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一种超声波测物体密度的仪器设计
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作者 韩晓静 高晨洋 +1 位作者 刘明慧 白雪 《计算机应用文摘》 2024年第10期51-52,55,共3页
传统的物体密度测量方法常常需要使用量筒测量物体的体积,存在方法单一、烦琐等问题。文章介绍了一种超声波测密度仪的设计方法,可利用超声波测距原理测量不规则物体的密度,解决了量筒测量物体体积中存在的诸多问题。该仪器能够较好地... 传统的物体密度测量方法常常需要使用量筒测量物体的体积,存在方法单一、烦琐等问题。文章介绍了一种超声波测密度仪的设计方法,可利用超声波测距原理测量不规则物体的密度,解决了量筒测量物体体积中存在的诸多问题。该仪器能够较好地应用于生产实践,为物体密度的测量赋予更高的便利性。 展开更多
关键词 超声波 测距 物体密度 设计方法
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探究流体静力三次称衡法测物体密度
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作者 张晓婉 王强 +1 位作者 孙强强 洪雪松 《实验教学与仪器》 2015年第11期29-30,共2页
所谓密度,即物质每单位体积内的质量.密度测量实验作为中学、大学实验课程里的一个重要实验,其在鉴别组成物体的材料、计算物体中所含各种物质的成分、计算很难称量的物体的质量或形状比较复杂的物体的体积、判定物体的空实心、计算液... 所谓密度,即物质每单位体积内的质量.密度测量实验作为中学、大学实验课程里的一个重要实验,其在鉴别组成物体的材料、计算物体中所含各种物质的成分、计算很难称量的物体的质量或形状比较复杂的物体的体积、判定物体的空实心、计算液体内部压强以及在工农业等领域有着广泛的应用.随着科学技术的发展,对于物体密度的测量,由规则固体的测量到不规则固体的测量,由固体的测量到液体的测量,测量密度在人们的日常生活中扮演着越来越重要的角色. 展开更多
关键词 物体密度 液体内部压强 密度测量 流体 实验课程 科学技术 日常生活 工农业
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测定常见物体密度的多种方案 被引量:1
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作者 沈大国 《物理教学探讨(中学教学教研版)》 2009年第5期55-56,共2页
学生在学习了测定物体密度方法的基本知识以后,笔者及时地引导学生,研究周围常见的许多物体,探究测量它们密度的不同方法。学生平时接触的物体有各种金属材料,例如:铜、铁、铝、金、银等,还有卵石、瓷砖、塑料、木料、玻璃、泡沫... 学生在学习了测定物体密度方法的基本知识以后,笔者及时地引导学生,研究周围常见的许多物体,探究测量它们密度的不同方法。学生平时接触的物体有各种金属材料,例如:铜、铁、铝、金、银等,还有卵石、瓷砖、塑料、木料、玻璃、泡沫塑料等。它们不仅密度相差大,而且往往形状不规则。为此,笔者给学生介绍了以下测量不同物体密度的方法。 展开更多
关键词 物体密度 测定 引导学生 泡沫塑料 金属材料 测量 学习
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测物体密度的常用方法(初二)
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作者 宋万银 《数理天地(初中版)》 2003年第1期32-33,共2页
一、测固体密度 1.用密度公式 (1)测固体的质量所用器材是天平,固体可分为:有腐蚀性固体、粉末和无腐蚀性固体.对于无腐蚀性的固体可以直接放在天平的托盘中称量,对于粉末及有腐蚀性的化学药品则需借助容器(瓶子、玻璃杯等)来称量,或者... 一、测固体密度 1.用密度公式 (1)测固体的质量所用器材是天平,固体可分为:有腐蚀性固体、粉末和无腐蚀性固体.对于无腐蚀性的固体可以直接放在天平的托盘中称量,对于粉末及有腐蚀性的化学药品则需借助容器(瓶子、玻璃杯等)来称量,或者在天平的托盘中分别放入相同纸片,再将粉末或固体放在纸上称量. 展开更多
关键词 物体密度 初二 测量方法 排水法 阿基米德定律 物理 公式法 实验步骤
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测量密度的实验误差
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作者 胡小波 《数理天地(初中版)》 2010年第1期28-29,共2页
测量物体密度的实验原理一般是ρ=m/V,实验中产生的误差来自对质量和体积的测量.
