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A nested case-control study of maternal-neonatal transmission of hepatitis B virus in a Chinese population 被引量:23
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作者 Li-Zhang Chen Wen-Qi Zhou +2 位作者 Shu-Shan Zhao Zhi-Yu Liu Shi-Wu Wen 《World Journal of Gastroenterology》 SCIE CAS CSCD 2011年第31期3640-3644,共5页
AIM:To examine the determinants of maternal-neonatal transmission of hepatitis B virus(HBV) METHODS:A nested case-control study was conducted in Changsha,Hunan,People's Republic of China from January 1,2005 to Sep... AIM:To examine the determinants of maternal-neonatal transmission of hepatitis B virus(HBV) METHODS:A nested case-control study was conducted in Changsha,Hunan,People's Republic of China from January 1,2005 to September 31,2006 To avoid potential maternal blood contamination,we collected vein blood of newborns immediately after birth and before initial hepatitis B vaccination to determine the HBV infection status of the newborn For each HBsAg-positive infant,one HBsAg-negative infant born to an HBsAg-positive mother was matched by hospital at birth(same),gender(same),and date of birth(within 1 mo) A faceto-face interview was conducted to collect clinical and epidemiological data Conditional logistic regression analysis was used to estimate the independent effects of various determinants on maternal-neonatal transmission of HBV RESULTS:A total of 141 HBsAg-positive infants and 141 individually matched HBsAg-negative infants were included in the final analysis Maternal first-degree family history of HBV infection,intrahepatic cholestasis,and premature rupture of membranes were risk factors for perinatal transmission of HBV,whereas systematic treatment and HBV immunoglobulin injections for mothers with HBV infection were protective factors for maternal-neonatal transmission of HBV,after adjustment for potential confounding factors CONCLUSION:For HBsAg-positive mothers,systematic treatment,HBV immunoglobulin administration,and controlling intrahepatic cholestasis and pregnancy complications may reduce the incidence of perinatal transmission of HBV. 展开更多
关键词 HBsAg-positive Hepatitis B virus Perinatal transmission:nested case-control study
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Insulin-like growth factor-1,IGF binding protein-3,and the risk of esophageal cancer in a nested case-control study 被引量:6
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作者 Yasushi Adachi Masanori Nojima +7 位作者 Mitsuru Mori Kentaro Yamashita Hiro-o Yamano Hiroshi Nakase Takao Endo Kenji Wakai Kiyomi Sakata Akiko Tamakoshi 《World Journal of Gastroenterology》 SCIE CAS 2017年第19期3488-3495,共8页
To assess the relationship between serum levels of insulin-like growth factor-1(IGF1)/IGF-binding protein-3(IGFBP3)and the risk of esophageal carcinoma.METHODSWe assessed the relationship between the serum levels of t... To assess the relationship between serum levels of insulin-like growth factor-1(IGF1)/IGF-binding protein-3(IGFBP3)and the risk of esophageal carcinoma.METHODSWe assessed the relationship between the serum levels of these molecules and the risk of esophageal cancer in a prospective,nested case-control study of participants from the Japan Collaborative Cohort Study.A baseline survey was conducted from 1988 to 1990.Of the 110585 enrolled participants,35%donated blood samples.Those who had been diagnosed with esophageal cancer were considered cases for nested case-control studies.A conditional logistic model was used to estimate odds ratios for the incidence of esophageal cancer associated with serum IGF1 and IGFBP3 levels.RESULTSThirty-one cases and 86 controls were eligible for the present assessment.The molar ratio of IGF1/IGFBP3,which