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Simulation of anchor chain based on lumped mass method 被引量:1
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作者 Xiaobin Jiang Jian Gan Shiyang Teng 《Theoretical & Applied Mechanics Letters》 CAS CSCD 2023年第4期311-319,共9页
In order to develop a anchoring operation simulation system and improve safety during anchoring operations,a relatively accurate mathematical model of anchoring operations needs to be established.In this paper,the str... In order to develop a anchoring operation simulation system and improve safety during anchoring operations,a relatively accurate mathematical model of anchoring operations needs to be established.In this paper,the stress condition of anchor chain under environmental and subsea geological conditions is further studied and the stress condition of anchor chain is analyzed based on the previous research.In this paper,a quasi-static model based on catenary method is used as the basis of dynamic analysis,and the dynamic model of anchor chain is established based on the concentrated mass method,which fully considers the influence of anchor chain weight,hydrodynamic force,ocean current and interaction with the seabed.The fourth-order Runge Kutta method was used to solve the model numerically,and a calculation procedure was developed.The accuracy of the model was verified by comparing the calculated results with the experimental results,indicating that the constructed anchor chain dynamics model has a high accuracy. 展开更多
关键词 Lump mass method Anchor chain Dynamic analysis
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Urinary Creatinine-Skeletal Muscle Mass Method:A Prediction Equation Based on Computerized Axial Tomography
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作者 ZI-MIAN WANG YUN-GAO SUN AND STEVEN B. HEYMSFIELD (Department of Medicine, Obesity Research Center, St. Luke’s-Roosevelt Hospital, Columbia University College of Physicians and Surgeons,Amsterdam Ave. 14C New York, N. Y., USA)(Obesity Research Center, We 《Biomedical and Environmental Sciences》 SCIE CAS CSCD 1996年第2期185-190,共6页
A classic body composition method is estimation of total body skeletal muscle mass (SM, kg) from 24 h urinary creatinine excretion (Cr, g). Two types of prediction equations were suggested: one assumes a constant SM/C... A classic body composition method is estimation of total body skeletal muscle mass (SM, kg) from 24 h urinary creatinine excretion (Cr, g). Two types of prediction equations were suggested: one assumes a constant SM/Cr ratio; and the other assumes a highly variable SM/Cr ratio. We explored these two extreme possibilities by measuring SM with whole-body computerized axial tomography and collecting Cr during meat-free dietary conditions in 12 healthy young men. Prediction equations were developed in the men that fit these two equation types, SM = 21.8×Cr (SD and CV of SM/Cr ratio, 1.3 kg and 6.0%,respectively) and SM = 18.9 × Cr + 4.1 (r = 0.92, p = 2.55 × 10-5, and SEE = 1.9 kg). The validity of each model is reviewed. This is the first investigation of Cr-SM method using modern techniques for quantifying total body SM mass 展开更多
关键词 mass Cr body SM Urinary Creatinine-Skeletal Muscle mass method
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Mass scale screening of common arboviral infections by an affordable,cost effective RT-PCR method 被引量:1
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作者 Debjani Taraphdar Arindam Sarkar Shyamalendu Chatterjee 《Asian Pacific Journal of Tropical Biomedicine》 SCIE CAS 2012年第2期97-101,共5页
Objective:To develop a rapid,cost effective RT-PCR method for the mass scale diagnosis of such diseases at the vireraia stage to find out the actual disease burden in that area.Methods:For this purpose,cases with the ... Objective:To develop a rapid,cost effective RT-PCR method for the mass scale diagnosis of such diseases at the vireraia stage to find out the actual disease burden in that area.Methods:For this purpose,cases with the history of only short febrile illness were considered.Thus 157 samples with the history of dengue/chikungunya like illness and only 58 samples with a history of acute encephalitis syndrome(AES)were selected.Results:Out of 157 samples,42 and 74 were detected as dengue and chikungunya,respectively and out of 58 AES cases only 23 could be detected as Japanese encephalitis by this RT-PCR method.Conclusions:This cost effective RT-PCR method can detect the total positive cases that remain undetected by EL1SA method.Moreover,this method is capable to detect the viral RNA from patients'sera even after the appearance of IgM antibody at one fifth costs as compared with the other commercially available kits. 展开更多
关键词 COST effective RT-PCR method mass SCREENING ARBOVIRUS
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Distinct element modelling of fracture plan control in continuum and jointed rock mass in presplitting method of surface mining 被引量:4
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作者 Sharafisafa Mansour Aliabadian Zeinab +1 位作者 Alizadeh Rezvan Mortazavi Ali 《International Journal of Mining Science and Technology》 SCIE EI 2014年第6期871-881,共11页
