检索结果-南通市图书馆

Grain size dependence of flow stress in ECAPed Ti with constant texture

在线全文

学校读者我要写书评

暂无评论

中国有色金属学会会刊：英文版 2012年第S3期22卷 673-677页

作者： chang-Young HYUN ho-Kyung KIM Department of Materials Science and Engineering Seoul National University of Science and Technology Department of Automotive Engineering Seoul National University of Science and Technology

The effect of grain size on the flow stress in an ECAPed Ti with a constant texture was investigated,assuming that 2,4,5 and 6 passes microstructures have a similar *** average size of recrystallized grains decreased to 0.5 μm,0.4 μm,and 0.3 μm with respect to the ECAP pass number of 2,4,and 6,*** ultimate tensile strength (UTS) and yield strength (YS) increase with an increase in the number of *** UTS and YS of the 6 passes ECAPed sample were found to be 740.2 MPa and 580.3 MPa,*** equation for the flow stress of an ECAPed Ti with a constant texture as a function of the strain and grain size was derived for the ECAPed *** following equation was finally obtained:σ(ε)=103.9+1825ε-9.6ε1/2·d-1/2+8.3d-1/2.

关键词： Ti mechanical properties grain size flow stress equal channel angular pressing

Strictosidine synthase,an indispensable enzyme involved in the biosynthesis of terpenoid indole andβ-carboline alkaloids

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Natural Medicines 2021年第8期19卷 591-607页

作者： CAO Ning WANG chang-hong The MOE Key Laboratory for Standardization of Chinese Medicines Shanghai R&D Centre for Standardization of Chinese MedicinesInstitute of Chinese Materia MedicaShanghai University of Traditional Chinese MedicineShanghai 201203China

Terpenoid indole(TIAs)andβ-carboline alkaloids(BCAs),such as suppressant reserpine,vasodilatory yohimbine,and antimalarial quinine,are natural compounds derived from *** compounds can exert powerful pharmacological effects but be obtained from limited source in *** whole biosynthetic pathway of TIAs and BCAs,The Pictet–Spengler reaction catalyzed by strictosidine synthase(STR;EC:4.***.3.2)is the rate-limiting ***,it is necessary to investigate their biosynthesis pathways,especially the role of STR,and related findings will support the biosynthetic generation of natural and unnatural *** review summarizes the latest studies concerning the function of STR in TIA and BCA biosynthesis,and illustrates the compounds derived from *** substrate specificity of STR based on its structure is also *** that contain sixbladed four-strandedβ-propeller folds in many organisms,other than plants,are *** presence of these folds may lead to similar functions among *** expression of STR gene can greatly influence the production of many *** is mainly applied to product various valuable drugs in plant cell suspension culture and biosynthesis in other carriers.

关键词： Biosynthesis Pictet-Spengler reaction β-Carboline alkaloids Strictosidine synthase Terpenoid indole

Integrated assessment of air quality and climate change for policy-making: highlights of IPCC AR5 and research challenges

在线全文

学校读者我要写书评

暂无评论

National Science Review 2014年第2期1卷 176-179页

作者： hong Liao Wenyuan chang Institute of Atmospheric Physics Chinese Academy of Sciences Climate change Research Center Chinese Academy of Sciences

Recently,air quality in China has received signiicant atention,especially since the unprecedented heavily polluted haze episodes were observed in populated areas of central and eastern China[1].Major atmospheric air pollutants include tropospheric ozone(O3)and aerosols(small liquid or solid particles,also called PM2.5 when referring to particles with diameters of 2.5μm or

关键词： IPCC Integrated assessment of air quality and climate change for policy-making highlights of IPCC AR5 and research challenges AR

The validity of the Reynolds equation in spool valve analysis considering cavitation

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Friction 2016年第3期4卷 266-276页

作者： Sung-ho hong Kyung-Woong KIM School of Mechanical Aerospace & Systems Engineering Korea Advanced Institute of Science and Technology 291 Daehak-ro Yuseong-guDaejeon 305-701 Republic of Korea

The purpose of this research is to investigate the validity of the Reynolds equation in spool valve analysis under cavitation. This study is carried out for a laminar and isothermal flow between a sleeve and spool with grooves. The pressure and lateral force obtained from the Reynolds equation and the Navier-Stokes equation are compared with variations of aspect ratio, cross sectional area, and number of grooves. The cavitation phenomenon is considered by using a cavitation model in the Navier-Stokes equation and the Reynolds cavitation boundary condition in the Reynolds equation. A large difference of more than 20% is found between the equations for a lateral force of spool valve with many grooves. It was found that the Reynolds equation is not suitable for calculation of a lateral force of the spool valve with multiple-grooves of which the width and depth are even larger than the clearance under cavitation.

关键词： validity Reynolds equation Navier-Stokes equation spool valve cavitation

Quasi-Maximum Likelihood Estimators in Generalized Linear Models with Autoregressive Processes

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2014年第12期30卷 2085-2102页

作者： hong chang HU Lei SONG School of Mathematics and Statistics Hubei Normal University Educational Research Institute

The paper studies a generalized linear model（GLM）yt = h（xt^T β）＋ εt,t = l,2,...,n,where ε1 = η1,ε1 =ρεt ＋ηt,t = 2,3,...;n,h is a continuous differentiable function,ηt＇s are independent and identically distributed random errors with zero mean and finite variance σ^***,the quasi-maximum likelihood（QML） estimators of β,p and σ^2 are ***,under mild conditions,the asymptotic properties（including the existence,weak consistency and asymptotic distribution） of the QML estimators are ***,the validity of method is illuminated by a simulation example.