关键词 实验误差 物体密度 测量 实验原理 体积
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“密度实验”中考题的基本类型
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作者 张友金 《中学理科(初中数理化)》 2000年第5期45-47,共3页
“测定物体密度”的实验,既是大纲要求学生掌握的实验,也是各地中考的热点之一,本文将近几年各地中考围绕此实验所考查的内容进行归类分析,供大家参考。
关键词 “测定物体密度 中考 题型 物理 实验题 归类分析
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物理实验教学改革探索 被引量:5
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作者 王昆林 《实验科学与技术》 2010年第6期57-58,173,共3页
从实验原理出发,介绍了笔者在实验教学中所选取的综合性、设计性、研究性实验;轨迹显现法研究阻尼振动与匀加速直线运动合成和漂浮性物体密度的测定。结合实验的教学过程可知综合性、设计性、研究性实验的选取是十分重要的,特别是实验... 从实验原理出发,介绍了笔者在实验教学中所选取的综合性、设计性、研究性实验;轨迹显现法研究阻尼振动与匀加速直线运动合成和漂浮性物体密度的测定。结合实验的教学过程可知综合性、设计性、研究性实验的选取是十分重要的,特别是实验中的创新之处,对于激发学生的学习兴趣,提高学生的综合能力和创新精神是十分有益的。 展开更多
关键词 综合性实验 设计性实验 研究性实验 轨迹显现 漂浮性物体密度
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Hydrolysis Mechanism of the NAMI-A-type Antitumor Complex (HL)[trans-RuCl4L(dmso-S)] (L=1-methyl-l,2,4-triazole)
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作者 陈兰美 陈锦灿 +3 位作者 廖思燕 刘江琴 罗辉 郑康成 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2011年第4期383-390,I0003,共9页
The hydrolysis process of Ru(III) complex (HL)[trans-RuC14L(dmso-S)] (L=l-methyl-l,2,4- triazole and dmso-S=S-dimethyl sulfoxide) (1), a potential antitumor complex similar to the well-known antitumor agent ... The hydrolysis process of Ru(III) complex (HL)[trans-RuC14L(dmso-S)] (L=l-methyl-l,2,4- triazole and dmso-S=S-dimethyl sulfoxide) (1), a potential antitumor complex similar to the well-known antitumor agent (Him)[trans-RuC14 (dmso-S)(im)] (NAMI-A, im=imidazole), was investigated using density functional theory combined with the conductor-like polarizable continuum model approach. Tile structural characteristics and the detailed energy profiles for the hydrolysis processes of this complex were obtained. For the first hydrolysis step, complex 1 has slightly higher barrier energies than the reported anticancer drug NAMI-A, and the result is in accordance with the experimental evidence indicating larger half-life for complex 1. For the second hydrolysis step, the formation of cis-diaqua species is thermodynamic preferred to that of trans isomers. In addition, on the basis of the analysis of electronic characteristics of species in the hydrolysis process, the trend in nucleophilic attack abilities of hydrolysis products by pertinent biomolecules is revealed and predicted. 展开更多
关键词 NAMI-A-type complex Anticancer activity HYDROLYSIS Density functional theory Conductor-like polarizable continuum model
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几个常见的隐含条件
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作者 李洪生 《数理天地(初中版)》 2013年第2期31-31,共1页
1.光滑 含义:没有摩擦力. 2.漂浮 含义:浮力等于重力,物体密度小于液体密度,V排〈V物.
