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Optimal Cutoffs of Grip Strength for Definition as Weakness in the Elderly
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作者 Renwei Dong Qi Guo Jiazhong Wang 《Journal of Biosciences and Medicines》 2014年第9期14-18,共5页
Objective:?To indentify Optimal cutoffs of grip strength for definition as weakness in the elderly. Methods: Our study population comprised 1317 subjects (mean ± SD age: 67.6 ± 6.0 years;44.3% men) from the ... Objective:?To indentify Optimal cutoffs of grip strength for definition as weakness in the elderly. Methods: Our study population comprised 1317 subjects (mean ± SD age: 67.6 ± 6.0 years;44.3% men) from the Hangu area of Tianjin, China. Data collection includes general physical examination, biochemical indicators and questionnaire. Mobility limitation was defined as a 4-m walking speed < 0.8 m/s and grip strength represents muscle strength. According to the ROC curve model, the cut-off point of grip strength was calculated, when mobility limitation was selected as the target variables. Results: According to the results of ROC curve, In man, grip strength is lower than 32.45 kg, the strength is weaker, Sensitivity is 79.7% and Specificity is 64.9%, the AUC is 0.764 (p < 0.001);In women, grip strength is lower than 18.20 kg, the strength is weaker, Sensitivity is 53.3% and Specificity is78.1%, the AUC is 0.703 (p < 0.001). Conclusions: Cut points for weakness derived from this large, diverse sample of older adults may be useful to identify populations who may benefit from interventions to improve muscle strength and function. 展开更多
关键词 cutoffs ELDERLY PEOPLE GRIP Strength WEAKNESS
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Analysis of petrophysical cutoffs of reservoir intervals with production capacity and with accumulation capacity in clastic reservoirs 被引量:4
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作者 Wang Yanzhong Cao Yingchang +3 位作者 Song Guoqi Song Ling Yang Tian Zhang Shaomin 《Petroleum Science》 SCIE CAS CSCD 2014年第2期211-219,共9页
Methodologies have been developed for calculating cutoffs of reservoir intervals with production capacity (RIPC) and reservoir intervals with accumulation capacity (RIAC) according to the types of pore throat stru... Methodologies have been developed for calculating cutoffs of reservoir intervals with production capacity (RIPC) and reservoir intervals with accumulation capacity (RIAC) according to the types of pore throat structures and dynamic force by using data from petrophysical analysis, production tests and mercury injection. The data are from clastic reservoirs in the third member (Es3) and the fourth member (Es4) of the Shahejie Formation in the Shengtuo area on the North Slope of the Dongying Sag, Jiyang Depression, China. The method of calculating cutoffs of RIPC is summarized as follows: 1) determination of permeability cutoffs of RIPC; 2) classification of types of pore-throat structures