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Research on Data Theory of Value
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作者 Li Haijian Zhao Li 《China Economist》 2024年第3期21-38,共18页
This paper explores the data theory of value along the line of reasoning epochal characteristics of data-theoretical innovation-paradigmatic transformation and,through a comparison of hard and soft factors and observa... This paper explores the data theory of value along the line of reasoning epochal characteristics of data-theoretical innovation-paradigmatic transformation and,through a comparison of hard and soft factors and observation of data peculiar features,it draws the conclusion that data have the epochal characteristics of non-competitiveness and non-exclusivity,decreasing marginal cost and increasing marginal return,non-physical and intangible form,and non-finiteness and non-scarcity.It is the epochal characteristics of data that undermine the traditional theory of value and innovate the“production-exchange”theory,including data value generation,data value realization,data value rights determination and data value pricing.From the perspective of data value generation,the levels of data quality,processing,use and connectivity,data application scenarios and data openness will influence data value.From the perspective of data value realization,data,as independent factors of production,show value creation effect,create a value multiplier effect by empowering other factors of production,and substitute other factors of production to create a zero-price effect.From the perspective of data value rights determination,based on the theory of property,the tragedy of the private outweighs the comedy of the private with respect to data,and based on the theory of sharing economy,the comedy of the commons outweighs the tragedy of the commons with respect to data.From the perspective of data pricing,standardized data products can be priced according to the physical product attributes,and non-standardized data products can be priced according to the virtual product attributes.Based on the epochal characteristics of data and theoretical innovation,the“production-exchange”paradigm has undergone a transformation from“using tangible factors to produce tangible products and exchanging tangible products for tangible products”to“using intangible factors to produce tangible products and exchanging intangible products for tangible products”and ultimately to“using intangible factors to produce intangible products and exchanging intangible products for intangible products”. 展开更多
关键词 Data theory of value data value generation data value rights determination data value pricing
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Multifractal estimation of NMR T_(2) cut-off value in low-permeability rocks considering spectrum kurtosis: SMOTE-based oversampling integrated with machine learning
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作者 Xiao-Jun Chen Rui-Xue Zhang +4 位作者 Xiao-Bo Zhao Jun-Wei Yang Zhang-Jian Lan Cheng-Fei Luo Jian-Chao Cai 《Petroleum Science》 SCIE EI CAS CSCD 2023年第6期3411-3427,共17页
The transverse relaxation time (T_(2)) cut-off value plays a crucial role in nuclear magnetic resonance for identifying movable and immovable boundaries, evaluating permeability, and determining fluid saturation in pe... The transverse relaxation time (T_(2)) cut-off value plays a crucial role in nuclear magnetic resonance for identifying movable and immovable boundaries, evaluating permeability, and determining fluid saturation in petrophysical characterization of petroleum reservoirs. This study focuses on the systematic analysis of T_(2) spectra and T_(2) cut-off values in low-permeability reservoir rocks. Analysis of 36 low-permeability cores revealed a wide distribution of T_(2) cut-off values, ranging from 7 to 50 ms. Additionally, the T_(2) spectra exhibited multimodal characteristics, predominantly displaying unimodal and bimodal morphologies, with a few trimodal morphologies, which are inherently influenced by different pore types. Fractal characteristics of pore structure in fully water-saturated cores were captured through the T_(2) spectra, which were calculated using generalized fractal and multifractal theories. To augment the limited dataset of 36 cores, the synthetic minority oversampling technique was employed. Models for evaluating the T_(2) cut-off value were separately developed based on the classified T_(2) spectra, considering the number of peaks, and utilizing generalized fractal dimensions at the weight <0 and the singular intensity range. The underlying mechanism is that the singular intensity and generalized fractal dimensions at the weight <0 can detect the T_(2) spectral shift. However, the T_(2) spectral shift has negligible effects on multifractal spectrum function difference and generalized fractal dimensions at the weight >0. The primary objective of this work is to gain insights into the relationship between the kurtosis of the T_(2) spectrum and pore types, as well as to predict the T_(2) cut-off value of low-permeability rocks using machine learning and data augmentation techniques. 展开更多
关键词 Nuclear magnetic resonance Low-permeability porous media T_(2)cut-off value Fractal and multifractal Data augmentation Machine learning
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APPLICATION OF THERMAL ANALYSIS TO THE QUICK DETERMINATION OF THE PROXIMATE ANALYSIS ITEMS AND CALORIC VALUE FOR COAL
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作者 Zhen Ku GUO Lan Xiang MENG China Commodity Inspection Institute,Beijing,100025Xin Yu REN Ya Zhong ZHANG Qinhuangdao Commodity Inspection Bureau,Hebei Province,066002 《Chinese Chemical Letters》 SCIE CAS CSCD 1993年第10期921-924,共4页
A research on the application of a TG-DTA(thermal gravimetry aifferential thermal analysis)to the quick determination of moisture,organic volatile fixed carbon,ash and caloric value for coal is described.
