• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 810
  • 523
  • 181
  • 134
  • 126
  • 50
  • 35
  • 35
  • 25
  • 19
  • 16
  • 11
  • 8
  • 8
  • 8
  • Tagged with
  • 2312
  • 408
  • 371
  • 288
  • 275
  • 245
  • 231
  • 217
  • 161
  • 148
  • 144
  • 142
  • 134
  • 133
  • 129
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

A study of changes in gene expression associated with floral induction

Hughes, Martin John Glenton January 1990 (has links)
No description available.
42

New teacher induction in China : a qualitative case study of practice and experience in Yinchuan city through the lens of Western literature and theories and concepts therein

Han, Xu January 2013 (has links)
The importance of designing and delivering comprehensive induction programmes for newly qualified school teachers (e.g. Draper and O’Brien, 2006) is widely accepted. In China, ongoing curriculum reform and teacher professionalization require such programmes to address issues such as teacher turnover, teacher performance and student learning outcomes.This thesis reports on the findings of a PhD project exploring induction of newly qualified teachers in Yinchuan city, China. The project centred on a qualitative case study involving new teachers, mentoring teachers, school principals and local education officials. Against a background review of the relevant induction policies and provision, topic-focussed interviews were conducted in 2009-10 on two separate occasions in their first year of teaching with 23 new secondary school teachers from different subject departments across 7 schools of various type, and with 6 local education officials, and 17 school principals and mentoring teachers. Drawing on an autobiographical approach, personal accounts from the participating teachers were subject to narrative analysis to explore the extent to which teachers’ perspectives changed during the first year of teaching. The conditions under which perspectives were more likely to change were also considered and three main themes emerged: job motivation, self-image and subjective educational theory. Within each of these themes, sub-themes with respect to the relational context in which teachers’ worked were identified as contributing to developing teachers’ professional identity. By using a voice-centred relational analytical method to allow flexibility in taking advantage of different types of narrative analysis methods, the data revealed interesting issues concerning new teachers’ expectations and perceptions of the teaching profession and the induction programme offered. The narratives were further explored based on the theoretical considerations of teacher’s professional identity, early professional learning (McNally, 2004) and various factors influencing teachers’ professional identity (Day and Gu, 2007). This study aims to deepen and further the emerging studies on teacher induction in China which mainly focused on large-size cities such as Shanghai and Beijing, and to identify some of the key characteristics of induction programmes by locating the study in the unique context and essential conditions of Yinchuan city, a medium-size city in China. It also attempts to benefit from a narrative approach and innovative analytical methods which give voice to the participants which hopefully would contribute to a more humanistic approach in looking at the phenomenon of new teacher induction in China.
43

Machine analysis : being a study of the application of the finite element method for solving the two-dimensional field of the single-phase shaded-pole induction motor

Najjar, Mohamad January 1985 (has links)
This thesis contains eight chapters, dealing with machine analysis and representation. A definition and a brief survey of previous investigation devoted to shaded-pole motors and the application of finite element method for solving the two-dimensional electromagnetic field is given in Chapter 1. An outline of the present investigation is also given. In Chapter 2, the experimental requirements and details of the equipment are given. This includes the techniques of recording the transient torque patterns and the method of measuring the complete torque-speed characteristics. The experimental methods for parameters determination are also mentioned. The finite element method is outlined in Chapter 3. This chapter deals also with the assumptions made, the formulation of the non-linear energy function, the solution of Poisson's equation and an example of a simple shape contianing 16 elements for illustrating the method. In Chapter 4, the computer program for the finite element is outlined. The iteration process and the numerical representation of the magnetization curve are mentioned. Application of the finite element method to the shaded-pole motor is also given. Calculation of parameters by finite element technique is given in Chapter 5. Self inductance is calculated using the concept of stored energy and the results of self and mutual inductances are tabulated. Basic performance equations of an electrical machine are derived in Chapter 6. Solution of the basic performance equations, by a step-by-step numerical method, is also given. In Chapter 7, the steady state performance equations are established in terms of harmonic currents and inductance coefficients. The flux linkages are evaluated by the approximated functions of mutual inductances. The electromagnetic torque is calculated from the stored energy in the magentic field. General conclusions and suggestion for further work are mentioned in Chapter 8.
44