represents the free and active form of IGF1,was not correlated with the risk of esophageal carcinoma.A higher molar difference between IGFBP3 and IGF1,which estimates the free form of IGFBP3,was associated with a decreased risk of esophageal carcinoma(P=0.0146),and people in the highest tertile had the lowest risk(OR=0.107,95%CI:0.017-0.669).After adjustment for body mass index,tobacco use,and alcohol intake,the molar difference of IGFBP3-IGF1 was inversely correlated with the risk of esophageal carcinoma(P=0.0150).CONCLUSIONThe free form of IGFBP3,which is estimated by this molar difference,may be inversely associated with esophageal cancer incidence. 展开更多
关键词 Esophageal cancer Insulin-like growth factor Insulin-like growth factor binding protein nested case-control study Odds ratio
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A Nested Case-Control Study to Explore the Association between Immunoglobulin G N-glycans and Ischemic Stroke 被引量:1
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作者 WANG Bi Yan SONG Man Shu +3 位作者 ZHANG Jie MENG Xiao Ni XING Wei Jia WANG You Xin 《Biomedical and Environmental Sciences》 SCIE CAS CSCD 2023年第5期389-396,共8页
Objective This study prospectively investigates the association between immunoglobulin G(IgG)N-glycan traits and ischemic stroke(IS) risk.Methods A nested case-control study was conducted in the China suboptimal healt... Objective This study prospectively investigates the association between immunoglobulin G(IgG)N-glycan traits and ischemic stroke(IS) risk.Methods A nested case-control study was conducted in the China suboptimal health cohort study,which recruited 4,313 individuals in 2013–2014. Cases were identified as patients diagnosed with IS, and controls were 1:1 matched by age and sex with cases. Ig G N-glycans in baseline plasma samples were analyzed.Results A total of 99 IS cases and 99 controls were included, and 24 directly measured glycan peaks(GPs) were separated from Ig G N-glycans. In directly measured GPs, GP4, GP9, GP21, GP22, GP23, and GP24 were associated with the risk of IS in men after adjusting for age, waist and hip circumference,obesity, diabetes, hypertension, and dyslipidemia. Derived glycan traits representing decreased galactosylation and sialylation were associated with IS in men(FBG2S2/(FBG2 + FBG2S1 + FBG2S2): odds ratio(OR) = 0.92, 95% confidence interval(CI): 0.87–0.97;G1n: OR = 0.74, 95% CI: 0.63–0.87;G0n: OR =1.12, 95% CI: 1.03–1.22). However, these associations were not found among women.Conclusion This study validated that altered Ig G N-glycan traits were associated with incident IS in men, suggesting that sex discrepancies might exist in these associations. 展开更多
关键词 Ischemic stroke Immunoglobulin G N-GLYCANS nested case-control study
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Nested case-control analysis with general additive-multiplicative hazard models
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作者 ZHENG Ming LIN Ren-xin +1 位作者 SUN Yi YU Wen 《Applied Mathematics(A Journal of Chinese Universities)》 SCIE CSCD 2012年第2期159-168,共10页
This paper discusses the nested case-control analysis under a class of general additive-multiplicative hazard models which includes the Cox model and the additive hazard model as special cases.A pseudo-score is constr... This paper discusses the nested case-control analysis under a class of general additive-multiplicative hazard models which includes the Cox model and the additive hazard model as special cases.A pseudo-score is constructed to estimate the regression parameters.The resulting estimator is shown to be consistent and asymptotically normally distributed.The limiting variance-covariance matrix can be consistently estimated by the nested case-control data.A simulation study is conducted to assess the finite sample performance of the proposed estimator and a real example is provided for illustration. 展开更多