according to mercury injection data and then relating porosity to permeability and determining the relationship between porosity and permeability according to each type of pore-throat structure; and 3) calculating porosity cutoffs of RIPC using established correlation between porosity and permeability according to the type of pore throat structure. The method of calculating cutoffs of RIAC includes: 1) establishing a functional relationship between oil-water interracial tension and formation temperature; 2) calculating limiting values of maximum connected pore-throat radii according to formation temperature and dynamic forces of each reservoir interval; 3) correlating permeability with maximum connected pore-throat radius and then obtaining permeability cutoffs of RIAC; and 4) calculating porosity cutoffs on the basis of permeability cutoffs according to specific correlations, suitable for the type of porethroat structure. The results of this study show that porosity and permeability cutoffs of clastic reservoirs decrease with depth. For a fixed permeability cutoff, the porosity cutoff of R1PC varies because the type of pore throat is different. At a fixed temperature, porosity and permeability cutoffs of RIAC decrease as dynamic force increases. For a fixed permeability cutoff of effective hydrocarbon accumulation, the porosity cutoff also varies with different types of pore throat. 展开更多
关键词 Effective reservoir petrophysical cutoff of reservoir intervals with production capacity(RIPC) petrophysical cutoff of reservoir intervals with accumulation capacity (RIAC) clastic rocks
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Physical-property cutoffs of tight reservoirs by field and laboratory experiments: a case study from Chang 6, 8–9 in Ordos Basin
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作者 Bingbing SHI Xiangchun CHANG +6 位作者 Zhongquan LIU Ye LIU Tianchen GE Pengfei ZHANG Yongrui WANG Yue WANG Lixin MAO 《Frontiers of Earth Science》 SCIE CSCD 2021年第2期471-489,共19页
Tight sandstone reservoirs are generally characterized by complex reservoir quality,non-Darcy flow,and strong heterogeneity.Approaches utilized for evaluating physical property cutoffs of conventional reservoirs maybe... Tight sandstone reservoirs are generally characterized by complex reservoir quality,non-Darcy flow,and strong heterogeneity.Approaches utilized for evaluating physical property cutoffs of conventional reservoirs maybe inapplicable.Thus,a comprehensive investigation on physical property cutoffs of tight sandstone reservoirs is crucial for the reserve evaluation and successful exploration.In this study,a set of evaluation approaches take advantage of field operations(i.e.,core drilling,oil testing,and wireline well logging data),and simulation experiments(i.e.,high-pressure mercury injection-capillary pressure(MICP)experiment,oil-water relative permeability experiment,nuclear magnetic resonance(NMR)experiment,and biaxial pressure