关键词： Generalized linear model quasi-maximum likelihood estimator autoregressive processes weak consistency asymptotic distribution

Efficacy of uncovered self-expandable metallic stent for colorectal obstruction by extracolonic malignancy

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastrointestinal Oncology 2020年第9期12卷 1005-1013页

作者： Joon Seong Ahn Sung Noh hong Dong Kyung chang Young-ho Kim Eun-Ran Kim Department of Internal Medicine Samsung Medical CenterSungkyunkwan University School of MedicineSeoul 06351South Korea

BACKGROUND Self-expandable metallic stent(SEMS)is widely used for malignant colorectal ***,SEMS has been used for palliative option for colorectal obstruction caused by extracolonic malignancy(ECM).AIM To evaluate the efficacy of SEMS for colorectal obstruction caused by ECM,and to identify the factors associated with stent *** Seventy-two patients who were treated with uncovered SEMS insertion for malignant colorectal obstructions caused by colorectal metastasis or peritoneal seeding of ECM at Samsung Medical Center between April 2012 to March 2016 were *** analyzed technical and clinical outcomes of stent insertion,the factors associated with stent occlusion and long term outcomes after stent *** Technical success rate was determined as 90.3%with a clinical success rate of 87.7%.Stent occlusion developed in 28.1%,with a median duration of 51 ***,81.3%with stent occlusion could be treated with secondary stent *** failure was observed to be related to the male sex(P=0.020)and right colon obstruction(P=0.017).Stent length≤10 cm was found to be associated with stent occlusion(P=0.003).Median survival time after stent insertion was 4.7 mo and 40.4%were able to receive their oncological treatments after stent insertion without *** Uncovered SEMS is effective for the treatment of colorectal obstruction caused by ECM,considering life expectancy of patients with ECM.

关键词： Self-expandable metallic stent Colorectal stent Colorectal obstruction Extracolonic malignancy Retrospective study

Synthesis of C-fused Penems By Br-or Cl-Promoted S-Heterocyclization

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chemical Research in Chinese Universities 2002年第1期18卷 93-94页

作者： SHI hong-chang Department of Chemistry Tsinghua UniversityBeijing 100084P.R.China

In the past several years, much research work has been done for the synthesis of C-fused bicyclo-β-lactam compounds and a concise "Double Annulation" procedure has been developed. The β-lactam ring is formed by the classical Staudinger reaction between α-(alkylthio) acyl chloride and an equivalent a, β-unsaturated imine. The sulfur ring is subsequently fused onto the β-lactam unit by means of a halogen-promoted heterocyclization process. This procedure was applied to the synthesis of penem as illustrated in Fig. 1. The obtained X-penems are a kind of important intermediates for synthesizing a series of β-lactam compounds, for example, they are carboxylated by coupling reactions on the C atom which is linked to halagen, forming penem. An important purpose in the research field is to probe into new β-lactam medicines.

关键词： β -Lactam S-heterocyclization Br-penem Cl-penem

A THREE-PARAMETER FAULT-DETECTION SOFTWARE RELIABILITY MODEL WITH THE UNCERTAINTY OF OPERATING ENVIRONMENTS

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Science and Systems Engineering 2017年第1期26卷 121-132页

作者： Kwang Yoon Song In hong chang hoang Pham Department of Computer Science and Statistics Chosun University Gwangju 62022 Korea Department of Industrial and Systems Engineering Rutgers University NJ 08855-8018 USA

As requirements for system quality have increased, the need for high system reliability is also increasing. Soflnvare systems are extremely important, in terms of enhanced reliability and stability, for providing high quality services to customers. however, because of the complexity of software systems, soft-ware development can be time-consuming and expensive. Many statistical models have been developed in the past years to estimate soflnvare reliability. In this paper, we propose a new three-parameter fault-detection software reliability model with the uncertainty of operating environments. The explicit mean value function solution for the proposed model is presented. Examples are presented to illustrate the goodness-of-fit of the proposed model and several existing non-homogeneous Poisson process （NHPP） models based on three sets of failure data collected from software applications. The results show that the proposed model fits significantly better than other existing NHPP models based on three criteria such as mean squared error （MSE）, predictive ratio risk （PRR）, and predictive power （PP）.

关键词： Nonhomogeneous Poisson process ratio risk predictive power fault detection software reliability mean squared error predictive

Constitutive model of disturbed soil-structure interface within mining subsidence areas

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Central South University 2017年第7期24卷 1676-1683页

作者： chang hong XIA Jun-wu Mechanics and Civil Engineering China University of Mining&TechnologyXuzhou 221116China Key Laboratory of Deep Coal Resources Mining of Ministry of Education(China University of Mining&Technology) Xuzhou 221116China

The characteristics of a disturbed soil-structure interface were studied based on the variation regularities of the disturbed soil within its mining subsidence area using direct shear *** effects of the initial moisture content on the shear strength parameters of the soil-structure interfaces were *** results indicate that the cohesion of the interface initially increased and then decreased as the initial moisture content *** addition,the friction angle of the interface decreased as the initial moisture content increased.A constitutive model of the disturbed soil-structure interface,a rigid-plastic model based on the initial void ratio and saturability(VSRP) model,was established based on the *** order to validate this model,a finite element analysis of DRS-1 direct shear tests was *** finite element model calculations coincided with the results of the DRS-1 direct shear *** proposed model also reflected the nonlinear features of the soil-structure interface.

关键词： mining subsidence areas soil-structure interface rigid-plastic model finite element method