Controlled blasting techniques are used to control overbreak and to aid in the stability of the remaining rock formation. Presplitting is one of the most common methods which is used in many open pit mining and surfac... Controlled blasting techniques are used to control overbreak and to aid in the stability of the remaining rock formation. Presplitting is one of the most common methods which is used in many open pit mining and surface blast design. The purpose of presplitting is to form a fracture plane across which the radial cracks from the production blast cannot travel. The purpose of this study is to investigate of effect of presplitting on the generation of a smooth wall in continuum and jointed rock mass. The 2D distinct element code was used to simulate the presplitting in a rock slope. The blast load history as a function of time was applied to the inner wall of each blasthole. Important parameters that were considered in the analysis were stress tensor and fracturing pattern. The blast loading magnitude and blasthole spacing and jointing pattern were found to be very significant in the final results. 展开更多
关键词 Controlled blasting Presplitting method Continuum and jointed rock mass Distinct element modelling
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An Explanation on the Electron Ionization Mass Spectra of Crown Ethers by MNDO Computational Method
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《Chemical Research in Chinese Universities》 SCIE CAS CSCD 1995年第3期202-205,共4页
he bond lengths and bond orders of four kinds of chemical bonds in crownethers(15) were calculated based on the model molecules using MNDO method.With the calculation results, some predictions to the EI mass spectral ... he bond lengths and bond orders of four kinds of chemical bonds in crownethers(15) were calculated based on the model molecules using MNDO method.With the calculation results, some predictions to the EI mass spectral fragmenta-tion behaviour of crown ethers are suggested. The EI mass spectra of studied crownethers are in satisfactory agreenient with the predictions. 展开更多
关键词 Crown ether MNDO method. EI mass spectra
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Source Apportionment of Ambient PM_(10) in the Urban Area of Longyan City,China:a Comparative Study Based on Chemical Mass Balance Model and Factor Analysis Method 被引量:1
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作者 QIU Li-min LIU Miao +2 位作者 WANG Ju ZHANG Sheng-nan FANG Chun-sheng 《Chemical Research in Chinese Universities》 SCIE CAS CSCD 2012年第2期204-208,共5页
In order to identify the day and night pollution sources of PM10 in ambient air in Longyan City,the authors analyzed the elemental composition of respirable particulate matters in the day and night ambient air samples... In order to identify the day and night pollution sources of PM10 in ambient air in Longyan City,the authors analyzed the elemental composition of respirable particulate matters in the day and night ambient air samples and various pollution sources which were collected in January 2010 in Longyan with inductivity coupled plasma-mass spectrometry(ICP-MS).Then chemical mass balance(CMB) model and factor analysis(FA) method were applied to comparatively study the inorganic components in the sources and receptor samples.The results of factor analysis show that the major sources were road dust,waste incineration and mixed sources which contained automobile exhaust,soil dust/secondary dust and coal dust during the daytime in Longyan City,China.There are two major sources of pollution which are soil dust and mixture sources of automobile exhaust and secondary dust during the night in Longyan.The results of CMB show that the major sources are secondary dust,automobile exhaust and road dust during the daytime in Longyan.The major sources are secondary dust,soil dust and automobile exhaust during the night in Longyan.The results of the two methods are similar to each other and the results will guide us to plan to control the PM10 pollution sources in Longyan. 展开更多
关键词 Factor analysis(FA) method Chemical mass balance(CMB) model Source apportionment Atmospheric particle PM10
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Study on Estimation Method of Rock Mass Discontinuity Shear Strength Based on Three-Dimensional Laser Scanning and Image Technique 被引量:22
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作者 唐辉明 葛云峰 +3 位作者 王亮清 苑谊 黄磊 孙淼军 《Journal of Earth Science》 SCIE CAS CSCD 2012年第6期908-913,共6页
The estimation of shear strength of rock mass discontinuity is always a focal, but difficult, problem in the field of geotechnical engineering. Considering the disadvantages and limitation of exist- ing estimation met... The estimation of shear strength of rock mass discontinuity is always a focal, but difficult, problem in the field of geotechnical engineering. Considering the disadvantages and limitation of exist- ing estimation methods, a new approach based on the shadow area percentage (SAP) that can be used to quantify surface roughness is proposed in this article. Firstly, by the help of laser scanning technique, the three-dimensional model of the surface of rock discontinuity was established. Secondly, a light source was simulated, and there would be some shadows produced on the model surface. Thirdly, to obtain the value of SAP of each specimen, the shadow detection technique was introduced for use. Fourthly, compared with the result from direct shear testing and based on statistics, an empirical for- mula was found among SAP, normal stress, and shear strength. Data of Yujian (~ River were used as an example, and the following conclusions have been made. (1) In the case of equal normal stress, the peak shear stress is positively proportional to the SAP. (2) The formula for estimating was derived, and the predictions of peak-shear strength made with this equation well agreed with the experimental re- suits obtained in laboratory tests. 展开更多
