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Catalytic asymmetric silicon-carbon bond-forming transformations based on Si–H functionalization

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Science China Chemistry 2023年第6期66卷 1654-1687页

作者： li li Wei-Sheng Huang Zheng xu li-wen xu China Key Laboratory of Organosilicon Chemistry and Material Technology of Ministry of Education Key Laboratory of Organosilicon Material Technology of Zhejiang ProvinceCollege of MaterialChemistry and Chemical EngineeringHangzhou Normal UniversityHangzhou 311121China State Key Laboratory for Oxo Synthesis and Selective Oxidation Suzhou Research InstituteLanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000China

In view of the exciting advancement on silicon–carbon bond-forming transformations achieved in the past decade,this review intends to show a unified illustration of the recent findings on enantioselective Si–H bond functionalization aided by asymmetric ***,this review describes the enantioselective silicon–carbon bond-forming Si–H bond functionalization,focusing on the reactivity and stereoselectivity in catalytic asymmetric hydrosilylation,carbene Si–H insertion,C–H silylation,and Si–C bond-forming cross-coupling reactions that were achieved with high enantioselectivity in the presence of transitionmetal catalyst *** review highlights recent and representative examples of the enantioselective Si–H bond functionalization,discusses the origins of silicon-involving stereoselectivities,and evaluates the substrate scopes and limitations in these catalytic asymmetric Si–H bond functionalization reactions due to the special reactivity of different hydrosilanes.

关键词： Si-H functionalization hydrosilylation C-H silylation carbene Si-H insertion asymmetric catalysis

The Minimax Estimator of Stochastic Regression Coefficients and Parameters in the Class of All Estimators

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Acta Mathematica Sinica,English Series 2007年第3期23卷 497-506页

作者： li wen xu Song Gui WANG Department of Mathematics Tsinghua University Beijing 100084 P. R. China College of Applied Sciences Beijing University of Technology Beijing 100022 P. R. China College of Applied Sciences Beijing University of Technology Beijing 100022. P. R. China

In this paper, the authors address the problem of the minimax estimator of linear combinations of stochastic regression coefficients and parameters in the general normal linear model with random effects. Under a quadratic loss function, the minimax property of linear estimators is investigated. In the class of all estimators, the minimax estimator of estimable functions, which is unique with probability 1, is obtained under a multivariate normal distribution.

关键词： minimax estimator stochastic regression coefficients quadratic loss function normal linear model

Bi-dimension decomposed hidden Markov models for multi-person activity recognition

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第6期10卷 810-819页

作者： Wei-dong ZHANG Feng CHEN wen-li xu Department of Automation Tsinghua University Beo'ing 100084 China

We present a novel model for recognizing long-term complex activities involving multiple persons. The proposed model, named ‘decomposed hidden Markov model’ (DHMM), combines spatial decomposition and hierarchical abstraction to capture multi-modal, long-term dependent and multi-scale characteristics of activities. Decomposition in space and time offers conceptual advantages of compaction and clarity, and greatly reduces the size of state space as well as the number of parameters. DHMMs are efficient even when the number of persons is variable. We also introduce an efficient approximation algorithm for inference and parameter estimation. Experiments on multi-person activities and multi-modal individual activities demonstrate that DHMMs are more efficient and reliable than familiar models, such as coupled HMMs, hierarchical HMMs, and multi-observation HMMs.

关键词： Multi-channel setting Hierarchical modeling Hidden Markov model Activity recognition

Learning robust principal components from L1-norm maximization

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Journal of Zhejiang University-Science C(Computers and Electronics) 2012年第12期13卷 901-908页

作者： Ding-cheng FENG Feng CHEN wen-li xu Tsinghua National Laboratory for Information Science and Technology Tsinghua University Beijing 100084 China Department of Automation Tsinghua University Beijing 100084 China

Principal component analysis(PCA) is fundamental in many pattern recognition *** research has been performed to minimize the reconstruction error in L1-norm based reconstruction error minimization(L1-PCA-REM) since conventional L2-norm based PCA(L2-PCA) is sensitive to ***,the variance maximization formulation of PCA with L1-norm(L1-PCA-VM) has been proposed,where new greedy and nongreedy solutions are *** with the gradient ascent perspective for optimization,we show that the L1-PCA-VM formulation is problematic in learning principal components and that only a greedy solution can achieve robustness motivation,which are verified by experiments on synthetic and real-world datasets.

关键词： Principal component analysis(PCA) Outliers L1-norm,Greedy algorithms Non-greedy algorithms

Diagnostic value of interleukin-8 in colorectal cancer:A case-control study and meta-analysis

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World Journal of Gastroenterology 2014年第43期20卷 16334-16342页

作者： wen-Jun Jin Jin-Ming xu wen-li xu Dong-Hua Gu Pei-Wei li Department of Clinical Laboratory Huzhou Central Hospital Department of Epidemiology and Health Statistics Zhejiang University School of Public Health Department of Pathology Huzhou Central Hospital

AIM: To assess the diagnostic value of serum interleukin-8 (IL-8) in the detection of colorectal cancer (CRC).