simulation experiment)were comparatively optimized to determine the physical property cutoffs of effective reservoirs in the Upper Triassic Chang 6,Chang 8 and Chang 9 oil layers of the Zhenjing Block.The results show that the porosity cutoffs of the Chang 6,Chang 8,and Chang 9 oil layers are 7.9%,6.4%,and 8.6%,and the corresponding permeability are 0.08 mD,0.05 mD,and 0.09 mD,respectively.Coupled with wireline well logging,mud logging,and oil testing,the cut-off of the thickness of single-layer effective reservoirs are approximately 3.0 m,3.0 m,and 2.0 m,respectively.Depending on the cutoffs of critical properties,a superimposed map showing the planar distribution of the prospective targets can be mapped,which may delineate the effective boundary of prospective targets for petroleum exploration of tight sandstone reservoirs. 展开更多
关键词 tight sandstone reservoirs cutoffs of petrophysical property field operations simulation experiments Yanchang Formation Ordos Basin
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An Inquiry about Seasonal Cutoffs in Lower Reaches of the Yellow River
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《Natural Disaster Reduction in China》 1998年第3期10-14,共5页
AnInquiryaboutSeasonalCutofsinLowerReachesoftheYelowRiverZhangBaoxiang(ShandongInstituteofHydraulics)Waterpr... AnInquiryaboutSeasonalCutofsinLowerReachesoftheYelowRiverZhangBaoxiang(ShandongInstituteofHydraulics)Waterproblemisoneofthewo... 展开更多
关键词 cutoffs SEASONAL LOWER AN
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A Dual Source Power Based EV Wireless Charging System
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作者 NAQVI Syed Zohair Raza XIAO Lan JIANG Menghan 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI CSCD 2024年第S01期35-42,共8页
Recently,there has been a huge increase in the usage of fuel resources for automobiles which is severely affecting the climate and causing global warming.The use of electric vehicle(EV)is an effective way to protect t... Recently,there has been a huge increase in the usage of fuel resources for automobiles which is severely affecting the climate and causing global warming.The use of electric vehicle(EV)is an effective way to protect the environment and reduce travel costs.However,the EV charging system has a single charging source,and the charging rate is limited.In this paper,an EV wireless charging system based on dual source power supply has been developed.It realizes intelligent switching between 12 V photovoltaic output and 220 V AC dual source power,and has wireless transmission function.Based on the proposed power supply architecture,the micro wireless charging model is built,which enables the EV model to store power and realize static and mobile control through the wireless induction charging system. 展开更多
关键词 renewable energy inductive coupling inductive charging CONVERTERS automatic changeover auto cutoff circuit