关键词 rock mechanics rock mass discontinuity shear strength estimation method three-dimensional laser scanning technique image recognition technique.
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An extended displacement discontinuity method for analysis of stress wave propagation in viscoelastic rock mass 被引量:9
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作者 L.F.Fan1,F.Ren1,G.W.Ma2 1 School of Civil and Environmental Engineering,Nanyang Technological University,Singapore,639798,Singapore 2 School of Civil and Resource Engineering,The University of Western Australia,Crawley,WA 6009,Australia 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE 2011年第1期73-81,共9页
An extended displacement discontinuity method (EDDM) is proposed to analyze the stress wave propagation in jointed viscoelastic rock mass (VRM).The discontinuities in a rock mass are divided into two groups.The primar... An extended displacement discontinuity method (EDDM) is proposed to analyze the stress wave propagation in jointed viscoelastic rock mass (VRM).The discontinuities in a rock mass are divided into two groups.The primary group with an average geometrical size larger than or in the same order of magnitude of wavelength of a concerned stress wave is defined as 'macro-joints',while the secondary group with a high density and relatively small geometrical size compared to the wavelength is known as 'micro-defects'.The rock mass with micro-defects is modeled as an equivalent viscoelastic medium while the macro-joints in the rock mass are modeled explicitly as physical discontinuities.Viscoelastic properties of a micro-defected sedimentary rock are obtained by longitudinally impacting a cored long sedimentary rod with a pendulum.Wave propagation coefficient and dynamic viscoelastic modulus are measured.The EDDM is then successfully employed to analyze the wave propagation across macro-joint in VRM.The effect of the rock viscosity on the stress wave propagation is evaluated by comparing the results of VRM from the presented EDDM with those of an elastic rock mass (ERM) from the conventional displacement discontinuity method (CDDM).The CDDM is a special case of the EDDM under the condition that the rock viscosity is ignored.Comparison of the reflected and transmitted waves shows that the essential rock viscosity has a significant effect on stress wave attenuation.When a short propagation distance of a stress wave is considered,the results obtained from the CDDM approximate to the EDDM solutions,however,when the propagation distance is sufficiently long relative to the wavelength,the effect of rock viscosity on the stress wave propagation cannot be ignored. 展开更多
关键词 stress wave propagation extended displacement discontinuity method (EDDM) viscoelastic rock mass (VRM) micro-defect macro-joint
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Reinforcing a Dangerous Rock Mass Using the Flexible Network Method
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作者 Yang Wendong Xie Quanmin Xia Yuanyou Li Xinping 《Journal of China University of Geosciences》 SCIE CSCD 2005年第4期354-358,共5页
Because the main failure type of a dangerous rock mass is collapse, the treatment of such a mass should focus on controlling collapse failure. When treating dangerous rock masses, disturbing the mass (e. g. by blast... Because the main failure type of a dangerous rock mass is collapse, the treatment of such a mass should focus on controlling collapse failure. When treating dangerous rock masses, disturbing the mass (e. g. by blasting) needs to be avoided, as this new damage could cause collapse. So the self-bearing capacity of the mountain mass must be used to treat the dangerous rock mass. This article is based on a practical example of the control of a dangerous rock mass at Banyan Mountain, Huangshi, Hubei Province. On the basis of an analysis of damage mechanism and the stability of the dangerous rock mass, a flexible network reinforcement method was designed to prevent the collapse of the rock mass. The deformations of section Ⅱ w of the dangerous rock mass before and after the flexible network reinforcement were calculated using the two-dimensional finite element method. The results show that the maximum deformation reduced by 55 % after the application of the flexible network reinforcement, from 45.99 to 20.75 ram, which demonstrates that the flexible network method is effective, and can provide some scientific basis for the treatment of dangerous rock masses. 展开更多
关键词 dangerous rock mass flexible network reinforcement method finite element analysis.