关键词 additive-multiplicative hazard nested case-control design pseudo-score survival analysis.
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Reduced risk of dementia in patients with type 2 diabetes mellitus using Chinese herbal medicine:A nested case-control study
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作者 Hou-Hsun Liao Hanoch Livneh +4 位作者 Hua-Lung Huang Jui-Yu Hung Ming-Chi Lu How-Ran Guo Tzung-Yi Tsai 《World Journal of Diabetes》 SCIE 2023年第11期1632-1642,共11页
BACKGROUND Dementia is a prevalent condition in type 2 diabetes mellitus(T2DM)patients.While Chinese herbal medicine(CHM)is often employed as complementary therapy for glycemic control,its effect in controlling likeli... BACKGROUND Dementia is a prevalent condition in type 2 diabetes mellitus(T2DM)patients.While Chinese herbal medicine(CHM)is often employed as complementary therapy for glycemic control,its effect in controlling likelihood of dementia has not yet been fully elucidated.AIM To compare the risk of dementia between T2DM patients with and without CHM treatment.METHODS We undertook a nested case-control study and obtained data on patients 20-70 years of age who received medical care for T2DM between 2001 and 2010 from the National Health Insurance Research database in Taiwan.Cases,defined as those with dementia that occurred at least one year after the diagnosis of T2DM,were randomly matched to controls without dementia from the study cohort at a 1:1 ratio.We applied conditional logistic regression to explore the associations between CHM treatment and dementia.RESULTS A total of 11699 dementia cases were matched to 11699 non-dementia controls.We found that adding CHM to conventional care was related to a lower risk of dementia[adjusted odds ratio(OR)=0.51],and high-intensity CHM treatment was associated with an adjusted OR of 0.22.CONCLUSION This study shows that the cumulative CHM exposure was inversely associated with dementia risk in an exposureresponse manner,implying that CHM treatment may be embraced as a disease management approach for diabetic patients to prevent dementia. 展开更多
关键词 Type 2 diabetes mellitus DEMENTIA Chinese herbal medicine nested case-control study Odds ratio
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Genome-wide association study reveals novel loci for adult type 1 diabetes in a 5-year nested case-control study
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作者 Yan Gao Shi Chen +9 位作者 Wen-Yong Gu Chen Fang Yi-Ting Huang Yue Gao Yan Lu Jian Su Ming Wu Jun Zhang Ming Xu Zeng-Li Zhang 《World Journal of Diabetes》 SCIE 2021年第12期2073-2086,共14页
BACKGROUND Type 1 diabetes(T1D)is a severe and prevalent metabolic disease.Due to its high heredity,an increasing number of genome-wide association studies have been performed,most of which were from hospital-based ca... BACKGROUND Type 1 diabetes(T1D)is a severe and prevalent metabolic disease.Due to its high heredity,an increasing number of genome-wide association studies have been performed,most of which were from hospital-based case-control studies with a relatively small sample size.The association of single nucleotide polymorphisms(SNPs)and T1D has been less studied and is less understood in natural cohorts.AIM To investigate the significant variants of T1D,which could be potential biomarkers for T1D prediction or even therapy.METHODS A genome-wide association study(GWAS)of adult T1D was performed in a nested case-control study(785 cases vs 804 controls)from a larger 5-year cohort study in Suzhou,China.Potential harmful or protective SNPs were evaluated for T1D.Subsequent expression and