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Innuendoes of Sterilisation Drilling in Surface Mining Operations—A Case Study
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作者 Richard Gyebuni Festus Kunkyin-Saadaari Isaac Ekow Anaman 《International Journal of Geosciences》 CAS 2024年第5期458-477,共20页
Surface mining operations play a crucial role in meeting the world’s increasing demand for mineral resources for the advancement of technology and debauched expansion of economies. The search for and exploitation of ... Surface mining operations play a crucial role in meeting the world’s increasing demand for mineral resources for the advancement of technology and debauched expansion of economies. The search for and exploitation of these mineral resources are therefore important for the sustainability of the mineral extraction industry. To this end, efficient mine planning must incorporate sterilisation drilling and effective waste rock management principles in the search and exploitation of these minerals. In this article, sterilisation drilling is being reviewed vis-a-vis the establishment of waste and tailings dump locations, backfilling of open pit excavations and mine closure giving critical attention to the minerals and mining laws of Ghana. Subsequently, a detailed case study of a surface mining operation that successfully incorporated sterilisation drilling in determining waste dump location in its mine planning process has been presented in this study. The findings indicate that the proposed waste dump location could present a potential mining prospect in the future based on enhanced milling capacity/technology and improved mineral commodity price;underscoring the significance of sterilization drilling in the sustainability of the mining industry. 展开更多
关键词 STERILISATION Exploration BACKFILLING Waste Dump Cutoff Grade
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Convergence Issues Associated with Cutoff Energies and Ab Initio Studies of Adsorption of CO on W and Pt
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作者 Sathya Hanagud Roussislava Zaharieva 《Journal of Materials Science and Chemical Engineering》 2024年第3期1-8,共8页
The experimental research programs of 1950s, to understand the adsorption of CO on W surfaces, changed to ab initio studies in 2000s. The goals were to seek improved practical applications. Most of the studies were ba... The experimental research programs of 1950s, to understand the adsorption of CO on W surfaces, changed to ab initio studies in 2000s. The goals were to seek improved practical applications. Most of the studies were based on density functional theory. Many studies also used programs, such as VASP (Vienna Abinitio simulation package) and CPMD. The computational procedures used plane wave approximations. This needed studies with selection of K points and cutoff energy selection to assure convergence in energy calculations. Observations and analysis of papers published from 2006 to 2022 indicate that the cutoff energies were selected arbitrarily without any needed convergence studies. By selecting a published 2006 paper, this paper has clearly showed that an arbitrary selection of cutoff energy, such as 460 eV, is not in the range of, cutoff energies that assure convergence of energy calculations, with ab initio methods and have indicated correction procedures. . 展开更多
