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经历建模过程,体验模型思想——《得数在5以内的加法》教学与思考
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作者 包建红 《教育视界》 2023年第35期56-58,共3页
模型意识的培育需要从低年级开始不断渗透模型思想,让学生在熟悉的生活、活动场景中发掘并提出适宜的数学问题,将具体的问题用数学语言表达出来,进而解决一类数学问题,把握其中一般的数量关系或空间形式。教学《得数在5以内的加法》,除... 模型意识的培育需要从低年级开始不断渗透模型思想,让学生在熟悉的生活、活动场景中发掘并提出适宜的数学问题,将具体的问题用数学语言表达出来,进而解决一类数学问题,把握其中一般的数量关系或空间形式。教学《得数在5以内的加法》,除了要让学生在具体的生活情境中初步理解加法的含义,还要引导他们经历建模的过程,感受其中的模型思想。 展开更多
关键词 得数在5以内的加法》 数学建模 模型思想 模型意识
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开放空间,让学生“飞”起来——“得数是10的加法和10减几”案例分析
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作者 陈红珍 《学周刊(下旬)》 2015年第3期161-161,共1页
"得数是10的加法和10减几"是义务教育教科书第一册第66-67页的内容。本课内容学习之前,学生已经比较熟练地掌握10的组成,并且通过一图四式的学习,初步认识了加减法的含义和加减法算式之间的联系。过去传统的教学注重书本知识... "得数是10的加法和10减几"是义务教育教科书第一册第66-67页的内容。本课内容学习之前,学生已经比较熟练地掌握10的组成,并且通过一图四式的学习,初步认识了加减法的含义和加减法算式之间的联系。过去传统的教学注重书本知识的传授,强调学生接受学习、机械训练,对学生获取新知的能力、分析和解决问题的能力却没有起到作用。而新课程则提倡学生主动参与、乐于探索、勤于动手,即要改变学生的数学学习方式,让学生积极、主动地探索,并发现问题、解决问题、发现数学的规律。 展开更多
关键词 得数 10的加减法
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《得数在5以内的加法》教学设计
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作者 胡媛媛 《今天》 2020年第19期122-122,211,共2页
1.知识积累出卡片游戏:小朋友,前段时间我们一起学习了分与合的知识,下面,老师随意抽出两张数字卡片,请你快速地说出它们合成几。【设计意图:以5以内的合成复习导入,为下面5以内的加法计算作好准备。】
关键词 得数 加法 教学设计
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准确把握切入点 拓展学生思维——珠心算结合教学《得数是7的加减法》教例评析
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作者 蒙仙花 《广西教育》 2004年第04A期36-37,共2页
关键词 珠心算结合教学 教学结构 得数是7的加减法》 教学案例 评析 小学 数学教学
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如何看待学生“凑得数”
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作者 王俊 曹娟 《中小学数学(小学版)》 2005年第1期38-39,共2页
四年级数学试卷上最后出了这样一道思考题:小明和小红共有200张画片,小明比小红的2倍少加张,小明和小红各有多少张画片?