splicing quantitative trait loci(eQTL and sQTL)analyses were carried out to identify target genes modulated by these SNPs.RESULTS A harmful SNP for T1D,rs3117017[odds ratio(OR)=3.202,95%confidence interval(CI):2.296-4.466,P=9.33×10-4]and three protective SNPs rs55846421(0.113,0.081-0.156,1.76×10-9),rs75836320(0.283,0.205-0.392,1.07×10-4),rs362071(0.568,0.495-0.651,1.66×10-4)were identified.Twenty-two genes were further identified as potential candidates for T1D onset.CONCLUSION We identified a potential genetic basis of T1D,both protective and harmful,using a GWAS in a larger nested case-control study of a Chinese population. 展开更多
关键词 Type 1 diabetes Genome-wide association study nested case-control study POLYMORPHISM
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Nested case-control study on risk factors for opportunistic infections in patients with inflammatory bowel disease 被引量:6
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作者 Shan-Shan Gong Yi-Hong Fan +2 位作者 Qing-Qing Han Bin Lv Yi Xu 《World Journal of Gastroenterology》 SCIE CAS 2019年第18期2240-2250,共11页
BACKGROUND When opportunistic infections occur, patients with inflammatory bowel disease(IBD) commonly display a significantly increased rate of morbidity and mortality.With increasing use of immunosuppressive agents ... BACKGROUND When opportunistic infections occur, patients with inflammatory bowel disease(IBD) commonly display a significantly increased rate of morbidity and mortality.With increasing use of immunosuppressive agents and biological agents,opportunistic infections are becoming a hot topic in the perspective of drug safety in IBD patients. Despite the well-established role of opportunistic infections in the prognosis of IBD patients, there are few epidemiological data investigating the incidence of opportunis-tic infections in IBD patients in China. Besides, the risk factors for opportunistic infection in Chinese IBD patients remain unclear.AIM To predict the incidence of opportunistic infections related to IBD in China, and explore the risk factors for opportunistic infections.METHODS A single-center, prospective study of IBD patients was conducted. The patients were followed for up to 12 mo to calculate the incidence of infections. For each infected IBD patient, two non-infected IBD patients were selected as controls. A conditional logistic regression analysis was used to assess associations between putative risk factors and opportunistic infections, which are represented as odds ratios(OR) and 95% confidence intervals(CIs).RESULTS Seventy(28.11%) out of 249 IBD patients developed opportunistic infections.Clostridium difficile infections and respiratory syncytial virus infections were found in 24 and 16 patients, respectively. In a univariate analysis, factors such as the severity of IBD, use of an immunosuppressant or immunosuppressants, high levels of fecal calprotectin, and C-reactive protein or erythrocyte sedimentation rate were individually related to a significantly increased risk of opportunistic infection. Multivariate analysis indicated that the use of any immunosuppressant yielded an OR of 3.247(95%CI: 1.128-9.341), whereas the use of any two immunosuppressants yielded an OR of 6.457(95%CI: 1.726-24.152) for opportunistic infection. Interestingly, when immunosuppressants were used in combination with infliximab(IFX) or 5-aminosalicylic acid, a significantly increased risk of opportunistic infection was also observed. The relative risk of opportunistic infection was greatest in IBD patients with severe disease activity(OR = 9.090; 95%CI: 1.532-53.941, relative to the remission stage). However, the use of IFX alone did not increase the risk of opportunistic infection.CONCLUSION Factors such as severe IBD, elevated levels of fecal calprotectin, and the use of immunosuppressive medications, especially when used in combination, are major risk factors for opportunistic infections in IBD patients. The use of IFX alone does not increase the risk of opportunistic infection. 展开更多