关键词 APPLICATION OF THERMAL ANALYSIS TO THE QUICK determination OF THE PROXIMATE ANALYSIS ITEMS AND CALORIC value FOR COAL DTA QUICK
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A circular zone counting method of identifying a Duffing oscillator state transition and determining the critical value in weak signal detection 被引量:3
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作者 李梦平 许雪梅 +1 位作者 杨兵初 丁家峰 《Chinese Physics B》 SCIE EI CAS CSCD 2015年第6期192-197,共6页
Identifying state transition and determining the critical value of the Duffing oscillator are crucial to indicating external signal existence and have a great influence on detection accuracy in weak signal detection. ... Identifying state transition and determining the critical value of the Duffing oscillator are crucial to indicating external signal existence and have a great influence on detection accuracy in weak signal detection. A circular zone counting (CZC) method is proposed in this paper, by combining the Duffing oscillator's phase trajectory feature and numerical calculation for quickly and accurately identifying state transition and determining the critical value, to realize a high- efficiency weak signal detection. Detailed model analysis and method construction of the CZC method are introduced. Numerical experiments into the reliability of the proposed CZC method compared with the maximum Lyapunov exponent (MLE) method are carried out. The CZC method is demonstrated to have better detecting ability than the MLE method, and furthermore it is simpler and clearer in calculation to extend to engineering application. 展开更多
关键词 identifying state transition determining critical value Duffing oscillator circular zone countingmethod maximum Lyapunov exponent method
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Dynamic monitoring of menopause hormone therapy and defining the cut-off value of endometrial thickness during uterine bleeding 被引量:3
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作者 Qiu Sheng Jun Yang +1 位作者 Qiaoling Zhao Fen Li 《The Journal of Biomedical Research》 CAS CSCD 2016年第3期191-196,共6页
The aim of this study was to evaluate the effects of low-dose tibolone therapy on ovarian area, uterine volume and endometrial thickness, and define the cut-off value of endometrial thickness for curettage during uter... The aim of this study was to evaluate the effects of low-dose tibolone therapy on ovarian area, uterine volume and endometrial thickness, and define the cut-off value of endometrial thickness for curettage during uterine bleeding. We followed 619 postmenopausal women, aged 40-60 years, for two years. There were 301 subjects in the low-dose tibolone treatment group and 318 subjects in the control group. The ovarian area, uterine volume and endometrial thickness in all participants were measured by transvaginal ultrasound prior to, one and two years post enrollment, respectively. Endometrial specimens were collected from all subjects with abnormal uterine bleeding during the follow-up period. We found that the uterine volume in the treatment group was greater than that in the control group, and the difference was significant (P〈0.05), but there were no significant differences in ovarian area and endometrial thickness between the two groups (P〉0.05). When the cut-off value for endometrial thickness was 7.35 ram, the sensitivity and specificity were 100% and 79.07%, respectively, and 85.71% and 93.02% when 7.55 mm was set as the cut-offduring tibolone therapy. The results indicate that low-dose tibolone therapy may postpone uterine atrophy and the cut-off value of endometrial thickness may be appropriately adjusted for curettage. 展开更多
关键词 low-dose tibolone ovarian area uterine volume ENDOMETRIUM dynamic monitoring cut-off value
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Cut-off Values of Diagnostic Indices to Detect Iron Deficiency in Chinese Breast-fed Infants 被引量:1