Rapid simulation of induction motors using a microprocessor system

Tait, Andrew James January 1984 (has links)
The work, of which this thesis is a record, is concerned with the development of a microprocessor based system to simulate, at a speed approaching real time, the steady state and transient response of induction motor drives under various conditions. This development proceeds by outlining the basic theory involved in the simulation of induction motors. This is followed by an analysis of the various integration methods available for the solution of ordinary differential equations. This analysis being primarily concerned with determining the most efficient means of solving the set of equations used to describe induction motor response. The third part of this work explains the development of a distributed processing system that was used to achieve the simulation. This part of the work starts by describing the procedures that were followed in the development of a single processor-co-processor system and continues to detail the extension from one microprocessor to four in order to increase the speed of solution.
45

Industrialised microprocessor field-oriented induction machine drive controller for production by local industry

25 February 2015 (has links)
D.Ing. / In this document the research related to the development of a microprocessor based field oriented controller is presented. An overview of the state-of-the-art is presented, with specific reference to all the different aspects related to the development of variable speed induction machine drives. During the development of it is necessary to use accurate system models. Such models are most useful when incorporated in a simulation program. In chapter 2 such a simulation program is described. Included in the simulation program are accurate models for the inverter and the induction machine. Effects such as resistance variation due to heating and inductance variation due to saturation are included. Modulation of the inverter output voltage wave from by the load current caused by the snubbers is also included. The development of a rotor current estimation strategy is presented in chapter 3. During the development extensive use was made of the simulation program. A new stationary reference frame current controller is also presented in chapter 3. Finally the implementation of the proposed field oriented controller is presented in chapter 4. As part of this a dual mode speed control algorithm was developed and implemented.
46

Rites of Passage: The Role of Induction in the Enculturation of Beginning Teachers

Blakley, Linda 22 May 2006 (has links)
Researchers have reported that by the year 2010, two million teachers will be needed in classrooms across the country. The shortage has been attributed to population increases and a rise in the number of teacher retirements. Other researchers contend that the shortage is due to rising attrition rates among new teachers. They claim that new teachers become dissatisfied with teaching due to poor working conditions. As a result, new teachers have prematurely departed the teaching profession in alarming numbers which has placed the educational system at large in a state of crisis. This dissertation examined the factors which impacted the working conditions of beginning teachers and their enculturation into teaching and school cultures. Novices' experiences before and after teacher education training included the influence of significant individuals prior to entry into teaching and their interactions with the principal, veteran teachers and students. The process of induction served as a means to facilitate or impede the enculturation process. Data gathered and generated for this qualitative study included survey, interview and observation. Through participants' shared experiences, both positive and negative factors influenced their enculturation into teaching and the school culture. As prospective teachers, significant individuals were a positive influence on new teachers' decisions to enter teaching and their educational perspectives. As new teachers, findings revealed four negative factors which hindered their enculturation process. First, the veteran-oriented school culture was unsupportive and prevented the school community from adequately addressing new teachers' needs during induction. Second, although new teachers expressed concerns about classroom management, discipline and student achievement in their interactions with students, these concerns did not have a significant negative impact on their enculturation. Third, new teachers' interactions with veteran teachers lacked collegiality and prevented the types of collaborative exchanges necessary to promote professional growth. Fourth, the empathy expressed for the new principal restricted opportunities for interactions and subsequently lowered new teachers' expectations of the principal's ability to provide support. The principal's inexperience and novice-status sanctioned the negative veteran-oriented culture which dominated the school environment, thus, limiting the impact of new teacher induction and impeding the enculturation of beginning teachers.
47

歸納法與槪率論 =: Induction and probability theory. / Induction and probability theory / Gui na fa yu gai lü lun =: Induction and probability theory.