关键词 nested case-control study OPPORTUNISTIC INFECTIONS INFLAMMATORY BOWEL disease
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Nested case-control study of multiple serological indexes and Brighton pediatric early warming score in predicting death of children with sepsis 被引量:5
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作者 Xiong Xie Ming Li +2 位作者 Tian-Tian Xiong Rui Wang Liang Xiao 《World Journal of Clinical Cases》 SCIE 2019年第4期431-440,共10页
BACKGROUND Currently, it is difficult to predict the complications of children at the early stage of sepsis. Brighton pediatric early warning score(PEWS) is a disease risk assessment system that is simple and easy to ... BACKGROUND Currently, it is difficult to predict the complications of children at the early stage of sepsis. Brighton pediatric early warning score(PEWS) is a disease risk assessment system that is simple and easy to operate, which has good sensitivity and specificity in disease recognition among children. Because detection indicators vary widely in children, a single indicator is difficult to assess the posttreatment status of children with sepsis.AIM To investigate the relationship between serological markers, Brighton PEWS, and death in children with sepsis after treatment.METHODS A total of 205 children diagnosed with sepsis at our hospital were enrolled. The baseline data, serum scores, and PEWS scores were recorded. In the nested casecontrol study, children who died during the study period were included in an observation group. According to the matching principle, the children who were not dead in the same cohort were included in a control group. The influencing factors of death in children with sepsis after treatment and the value of each evaluation index in predicting the prognosis of children were analyzed.RESULTS A total of 96 children were enrolled in the study, including 48 each in the observation group and the control group. Multivariate logistic regression analysis indicated that antibacterial treatments within 1 h(P = 0.017), shock(P = 0.044),multiple organ dysfunction syndrome(MODS)(P = 0.027), serum procalcitonin(PCT)(P = 0.047), serum albumin(ALB)(P = 0.024), and PEWS(P = 0.012) were independent risk factors for the death of children with sepsis. The area under the curve of the combination of ALB, PCT, and PEWS to predict the death in children with sepsis was the highest(0.908).CONCLUSION Antibacterial treatments within 1 h, shock, MODS, PCT, ALB, and PEWS are independent risk factors for the death of children with sepsis. The predictive accuracy of the combination of PCT, ALB, and PEWS for the prognosis of children with sepsis is the best. 展开更多
关键词 SEROLOGICAL indicators PEDIATRIC EARLY WARMING SCORE SEPSIS nested casecontrol study Systemic inflammatory reaction syndrome
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Plasma succinate and the risks of cardiovascular events and recurrent stroke after ischemic stroke:A nested case-control study
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作者 Leping Zhang Hongyu Chen +4 位作者 Xiaoqing Bu Zhong Ju Tan Xu Yonghong Zhang Chongke Zhong 《Chinese Medical Journal》 2025年第12期1487-1489,共3页