关键词 四年级 思考题 小学 数学 列式计算 “凑得数 应用题 数量关系
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弯槽段冰塞形成及其厚度分布的试验研究 被引量:10
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作者 王军 高月霞 +2 位作者 尹运基 郭力文 赵慧敏 《冰川冻土》 CSCD 北大核心 2007年第5期764-769,共6页
河流冰塞是寒冷地区河流的共性问题,弯槽段易于卡封是客观存在的现象,但对其形成机理的认识尚有待探索.借助于实验室的试验水槽,通过改变水流条件和冰流量条件,研究了弯槽段冰塞形成和厚度分布的规律.结果表明:当弯槽段先铺有模拟冰盖时... 河流冰塞是寒冷地区河流的共性问题,弯槽段易于卡封是客观存在的现象,但对其形成机理的认识尚有待探索.借助于实验室的试验水槽,通过改变水流条件和冰流量条件,研究了弯槽段冰塞形成和厚度分布的规律.结果表明:当弯槽段先铺有模拟冰盖时,初始冰塞头部向下游推进的速度随水流的Fr增加而增加;当在弯槽尾部加上模拟的初封条件时,水流条件的变化可以产生冰塞发展的两种不同顺序,提出了实验室条件下的弯槽段冰塞体形成与否的临界Fr数. 展开更多
关键词 冰塞 厚度分布 冰塞堆积顺序 佛汝得数 临界值
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水平旋转圆筒表面对流质交换准则关联式
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作者 马洪亭 张于峰 邓娜 《哈尔滨工业大学学报》 EI CAS CSCD 北大核心 2008年第2期314-318,共5页
为研究高葛拉晓夫数下水平旋转圆筒表面稳定传质状态下局部舍伍得数、旋转雷诺数、高葛拉晓夫数和施米特数之间的关系,用特制的微型热偶式干湿球温度计和量热计对圆筒表面的温度边界层和浓度边界层进行了测试,发现了旋转对于圆筒表面顺... 为研究高葛拉晓夫数下水平旋转圆筒表面稳定传质状态下局部舍伍得数、旋转雷诺数、高葛拉晓夫数和施米特数之间的关系,用特制的微型热偶式干湿球温度计和量热计对圆筒表面的温度边界层和浓度边界层进行了测试,发现了旋转对于圆筒表面顺向侧和逆向侧对流传质的影响特点,揭示了局部对流质交换系数h和平均对流质交换系数h随旋转转雷诺数Rer变化的规律.根据实验数据,归纳和整理出了稳定传质状态下水平旋转圆筒表面的准则关联式及临界雷诺数Rer,cri的判别式. 展开更多
关键词 水平旋转圆筒 对流质交换 平均舍伍得数Sh 准则关联式
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大空间建筑顶部送风系统模型试验自模区的试验判定
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作者 张治 余宇锋 熊翰林 《暖通空调》 北大核心 2010年第1期115-118,共4页
以某地下大型厂房为例,把弗劳德数转化成具有相同物理意义的热量阿基米得数,对顶部送风系统模型试验所测的数据运用数理统计的方法进行适当的处理与分析,得出了模型与原型的气流流动都处于弗劳德数自模区的重要结论。
关键词 大空间建筑 顶部送风 模型试验 弗劳德数 热量阿基米得数 自模区
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消力池水跃消能试验分析 被引量:3
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作者 邸国平 李治勤 《山西水利科技》 2010年第3期11-12,共2页
通过对水库溢洪道进行水工模型试验,从原方案到修改方案进行了消力池体型尺寸修改和加设消能工的多次试验,提出方案五为最优方案,并从跃前弗汝得数与消能系数的关系上论证了最优方案的合理性。
关键词 消力池 弗汝得数 消能系数 水跃
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Prediction of Subcellular Localization of Eukaryotic Proteins Using Position-Specific Profiles and Neural Network with Weighted Inputs 被引量:3
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作者 邹凌云 王正志 黄教民 《Journal of Genetics and Genomics》 SCIE CAS CSCD 北大核心 2007年第12期1080-1087,共8页
Subcellular location is one of the key biological characteristics of proteins. Position-specific profiles (PSP) have been introduced as important characteristics of proteins in this article. In this study, to obtain... Subcellular location is one of the key biological characteristics of proteins. Position-specific profiles (PSP) have been introduced as important characteristics of proteins in this article. In this study, to obtain position-specific profiles, the Position Specific lterative-Basic Local Alignment Search Tool (PSI-BLAST) has been used to search for protein sequences in a database. Position-specific scoring matrices are extracted from the profiles as one class of characteristics. Four-part amino acid compositions and lst-7th order dipeptide compositions have also been calculated as the other two classes of characteristics. Therefore, twelve characteristic vectors are extracted from each of the protein sequences. Next, the characteristic vectors are weighed by a simple weighing function and inputted into a BP neural network predictor named PSP-Weighted Neural Network (PSP-WNN). The Levenberg-Marquardt algorithm is employed to adjust the weight matrices and thresholds during the network training instead of the error back propagation algorithm. With a jackknife test on the RH2427 dataset, PSP-WNN has achieved a higher