The Development of Library and Information Profession in the Chinese Academy of Sciences     

Meng GuangjunWang Bing 《图书情报工作》1996,(1)

1　Introduction　　Overthepast45years(1950～1995),undertheleadershipoftheChineseAcademyofSciences(CAS),andinacommoneffortofthestaffmembers,thelibraryandinformationsystemofCAShasbecomeasys-temwithmulti-disciplines,multi-levelsandmulti-functions.Thesystemi…  相似文献   

ON THE MATHEMAITCAL UNDERSTANDING OF CHAOS     

Li Ji-bin 《蒙自师范高等专科学校学报》1990,(4)

<正> Chaotic motion refers to complicated orbits in dynamical systems.It occurs even in deterministic system governed by simple differential equations and its present has been experimentally verified for many system in several disciplines.In this paper we discuss some of mathematical understanding of chaos.  相似文献   

Modeling of Normal Perforation of Reinforced Concrete Slabs by a Rigid Projectile   总被引：2，自引：0，他引：2  

CHEN Xiaowei  LI Xiaoli 《天津大学学报(英文版)》2006,12(Z1)

An analytical model on the normal perforation of reinforced concrete slabs is constructed. The effect of reinforcing bars is further hybridized in a general three-stage model consisting of initial cratering, tunnelling and shear plugging. Besides three dimensionless numbers, i. e. , the impact function /, the geometry function of projectile N and the dimensionless thickness of concrete target X, which are employed to predict the ballistic performance of perforation of concrete slabs, the reinforcement ratioρs of concrete and the tensile strength fs of reinforcing bars are considered as the other main factors influencing the perforation process. Simpler solutions of ballistic performances of normal perforation of reinforced concrete slabs are formulated. Theoretical predictions agree well with individual published experimental data.  相似文献   

Relations of Children's Effortful Control and Teacher-Child Relationship Quality to School Attitudes in a Low-Income Sample     

Silva KM  Spinrad TL  Eisenberg N  Sulik MJ  Valiente C  Huerta S  Edwards A  Eggum ND  Kupfer AS  Lonigan CJ  Phillips BM  Wilson SB  Clancy-Menchetti J  Landry SH  Swank PR  Assel MA  Taylor HB;School Readiness Consortium 《Early education and development》2011,22(3):434-460

RESEARCH FINDINGS: The purpose of this study was to examine the relations of children's effortful control and quality of relationships with teachers to school attitudes longitudinally in an ethnically diverse and economically disadvantaged sample. Data were collected as part of a larger intervention project during mid-fall, winter, and late spring (ns = 823, 722, and 758, respectively) for 2 cohorts of 3- to 5-year-olds (collected during 2 different school years). Children's effortful control was assessed in the fall with parents' and teachers' reports and 2 behavioral measures. Teacher-child relationship quality was assessed mid-year with teachers' reports of closeness and conflict. Attitudes toward school were assessed in late spring using teachers' and students' reports of school avoidance and liking. Effortful control, in general, was positively correlated with teacher-child closeness and school liking and negatively correlated with conflict and school avoidance. Using structural equation modeling and controlling for sex and ethnicity, we found that effortful control was positively related to teacher-child relationship quality, which in turn was positively related to school attitudes. Furthermore, the relation of effortful control to school attitudes was mediated by teacher-child relationship quality. PRACTICE OR POLICY: Results provide evidence for the importance of relational processes that take place within the classroom context and have implications for teachers and clinicians working to increase school success in ethnic minority and low-income children.  相似文献   

Distribution Regularity of Muzzle Shock-Wave Inside Protective Cover     

WU Jun  LIU Jingbo  DU Yixin 《天津大学学报(英文版)》2006,12(Z1)

The injury of gunners caused by muzzle shock-wave has always been a great problem when firing inside the protective cover. The distribution regularity and personnel injury from the muzzle blast-wave were investigated by both test and numerical simulation. Through the inside firing test, the changes of overpressure and noise have been measured at different measuring points in the thin-wall cover structure with different open widths and shallow covering thickness. The distribution regularity of muzzle shock-wave with different firing port widths is calculated by ANSYS/LSDYNA software. The overpressure distribution curves of muzzle shock-wave inside the structure can be obtained by comparing the test results with the numerical results. Then, the influence of open width and shallow covering thickness is proposed to give a reference to the protective design under the condition of the inside firing with the same cannon caliber.  相似文献   