To the Editor:Stroke is among the leading public health problems in China,with high rates of recurrent stroke,cardiovascular events and mortality,resulting in a considerable medical and economic burden.[1]The identifi... To the Editor:Stroke is among the leading public health problems in China,with high rates of recurrent stroke,cardiovascular events and mortality,resulting in a considerable medical and economic burden.[1]The identification of new molecular markers and therapeutic targets is necessary to better refine the risk prediction of cardiovascular events and develop new treatment strategies for ischemic stroke.Succinate is a tricarboxylic acid(TCA)cycle intermediate and has received considerable attention for its involvement in various signaling pathways associated with cardiovascular diseases.[2–4]Recent studies have reported that succinate is a novel mediator that promotes atherosclerotic lesion progression,fibroblast activation,and apoptosis resistance. 展开更多
关键词 recurrent stroke nested case control study identification new molecular markers therapeutic targets ischemic stroke plasma succinate cardiovascular events better refine risk prediction cardiovascular events develop new treatment strategies
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Association between serum albumin with geriatric nutritional risk index and osteopenia in Chinese elderly men:a nested case-control study
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作者 Ting Li Jing Zeng +12 位作者 Xinyu Miao Zimo Pan Fan Hu Xiaoyan Cai Xinjiang Wang Guanzhong Liu Xinghe Hu Xinli Deng Meiliang Gong Xue Yang Yanping Gong Nan Li Chunlin Li 《Asia Pacific Journal of Clinical Nutrition》 2024年第4期569-580,共12页
Background and Objectives:Malnutrition is associated with a higher risk of osteoporosis.We aim to assess the relationship between serum albumin with geriatric nutritional risk index and osteopenia in Chinese elderly m... Background and Objectives:Malnutrition is associated with a higher risk of osteoporosis.We aim to assess the relationship between serum albumin with geriatric nutritional risk index and osteopenia in Chinese elderly men.Methods and S tudy Design:This is a nested case-control study from a prospective cohort enrolled 1109 indi viduals who were followed for seven years.Demographic data,medical history,signs and symptoms,and labora tory parameters were collected and analysed.Nutritional status and Geriatric Nutritional Risk Index(GNRI)were assessed.The nutrition-related indexes predictive value for osteopenia development was analyzed through multi variate Cox regression analysis and by creating a receiver operating characteristic curve(ROC),calculating the area under the curve(AUC).Kaplan-Meier(K-M)method was further used to find the nutritional status level in the elderly men.Results:The ALB and GNRI correlated with the risk of osteopenia in Chinese elderly men.Af ter adjusting for all covariates,people with higher ALB level(HR:0.821;95%CI:0.790-0.852)and higher GNRI score(HR:0.889;95%CI:0.869-0.908)had a smaller risk of o steopenia.ROC analysis showed that the AUC for ALB was 0.729(p˂0.05)and for the GNRI score was 0.731(p˂0.05).K-M curve indicated a significant difference in ALB level(p˂0.001)and GNRI score(p˂0.001)in the respective subgroups.Conclusions:This study found that lower ALB level and lower GNRI score are associat ed with a higher prevalence of osteopenia among elderly men in China. 展开更多
关键词 OSTEOPOROSIS serum albumin geriatric nutrition risk index Chinese elderly men nested case-control study
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Extended Nested Array with a Filled Sensor for DOA Estimation of Non-circular Signals
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作者 LI Xiaolong ZHANG Xiaofei SHEN Zihan 《Transactions of Nanjing University of Aeronautics and Astronautics》 2025年第1期90-100,共11页