overall prediction accuracy of 88.4% rather than the prediction results by the general BP neural network, Markov model, and fuzzy k-nearest neighbors algorithm on this dataset. In addition, the prediction performance of PSP-WNN has been evaluated with a five-fold cross validation test on the PK7579 dataset and the prediction results have been consistently better than those of the previous method on the basis of several support vector machines, using compositions of both amino acids and amino acid pairs. These results indicate that PSP-WNN is a powerful tool for subcellular localization prediction. At the end of the article, influences on prediction accuracy using different weighting proportions among three characteristic vector categories have been discussed. An appropriate proportion is considered by increasing the prediction accuracy. 展开更多
关键词 subcellular localization PSI-BLAST position-specific scoring matrices weighting function BP neural network
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巧算2019
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作者 叶明珠 《数学小灵通(烧脑版)(中高年级)》 2019年第3期17-17,10,共2页
四年级一班要评选'数学智多星'了。老师给大家出了一道智趣题:在下式左边的适当地方添上'+、-、×、÷'及括号,使等式成立。666666666666=2019淘淘是这样想的:算式左边6的个数比较多,得数又比较大,随意试填找... 四年级一班要评选'数学智多星'了。老师给大家出了一道智趣题:在下式左边的适当地方添上'+、-、×、÷'及括号,使等式成立。666666666666=2019淘淘是这样想的:算式左边6的个数比较多,得数又比较大,随意试填找答案肯定不行。怎么办呢?对了,先试算出一个与结果比较接近的数,再用剩下的6作调整会比较容易. 展开更多
关键词 等式 得数 算式 下式 试算 个数 智趣 大家
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不要只看“部分”
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作者 黄青辉 《数学小灵通(启智版)(低年级)》 2019年第10期44-44,共1页
[病例]5+( )=6+3 [病症] 5+(1)=6+3 [诊断] '病症'出错的主要原因是只看了算式的一部分,错以为等号右边6+3中的6等于左边的算式.其实,等号左右两边算式的得数相等,也就是5+( )的得数与6+3的得数相等.解答这道题时,先把右边算式... [病例]5+( )=6+3 [病症] 5+(1)=6+3 [诊断] '病症'出错的主要原因是只看了算式的一部分,错以为等号右边6+3中的6等于左边的算式.其实,等号左右两边算式的得数相等,也就是5+( )的得数与6+3的得数相等.解答这道题时,先把右边算式6+3的得数算出来:6+3=9,所以等号左边的5+( )也应该等于9. 展开更多
关键词 部分 算式 道题 得数 病例 病症
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Identity-Based Encryption with Keyword Search from Lattice Assumption 被引量:6
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作者 Xiaojun Zhang Chunxiang Xu +1 位作者 Liming Mu Jie Zhao 《China Communications》 SCIE CSCD 2018年第4期164-178,共15页
Public key encryption scheme with keyword search (PEKS) enables us to search the encrypted data in a cloud server with a keyword, and no one can obtain any infor- mation about the encrypted data without the trapdoor... Public key encryption scheme with keyword search (PEKS) enables us to search the encrypted data in a cloud server with a keyword, and no one can obtain any infor- mation about the encrypted data without the trapdoor corresponding to the keyword. The PEKS is useful to keep the management of large data storages secure such as those in a cloud. In this paper, to protect against quantum computer attacks, we present a lattice-based identity-based encryption scheme with key- word search. We have proved that our scheme can achieve ciphertext indistinguishability in the random oracle model, and our scheme can also achieve trapdoor security. In particular, our scheme can designate a unique tester to test and return the search results, therefore it does not need a secure channel. To the best of our knowledge, our scheme is the first iden- tity-based encryption scheme with keyword search from lattice assumption. 展开更多
关键词 public key encryption keywordsearch ciphertext indistinguishability latticeassumption.