关键词： Interleukin-8 Colorectal cancer Diagnostic value Case-control study Meta-analysis

Temporal trends in the prevalence of major birth defects in China:a nationwide population-based study from 2007 to 2021

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World Journal of Pediatrics 2024年第11期20卷 1145-1154页

作者： wen-Yan li Zhi-Yu Chen wen-li xu Yu-Yang Gao Zhen liu Qi li li Dai National Center for Birth Defects Monitoring West China Second University HospitalSichuan UniversityChengdu610041SichuanChina Key Laboratory of Birth Defects and Related Diseases of Women and Children Ministry of EducationSichuan UniversityNo.17 Section 3 RenminnanluChengdu610041China The Joint Laboratory for Pulmonary Development and Related Diseases West China Second University HospitalSichuan UniversityChengdu610041China NHC Key Laboratory of Chronobiology Sichuan UniversityChengdu610041SichuanChina Med-X Center for Informatics Sichuan UniversityChengdu610041SichuanChina

Background Birth defects constitute a significant public health issue worldwide,yet there is a lack of comprehensive population-based data for the Chinese *** We analyzed data from the China National Population-based Birth Defects Surveillance System from 2007 to 2021,we calculated the prevalence rates of selected birth defects,stratified by maternal residence,geographic region,maternal age,and infant *** Joinpoint regression model was utilized to assess trends and annual percent changes in *** From 2007 to 2021,significant downward trends in prevalence were observed for neural tube defects(NTDs),hydrocephalus,cleft lip with or without palate(CL/P),limb reduction defects(LRD),omphalocele,Down syndrome,and tetralogy of Fallot(TOF).Conversely,upward trends were identified for hypospadias,cleft palate(CP),microtia/anotia,polydactyly,syndactyly,ventricular septal defect(VSD),atrial septal defect/patent foramen ovale(ASD/PFO),and patent ductus arteriosus(PDA).Younger mothers exhibited a higher prevalence of hydrocephalus,gastroschisis,CL/P,and polydactyly,while anotia/microtia,Down syndrome,and congenital heart diseases(CHDs)were more common in mothers aged 35 years or *** variations in the prevalence of anencephalus,spina bifida,CL/P,anorectal atresia/stenosis,hypospadias,polydactyly,syndactyly,VSD,ASD/PFO,and PDA were found across different maternal residences and geographic *** This study highlights the diverse trends and prevalence patterns of major birth defects,underscoring the necessity for defect-specific public health interventions.

关键词： Birth defects China Epidemiology Prevalence Trend

Consistent Nonnegative Estimates of Variance Components

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Acta Mathematicae Applicatae Sinica 2010年第2期26卷 177-186页

作者： li-wen xu Song-gui Wang Jian-hong Shi College of Sciences North China University of Technology Beijing 100144 China College of Applied Sciences Beijing University of Technology Beijing 100022 China School of Mathematics and Computer Sciences Shanxi Normal University Linfen 041004 China

In this paper, the estimation of variance components in the linear mixed model with two random effects is investigated. The class of combination estimates based on the quadratic invariant statistics and consistent nonnegative estimates are obtained. Furthermore, it is shown that the consistent nonnegative estimate dominates ANOVA estimate under some conditions.

关键词： linear mixed models invariant statistics consistency nonnegative estimate

A component-based aircraft instrument rapid modeling tool

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Journal of Zhejiang University-Science C(Computers and Electronics) 2010年第11期11卷 911-918页

作者： Fang-wen li xu-kun SHEN State Key Lab of Virtual Reality Technology and Systems School of Computer Science Beihang University Beijing 100191 China

Component-based software reuse and development is considered to be the best way to improve the efficiency and quality of *** meet the demands of aircraft instrument exhibition in an aviation virtual library,we present a modeling and simulation tool for cockpit instruments on component methods,achieving display functionality and providing a visual interaction platform in the aviation virtual *** the rapid model construction and reuse of virtual library resources,we classify entities in the cockpit into several categories by their behavior,and design a template for each category to describe its *** efficiently reduces the modeling cycle,and thus largely helps users to take advantage of the library resource.

关键词： Components Rapid modeling Simulation

Epidemiology of congenital diaphragmatic hernia among 24 million Chinese births:a hospital-based surveillance study

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World Journal of Pediatrics 2024年第7期20卷 712-722页

作者： Zhi-Yu Chen Jing Tao wen-li xu Yu-Yang Gao wen-Yan li Zhen liu Jia-Yuan Zhou li Dai National Center for Birth Defects Monitoring West China Second University HospitalSichuan UniversityNo.17 Section 3 RenminnanluChengdu 610041China The Joint Laboratory for Pulmonary Development and Related Diseases West China Institute of Women and Children’s HealthWest China Second University HospitalSichuan UniversityChengduChina Key Laboratory of Birth Defects and Related Diseases of Women and Children Ministry of EducationSichuan UniversityChengduChina NHC Key Laboratory of Chronobology Sichuan UniversityChengduChina Med‑X Center for Informatics Sichuan UniversityChengduChina

Background The prevalence of congenital diaphragmatic hernia(CDH)varies across countries,with limited information available on its epidemiology in *** study aimed to investigate the prevalence,time trends,and perinatal outcomes of CDH in China,as well as its associated malformations and potential associations with maternal and infant *** This study included all birth and CDH cases from the Chinese Birth Defects Monitoring Network between 2007 and 2019,with CDH cases classified as either isolated or *** employed the joinpoint regression model to calculate the trends of prevalence and the annual percent change,with Poisson regression used for adjusted prevalence rate ratios.A P value≤0.05 was considered statistically *** A total of 4397 CDH cases were identified among 24,158,029 births in the study period,yielding prevalence rates of 1.82,1.13 and 0.69 per 10,000 for overall,isolated,and associated CDH,*** prevalence of each type of CDH increased over *** prevalence of overall CDH varied significantly by infant sex(male ***,1.91/10,000 vs.1.63/10,000),maternal residence(urban ***,2.13/10,000 vs.1.45/10,000),maternal age(lies were the most common malformations associated with *** with associated CDH had a higher risk of premature birth and perinatal death than those with isolated *** The increasing prevalence and high perinatal mortality rate of CDH highlight the need for further etiological,epidemiological,and clinical studies among the Chinese population.

关键词： China Congenital diaphragmatic hernia Epidemiology Prevalence