Sparse array design has significant implications for improving the accuracy of direction of arrival(DOA)estimation of non-circular(NC)signals.We propose an extended nested array with a filled sensor(ENAFS)based on the... Sparse array design has significant implications for improving the accuracy of direction of arrival(DOA)estimation of non-circular(NC)signals.We propose an extended nested array with a filled sensor(ENAFS)based on the hole-filling strategy.Specifically,we first introduce the improved nested array(INA)and prove its properties.Subsequently,we extend the sum-difference coarray(SDCA)by adding an additional sensor to fill the holes.Thus the larger uniform degrees of freedom(uDOFs)and virtual array aperture(VAA)can be abtained,and the ENAFS is designed.Finally,the simulation results are given to verify the superiority of the proposed ENAFS in terms of DOF,mutual coupling and estimation performance. 展开更多
关键词 non-circular signal extended nested array sparse array direction of arrival(DOA)estimation sum-difference coarray
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应用PCR及Nested-PCR技术检测柑橘黄龙病病原研究 被引量:35
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作者 丁芳 易干军 王国平 《园艺学报》 CAS CSCD 北大核心 2004年第6期803-806,共4页
以采自田间和广东省农业科学院果树研究所防虫隔离网室内嫁接并感染黄龙病的5个柑橘品种叶片为材料,以草本指示植物长春花(Catharanthusroseas)和木本指示植物柑(CitrusreticulataBlanco)鉴定为基础,采用改良的CTAB法提取总DNA,在此... 以采自田间和广东省农业科学院果树研究所防虫隔离网室内嫁接并感染黄龙病的5个柑橘品种叶片为材料,以草本指示植物长春花(Catharanthusroseas)和木本指示植物柑(CitrusreticulataBlanco)鉴定为基础,采用改良的CTAB法提取总DNA,在此基础上进行常规PCR与NestedPCR检测,并对特异目的片段进行克隆、测序。试验证明NestedPCR比常规PCR的灵敏度更高。这两种方法均可以检测出未显症的黄龙病材料,但NestedPCR可以在木本指示植物嫁接后40d左右、草本指示植物摩擦接种1个月左右检测到病原;而常规PCR在木本植物嫁接后60d左右、草本植物摩擦接种近2个月左右才能检测到病原。常规PCR所能检测到的最低DNA的量为pg数量级;NestedPCR检测病原DNA灵敏度约为常规PCR的104倍。 展开更多
关键词 柑橘 黄龙病 PCR nested—PCR 检测
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广西砂糖橘黄龙病亚洲种的Nested-PCR检测 被引量:8
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作者 黄宏明 王茜 +2 位作者 徐宁 韦宗便 廖惠红 《南方农业学报》 CAS CSCD 北大核心 2013年第12期1997-2000,共4页
【目的】利用柑橘黄龙病病原亚洲种16S rDNA序列的特异引物检测疑似黄龙病的砂糖橘叶片样品,为砂糖橘黄龙病的综合防控提供理论依据。【方法】选取采自广西9市17个采样点的214份疑似黄龙病及无症状砂糖橘叶片样品,用试剂盒法提取叶脉基... 【目的】利用柑橘黄龙病病原亚洲种16S rDNA序列的特异引物检测疑似黄龙病的砂糖橘叶片样品,为砂糖橘黄龙病的综合防控提供理论依据。【方法】选取采自广西9市17个采样点的214份疑似黄龙病及无症状砂糖橘叶片样品,用试剂盒法提取叶脉基因组DNA,采用柑橘黄龙病亚洲种16S rDNA特异引物进行PCR扩增,扩增结果在1%琼脂糖凝胶电泳上检测,统计待检样品柑橘黄龙病病原菌亚洲种的带菌率。【结果】对214份样品的Nested-PCR扩增结果,部分样品可得到1160 bp左右的特异条带,与预期大小相符但条带明暗不同。来自广西9市17个采样点的砂糖橘叶片样品均检测出黄龙病亚洲种病原,平均检出率均在66.0%以上,其中检出率最高的是来自东兴市的样品,检出率为100.0%,检出率最低的是来自南宁市的样品,检出率为66.9%;斑驳、缺素型黄化、叶脉黄化、小叶和无症状叶片样品中均可检测出黄龙病亚洲种。【结论】Nested-PCR技术具有灵敏度高、特异性强的特点,能够快速、准确检测出各种症状样品的黄龙病病原,可用于柑橘黄龙病的早期诊断。 展开更多
关键词 砂糖橘 黄龙病病原 检测率 nested—PCR 广西
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基于Nested Logit模型的铁路旅客客运产品选择研究 被引量:14
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作者 王文宪 陈钉钧 +1 位作者 吕红霞 江峰 《交通运输系统工程与信息》 EI CSCD 北大核心 2015年第4期140-146,共7页
通过成都—武汉既有线出行旅客的问卷调查,以及样本数据的归纳分析,对旅客客运产品选择行为特征进行描述.基于随机效用最大化理论,以乘车方式与客运产品作为选择肢,旅客主体、出行特性及列车服务特性的各项指标作为效用变量,构建了乘车... 通过成都—武汉既有线出行旅客的问卷调查,以及样本数据的归纳分析,对旅客客运产品选择行为特征进行描述.基于随机效用最大化理论,以乘车方式与客运产品作为选择肢,旅客主体、出行特性及列车服务特性的各项指标作为效用变量,构建了乘车方式位于上层、客运产品位于下层的Nested Logit模型.模型的上下层参数标定结果表明,旅客的收入状况、出行目的、出行距离、列车票价及运行时间对其乘车方案选择具有显著影响,旅客的年龄、出行费用来源、收入状况、出行距离,以及列车票价、运行时间对其客运产品选择具有显著影响.模型能较为准确地反映铁路客运产品的实际需求,从而为其合理设计与调整提供理论依据. 展开更多
关键词 铁路运输 效用变量 乘车方式 客运产品 nested LOGIT模型
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大豆油中转基因成分的Nested PCR和Semi-nested PCR检测方法研究 被引量:10
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作者 闻伟刚 崔俊霞 赵秀玲 《生物技术通报》 CAS CSCD 2005年第6期84-87,共4页
对大豆油中DNA提取方法进行了研究,结果表明CTAB、SDS和Wizard试剂盒提取大豆油DNA均具有良好的效果。利用nested PCR和semi-nested PCR检测大豆(Roundup Ready)油中的转基因成分发现,该方法能够检测到大豆原油中的Lectin基因(112bp)、C... 对大豆油中DNA提取方法进行了研究,结果表明CTAB、SDS和Wizard试剂盒提取大豆油DNA均具有良好的效果。利用nested PCR和semi-nested PCR检测大豆(Roundup Ready)油中的转基因成分发现,该方法能够检测到大豆原油中的Lectin基因(112bp)、CaMV35S基因(147bP)和CP4-EPSPS基因(205bp),检测灵敏度达到10-6ng/μl;但该方法未能从人豆成品油(一级)中扩增到上述基因,当中的转基因成分DNA含量低于10-12ng/μl。 展开更多
关键词 大豆油 转基因成分 nested PCR Semi-nested PCR检测