关键词 CO Adsorption Tungsten and Pt surfaces Cutoff Energy Selection Convergence of Ab Initio Energy
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应用ROC曲线评价CEA、CYFRA21-1、SCC对非小细胞肺癌的诊断价值 被引量:43
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作者 罗疏薇 欧春萍 +1 位作者 张莉萍 陈宏础 《重庆医学》 CAS CSCD 北大核心 2011年第3期250-252,255,共4页
目的探讨癌胚抗原(CEA)、细胞角蛋白19片段抗原(CYFRA21-1)、鳞癌相关抗原(SCC)对非小细胞肺癌(NSCLC)的诊断价值并找出此3种肿瘤标志物(TM)对NSCLC的临床诊断界值(cut off值)。方法对99例NSCLC患者、50例肺部良性疾病患者以及50例健康... 目的探讨癌胚抗原(CEA)、细胞角蛋白19片段抗原(CYFRA21-1)、鳞癌相关抗原(SCC)对非小细胞肺癌(NSCLC)的诊断价值并找出此3种肿瘤标志物(TM)对NSCLC的临床诊断界值(cut off值)。方法对99例NSCLC患者、50例肺部良性疾病患者以及50例健康体检者血清中CEA、CYFRA21-1、SCC水平进行检测。CEA、CYFRA21-1采用电化学发光免疫分析法测定,SCC采用化学发光微粒子免疫分析法测定。利用ROC曲线对此3项TM的检测结果进行分析,评价其对NSCLC的诊断价值并找出其cut off值。结果 (1)NSCLC组中CEA、CYFRA21-1水平与良性疾病组及健康组比较差异均有统计学意义(P<0.05)。腺癌组CEA水平显著高于鳞癌组、良性疾病组和健康组(P<0.05)。腺癌组和鳞癌组CYFRA21-1水平均显著高于良性疾病组和健康组(P<0.05),而腺癌组CYFRA21-1水平与鳞癌组比较差异无统计学意义(P>0.05)。鳞癌组SCC水平与腺癌组、良性疾病组和健康组比较差异均有统计学意义(P<0.05)。此3项TM水平在良性疾病组与健康组中差异无统计学意义(P>0.05)。(2)CEA、CYFRA21-1对NSCLC诊断均有较好的准确性,其曲线下面积(AUC)分别为0.74±0.042、0.72±0.042,cut off值特异性均达到82%。CEA对腺癌的诊断有较高的特异性;CYFRA21-1对鳞癌的诊断有较高的特异性;鳞癌组SCC的特异性虽然较高,但敏感性却较低。(3)CEA、CYFRA21-1和SCC在NSCLC中的cut off值分别为3.35、2.98、1.05ng/mL。结论 CEA、CYFRA21-1对NSCLC有较好的诊断价值。CEA是诊断腺癌最有价值的指标,CYFRA21-1对鳞癌的诊断具有较高的价值,而SCC对NSCLC的诊断价值有限,仅对鳞癌的诊断具有一定作用。 展开更多
关键词 ROC曲线 癌胚抗原 角蛋白质类 CUTOFF值 鳞状细胞癌相关抗原
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核磁共振测井T_(2cutoff)确定方法及适用性分析 被引量:50
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作者 肖亮 肖忠祥 《地球物理学进展》 CSCD 北大核心 2008年第1期167-172,共6页
T2cutoff是核磁共振测井中的一个重要参数,它决定了核磁共振测井测量的有效孔隙度、渗透率、自由流体饱和度、束缚水饱和度等参数的精确程度.目前国内外普遍选取的T2cutoff为:砂泥岩储层取33ms,碳酸盐岩储层取92ms.实际研究发现T2cutof... T2cutoff是核磁共振测井中的一个重要参数,它决定了核磁共振测井测量的有效孔隙度、渗透率、自由流体饱和度、束缚水饱和度等参数的精确程度.目前国内外普遍选取的T2cutoff为:砂泥岩储层取33ms,碳酸盐岩储层取92ms.实际研究发现T2cutoff应是变化的量而并非单一值.简单的运用单一的T2cutoff来计算各种地层参数势必会产生误差甚至得出错误的解释结论.叙述了33ms作为T2cutoff的由来及其不合理性,同时分析了目前国内外确定T2cutoff的各种方法及其适用性. 展开更多
关键词 核磁共振测井 T2cutoff 综合物性指数 油柱高度 适用性 束缚水饱和度 分析
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血浆同型半胱氨酸的CutOff值及其临床意义探讨 被引量:9
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作者 郑美丽 王清涛 +3 位作者 惠汝太 霍勇 徐希平 杨新春 《中国医学前沿杂志(电子版)》 2013年第11期20-24,共5页
同型半胱氨酸(homocysteine,Hcy)不但是脑卒中发生的独立危险因子,而且与高血压有协同作用,被《中国高血压防治指南(2010版)》确定为心血管八大危险因素之一。脑卒中是我国居民第一位死因,由于遗传和生活习惯的差异,中国人群的Hcy水平... 同型半胱氨酸(homocysteine,Hcy)不但是脑卒中发生的独立危险因子,而且与高血压有协同作用,被《中国高血压防治指南(2010版)》确定为心血管八大危险因素之一。脑卒中是我国居民第一位死因,由于遗传和生活习惯的差异,中国人群的Hcy水平显著高于西方国家,因此在我国强调控制高血压的同时,加强控制高Hcy水平等其他脑卒中高发危险因素意义更加重大。国内外大量研究证明,在叶酸缺乏或者没有强化叶酸的地区,Hcy水平高于10μmol/L的人群脑卒中发生率显著增加,尤其是对于同时伴有高血压的患者而言;补充叶酸以降低Hcy水平能够显著降低脑卒中发生风险。此外,没有资料表明Hcy在人体内具有重要生理功能,关于补充叶酸以预防心脑血管事件发生的研究在Hcy水平较低的受试人群也仍然显示了有益的效果,而且补充小剂量叶酸以降低血浆Hcy水平(即使在<10μmol/L的情况下)在降低脑卒中发生风险的同时并不增加其他任何健康风险。《中国高血压防治指南》制定的高Hcy Cut Off值(>10μmol/L)可作为我国医务工作者规范开展脑卒中预防工作的参考,在临床实践中,提高Hcy的Cut Off值(如>12μmol/L或>15μmol/L)等将使大量潜在脑卒中高发人群得不到及时关注和干预,增加脑卒中发生风险,尤其是在高血压患者群中。因此在中国高血压患者群中较好地控制血浆Hcy水平对于开展我国脑卒中防治工作有着重要意义。 展开更多