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A Study on Propagation Mechanism of Fracture Systems in Rock Masses by Discontinuity Displacement Method
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作者 Tang HuimingChina University of Geosciences . Wihan 430074 《Journal of Earth Science》 SCIE CAS CSCD 1993年第1期111-114,共4页
The main task of fracture mechanics of rock masses is the study on the propagating mechanism of fractures in rock masses , which can be efficiently conducted by discontinuty displacement (DD) numerical evaluation . Fi... The main task of fracture mechanics of rock masses is the study on the propagating mechanism of fractures in rock masses , which can be efficiently conducted by discontinuty displacement (DD) numerical evaluation . Firstly ,the element stress and displacement are analysed and the principle and steps of the numerical calculation of stress intensity factor and fracture extension force are introduced .The numerical results of parallel and echelon fracture systems ,which are compared with real field fractures .are presented. Finally . a simple engineering application example is presented . 展开更多
关键词 fracture mechanics of rock masses discontinuity displacement method (DDM ) stress- intensity factor fracture extension force parallel fracture echelon fracture .
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A novel sample preparation method of matrix-assisted laser desorption/ionization time of flight mass spectrometry for polystyrene
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作者 Shu Zhang Zhen Wen Zhao +3 位作者 Lei Xiong Bin Xin Wei Hua Hu Shao Xiang Xiong 《Chinese Chemical Letters》 SCIE CAS CSCD 2007年第6期718-721,共4页
A novel sample preparation method of matrix-assisted laser desorption/ionization mass spectrometry for polystyrene was reported. Compared to the conventional dried-droplet method, the efficiency of ionization and sign... A novel sample preparation method of matrix-assisted laser desorption/ionization mass spectrometry for polystyrene was reported. Compared to the conventional dried-droplet method, the efficiency of ionization and signal intensity of mass spectra were improved. The mechanism was also analyzed. 展开更多
关键词 POLYSTYRENE Matrix-assisted laser desorption/ionization time of flight mass spectrometry Three-layer method
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吹扫捕集/气相色谱质谱法测定水中多种VOCs 被引量:1
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作者 雷琼 何娟 +2 位作者 赵海玲 陈如意 刘慧 《中国给水排水》 北大核心 2025年第8期130-136,共7页
针对生活饮用水中多种挥发性有机物(VOCs)的日常监测需求,依据《生活饮用水标准检验方法》(GB/T 5750—2023)对《生活饮用水标准检验方法第8部分:有机物指标》(GB/T 5750.8—2023)4.2节进行吹扫条件优化及色谱柱选择,建立了一种适用于... 针对生活饮用水中多种挥发性有机物(VOCs)的日常监测需求,依据《生活饮用水标准检验方法》(GB/T 5750—2023)对《生活饮用水标准检验方法第8部分:有机物指标》(GB/T 5750.8—2023)4.2节进行吹扫条件优化及色谱柱选择,建立了一种适用于同时快速测定生活饮用水中56种VOCs的吹扫捕集/气相色谱质谱法。优化后方法测定56种VOCs的可检测线性范围为0.1~100μg/L,相关系数为0.9990~0.9997,各目标物的检出限范围为0.0037~0.52μg/L,低、中、高3组加标样(n≥6)的平均回收率为73.0%~118%,相对标准偏差(RSD)均小于10%。该方法线性范围较宽、检出限较低、准确度较高、操作简便,可以推广至大部分实验室,尤其是基层实验室。 展开更多