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RP/SP融合数据的Mixed Logit和Nested Logit模型估计对比 被引量:14
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作者 张天然 杨东援 +1 位作者 赵娅丽 叶亮 《同济大学学报(自然科学版)》 EI CAS CSCD 北大核心 2008年第8期1073-1078,1084,共7页
分析了RP/SP(revealed preference/stated preference)融合数据对交通行为研究的重要性,通过实际调查的RP/SP融合数据,对比了用Mixed Logit和Nested Logit模型的估计结果.得出了以下结论:RP/SP融合数据中,有时同类型交通方式的关联性要... 分析了RP/SP(revealed preference/stated preference)融合数据对交通行为研究的重要性,通过实际调查的RP/SP融合数据,对比了用Mixed Logit和Nested Logit模型的估计结果.得出了以下结论:RP/SP融合数据中,有时同类型交通方式的关联性要比RP和SP数据之间的关联性强,应用不同的Nested Logit模型分层方法进行估计对比;Mixed Logit考虑了个体的异质性,假定参数为随机分布,同时体现了RP/SP数据的关联性和同类型交通方式的关联性,能够得到更好的参数估计结果;Mixed Logit模型能更现实地反映不同交通方式使用者对时间和费用敏感性的不同(时间价值的不同),体现小汽车使用者比公共交通使用者具有更高时间价值的现实情况. 展开更多
关键词 RP/SP融合数据 MIXED Logit(RPL/RCL)模型 异质性 nested LOGIT模型
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应用nested和touch down PCR技术分离牦牛CAPN1大亚基基因EST 被引量:6
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作者 蔡欣 吴建平 +3 位作者 徐明旭 张利平 汪虹英 刘雅楠 《西北农林科技大学学报(自然科学版)》 CSCD 北大核心 2005年第2期14-18,共5页
 钙激活中性蛋白酶1(CAPN1)基因是影响肉嫩度的侯选基因。根据GeneBank中已公布的CAPN1基因cDNA序列设计同源PCR引物,通过RT,nested和touch-downPCR技术从牦牛肌肉组织总RNA中分离目的序列,与pGEM-T-easy载体连接后转化DH5α感受态菌株...  钙激活中性蛋白酶1(CAPN1)基因是影响肉嫩度的侯选基因。根据GeneBank中已公布的CAPN1基因cDNA序列设计同源PCR引物,通过RT,nested和touch-downPCR技术从牦牛肌肉组织总RNA中分离目的序列,与pGEM-T-easy载体连接后转化DH5α感受态菌株,通过PCR扩增、限制性酶切和测序分析鉴定阳性克隆。分离到的基因片段为牦牛CAPN1大亚基的部分编码序列,在GeneBank中的注册号为AY197555,与奶牛、人、食蟹猴、小鼠、绵羊以及大鼠相应序列的同源性分别为98%,89%,89%,83%,96%和81%,在不同物种之间具有较强的保守性。CAPN1基因EST的分离为进一步研究牦牛CAPN1基因奠定了基础。此研究表明,在总RNA质量不理想的情况下,同时采用这2种技术可以较大限度地获取目的序列。 展开更多
关键词 nested和touch-down PCR EST分离 CAPN1大亚基基因 牦牛
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基于Nested-Logit模型的经济圈交通方式划分方法研究 被引量:12
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作者 易富君 邓卫 周竹萍 《交通运输系统工程与信息》 EI CSCD 2009年第4期110-115,共6页
在分析经济圈交通方式选择影响因素的基础上,利用出行费用、出行时间和舒适性等指标作为广义费用函数的主要构成属性,建立了基于Nested-Logit模型的经济圈交通方式划分方法.并采用出行疲劳恢复时间来描述不同交通方式出行的舒适程度,然... 在分析经济圈交通方式选择影响因素的基础上,利用出行费用、出行时间和舒适性等指标作为广义费用函数的主要构成属性,建立了基于Nested-Logit模型的经济圈交通方式划分方法.并采用出行疲劳恢复时间来描述不同交通方式出行的舒适程度,然后用时间价值的计算方法求得疲劳恢复时间的价值.Nested-Logit模型是在一般多项Logit模型基础上的一种改进模型,考虑了各交通方式之间的相关性,对具有相似性的交通方式进行了分类,因此该模型更接近实际情况,相对合理.同时通过分析这两种模型的内在关系,提出了一种求解Nested-Logit模型的方法,该方法程序化强,便于应用.最后以长三角经济圈部分城市之间的交通方式划分作为实例,说明了该方法有效可行. 展开更多
关键词 经济圈 nested—Logit模型 交通方式划分 疲劳恢复曲线
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基于家庭属性和Nested Logit模型的学生出行选择特性分析 被引量:10
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作者 马书红 付建川 姚志刚 《重庆交通大学学报(自然科学版)》 CAS 北大核心 2015年第4期122-127,共6页
运用非集计模型中Nested Logit模型的理论与方法,以中小学生出行方式选择行为为对象,研究个人属性、家庭属性和出行特性对学生出行方式选择的影响。模型分上下两层,上层为公共交通和私人交通方式的选择,下层为小汽车、摩托车、自行车及... 运用非集计模型中Nested Logit模型的理论与方法,以中小学生出行方式选择行为为对象,研究个人属性、家庭属性和出行特性对学生出行方式选择的影响。模型分上下两层,上层为公共交通和私人交通方式的选择,下层为小汽车、摩托车、自行车及步行交通方式的选择;利用SPSS软件对模型进行标定和检验,分析各因素对学生出行选择的影响。结果表明:家庭收入对于上下层交通方式选择影响大,收入高的家庭,学生出行更倾向于选择私人交通方式;是否拥有公交卡对上层交通方式影响最明显,当学生拥有公交卡时,其选择公共交通方式是私人方式的38倍;家庭交通工具拥有量和是否有人接送是下层交通方式选择的主要因素,家庭小汽车数量增加或有人接送时,学生出行选择小汽车的概率增加。 展开更多
关键词 交通工程 学生出行 行为 家庭属性 nested LOGIT模型 出行方式选择
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分布式nested阵列及其高精度DOA估计 被引量:12
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作者 王毅 陈伯孝 +1 位作者 杨明磊 郑桂妹 《系统工程与电子技术》 EI CSCD 北大核心 2015年第2期253-258,共6页
为了进一步提高分布式阵列的自由度和分辨力,提出一种分布式nested阵列。该阵列将nested阵列作为分布式阵列的子阵。基于Khatri-Rao积,nested子阵可提高整个阵列的自由度。分布式nested阵列以较少的阵元数及硬件成本实现大的孔径和较高... 为了进一步提高分布式阵列的自由度和分辨力,提出一种分布式nested阵列。该阵列将nested阵列作为分布式阵列的子阵。基于Khatri-Rao积,nested子阵可提高整个阵列的自由度。分布式nested阵列以较少的阵元数及硬件成本实现大的孔径和较高的分辨力,而且提高了目标波达方向(direction of arrival,DOA)估计的精度。并利用基于Khatri-Rao积的空间平滑酉旋转不变子空间(estimation of signal parameters via rotational invariance techniques,ESPRIT)算法进行DOA估计。其先对协方差矩阵向量化提高自由度,然后利用空间平滑对新数据协方差矩阵进行秩恢复,最后使用双尺度酉ESPRIT算法得到DOA估计。仿真结果证明所提方法的有效性。 展开更多
关键词 分布式nested阵列 KHATRI-RAO积 酉旋转不变子空间 波达方向
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