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作者 WU Qin REN Jie +8 位作者 YANG Li Chen LIU Jie WEI Jun ZHANG Wei LI Na WANG Yue Jiao YAN Li Huang MA Jian Rong YANG Xiao Guang 《Biomedical and Environmental Sciences》 SCIE CAS CSCD 2016年第11期829-833,共5页
Iron deficiency anemia is one of the most prevalent nutritional deficiency worldwide. The commonly used cut-off values for identifying iron deficiency are extrapolated from older children and may not be suitable for i... Iron deficiency anemia is one of the most prevalent nutritional deficiency worldwide. The commonly used cut-off values for identifying iron deficiency are extrapolated from older children and may not be suitable for infants. Therefore, our study aimed to establish appropriate cut-off values for the evaluation of iron status in Chinese infants. Pregnant women who delivered at 〉37 gestational weeks with normal iron status were recruited. Later, infants with normal birth weight and who were breastfed in the first 4 months were selected. Blood samples were collected to assess hemoglobin, serum ferritin, soluble transferrin receptor, mean corpuscular volume and free erythrocyte protoporphyrin. Cut-offs of all iron indices were determined as the limit of 95% confidence interval. 展开更多
关键词 cut-off values of Diagnostic Indices to Detect Iron Deficiency in Chinese Breast-fed Infants FEP
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Diversity among the Values of Administrators in Different Organizations and the Determinants of Ethics in Decision-making
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作者 吴成丰 《Journal of China Textile University(English Edition)》 EI CAS 2000年第2期117-121,共5页
The purpose of the research is to discuss the differentperformances of administrators’ values in different orga-nizations in Taiwan province and the determinants ofethics of administrators in decision - making. Throu... The purpose of the research is to discuss the differentperformances of administrators’ values in different orga-nizations in Taiwan province and the determinants ofethics of administrators in decision - making. Throughthe understanding of these issues, the research expects tohelp the internal operation of ethical behaviors in the or-ganization in order to establish business ethics. The re-search used empirical examination and stratified sam-pling to select 231 top, middle and low administrators inmanufacture, service, government and non - profit -making organizations as target. The result showed thatthe main determinant of ethics of administrators in deci-sion - making was "corporate interest". Besides, the ad-ministrators in the four organizations showed distinctivevalues. The non - profit - making organizations showedhigher sense of values such as"caring self - discipline"and "safety belonging"than profit - making groups did. 展开更多
关键词 value determinANT of ETHICS business ETHICS
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ORTHOGONAL POLYNOMIALS AND DETERMINANT FORMULAS OF FUNCTION-VALUED PADE-TYPE APPROXIMATION USING FOR SOLUTION OF INTEGRAL EQUATIONS 被引量:2
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作者 顾传青 潘宝珍 吴蓓蓓 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2006年第6期853-860,共8页
To solve Fredholm integral equations of the second kind, a generalized linear functional is introduced and a new function-valued Padé-type approximation is defined. By means of the power series expansion of the s... To solve Fredholm integral equations of the second kind, a generalized linear functional is introduced and a new function-valued Padé-type approximation is defined. By means of the power series expansion of the solution, this method can construct an approximate solution to solve the given integral equation. On the basis of the orthogonal polynomials, two useful determinant expressions of the numerator polynomial and the denominator polynomial for Padé-type approximation are explicitly given. 展开更多
关键词 generalized linear functional function-valued Padé-type approximation Fredholm integral equation orthogonal polynomial determinant formula