关键词 HCY 血浆 CUTOFF 脑卒中 血管疾病 血管病
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血清f-PSA/t-PSA临床诊断值的确定及应用 被引量:3
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作者 夏吉荣 朱丹 +3 位作者 严立 陈瀑 陈宏础 张莉萍 《临床检验杂志》 CAS CSCD 北大核心 2010年第3期194-195,共2页
目的探讨游离前列腺特异性抗原/总前列腺特异性抗原(f-PSA/t-PSA;F/T)的最佳临床诊断值,并验证其临床应用的有效性。方法用微粒子捕获酶免疫技术测定67例前列腺癌和562例非前列腺癌患者的血清t-PSA和f-PSA,并计算F/T比值,经统计分析,确... 目的探讨游离前列腺特异性抗原/总前列腺特异性抗原(f-PSA/t-PSA;F/T)的最佳临床诊断值,并验证其临床应用的有效性。方法用微粒子捕获酶免疫技术测定67例前列腺癌和562例非前列腺癌患者的血清t-PSA和f-PSA,并计算F/T比值,经统计分析,确定F/T的临床诊断值,并进行临床病例验证。结果F/T比值为0.15时对前列腺癌诊断的敏感性为89.3%、特异性为88.0%。结论选择F/T比值为0.15作为临床诊断界值,可最大效率提高前列腺癌的鉴别诊断率。 展开更多
关键词 前列腺癌 前列腺特异性抗原 CUTOFF值 F-PSA/T-PSA
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Lattice-Matched InP-Based HEMTs with T^T of 120GHz 被引量:2
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作者 陈立强 张海英 +2 位作者 尹军舰 钱鹤 牛洁斌 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2005年第3期472-475,共4页
Lattice matched InP based InAlAs/InGaAs HEMTs with 120GHz cutoff frequency are reported.These devices demonstrate excellent DC characteristics:the extrinsic transconductance of 600mS/mm,the threshold voltage of -1 ... Lattice matched InP based InAlAs/InGaAs HEMTs with 120GHz cutoff frequency are reported.These devices demonstrate excellent DC characteristics:the extrinsic transconductance of 600mS/mm,the threshold voltage of -1 2V,and the maximum current density of 500mA/mm. 展开更多
关键词 cutoff frequency high electron mobility transistors INALAS/INGAAS INP
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Ultrahigh-Speed Lattice-Matched In_(0.53)Ga_(0.47)As/In_(0.52)Al_(0.48)As HEMTs with 218GHz Cutoff Frequency 被引量:1
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作者 刘亮 张海英 +5 位作者 尹军舰 李潇 徐静波 宋雨竹 牛洁斌 刘训春 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2007年第12期1864-1867,共4页
Lattice-matched In0.5 Ga0.47 As/In0.52 Al 0.48 As high electron mobility transistors (HEMTs) with a cutoff frequency (ft) as high as 218GHz are reported. This fT is the highest value ever reported for HEMTs in Chi... Lattice-matched In0.5 Ga0.47 As/In0.52 Al 0.48 As high electron mobility transistors (HEMTs) with a cutoff frequency (ft) as high as 218GHz are reported. This fT is the highest value ever reported for HEMTs in China. These devices also demonstrate excellent DC characteristics:the extrinsic transconductance is 980mS/mm and the maximum current density is 870mA/mm. The material structure and all the device fabrication technology in this work were developed by our group. 展开更多
关键词 cutoff frequency high electron mobility transistor lnGaAs/InA1As lnP
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In_(0.53)Ga_(0.47)As/In_(0.52)Al_(0.48)As HEMTs with f_(max) of 183GHz 被引量:1