关键词 吹扫捕集 气相色谱质谱法 挥发性有机物 生活饮用水
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A mass-conserved multiphase lattice Boltzmann method based on high-order difference
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作者 Zhang-Rong Qin Yan-Yan Chen +2 位作者 Feng-Ru Ling Ling-Juan Meng Chao-Ying Zhang 《Chinese Physics B》 SCIE EI CAS CSCD 2020年第3期292-302,共11页
The Z–S–C multiphase lattice Boltzmann model [Zheng, Shu, and Chew(ZSC), J. Comput. Phys. 218, 353(2006)]is favored due to its good stability, high efficiency, and large density ratio. However, in terms of mass cons... The Z–S–C multiphase lattice Boltzmann model [Zheng, Shu, and Chew(ZSC), J. Comput. Phys. 218, 353(2006)]is favored due to its good stability, high efficiency, and large density ratio. However, in terms of mass conservation, this model is not satisfactory during the simulation computations. In this paper, a mass correction is introduced into the ZSC model to make up the mass leakage, while a high-order difference is used to calculate the gradient of the order parameter to improve the accuracy. To verify the improved model, several three-dimensional multiphase flow simulations are carried out,including a bubble in a stationary flow, the merging of two bubbles, and the bubble rising under buoyancy. The numerical simulations show that the results from the present model are in good agreement with those from previous experiments and simulations. The present model not only retains the good properties of the original ZSC model, but also achieves the mass conservation and higher accuracy. 展开更多
关键词 LATTICE BOLTZMANN method HIGH-ORDER difference mass conservation large density ratio
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柔性航天器动力学方程一般形式的工程简化方法
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作者 邹元杰 邓润然 +1 位作者 史纪鑫 葛东明 《中国空间科学技术(中英文)》 北大核心 2025年第2期70-78,共9页
在完备的柔性航天器动力学二阶微分方程一般形式的基础上,提出一般方程的工程简化方法。首先,采用平动集中质量方法对相关积分项进行了简化处理,忽略单元自身转动惯量对总惯量的影响以及板壳单元、梁单元等转角运动的影响,将体积分运算... 在完备的柔性航天器动力学二阶微分方程一般形式的基础上,提出一般方程的工程简化方法。首先,采用平动集中质量方法对相关积分项进行了简化处理,忽略单元自身转动惯量对总惯量的影响以及板壳单元、梁单元等转角运动的影响,将体积分运算统一转化为节点相关变量与平动质量乘积的求和运算;其次,依据“小变形假设”,对含结构变形参量的方程系数矩阵进行简化,忽略结构振动位移对节点位置矢量的影响,使非线性系数矩阵转化为常系数矩阵。通过简化处理,柔性航天器动力学方程一般形式的所有项均被保留,而其积分项和系数矩阵的计算,在满足工程精度要求的前提下得到大幅简化,便于编程实现和工程实施。提出的工程简化方法主要用于柔性航天器在大范围、复杂运动过程中的动力学仿真分析,后续可以由单体动力学进一步拓展至多体动力学,解决在轨组装航天器、空间机器人/机械臂等空间结构系统的柔性多体动力学问题。数值算例验证了工程简化方法的合理性和有效性。 展开更多
关键词 柔性航天器 动力学 一般形式 工程简化方法 平动集中质量方法
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Overhanging rock slope by design:An integrated approach using rock mass strength characterisation,large-scale numerical modelling and limit equilibrium methods 被引量:10
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作者 Paul Schlotfeldt Davide Elmo Brad Panton 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2018年第1期72-90,共19页