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Wild-type MIC Distribution and Epidemiological Cut-off Value and Resistant Characteristics of Colistin Against Escherichia Coli from Chickens
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作者 Liu Yu-hao Hu Wan-jun +5 位作者 Tian Er-jie Muhammad Ishfaq Zhang Xiu-ying Chen Chun-li Li Ji-chang 《Journal of Northeast Agricultural University(English Edition)》 CAS 2021年第2期88-96,共9页
The aim of the present study was to investigate minimum inhibitory concentration(MIC)distributions by broth microdilution(BMD)method and to determine the preliminary epidemiological cut-off value(ECV)of colistin by ep... The aim of the present study was to investigate minimum inhibitory concentration(MIC)distributions by broth microdilution(BMD)method and to determine the preliminary epidemiological cut-off value(ECV)of colistin by epidemiological cut-off(ECOFF)finder against E.coli from chickens in China.Anal swabs were collected from chicken farms in China.BMD method was used to measure MIC50 and MIC90 of colistin which were 2 and 4μg•mL^(-1),respectively.MIC frequency distributions for colistin were used to estimate preliminary ECV(8μg•mL^(-1)).High percentages of resistance to ampicillin(94.12%),nalidixic acid(94.12%),enrofloxacin(94.12%),tetracycline(94.12%),ciprofloxacin(88.24%),florfenicol(88.24%),neomycin(64.71%),gentamicin(58.82%),levofloxacin(58.82%),doxycycline(88.24%)and cefalexin(76.47%)were found.In addition,low percentages of resistance to amikacin(5.88%),spectinomycin(17.65%)and fosfomycin(41.18%)were noted.Notably,amoxicillin,sulfisoxazole and trimethoprim resulted in a 100%resistance generation efficacy rate.Prevalence of mcr-1 in E.coli(9/17)in chromosomal DNA was higher than mcr-4(2/17)gene,and mcr-1(5/17)was higher than mcr-4(3/17)in plasmid. 展开更多
关键词 E.COLI broth microdilution(BMD)method epidemiological cut-off value(ECV) mcr-1 mcr-4 COLISTIN
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Estimation of Acute Toxicity of Ammonium Sulphate to the Fresh Water Catfish,Heteropneustes fossilis——Ⅰ.Analysis of LC_(50) Values Determined by Various Methods
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作者 TARUNK.BANERJEE 《Biomedical and Environmental Sciences》 SCIE CAS CSCD 1993年第1期31-36,共6页
The acute toxic effects of ammonium sulphate to fresh-water catfish, Heteropneustes fossilis (H.fossilis) have been studied by determining LC50 values with 95% confidence limits, by the graphic method, the logistic me... The acute toxic effects of ammonium sulphate to fresh-water catfish, Heteropneustes fossilis (H.fossilis) have been studied by determining LC50 values with 95% confidence limits, by the graphic method, the logistic method, the Spearman and Karber method and the trimmed Spearman-Karber method. The trimmed Spearman-Karber method was found the most ideal for ammonium salt toxicity test. The flaws in the trimmed Spearman-Karber method are also discussed. 展开更多
关键词 values determined by Various Methods Analysis of LC Estimation of Acute Toxicity of Ammonium Sulphate to the Fresh Water Catfish Heteropneustes fossilis
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The determination of the relative permittivity of periodic stratified media based on the iterative time-reversal method 被引量:1
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作者 章志敏 王秉中 +2 位作者 梁木生 纪晴 宋钢兵 《Chinese Physics B》 SCIE EI CAS CSCD 2014年第4期694-699,共6页
In this paper, we present a new method to determine the relative permittivity of periodic stratified media using the iterative time-reversal method. Based on transmission line theory, the focal peak value of iterative... In this paper, we present a new method to determine the relative permittivity of periodic stratified media using the iterative time-reversal method. Based on transmission line theory, the focal peak value of iterative time-reversal electro- magnetic waves, which contain information about the periodic stratified medium, is computed in pulse-echo mode. Using the relationship between the focal peak value and the relative permittivity of the periodic stratified medium, the relative permittivity can be obtained by measuring the focal peak value. Numerical simulations are conducted, and the results demonstrate the feasibility of the proposed approach to the measurement of the relative permittivity of a periodic stratified medium. 展开更多