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作者 刘亮 张海英 +7 位作者 尹军舰 李潇 杨浩 徐静波 宋雨竹 张健 牛洁斌 刘训春 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2007年第12期1860-1863,共4页
By epitaxial layer structure design and key fabrication process optimization,a lattice-matched InP-based In0.53Ga0.47 As-In0.52Al0.48As HEMT with an ultra high maximum oscillation frequency (fmax) of 183GHz was fab-... By epitaxial layer structure design and key fabrication process optimization,a lattice-matched InP-based In0.53Ga0.47 As-In0.52Al0.48As HEMT with an ultra high maximum oscillation frequency (fmax) of 183GHz was fab- ricated. The fmax is the highest value for HEMTs in China. Also, the devices are reported, including the device structure, the fabrication process, and the DC and RF performances. 展开更多
关键词 maximum oscillation frequency/power-gain cutoff frequency high electron mobility transistor InGaAs/InAIAs INP
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随钻核磁共振测井横向弛豫时间截止值计算方法与应用 被引量:1
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作者 张冲 孙康 +3 位作者 康楠 张占松 唐磊 何伟 《长江大学学报(自然科学版)》 2023年第1期21-29,共9页
横向弛豫时间(T2)截止值(T2cutoff)是核磁共振测井评价束缚水饱和度、渗透率的关键参数,由于随钻核磁共振与电缆、岩心核磁共振的测量在仪器参数、测量环境等方面存在较大差异,导致岩心核磁实验确定的T2cutoff评价模型在随钻核磁共振测... 横向弛豫时间(T2)截止值(T2cutoff)是核磁共振测井评价束缚水饱和度、渗透率的关键参数,由于随钻核磁共振与电缆、岩心核磁共振的测量在仪器参数、测量环境等方面存在较大差异,导致岩心核磁实验确定的T2cutoff评价模型在随钻核磁共振测井资料中难以取得良好的应用效果。依据含泥砂岩T2cutoff的影响因素,建立基于岩石孔隙结构特征参数的变T2cutoff评价模型;同时以岩石孔隙半径为中间参数,建立随钻核磁横向弛豫时间校正模型,消除岩心与随钻的刻度差异。研究结果表明:含泥砂岩T2cutoff主要受岩石微小孔隙及大孔隙发育程度的影响,微小孔隙越发育,T2cutoff越小;相同孔隙半径下,岩心核磁与随钻核磁横向弛豫时间呈乘幂变换关系,校正系数与随钻核磁小孔隙分量、孔隙分量中值、随钻核磁孔隙度具有高相关性。将建立的横向弛豫时间校正模型、变T2cutoff评价模型应用到渤海A油田的束缚水饱和度评价中,结果显示,束缚水饱和度计算的平均绝对误差由校正前的11.51%降低为4.62%,表明该方法有效提高了随钻核磁共振测井评价储层束缚水饱和度的精度,也为随钻核磁共振测井T2cutoff的确定提供了一个新的思路。 展开更多
关键词 横向弛豫时间截止值(T2cutoff) 随钻核磁共振测井 横向弛豫时间校正 束缚水饱和度
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双抗原夹心ELISA法与间接ELISA法检测抗-HCV比较分析 被引量:1
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作者 黄乙清 《中国输血杂志》 CAS CSCD 北大核心 2012年第S1期72-72,共1页
目的比较分析双抗原夹心ELISA法试剂与间接ELISA法试剂检测抗-HCV灵敏度和特异性,为更好从方法学选择使用试剂提供参考依据。方法采用两种不同厂家间接法HCV抗体ELISA检测试剂盒及双抗原夹心法试剂盒对1500份无偿献血者标本平行检测。... 目的比较分析双抗原夹心ELISA法试剂与间接ELISA法试剂检测抗-HCV灵敏度和特异性,为更好从方法学选择使用试剂提供参考依据。方法采用两种不同厂家间接法HCV抗体ELISA检测试剂盒及双抗原夹心法试剂盒对1500份无偿献血者标本平行检测。结果间接法有82份阳性,双抗原夹心法有62份阳性。两种方法阳性标本再进行病毒核酸(NAT)检测有47份HCVRNA阳性.其中有2份标本双抗原夹心ELISA法未检出,间接法结果S/CO值略高于cutoff范围及NAT均判为阳性,证实双抗原夹心ELISA法对低值阳性也存在漏检可能。 展开更多
关键词 双抗原夹心法 试剂检测 HCV 平行检测 间接法 CUTOFF 特异性 病毒核酸 总符合率 RNA
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应用定值血清控制HBsAg检测中Cutoff值 被引量:2
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作者 鲍淳茂 《浙江预防医学》 1999年第10期61-63,共3页
采用ELISA方法测定HBsAg,判定HBsAg阴、阳性的标准是Cutoff值,然而ELISA方法受操作、仪器、试剂、环境、温度等多种条件因素影响,同一被测物每次测得的OD值会产生变异,用不同批号的试剂测定同一被测物,测得的OD值也存在显著性差异,如果C... 采用ELISA方法测定HBsAg,判定HBsAg阴、阳性的标准是Cutoff值,然而ELISA方法受操作、仪器、试剂、环境、温度等多种条件因素影响,同一被测物每次测得的OD值会产生变异,用不同批号的试剂测定同一被测物,测得的OD值也存在显著性差异,如果Cutoff值始终定为0.105来判定结果是不准确的,因此每次实验的Cutoff值应该由一种标准品对其进行校正。本次实验也证明了在一定浓度范围内,HBsAg的浓度与测得的OD值成正比,因此每一次实验可采用定值血清来校正Cutoff值,使被测物的测定结果更加合理和准确。材料与方法1.标本:4ng、2ng HBsAg定值血清,卫生部临检中心生产。2.仪器:法国paster酶标仪(LP40) 展开更多