Overhanging rock slopes(steeper than 90°) are typically avoided in rock engineering design, particularly where the scale of the slope exceeds the scale of fracturing present in the rock mass. This paper highlight... Overhanging rock slopes(steeper than 90°) are typically avoided in rock engineering design, particularly where the scale of the slope exceeds the scale of fracturing present in the rock mass. This paper highlights an integrated approach of designing overhanging rock slopes where the relative dimensions of the slope exceed the scale of fracturing and the rock mass failure needs to be considered rather than kinematic release of individual blocks. The key to the method is a simplified limit equilibrium(LE) tool that was used for the support design and analysis of a multi-faceted overhanging rock slope. The overhanging slopes required complex geometries with constantly changing orientations. The overhanging rock varied in height from 30 m to 66 m. Geomechanical modelling combined with discrete fracture network(DFN)representation of the rock mass was used to validate the rock mass strength assumptions and the failure mechanism assumed in the LE model. The advantage of the simplified LE method is that buttress and support design iterations(along with sensitivity analysis of design parameters) can be completed for various cross-sections along the proposed overhanging rock sections in an efficient manner, compared to the more time-intensive, sophisticated methods that were used for the initial validation. The method described presents the development of this design tool and assumptions made for a specific overhanging rock slope design. Other locations will have different geological conditions that can control the potential behaviour of rock slopes, however, the approach presented can be applied as a general guiding design principle for overhanging rock cut slope. 展开更多
关键词 Rock slopes Discrete fracture network(DFN) Rock mass strength characterisation Numerical modelling Limit equilibrium(LE) methods
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地下水中全氟与多氟烷基化合物分析方法研究进展 被引量:1
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作者 龚利强 李志鸿 +1 位作者 周波 周正元 《岩矿测试》 北大核心 2025年第4期562-575,共14页
全氟与多氟烷基化合物(PFAS)是一类人工合成的化学品,属于典型的持久性有机污染物(POPs)和新兴污染物,在全球范围内的水环境中被广泛检出,对人体健康及生态系统构成潜在威胁。地下水中的PFAS浓度通常为痕量水平,这对现有监测方法的灵敏... 全氟与多氟烷基化合物(PFAS)是一类人工合成的化学品,属于典型的持久性有机污染物(POPs)和新兴污染物,在全球范围内的水环境中被广泛检出,对人体健康及生态系统构成潜在威胁。地下水中的PFAS浓度通常为痕量水平,这对现有监测方法的灵敏度和准确性提出了严峻挑战。然而,现有的主流监测方法仍存在样品代表性不足、成本高昂、操作复杂等问题,难以全面满足实际需求,亟需进一步优化和创新。针对研究现状,本文系统梳理了近年来地下水中典型PFAS监测涉及的样品采集、样品前处理及分析检测技术研究最新进展。在样品采集领域,被动采样技术的兴起为地下水低成本持续监测提供了可能;在样品前处理领域,膜式固相萃取、分散固相萃取等新技术的引入有效地缩短了现今固相萃取法的样品前处理时间,提高了分析效率;在检测方法领域,高灵敏度的液相色谱-串联质谱法仍是PFAS定量检测的主流手段,高分辨质谱非靶向筛查使地下水中PFAS的定性识别不再依赖标准品,而传感检测等技术的运用则为地下水现场快检提供了新的手段。未来相关研究应重点关注高通量、自动化的前处理方法及灵敏、准确、特异的PFAS定性、定量检测方法的开发与完善。 展开更多
关键词 全氟与多氟烷基化合物 地下水 新污染物 样品前处理 检测方法 质谱法
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首批比伐芦定国家对照品的研制
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作者 任丽萍 贺兰英 +3 位作者 廖海明 王瑾 杨洪淼 范慧红 《药物分析杂志》 北大核心 2025年第5期851-858,共8页