A generalization of Kempe’s linkages     

MAO De-can  LUO Yao-zhi  YOU Zhong 《浙江大学学报(A卷英文版)》2007,(7)

A new, general type of planar linkages is presented, which extends the classical linkages developed by Kempe consisting of two single-looped kinematic chains of linkages, interconnected by revolute hinges. Together with a locking device, these new linkages have only one degree of freedom (DOF), which makes them ideal for serving as deployable structures for different purposes. Here, we start with a fresh matrix method of analysis for double-loop planar linkages, using 2D transformation matrices and a new symbolic notation. Further inspection for one case of Kempe’s linkages is provided. Basing on the inspection, by means of some novel algebraic and geometric techniques, one particularly fascinating solution was found. Physical models were built to show that the derivation in this paper is valid and the new mechanisms are correct.  相似文献   

Cellular automata modeling of pedestrian’s crossing dynamics     

张晋  王慧Institute of Systems Engineering  Zhejiang University  Hangzhou  China  李平 《Journal of Zhejiang University. Science. B》2004,(7)

INTRODUCTION Computer simulation of traffic can give insightinto a wide variety of phenomena observed in realtraffic flow; lead to a greater understanding of itsbasic principles; and can also help researchers ex-plore the effects of implementing new traffic rulesand control systems without doing potentially ha-zardous experiments with real traffic. Approachesthat apply classic differential equation methods tomodel the nonlinear dynamics of this problem candescribe only part of the ph…  相似文献   

ADHD: a psychological response to an evolving concept. (Report of a Working Party of the British Psychological Society)   总被引：1，自引：0，他引：1  

Reason R;Working Party of the British Psychological Society 《Journal of learning disabilities》1999,32(1):85-91

The British Psychological Society is the only national organization of psychologists within the United Kingdom representing all aspects of psychology and all subspecialisms within psychology. It is both a learned scientific society and a professional association. To address the concept of attention-deficit/hyperactivity disorder (ADHD), the Professional Affairs Board of the Society convened a Working Party, consisting of individuals nominated by subsystems of the Society because of their recognized professional and academic expertise. They covered a range of specialisms, including educational, clinical, criminological, neurological, and cognitive psychology. A report by the Working Party was published in September 1996. It had two main aims: first, to outline the research that was relevant to current understanding of the notion of ADHD from an historical, psychological, and biological perspective, and, second, to consider implications for practice in the light of the information obtained. The focus was predominantly on children, although it was recognized that problems could persist into adulthood. The intention was to write a report for professionals that also would be accessible to a wider audience. This article is a highly abridged version of the report. It omits the references to research reviews and research studies contained in the full account. Selected extracts are included in order to justify the conclusions and the recommendations that are made and to inform a North American audience of developments in the United Kingdom.  相似文献   

Experimental Study of Structure Shock Vibration in Soil Caused by Explosion of Conventional Weapons     

FENG Jinji  XIE Qingliang  ZHAO Dayong 《天津大学学报(英文版)》2006,12(Z1)

When hitting underground structures directly or exploding in rock-soil media near underground structures, the conventional weapons with large charge weight will make underground structures be subjected to strong shock vibration and cause personal casualty and damage of precision electronic equipments. The shock vibration has become one of the cardinal killing means of weapons. However, the existing methods of predicting structure shock vibration are limited evidently. In this paper the coupling coefficient of acceleration in clayey soil is obtained firstly. Subsequently based on repeated experiments of chemical explosion, after dimension analysis and by using method of multivariate stepwise regression, the calculation formulae of shock vibration acceleration for the underground structure are obtained finally. The formulae consider top and side explosion respectively, taking into account the effects of penetration depth, charge weight, distance to explosion center, rock-soil media, size of structure and buried depth. They are easy to use with high practicability and degree of confidence, and can provide credible evidence for prediction of shock vibration and vibration isolating design of underground structure.  相似文献   

A New Potent Inhibitor of Thrombin from the Leech Haemendipsa Yanyuanensis   总被引：1，自引：0，他引：1  

ZHAO Rong le College of Life Sciences  Beijing Normal University  Beijing  China 《上海大学学报(英文版)》2001,(1)

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