关键词 iterative time reversal periodic stratified medium peak value detection relative permittivity determination
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The Diagnostic Value of Serum TgAb in the Tg-Negative and TgAb-Positive DTC Patients after Successful Ablation 被引量:2
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作者 Qun Fan Xinhui Su Anren Kuang 《Journal of Cancer Therapy》 2016年第12期889-900,共13页
Objective: The aim of this retrospective study was to evaluate diagnostic accuracy of serum thyroglobulin antibody (TgAb) in thyroglobulin (Tg)-negative and TgAb-positive (Tg<sup>-</sup>TgAb<sup>+<... Objective: The aim of this retrospective study was to evaluate diagnostic accuracy of serum thyroglobulin antibody (TgAb) in thyroglobulin (Tg)-negative and TgAb-positive (Tg<sup>-</sup>TgAb<sup>+</sup>) patients with differentiated thyroid carcinoma (DTC). Method: We studied 341 patients with histologically confirmed DTC who had undergone remnant ablation and showed Tg<sup>-</sup>TgAb<sup>+</sup> assessed by electrochemiluminescence immunoassay (ECLIA). The cases were divided into two groups, including recurrence group 119 cases and no evidence of disease (NED) group 222 cases. Receiver operating characteristic (ROC) curve analysis was carried out. The symmetric measures of the two diagnostic methods (the golden standard and the diagnostic standard as serum TgAb level alone) were analyzed using McNemar test and measure of agreement Kappa. Results: Serum TgAb level (1381.292 ± 1017.221) IU/ml of patients with recurrent group was significantly higher than that (125.559 ± 314.047) IU/ml of NED group (P = 0.000 0.001). The area under the ROC curve was 0.962 and its asymptotic 95% confidence interval (CI) was (0.942, 0.982) that was high statistical significance. The cut-off value of TgAb was determined and interpreted at 246.695 IU/ml with sensitivity (92.40%) and specificity (92.30%). McNemar test showed that the diagnostic results of the two methods were not significant difference (P = 0.230 > 0.05). Measure of agreement Kappa was 0.841, P = 0.000 0.001 that showed the agreement of the two diagnostic methods was significant. Conclusion: Serum TgAb is a useful tumor marker for recurrence in Tg-negative and TgAb-positive DTC patients who underwent thyroidectomy and remnant ablation. The cut-off value of TgAb is 246.695 IU/ml, that is to say, serum TgAb level upon 246.695 IU/ml may be associated with the persistence or recurrence of DTC. 展开更多
关键词 DTC TGAB cut-off value
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Value Assessment of Wetland Ecosystem Services in the Da Hinggan Mountains, China
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作者 ZHANG Tingting LYU Xianguo +6 位作者 ZOU Yuanchun LIU Jiping JIANG Ming XU Chunguang ZHOU Cuicui XU Chen XUE Zhenshan 《Chinese Geographical Science》 SCIE CSCD 2022年第2期302-311,共10页
This study examined regional differences in ecosystem services for the Da Hinggan Mountains(DHM),China.A correction index was constructed based on ten-year average net primary productivity(NPP)data.A new equivalent fa... This study examined regional differences in ecosystem services for the Da Hinggan Mountains(DHM),China.A correction index was constructed based on ten-year average net primary productivity(NPP)data.A new equivalent factor table that was suitable for the assessment of wetlands in the DHM was formed by using the expert weight determination method(EWDM).An evaluation model was established for evaluating the ecosystem service value(ESV)of wetlands in the DHM.The results show that in 2020,the total ESV of wetlands reached 93361×10^(6) USD,with