动学习的提出正是为了解决这一问题,其旨在选... 详细信息

随着深度学习技术的不断进步,其已经在许多领域广泛应用。但深度模型的训练需要消耗大量标注数据,时间与资源成本高,如何利用尽可能少的标注数据达到最佳模型效果成为一个重要的研究课题。主动学习的提出正是为了解决这一问题,其旨在选择最有价值的样本进行标注并用于模型训练。传统的主动学习策略通常关注不确定性或多样性,旨在查询最困难或最具代表性的样本。然而,在主动学习问题中,这些方法通常没有考虑标注样本和无标注样本之间的交互作用。另一类主动学习方法则使用辅助网络进行样本选择,但这些方法通常会增加计算复杂度。在上述背景下,提出一种新的主动学习算法,旨在通过考虑不同样本之间的相互作用,综合衡量候选样本对其他样本的影响力与不确定性,来最大限度地提高模型的整体性能增益。所提算法首先根据样本隐含层表征之间的距离估计样本相互之间的影响力,进一步根据候选样本的影响力与无标注样本的不确定性估计该样本能够带来的潜在增益,并迭代地选择全局增益最大的样本进行标注。进一步在一系列不同领域的多种任务上将该方法与其他主动学习策略进行了比较,实验结果表明,该方法在所有任务中的表现均显著优于所有基线方法。进一步的量化分析实验也证明该方法在不确定性和多样性之间取得了良好的权衡,并探究了主动学习不同阶段应该注重的因素。

关键词：主动学习深度学习不确定性

高速公路对绿色经济效率的影响分析--基于产业结构优化视角

在线全文

学校读者我要写书评

暂无评论

生态经济 2025年第1期41卷 114-122页

作者：樊建强谢靖雯长安大学经济与管理学院陕西西安710064

当前中国高速公路建设布局日趋完善,探究如何发挥其对地区产业结构优化的有力支持,进而助力绿色经济发展转型具有重要意义。论文基于2006—2019年中原城市群27个城市的面板数据,运用超效率SBM模型测算其绿色经济效率,从产业结构优化的... 详细信息

当前中国高速公路建设布局日趋完善,探究如何发挥其对地区产业结构优化的有力支持,进而助力绿色经济发展转型具有重要意义。论文基于2006—2019年中原城市群27个城市的面板数据,运用超效率SBM模型测算其绿色经济效率,从产业结构优化的视角实证分析了高速公路对绿色经济效率的影响,并以产业结构优化为中介与门槛变量,进一步探讨产业结构优化对于高速公路影响绿色经济效率的门槛效应。研究结果表明:中原城市群高速公路与绿色经济效率间呈现先抑制后促进的“U”型关系;产业结构优化在高速公路和绿色经济效率间发挥部分中介作用;产业结构优化存在单一门槛效应,随着产业结构优化水平的提升,高速公路对绿色经济效率由抑制作用转为促进作用。

关键词：绿色经济效率高速公路产业结构优化超效率SBM 中原城市群

Turbulent Agglomeration of Microparticles in a Cylinder Wake Flow Using LES-DEM:Focusing on the Effect of the Reynolds Number

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2025年第1期 34-49页

作者： WANG Shuang MU Lin LI Xue xie Jun DONG Ming School of Energy and Power Engineering Dalian University of Technology School of Optical Information and Energy Engineering Wuhan Institute of Technology School of Energy and Environment Shenyang Aerospace University

Turbulent agglomeration is viewed as a promising technology for enhancing fine particle removal *** better understand particle transport,agglomeration behaviors,and fluid-particle interactions,we numerically explored these phenomena under cylindrical vortex wake influence using a coupled large eddy simulation and discrete element method（LES-DEM） *** validity of the LES approach was verified by comparison with available direct numerical simulation（DNS） *** adopted the Johnson-Kendall-Roberts（JKR） contact model for particle-particle *** particle dispersion and agglomeration characteristics of particles with different diameters（dp=2-20 μm） in the laminar and transition of shear layer（TrSL） flow regimes were *** particles were concentrated at the vortex centers,while larger particles accumulated around the *** agglomeration efficiency exhibited an M-shaped profile spanwise（y-direction）.With increasing Reynolds number,the agglomeration efficiency and turbulence intensity *** particle agglomeration efficiency peaks at a certain Reynolds ***,at higher Reynolds numbers,reducing the residence time of particles in the flow field decreases the agglomeration efficiency.

