晶体管单管放大电路实验中出现的问题及改进措施

在模拟电子技术的共射极单管放大电路实验中,出现与理论不相符的现象,在输入为正弦交流信号的情况下,输出端却观察不到同频率的放大的正弦交流信号,取而代之的是一调幅信号.通过对实验系统的观察分析,发现出现这种现象是因为实验板的较宽的铜箔导线之间存在分布电容.由此确定实验系统的改进措施,即在三极管的基极和射极之间加一电容,最终问题得以解决.     

中国现行高校学生资助政策评估

2007年,国务院发布了《关于建立健全普通本科高校高等职业学校和中等职业学校家庭经济困难学生资助政策体系的意见》。本文基于简单随机样本,运用非参数和半参数等方法对我国现行高校学生资助政策予以评估,考察各种类型学生资助的分配情况。研究发现:政府资助在不同大学间公平分配,同时在学校内部分配时能够惠及家庭经济困难学生;与此相反,大学资助和社会资助不能完全惠及家庭经济困难学生。此外,在最具选择性大学就读的学生得到了更多的学生资助而支付更低的学费。最后,还有相当比例的家庭经济困难学生没有得到任何资助。     

组织结构视角下我国学术会议绩效评价管理研究

近年来随着我国学术会议活动规模和公共经费支持力度不断攀升,亟需建立起长期化、科学化、规范化的学术会议评价机制来保障会议质量,提升会议绩效。当前学术会议评价管理研究中缺乏一种系统性的分析视角和框架,因此对学术会议的绩效内涵、生成方式及评价管理要点缺乏系统性梳理。本研究从新组织结构学派分析视角出发,首先明确了学术会议作为一类组织的特征要素,并对学术会议组织结构中主要功能模块及其关系进行了分析。进而,本文对学术会议组织的绩效内涵及典型组织绩效的生成步骤加以厘清。在此基础上,我们对组织结构类型与学术会议类型间的对应关系进行了分析,并明确了不同类型学术会议的绩效管理评价中的要素、要点和方法工具。     

科技创新政策文本本体设计与标注应用研究

[目的/意义]旨在为提升政策文本的自动化处理程度提供参考。[方法/过程]在梳理已有政策本体及其构建方式基础上,提出由词汇语义主导的自下而上的本体构建方法,运用本体构建工具Protégé5.5.0构建科技创新政策文本本体,对部分政策内容进行标注并可视化。[结果/结论]该本体适用于科技创新政策文本的结构化语义抽取,能够在一定程度上揭示科技创新政策的结构化语义特征。     

思政融入“电工电子学”课程的研究和探索

针对电工电子学课程的教学特点和教学内容,设计和改进教学方法和手段,将思政元素有机地融入每堂课的教学,探索了该课程与思政教育的结合方式,挖掘本课程能够结合“思政”的切入点和教育资源,建立了全过程、全方位、有案例的“课程思政”体系。教学实践证明这些改革和探索达到了较好的教学效果。     

初探核心素养课改背景下的高中英语概要写作教学

在核心素养课改背景下的高中英语教学中,越来越重视对学生能力的培养,在高中英语写作教学中逐渐加强了对概要写作方式的重视程度,概要写作主要是指对文章内容进行简要概括,体现出文章中的大意和中心,进而使一些概括性较强的词或者是语句得以呈现。     

“互联网+”时代背景下“科研思路与方法”教学模式探讨

当前,国家对大学本科的教育愈发重视,提出了多种教改方案。面对“互联网+”快速发展的形势,文章分析了“互联网+”时代背景下“科研思路与方法”新型教学模式的优势以及如何高效率地构建。通过教师、学生、互联网三者协调配合以及师生的线上互动交流和讨论,可以充分调动学生独立思考、自主学习的积极性,同时增加了教学趣味性,提高了教学质量。     

Electro-mechanically controlled assembly of reconfigurable 3D mesostructures and electronic devices based on dielectric elastomer platforms

The manufacture of 3D mesostructures is receiving rapidly increasing attention, because of the fundamental significance and practical applications across wide-ranging areas. The recently developed approach of buckling-guided assembly allows deterministic formation of complex 3D mesostructures in a broad set of functional materials, with feature sizes spanning nanoscale to centimeter-scale. Previous studies mostly exploited mechanically controlled assembly platforms using elastomer substrates, which limits the capabilities to achieve on-demand local assembly, and to reshape assembled mesostructures into distinct 3D configurations. This work introduces a set of design concepts and assembly strategies to utilize dielectric elastomer actuators as powerful platforms for the electro-mechanically controlled 3D assembly. Capabilities of sequential, local loading with desired strain distributions allow access to precisely tailored 3D mesostructures that can be reshaped into distinct geometries, as demonstrated by experimental and theoretical studies of ∼30 examples. A reconfigurable inductive–capacitive radio-frequency circuit consisting of morphable 3D capacitors serves as an application example.     

Rapid phenotypic evolution with shallow genomic differentiation during early stages of high elevation adaptation in Eurasian Tree Sparrows

Known as the ‘third polar region’, the Qinghai-Tibet Plateau represents one of the harshest highland environments in the world and yet a number of organisms thrive there. Previous studies of birds, animals and humans have focused on well-differentiated populations in later stages of phenotypic divergence. The adaptive processes during the initial phase of highland adaptation remain poorly understood. We studied a human commensal, the Eurasian Tree Sparrow, which has followed human agriculture to the Qinghai-Tibet Plateau. Despite strong phenotypic differentiation at multiple levels, in particular in muscle-related phenotypes, highland and lowland populations show shallow genomic divergence and the colonization event occurred within the past few thousand years. In a one-month acclimation experiment investigating phenotypic plasticity, we exposed adult lowland tree sparrows to a hypoxic environment and did not observe muscle changes. Through population genetic analyses, we identified a signature of polygenic adaptation, whereby shifts in allele frequencies are spread across multiple loci, many of which are associated with muscle-related processes. Our results reveal a case of positive selection in which polygenic adaptation appears to drive rapid phenotypic evolution, shedding light on early stages of adaptive evolution to a novel environment.     

北京高校图书馆读者工作研讨会综述

2007年5月16-17日,由北京高校图工委和中国人民大学图书馆共同主办的北京高校图书馆读者工作研讨会在北京召开,28家高校图书馆的近百名代表参加了会议.……