the forest swamp and marsh ecosystems contributing the most.From the perspective of value composition,regulating services and supporting services are the main service functions of wetlands in the DHM.From 2010 to2020,ESV provided by wetlands increased by 4337×10^(6) USD/yr in the DHM.The value of forest swamp and peatland ecosystems increased by 18.6%and 12.7%,respectively,whereas the value of swamp,shrub swamp,and marsh decreased.The research results are of significance for contributing to local government performance evaluation and determining financial compensation for the provision of wetland ecosystem services. 展开更多
关键词 WETLANDS ecosystem services value net primary productivity(NPP) Da Hinggan Mountains expert weight determination
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An integrated method for matching forest machinery and a weight-value adjustment
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作者 Dan Li 《Journal of Forestry Research》 SCIE CAS CSCD 2014年第3期683-688,共6页
Proper matching of forestry machinery is important when raising mechanization levels for forestry production. In the matching process, forestry machinery needs not only expertise, but also improved methods for solving... Proper matching of forestry machinery is important when raising mechanization levels for forestry production. In the matching process, forestry machinery needs not only expertise, but also improved methods for solving problems. I propose combination of case-based reasoning (CBR) and rule-based reasoning (RBR) by calculating the similarity of quantitative parameters of various forestry machines in an analytical and hierarchical process. I calculated the similarity of machin-ery used in forest industries to enable better selection and matching of equipment. I propose a weight-value adjusting method based on sums of squares of deviations in which the individual parameter weights were modified in the process of application. During the process of system design, I put forward a design method knowledge base and generated a dynamic web reasoning framework to integrate the processes of forest industry machinery selection and weight-value adjustment. This enables expansion of the scope of the complete system and enhancement of the reasoning efficiency. I demonstrate the validity and practicability of this method using a practical example. 展开更多
关键词 forest industry machinery Selection and matching weight-value determination reasoning process integration method
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Computational Aspect For Function-Valued Padé-Type Approximation
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作者 Chuanqing Gu Jindong Shen 《Numerical Mathematics A Journal of Chinese Universities(English Series)》 SCIE 2007年第2期171-180,共10页
The computational problems of two special determinants are investigated. Those determinants appear in the construction of the function-valued Pade-type approximation for computing Fredholm integral equation of the sec... The computational problems of two special determinants are investigated. Those determinants appear in the construction of the function-valued Pade-type approximation for computing Fredholm integral equation of the second kind. The main tool to be used in this paper is the well-known Schur complement theorem. 展开更多
关键词 函数值Padé逼近 计算问题 行列式 Schur余角定理
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Cut-off value of glycated hemoglobin A1c for detecting diabetic retinopathy in the Chinese population
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作者 Yan Wen Qing Wang 《World Journal of Diabetes》 SCIE 2024年第7期1531-1536,共6页