关键词：

Spatial Sound——History, Principle,Progress and Challenge

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Electronics 2020年第3期29卷 397-416页

作者： xie Bosun Acoustic Laboratory School of Physics and Optoeletronics South China University of Technology

The aim of spatial sound or spatial audio is to reproduce the spatial information of sound,so as to recreate the desired spatial auditory events or perceptions. Recently, spatial sound becomes a hot topic in the fields of acoustics, signal processing, and communication. A series of spatial sound techniques have been developed and applied to a wide area of scientific research, engineering, and amusement. The history, principle, progress and applications of spatial sound technique are comprehensively reviewed in this article. Especially, spatial sound techniques based on different principles are united within the framework of spatial sampling and reconstruction theorem of sound *** challenges and prospects of spatial sound are also addressed.

关键词： Spatial hearing Spatial sound Sound reproduction

Modelling the Dropout Patterns of MOOC Learners

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Tsinghua Science and Technology 2020年第3期25卷 313-324页

作者： Zheng xie the College of Liberal Arts and Sciences National University of Defense Technology

We conduct a survival analysis for the viewing durations of massive open online *** hazard function of the empirical duration data presents as a bathtub curve with the Lindy effect in its *** understand the evolutionary mechanisms underlying these features,we categorize learners into two classes based on their different distributions of viewing durations,namely lognormal distribution and power law with exponential *** random differential equations are provided to describe the growth patterns of viewing durations for the two classes *** expected duration change rate of the learners featured by lognormal distribution is supposed to be dependent on their past duration,and that of the remainder of learners is supposed to be inversely proportional to *** to the equations predict the features of viewing duration distributions,and those of the hazard *** equations also reveal the features of memory and memorylessness for the respective viewing behaviors of the two classes.

关键词： data science applications in education distance education and online learning evaluation methodologies

Reviews of clean coal conversion technology in China:Situations & challenges

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Engineering 2021年第7期34卷 62-69页

作者： Kechang xie State Key Laboratory of Clean and Efficient Coal Utilization Key Laboratory of Coal Science and Technology(Taiyuan University of Technology)Ministry of EducationTaiyuan 030024China

It is important to develop the advanced coal to chemicals industry(ACCI)against a backdrop of coal-based energy structures,excessive imported oil and natural gas,and strict environmental constraints in *** this study,the technology and industry of China’s ACCI are reviewed to explain the effect of using coal to replace oil and natural gas,and the corresponding resource and environmental burdens that this will *** trends in technology and industry are also proposed to explore future *** review shows that although excellent progress has been made on an industrial scale,demonstrative level,and in terms of technology and equipment,the lack of strategic understanding,severe external constraints,partly underdeveloped technologies,and weak foundations must be immediately ***,it is necessary to clarify the importance that the ACCI has on the energy revolution and energy *** on technological innovation,a variety of external factors should be considered as a whole with emphasis on filling the knowledge gap of theoretical foundations and industry standards to support high-quality development for ACCI.

关键词： Advanced coal to chemicals industry Strategic understanding Clean energy

Short Annealing:a Shortcut for Efficient Perovskite Solar Modules

在线全文

学校读者我要写书评

暂无评论

材料导报 2020年第20期34卷 20003-20004页

作者： xie Jiale Institute of Photovoltaics Southwest Petroleum UniversityChengdu 610500P.R.China

Photo of a minimodule and its electroluminescence in dark captured by an infrared responsive camera under a forward bias of 12 V.(b)The I-V curves of a small cell(8 mm 2)and a minimodule(21.5 cm 2)under AM1.5 illumination.(c)The efficiency of a minimodule under different illumination intensity.(d)The V OC of devices as a function of illumination intensity with perovskite films annealed for 3 min during an aging period of 0 days,3 days,9 days,and 20 days.(e)XRD patterns of perovskites annealed for 3 min and 20 min before and after aging.

关键词： aging illumination annealed