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Enhancing manual P-phase arrival detection and automatic onset time picking in a noisy microseismic data in underground mines 被引量:4
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作者 Mborah Charles Ge Maochen 《International Journal of Mining Science and Technology》 EI CSCD 2018年第4期683-691,共9页
Accurate detection and picking of the P-phase onset time in noisy microseismic data from underground mines remains a big challenge. Reliable P-phase onset time picking is necessary for accurate source location needed ... Accurate detection and picking of the P-phase onset time in noisy microseismic data from underground mines remains a big challenge. Reliable P-phase onset time picking is necessary for accurate source location needed for planning and rescue operations in the event of failures. In this paper, a new technique based on the discrete stationary wavelet transform (DSWT)and higher order statist!cs, is proposed for processing noisy data from underground mines. The objectives of this method are to (1) Improve manual detection and tPicking of P-phase onset; and (ii) provide an automatic means of detecting and picking P-phase onset me accurately. The DSWT is first used to filter the signal over several scales. The manual P-phase onset detection and picking are then obtained by computing the signal energy across selected scales with frequency bands that capture the signal of interest. The automatic P-phase onset, on the other hand, is achieved by using skewness- and kurtosis-based criterion applied to selected scales in a time-frequency domain. The method was tested using synthetic and field data from an underground limestone mine. Results were compared with results obtained by using the short-term to long-term average (STA/LTA) ratio and that by Reference Ge et al. (2009). The results show that the me!hod provides a more reliable estimate of the P-phase onset arrival than the STA]LTA method when the signal to noise ratio is very low. Also, the results obtained from the field data matched accurately with the results from Reference Ge et al. (2009). 展开更多
关键词 Manual P-phase detection Automatic onset picking Noisy microseismic data Kurtosis Skewness
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SIMPLE QUALITY ASSESSMENT FOR BINARY IMAGES 被引量:2
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作者 Zhang Chun'e Qiu Zhengding 《Journal of Electronics(China)》 2007年第2期204-208,共5页
Usually image assessment methods could be classified into two categories: subjective as-sessments and objective ones. The latter are judged by the correlation coefficient with subjective quality measurement MOS (Mean ... Usually image assessment methods could be classified into two categories: subjective as-sessments and objective ones. The latter are judged by the correlation coefficient with subjective quality measurement MOS (Mean Opinion Score). This paper presents an objective quality assessment algorithm special for binary images. In the algorithm, noise energy is measured by Euclidean distance between noises and signals and the structural effects caused by noise are described by Euler number change. The assessment on image quality is calculated quantitatively in terms of PSNR (Peak Signal to Noise Ratio). Our experiments show that the results of the algorithm are highly correlative with subjective MOS and the algorithm is more simple and computational saving than traditional objective assessment methods. 展开更多
关键词 Image quality assessment Euclidean distance Euler number
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Wage and Income Distribution in China:Review and Outlook 被引量:5
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作者 Zhang Juwei Zhao Wen 《China Economist》 2019年第1期94-132,共39页
Under the planned economy,China’s distribution relations were relations among the state,state-run enterprises,employees and the collective economy;relations between heavy industry and light industry;and relations bet... Under the planned economy,China’s distribution relations were relations among the state,state-run enterprises,employees and the collective economy;relations between heavy industry and light industry;and relations between cities and the countryside.After China’s transition to a market-oriented economy,the distribution relations among the state,state-run enterprises and employees evolved into distribution relations between the government,enterprises and households;the distribution relations between heavy industry and light industry evolved into distribution relations between the state sector and the private sector;and the distribution relations between cities and the countryside evolved into distribution relations between original urban dwellers and migrant populations.Wage system reform was carried out throughout the transition of these three types of distribution relations.Income distribution contradictions in China,which are a problem left over from history and intrinsic to the market-based economy,eased over the years.Some people and regions achieved prosperity,and urban-rural and interregional income gaps narrowed.However,widening household income gaps pose barriers to China’s economic sustainability and vision of building a moderately prosperous society in all respects.Mechanisms to promote common prosperity are incomplete and inadequate.The disequilibrium of functional distribution is an important cause of these income inequalities.The overall wage level of ordinary workers is low.In the future,China'should give full play to the decisive role of the market in primary distribution to ensure proper return to all types of factors,and enhance redistribution to achieve common prosperity for all its people. 展开更多
关键词 WAGE income distribution labor compensation household income Ginicoefficient personal income tax
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Some Hardy Type Inequalities in R^n 被引量:1
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作者 HAN Ya-zhou NIU Peng- cheng 《Chinese Quarterly Journal of Mathematics》 CSCD 北大核心 2006年第3期322-325,共4页
Some Hardy type inequalities on the ball and its complementary set in the Euclidean space are established by using the Picone type identity and constructing suitable auxiliary functions.