关键词 HBSAG 血清 CUTOFF值 乙型肝炎 ELISA
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GU油田多层砂岩储层岩石物理评价
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作者 杨景强 刘如红 +2 位作者 张立秋 彭丹丹 王春阳 《石油地球物理勘探》 EI CSCD 北大核心 2013年第A01期170-174,185,共6页
以GU工区为例,通过对测井资料质量控制、预处理、数字处理多矿物模型选取、饱和度模型选择应用以及cutoff值的确定等工作,对多层砂岩储层岩石物理的评价进行了论述。结合实际资料应用分析表明,交会图、频率分布图等图形分析技术在数据... 以GU工区为例,通过对测井资料质量控制、预处理、数字处理多矿物模型选取、饱和度模型选择应用以及cutoff值的确定等工作,对多层砂岩储层岩石物理的评价进行了论述。结合实际资料应用分析表明,交会图、频率分布图等图形分析技术在数据质量控制、cutoff值确定等方面具有很强的实用性。但由于研究区缺乏密闭取心饱和度资料,文中重点对由电阻率模型计算的含水饱和度和基于J函数获取的原始含水饱和度数据进行比对基础上,按照国际上较通用的厚度划分流程,应用黏土含量、孔隙度、含水饱和度三个参数的cutoff值,成功地对毛砂岩、储层以及净产层三类厚度进行了划分。 展开更多
关键词 岩石物理评价 预处理 含水饱和度 cutoff值确定
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Second-Order Raman Scattering from n- and p-Type 4H-SiC
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作者 高欣 孙国胜 +4 位作者 李晋闽 王雷 赵万顺 张永新 曾一平 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2004年第12期1555-1560,共6页
The results of second-order Raman-scattering experiments on n- and p-type 4H-SiC are presented,covering the acoustic and the optical overtone spectral regions.Some of the observed structures in the spectra are assigne... The results of second-order Raman-scattering experiments on n- and p-type 4H-SiC are presented,covering the acoustic and the optical overtone spectral regions.Some of the observed structures in the spectra are assigned to particular phonon branches and the points in the Brillouin zone from which the scattering originates.There exists a doublet at 626/636cm -1 with energy difference about 10cm -1 in both n- and p-type 4H-SiC,which is similar to the doublet structure with the same energy difference founded in hexagonal GaN,ZnO, and AlN.The cutoff frequency at 1926cm -1 of the second-order Raman is not the overtone of the A 1(LO) peak of the n-type doping 4H-SiC,but that of the undoping one.The second-order Raman spectrum of 4H-SiC can hardly be affected by doping species or doping density. 展开更多
关键词 H-SiC second-order Raman cutoff frequency
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不同程度的溶血标本和带血球标本对酶联免疫吸附试验一步法检测乙肝病毒血清标志物的影响 被引量:10
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作者 周峰 宋忠琴 《实用医技杂志》 2006年第22期3966-3967,共2页
目的探讨不同程度的溶血和带血球标本对酶联免疫吸附试验(ELISA)法检测乙肝病毒表面抗原(HB-sAg)、表面抗体(HBsAb)、e抗原(HBeAg)、核心抗体(HBcAg)的影响。方法用100例健康人(HBsAg、HBsAb、HBeAg、HBcAb均为阴性)的血液标本,用血红... 目的探讨不同程度的溶血和带血球标本对酶联免疫吸附试验(ELISA)法检测乙肝病毒表面抗原(HB-sAg)、表面抗体(HBsAb)、e抗原(HBeAg)、核心抗体(HBcAg)的影响。方法用100例健康人(HBsAg、HBsAb、HBeAg、HBcAb均为阴性)的血液标本,用血红蛋白标准液配成不同程度的溶血血清或加入不等量的红细胞血清,用ELISA一步法分别检测HBsAg、HBsAb、HBeAg、HBcAb,通过对检测结果的观察来分析溶血或带血球标本对ELISA一步法检测乙肝病毒不同标志物的干扰程度。结果当溶血(Hb≥10g/L)或红细胞浓度达到一定量(≥0.125×1012/L)时,前3项42%以上的标本OD均大于cutoff值(P<0.001);当溶血(Hb≥5g/L)或红细胞浓度达到(0.25×1012/L)时,原倍HBcAb100%呈阳性反应(P<0.001)。结论当溶血程度达到Hb≥10g/L,红细胞浓度≥0.125×1012/L时对ELISA法检测乙肝病毒标志物有影响,会使标本呈假阳性反应。 展开更多
关键词 酶联免疫吸附试验 标本溶血 带血球标本 CUTOFF值
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