BACKGROUND Glycated hemoglobin A1c(HbA1c)is considered the most suitable for diabetes mellitus diagnosis due to its accuracy and convenience.However,the effect of HbA1c on diabetic retinopathy(DR)in the Han and Korean... BACKGROUND Glycated hemoglobin A1c(HbA1c)is considered the most suitable for diabetes mellitus diagnosis due to its accuracy and convenience.However,the effect of HbA1c on diabetic retinopathy(DR)in the Han and Korean populations in Jilin,China,remains inconclusive.AIM To determine the best cut-off of HbA1c for diagnosing DR among the Chinese.METHODS This cross-sectional study included 1933 participants from the Yanbian area of Jilin Province,China.Trained investigators employed a questionnaire-based survey,physical examination,laboratory tests,and fundus photography for the investigation.The best cut-off value for HbA1c was established via the receiver operating characteristic curve.The factors associated with HbA1c-associated risk factors were determined via linear regression.RESULTS The analysis included 887 eligible Chinese Han and Korean participants,591 of whom were assigned randomly to the training set and 296 to the validation set.The prevalence of DR was 3.27% in the total population.HbA1c of 6.2% was the best cut-off value in the training set,while it was 5.9% in the validation set.In both Chinese Han and Korean populations,an HbA1c level of 6.2% was the best cut-off value.The optimal cut-off values of fasting blood glucose(FBG)≥7 mmol/L and<7 mmol/L were 8.1% and 6.2% respectively in Han populations,while those in Korean populations were 6.9%and 5.3%,respectively.Age,body mass index,and FBG were determined as the risk factors impacting HbA1c levels.CONCLUSION HbA1c may serve as a useful diagnostic indicator for DR.An HbA1c level of 6.2% may be an appropriate cut-off value for DR detection in the Chinese population. 展开更多
关键词 Diabetic retinopathy Glycated hemoglobin A1c cut-off value Age Body mass index Fasting blood glucose
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双源双能量CT碘值测定在胃癌术前T分期诊断中的价值
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作者 吴守红 翟红伟 杨琦 《中国卫生标准管理》 2024年第1期137-141,共5页
目的探讨双源双能量CT碘值测定在胃癌术前T分期诊断中的应用价值。方法选取2022年4—5月在福建省立医院放射科接受双源双能量CT,后经手术病理诊断确诊为T分期的138例胃癌患者。患者均采用双源双能量CT检查。比较T_(1)期、T_(2~3)期患者... 目的探讨双源双能量CT碘值测定在胃癌术前T分期诊断中的应用价值。方法选取2022年4—5月在福建省立医院放射科接受双源双能量CT,后经手术病理诊断确诊为T分期的138例胃癌患者。患者均采用双源双能量CT检查。比较T_(1)期、T_(2~3)期患者动脉期、静脉期正常胃壁、胃壁内层、胃壁外层碘含量,比较40、60、120 keV时影像学图像质量主观指标与客观指标。结果T_(1)期、T_(2~3)期患者动脉期、静脉期胃壁内层与胃壁外层碘含量比较,差异有统计学意义(P<0.001);胃壁内层与正常胃壁碘含量比较,差异有统计学意义(P<0.001);胃壁外层与正常胃壁碘含量比较,差异无统计学意义(P=0.130、0.262、0.231、0.022)。60 keV[(3.28±0.38)分]时总体图像质量评分高于40、120 keV[(3.01±0.43)、(3.14±0.41)分],差异有统计学意义(P<0.001,P=0.004);40 keV与60 keV、40 keV与120 keV、60 keV与120 keV病灶显著性评分比较,差异均无统计学意义(P=0.129、0.054、0.713)。40keV时CT值、图像噪声、信噪比(signal-noise ratio,SNR)、对比度噪声比(clinical nursing research,CNR)高于60、120keV时,60 keV时CT值、图像噪声、SNR、CNR高于120keV时,差异有统计学意义(P<0.001)。结论采用双源双能量CT碘值测定方式,对于鉴别诊断T_(1)期、T_(2~3)期胃癌具有一定价值,且能够提高图像的质量,对于提高胃癌术前T分期的准确率有重要意义。 展开更多
关键词 胃癌 T分期 双源双能量CT 碘值测定 图像质量
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矩阵最小奇异值的两个估计
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作者 弋苑 胡兴凯 《高校应用数学学报(A辑)》 北大核心 2024年第2期248-252,共5页
利用行列式和Frobenius范数,给出了非奇异矩阵最小奇异值的两个估计.在某些情况下,数值例子表明所得的估计优于已存在的结果.
关键词 最小奇异值 FROBENIUS范数 行列式
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基于钻屑量界限方程的冲击危险性判定新方法
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作者 杜才溢 张玉江 +6 位作者 孟鑫 李杰 孔凯 杜晓峰 王博 郭育霞 刘辉 《矿业安全与环保》 CAS 北大核心 2024年第1期86-91,共6页
为提高钻屑法判定冲击危险性的精度,基于钻屑法原理及评价指标,对实际钻屑量数据进行拟合,提出一种基于钻屑量界限方程的冲击危险性判定方法(以下简称“钻屑量界限方程方法”):利用实际钻屑量自回归判定冲击危险性,将钻屑法判定冲击危... 为提高钻屑法判定冲击危险性的精度,基于钻屑法原理及评价指标,对实际钻屑量数据进行拟合,提出一种基于钻屑量界限方程的冲击危险性判定方法(以下简称“钻屑量界限方程方法”):利用实际钻屑量自回归判定冲击危险性,将钻屑法判定冲击危险性分区细化为冲击危险区、潜在冲击危险区和无冲击危险区。以古城煤矿3208工作面运输巷为工程背景进行了应用,结果表明:钻屑量界限方程方法与现场动力效应及微震监测指标判定结果相符,可有效提高钻屑法判定冲击危险性的精度,减少误判。 展开更多
关键词 钻屑法 钻屑量 冲击地压 冲击危险性 钻屑指标临界值 判定方法
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传染病筛查试验项目临界值验证方案及其意义
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作者 李潇涵 李冬冬 《检验医学》 CAS 2024年第7期700-703,共4页
临界值对于传染病筛查定性试验结果判定非常重要。然而,临界值验证是否必要,如何验证,相关指南尚无明确建议。文章对现行性能验证相关标准、指南和文献进行综合分析,探讨传染病筛查项目临界值验证的意义和验证方案的可行性,供临床实验... 临界值对于传染病筛查定性试验结果判定非常重要。然而,临界值验证是否必要,如何验证,相关指南尚无明确建议。文章对现行性能验证相关标准、指南和文献进行综合分析,探讨传染病筛查项目临界值验证的意义和验证方案的可行性,供临床实验室参考。 展开更多
关键词 传染病筛查 临界值 定性项目 性能验证
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