关键词 Hardy inequality Picone identity
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New approach to acquisition of the load parameter for NOW
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作者 董岚 李东 +1 位作者 刘红霞 刘巍 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2003年第1期77-79,共3页
In order to solve the problem of significant fluctuation of workload at each node, a new approach is proposed for acquisition of load parameter for Now, a network of heterogeneous computational resource. The current m... In order to solve the problem of significant fluctuation of workload at each node, a new approach is proposed for acquisition of load parameter for Now, a network of heterogeneous computational resource. The current methods in use for acquisition of workload are reviewed for comparison and the implemention of prediction model is described in detail. It is concluded from the analysis of experimental results that the prediction method takes less time and has better predictability, and it gives a beneficial support to task scheduling and dynamic load balance. 展开更多
关键词 NOW Markov procedure
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Ultrasound Elastography of Ethanol-induced Hepatic Lesions:In Vitro Study
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作者 Li-gang Cui Jin-hua Shao +2 位作者 Jin-rui Wang Jing Bai Yi-zhuo Zhang 《Chinese Medical Sciences Journal》 CAS CSCD 2009年第2期81-85,共5页
Objective To study the value of ultrasound elastography in evaluation of ethanol-induced lesions of liver. Methods Alcohol with a dose of 2 ml was injected into a fresh porcine liver under ultrasound guidance to creat... Objective To study the value of ultrasound elastography in evaluation of ethanol-induced lesions of liver. Methods Alcohol with a dose of 2 ml was injected into a fresh porcine liver under ultrasound guidance to create stiff necrosis. Then freehand elastography of the lesion from the identical scan plane was obtained with SONOLINE Antares system using VF10-5 probe at about every 30 seconds till 6 minutes later. The original high quality radiofrequency data were acquired through an ultrasound research interface which was provided by the ultrasound system. Then, corresponding elastograms were produced offline using cross-correlation technique and compared with gross pathology findings. Results Gray-scale sonogram showed a hyperechoic area with acoustic shadow below appeared immediately after alcohol injection. The hyperechoic area tended to be diffuse and its boundary to be illegible with time. On the contrary, the ethanol-induced lesion in elastogram appeared as a low swain hard region surrounded by high strain soft hepatic tissues, with clear but irregular boundaries. Sequential elastograms with the sketched lesion boundaries showed that the lesion area increased in the first 3 minutes after ethanol injection, and then reached a plateau which corresponding to gross specimen. Conclusion Ultrasound elastography is capable of detecting and evaluating the diffusion of ethanol-induced hepatic lesion, and more sensitive and accurate than routine sonography. 展开更多
关键词 ELASTOGRAPHY ULTRASOUND hepatic cirrhosis ETHANOL
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Application of Virtual Instrumentation in HL-2A DAPS
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作者 ZHAO Li CHEN Liaoyuan LUO Cuiwen LIYongge PAN Wei SONG Xianming WANG Minghong 《Southwestern Institute of Physics Annual Report》 2005年第1期79-81,共3页
HL-2A DAPS is a large scale special data system for HL-2A tokamak . Technology of network, communication, data acquisition, data processing, real-time display, data management and systems management have been used in ... HL-2A DAPS is a large scale special data system for HL-2A tokamak . Technology of network, communication, data acquisition, data processing, real-time display, data management and systems management have been used in this system. With higher quality products and lower design costs, virtual instrumentation has been widely used in HL-2A DAPS. Vh-tual instrumentation combines mainstream commercial technologies, with flexible software and a wide variety of measurement and control hardware. It's easily to create user-defined systems that meet the exact application needs for the experiment. 展开更多
关键词 Virtual instrumentation LabVIEW Data acquisition
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