目的:为有效控制比伐芦定注射剂的产品质量,研制比伐芦定首批含量测定用国家对照品,同时探索合成肽类标准物质定量赋值的其他方法。方法:采用红外光谱、紫外光谱、液相色谱、质谱等技术对其进行结构确证,利用高效液相色谱法进行有关物... 目的:为有效控制比伐芦定注射剂的产品质量,研制比伐芦定首批含量测定用国家对照品,同时探索合成肽类标准物质定量赋值的其他方法。方法:采用红外光谱、紫外光谱、液相色谱、质谱等技术对其进行结构确证,利用高效液相色谱法进行有关物质的测定,采用质量平衡法确定比伐芦定的含量,同时通过经肽纯度校正的肽含量方法进行验证,并对供试品进行均匀性和稳定性考察。结果:首批比伐芦定国家对照品以C_(98)H_(138)N_(24)O_(33)计,含量为88.8%,均匀性和稳定性考察结果符合规定。结论:根据合成肽的结构特点,采用不同方法进行定性与定量研究,可以确保国家对照品赋值的准确性。 展开更多
关键词 比伐芦定 国家对照品 质量平衡法 含量测定
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Calculation of Neutron-Proton Mass Difference by the Monte Carlo Method
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作者 A. A. Sobko S. A. Garelina 《Journal of Applied Mathematics and Physics》 2020年第10期2157-2166,共10页
Calculation results of the Monte Carlo method of the average energy of the electrostatic interaction between the quarks are presented to the neutron and proton. The proposed model of the distribution of quarks in prot... Calculation results of the Monte Carlo method of the average energy of the electrostatic interaction between the quarks are presented to the neutron and proton. The proposed model of the distribution of quarks in protons and neutrons is possible to assess the area which included a strong (gluon) interaction. Given the fact that the probability of finding a quark in the field with strong interaction is less than one, there is a good agreement between the experimental and calculated values of the mass difference between the neutron and the proton. 展开更多
关键词 mass of the Proton The Neutron mass The Coulomb Interaction The Monte Carlo method
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1,2-苯并异噻唑啉-3-酮纯度标准物质定值及不确定度评估
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作者 叶长文 丁丽 +5 位作者 党伟 陈宸 李栋 田斌强 高芹 贺琛 《分析试验室》 北大核心 2025年第6期930-938,共9页
建立了1,2-苯并异噻唑啉-3-酮(BIT)纯度标准物质的制备、定值和不确定度评定方法。采用重结晶法制备BIT纯度标准物质,通过质谱、红外光谱、紫外光谱及核磁共振(NMR)对重结晶样品进行定性分析,通过气相色谱法(GC)、电感耦合等离子质谱法(... 建立了1,2-苯并异噻唑啉-3-酮(BIT)纯度标准物质的制备、定值和不确定度评定方法。采用重结晶法制备BIT纯度标准物质,通过质谱、红外光谱、紫外光谱及核磁共振(NMR)对重结晶样品进行定性分析,通过气相色谱法(GC)、电感耦合等离子质谱法(ICP-MS)和顶空气相色谱法(HS-GC)分别测定样品中的水分、无机元素和挥发性杂质含量。采用质量平衡法(MB)和差示扫描量热法(DSC)对标准物质的纯度进行联合定值,通过高效液相色谱法(HPLC)对标准物质进行均匀性和稳定性检验,并评价了定值结果的不确定度。结果表明,重结晶法制备的BIT纯度标准物质定值结果为99.8%,合成扩展不确定度为0.4%(k=2)。经过检验,BIT纯度标准物质均匀性良好,并且能够稳定保存12个月。 展开更多
关键词 1 2-苯并异噻唑啉-3-酮 纯度标准物质 高效液相色谱法 质量平衡法 差示扫描量热法 不确定度
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预应力下车载液氢气瓶振动特性分析
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作者 吕辉 郝朝阳 +2 位作者 李沐泽 宋建豪 姜悦 《低温与超导》 北大核心 2025年第6期80-87,97,共9页
车载液氢气瓶是氢燃料电池汽车的关键储能部件,其振动特性影响行驶安全与结构可靠性。本文以1350 L车载液氢气瓶为对象,通过自由模态试验与有限元仿真验证模型,结合虚拟质量法与正交试验,系统分析充装率、压力及加速度对振动特性的影响... 车载液氢气瓶是氢燃料电池汽车的关键储能部件,其振动特性影响行驶安全与结构可靠性。本文以1350 L车载液氢气瓶为对象,通过自由模态试验与有限元仿真验证模型,结合虚拟质量法与正交试验,系统分析充装率、压力及加速度对振动特性的影响。结果表明:随着充装率提升,液氢质量效应虽降低固有频率,但低温与高压增强材料刚度,致固有频率整体上升;高阶模态对质量变化更敏感,X轴加速度对低阶模态影响最显著。谐响应分析显示,低充装率下第二阶模态(44 Hz)易致共振,50%以上充装率下未激发一阶模态。研究揭示了低温、高压与液氢质量的耦合机制,为结构设计与安全评估提供理论支持。 展开更多
关键词 车载液氢气瓶 充装率 虚拟质量法 正交试验 谐响应
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