关键词 隐含条件 液体密度 物体密度 摩擦力 漂浮 浮力
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中考必背的25个实验
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《中考金刊》 2010年第7期102-105,128,共5页
在物理中考中,测量型实验注重对测量仪器的正确使用及读数;探究型实验重在考查探究的过程及思想,常伴随实验步骤的考查,要求与难度较大。分析历年中考的特点.预计2010年中考物理实验的考查依然会重点关注探究平面镜成像特点、探究... 在物理中考中,测量型实验注重对测量仪器的正确使用及读数;探究型实验重在考查探究的过程及思想,常伴随实验步骤的考查,要求与难度较大。分析历年中考的特点.预计2010年中考物理实验的考查依然会重点关注探究平面镜成像特点、探究凸透镜成像规律、测物体密度、测电阻、测小灯泡功率、探究影响摩擦力的因素、验证杠杆的平衡条件等实验。虽然实验题考查的形式多种多样。但万变不离其宗.同学们只要理解并掌握好物理教材中的基本实验,解题时便可得心应手。 展开更多
关键词 实验步骤 中考 凸透镜成像规律 物理实验 2010年 测量仪器 成像特点 物体密度
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Effects of 3 months of full-court and half-court street basketball training on health profile in untrained men 被引量:5
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作者 Morten B.Randers Marie Hagman +4 位作者 Jonathan Brix Jesper F.Christensen Mogens T.Pedersen Jens J.Nielsen Peter Krustrup 《Journal of Sport and Health Science》 SCIE 2018年第2期132-138,共7页
Purpose: The aim of the present study was to investigate whether street basketball organized as 3 v 3 on either a half court(HC) with 1 basket or a full court(FC) with 2 baskets could improve fitness and health profil... Purpose: The aim of the present study was to investigate whether street basketball organized as 3 v 3 on either a half court(HC) with 1 basket or a full court(FC) with 2 baskets could improve fitness and health profiles of untrained men after 3 months of supervised training.Methods: Thirty-five untrained men(aged 20—42 years) completed the pre-and post-intervention testing(FC: n = 13, HC: n = 12, CO(control):n = 10). The training attendance was 2.0 ± 0.4 and 1.9 ± 0.3 times per week in FC and HC, respectively. Mean heart rate(HR) was 83.8 ± 6.0 percent of maximal heart rate(%HR_(max)) and 84.5 ± 2.9 %HR_(max) in FC and HC, respectively.Results: The 3 months of street basketball training on an FC with 2 baskets increased maximal oxygen uptake(2.4 mL/min/kg(95% confidence interval(CI): 1.0—3.9)), time to exhaustion(47 s(95%CI: 26—67)), lean body mass(0.8 kg(95%CI: 0.1—1.5)), and bone mineral density(0.021 g/cm^2(95%CI: 0.011—0.031)), whereas mean arterial pressure(—5.6 mm Hg(95%CI: —7.5 to 3.7)), body fat percentage(—1.6%,(95%CI: —2.5 to —0.7)), heart rate(—18 bpm(95%CI: —24 to —12)), and blood lactate(median: —1.4 mmol/L(interquartile range: —1.5 to —0.6)) during submaximal running were lowered. The changes were less pronounced after the training period when playing on an HC with 1 basket, but increases in maximal oxygen uptake(1.6 mL/min/kg(95%CI: —0.1 to 3.3)), time to exhaustion(28 s(95%CI: 9—47)), lean body mass(1.3 kg(95%CI: 0.3—2.4)), and lower body fat percentage(—0.9%(95%CI: —1.9 to —0.1)) were observed in this group.Conclusion: Three months of 3 v 3 street basketball training improved fitness and led to broad-spectrum improvements in variables related to overall health profile, with the most marked effects observed when playing on an FC with 2 baskets. 展开更多
关键词 Blood pressure Body composition Cardiovascular fitness Maximal oxygen uptake Muscoloskeletal fitness Physical demands Small-sided games Team sport
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An efficient approach for shadow detection based on Gaussian mixture model 被引量:2
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作者 韩延祥 张志胜 +1 位作者 陈芳 陈恺 《Journal of Central South University》 SCIE EI CAS 2014年第4期1385-1395,共11页
An efficient approach was proposed for discriminating shadows from moving objects. In the background subtraction stage, moving objects were extracted. Then, the initial classification for moving shadow pixels and fore... An efficient approach was proposed for discriminating shadows from moving objects. In the background subtraction stage, moving objects were extracted. Then, the initial classification for moving shadow pixels and foreground object pixels was performed by using color invariant features. In the shadow model learning stage, instead of a single Gaussian distribution, it was assumed that the density function computed on the values of chromaticity difference or bright difference, can be modeled as a mixture of Gaussian consisting of two density functions. Meanwhile, the Gaussian parameter estimation was performed by using EM algorithm. The estimates were used to obtain shadow mask according to two constraints. Finally, experiments were carried out. The visual experiment results confirm the effectiveness of proposed method. Quantitative results in terms of the shadow detection rate and the shadow discrimination rate(the maximum values are 85.79% and 97.56%, respectively) show that the proposed approach achieves a satisfying result with post-processing step. 展开更多
关键词 shadow detection Gaussian mixture model EM algorithm
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Molar volume of eutectic solvents as a function of molar composition and temperature 被引量:1
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作者 Farouq S.Mjalli 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2016年第12期1779-1785,共7页
The conventional Rackett model for predicting liquid molar volume has been modified to cater for the effect of molar composition of the Deep Eutectic Solvents(DES). The experimental molar volume data for a group of co... The conventional Rackett model for predicting liquid molar volume has been modified to cater for the effect of molar composition of the Deep Eutectic Solvents(DES). The experimental molar volume data for a group of commonly used DES has been used for optimizing the improved model. The data involved different molar compositions of each DES. The validation of the new model was performed on another set of DESs. The average relative deviation of the model on the training and validation datasets was approximately 0.1% while the Rackett model gave a relative deviation of more than 1.6%. The modified model deals with variations in DES molar composition and temperature in a more consistent way than the original Rackett model which exhibits monotonic performance degradation as temperature moves away from reference conditions. Having the composition of the DES as a model variable enhances the practical utilization of the predicting model in diverse design and process simulation applications. 展开更多
关键词 Molar volume Density Physical properties Ionic liquids Eutectic solvents
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Density and Excess Molar Volume of Binary Mixtures ofp-Xylene+Acetic Acid and o-Xylene+Acetic Acid at Different Temperatures and Pressures
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作者 杨天宇 夏淑倩 +1 位作者 邸志国 马沛生 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2008年第2期247-255,共9页
A new apparatus was designed with a thick-walled glass capillary, electric heater tube with red copper and heat preservation. The thick-walled glass capillary was used for its advantages of resistance to acid corrosio... A new apparatus was designed with a thick-walled glass capillary, electric heater tube with red copper and heat preservation. The thick-walled glass capillary was used for its advantages of resistance to acid corrosion and pressure, and ease of observation. The experimental densities over the entire range of mole fraction for the binary mixture of p-xylene+acetic acid and o-xylene+acetic acid were measured using the new apparatus at temperatures ranging from 313.15K to 473.15K and pressure ranging from 0.20 to 2,0 MPa. The density values were used in the determination of excess molar volumes, W. The Redlich-Kister equation was used to fit the excess molar volume values, and the coefficients and estimate ot the standard error values were presented. The experimental resuits prove that the density measurement apparatus is successful. 展开更多
关键词 DENSITY excess molar volume P-XYLENE O-XYLENE acetic acid
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VITAMIN-D RECEPTOR GENE POLYMORPHISM AND ITS RELATIONSHIP WITH BONE MINERAL DENSITY IN POSTMENOPAUSAL OSTEOPOROTIC WOMEN IN SHANGHAI
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作者 王卫庆 高国峰 +2 位作者 宁光 王曙 罗邦尧 《Journal of Shanghai Second Medical University(Foreign Language Edition)》 2002年第1期25-25,共1页
Objective To examine the relationship between the vitamin D receptor(VDR) gene polymorphism and osteoporosis in postmenopausal women in Shanghai. Methods 102 postmenopausal women recruited from Ruijin Hospital were os... Objective To examine the relationship between the vitamin D receptor(VDR) gene polymorphism and osteoporosis in postmenopausal women in Shanghai. Methods 102 postmenopausal women recruited from Ruijin Hospital were osteoporotic. We measured the lumbar vertebrae and femur of all patients with a modal dual-energy X-ray absorptionmetry, and also the serum osteocalcin by ELISA. The VDR gene was amplified using a polymerase chain reaction (PCR). The VDR genotypes were determined by the PCR-RFLP. Results bb, aa and TT genotype were found mainly in these osteoporosis patients, only one BB and two tt were found among these patients. No significant association was observed among three subgroups of bb, Bb and BB. Conclusion The rareness of B and t alleles suggested that it is unlikely that they are important factors for the heredity of osteoporosis in Chinese women. Thus VDR gene typing may be of little value in assessing the osteoporosis risk in Chinese population. 展开更多
关键词 osteoporosis vitamin D receptor bone mineral density
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The Effects of Cells Density Arrangement in Chlorella vulgaris Culture to C02 Fixation and Essential Substances Production
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作者 Dlanursanti Anondho Wijanarko Muhammad Nasikin 《Journal of Chemistry and Chemical Engineering》 2012年第2期153-157,共5页
Global warming that triggered the climate change is largely due to increased CO2 concentrations. Utilization of Chlorella sp. to reduce CO2 gas is a promising potential. Chlorella can efficiently reduce CO2 and easily... Global warming that triggered the climate change is largely due to increased CO2 concentrations. Utilization of Chlorella sp. to reduce CO2 gas is a promising potential. Chlorella can efficiently reduce CO2 and easily be adapted into the photobioreactor system engineering. In this research, the type of microalgae which is used is Chlorella vulgaris in Benneck medium. The system of used reactor is mid-scale bubble column photobioreactor flowed by air which contains 5% CO2. Chlorella vulgaris biomass production will be increased by adjusting the cell density in the photobioreactor. These arrangements will be implemented through a continuous treatment of cell entrapment. The arrangement of cell density in continuous reactor has been proven to increase production of Chlorella vulgaris biomass about 1.25 times more than cultivation without arrangement of cell density by using the same number of inoculums. The results also have shown that the average rate of CO2 fixation and Carbon Transfer Rate (CTR) are obtained at cell entrapment condition about 17 times larger. Continuous cellular entrapment method is very potential to be developed as a method for the production of biomass. Lipids and carotene that have been produced from Ch. vulgaris respectively are 18.24% and 9.42 ppm. 展开更多
关键词 Chlorella vulgaris biomass production cell entrapment CO2 fixation Carbon Transfer Rate.
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A Generalized Equation of State for High-Pressure Liquids
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作者 LIANG Yan-bo TONG Jing-shan 《Journal of China University of Mining and Technology》 2005年第4期376-378,共3页
An equation of state (EOS) for high-pressure liquids, i.e., Tait EOS, is deduced according to isothermal 1 3V compressibility KT= -1/V· (2V/2p)T·.Based on the equation, a generalized EOS for high pressu... An equation of state (EOS) for high-pressure liquids, i.e., Tait EOS, is deduced according to isothermal 1 3V compressibility KT= -1/V· (2V/2p)T·.Based on the equation, a generalized EOS for high pressure-liquids is established by using the reduced state principle and introducing a characteristic parameter-configuration factor ξ. Reasonably satisfactory P-V-T data for many organic compounds, including some polar components, were calculated by using the equation. 展开更多
关键词 equation of state for high-pressure liquids organic compounds P-V-T data
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利用生活物品巧测密度
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作者 孙九云 《中学物理教学参考》 2021年第18期53-55,共3页
利用生活物品,从漂和称两个角度巧妙测量密度,提高学生探究能力,培养学生的物理学科核心素养。
关键词 生活物品 物理实验 物体密度
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偏大、偏小轻松判
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作者 卢炜平 李学利 《初中生学习指导》 2021年第12期47-47,共1页
初中物理测量物体密度时经常会遇到测量值偏大、偏小的问题。那么,如何正确判断测量值到底是"偏大"还是"偏小"呢?其实只要记住,先测量的值是准确的,后测量的值由于沾水、残留等会造成不准确,就一定能正确判断了。... 初中物理测量物体密度时经常会遇到测量值偏大、偏小的问题。那么,如何正确判断测量值到底是"偏大"还是"偏小"呢?其实只要记住,先测量的值是准确的,后测量的值由于沾水、残留等会造成不准确,就一定能正确判断了。下面举例说明。例小明在"测量物质的密度"实验中,进行下列操作. 展开更多
关键词 初中物理 正确判断 物质的密度 测量值 轻松 物体密度 举例说明
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物休浮沉条件的应用
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作者 杨元俊 《初中生之友(学习号)(下)》 2015年第4期16-21,共6页
物体浮沉条件的应用涉及的考点是阿基米德原理,着重考查考生对浮沉条件、原理的理解、应用和识图能力。解决这类问题的一般思路和方法是:首先.根据题目给出的图形,分析物体在液体中的状态;其次,利用物体的浮沉条件,分析物体所受... 物体浮沉条件的应用涉及的考点是阿基米德原理,着重考查考生对浮沉条件、原理的理解、应用和识图能力。解决这类问题的一般思路和方法是:首先.根据题目给出的图形,分析物体在液体中的状态;其次,利用物体的浮沉条件,分析物体所受重力和浮力的大小关系或者物体密度和液体密度的关系.分析过程中确定力的关系要从力的角度去判断,确定密度的关系要从密度的角度去判断:最后,根据物体所受重力和浮力的大小关系或者物体密度和液体密度的关系逐步解决各个问题。下面结合2014年各地中考题,剖析不同命题背景下“物体浮沉条件应用”考点的解题技巧。 展开更多
关键词 物体浮沉条件 应用 阿基米德原理 液体密度 物体密度 大小关系 识图能力 解题技巧
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