January 1984 (has links)
陳浩琛. / Thesis (M.A.)--香港中文大學硏究院哲學部. / Manuscript. / Includes bibliographical references: leaves 17-30 (3d. group) / Chen Haochen. / Thesis (M.A.)--Xianggang Zhong wen da xue yan jiu yuan zhe xue bu. / 序言 --- p.I-III / Chapter 第一部份 --- 歸納法的問題及其解答 / Chapter 第1章 --- 歸納法的問題 / Chapter 1.1 --- 歸納的跳躍 --- p.1-2 / Chapter 1.2 --- 科學方法及歸納推論 --- p.2-5 / Chapter 1.3 --- 休謨吊詭 --- p.5-6 / Chapter 第2章 --- 休謨吊詭的解答 / Chapter 2.1 --- 基本原則的進路 --- p.7-13 / Chapter 2.2 --- 自相支持的歸納論証的進路 --- p.13-21 / Chapter 2.3 --- 消解的進路 --- p.21-28 / Chapter 2.4 --- 日常語言分析的進路 --- p.29-34 / Chapter 2.5 --- 實效証立的進路 --- p.34-39 / Chapter 第二部份 --- 概率的形式系統及其語意解釋 / 概要 --- p.40-41 / Chapter 第3章 --- 概率的形式系統 / Chapter 3.1 --- 離散空間中之概率 --- p.42-46 / Chapter 3.2 --- 條件概率 --- p.46-49 / Chapter 3.3 --- 具努里試驗 --- p.50-51 / Chapter 3.4 --- 中間項 --- p.51-55 / Chapter 3.5 --- 大數律 --- p.55-58 / Chapter 3.6 --- 連續空間中之概率 --- p.58-64 / Chapter 第4章 --- 語意解釋的判準 --- p.65-67 / Chapter 第5章 --- 古典解釋 --- p.68-75 / Chapter 第6章 --- 頻率解釋 / Chapter 6.1 --- 頻率極限 --- p.76-78 / Chapter 6.2 --- 有限序列的頻率解釋 --- p.78-80 / Chapter 6.3 --- 頻率的極限是否存在 --- p.80-88 / Chapter 6.4 --- 趨同規則 --- p.88-97 / Chapter 6.5 --- 單個事件 --- p.97-101 / Chapter 第7章 --- 邏輯解釋 / Chapter 7.1 --- 邏輯解釋概要 --- p.102-105 / Chapter 7.2 --- 結構描述 --- p.105-110 / Chapter 7.3 --- 歸納邏輯(概率邏輯)的公理系統 --- p.111-116 / Chapter 7.4 --- 適當性條件 --- p.116-123 / Chapter 7.5 --- C-函數的決定 --- p.123-136 / Chapter 7.6 --- 邏輯概率在決定實際判斷上的應用 --- p.136-142 / 餘論 --- p.143-145 / 註目 --- p.I-XI / 附錄 --- p.XII-XVI / 參考書目 --- p.XVII-XXX
48

Regulation of the human β-interferon promoter

King, Peter James January 1997 (has links)
No description available.
49

Über die elektromotorischen Kräfte, welche durch den Magnetismus in von einem wärmestrome durchflossenen Metall-platten geweckt Werden ...

Nernst, Walther, January 1887 (has links)
Inaug.-dis.--Würzburg.
50

Polycyclic aromatic hydrocarbons and amiodarone pharmacokinetics

Elsherbiny, Marwa 11 1900 (has links)
In the treatment of arrhythmias, amiodarone is a primary therapeutic agent. Cytochromes P450 (CYP) 1A1 and 1A2 facilitate biotransformation of amiodarone to the biologically active desethylamiodarone. Side effects have been reported during therapy and some are correlated with increased desethylamiodarone levels. Exposure to polycyclic aromatic hydrocarbons (PAH) like -naphthoflavone induces CYP1A1 and CYP1A2 and therefore can increase desethylamiodarone levels. Desethylamiodarone, however, was reported to inactivate human CYP1A1 and therefore can conceivably inhibit its CYP1A1-mediated formation. Our primary objective was to investigate the effect of -naphthoflavone on amiodarone disposition. Since rats were used, CYP isoenzymes involved in desethylamiodarone formation in human were compared to their rat counterparts. The effect of ketoconazole on desethylamiodarone formation, the inactivating potential of desethylamiodarone on CYP1A1 and the mechanism of -naphthoflavone-amiodarone interaction were assessed. Human CYP1A1 and rat CYP2D1 had the highest intrinsic clearance (Clint) for desethylamiodarone. Human and rat CYP1A2 had the lowest Clint. Ketoconazole (18.8 M) inhibited all isoforms except for rat CYP1A2; it potently inhibited human CYP1A1 and CYP3A4 and rat CYP2D2 and CYP1A1. After a single amiodarone dose was administered to control and -naphthoflavone pretreated rats, the plasma area under concentration-time curve (AUC) of desethylamiodarone increased. With multiple doses, amiodarone AUC(0-24h) decreased in -naphthoflavone plasma (30%), lung (35%), liver (48%), kidney (52%), heart (34%), and intestine (43%). Desethylamiodarone AUC(0-24h) increased in -naphthoflavone plasma (36%), lung (56%), liver (101%), kidney (65%), and heart (73%). Desethylamiodarone caused no inactivation of CYP1A1 when preincubations were diluted and nicotinamide adenine dinucleotide phosphate (NADPH) was added in the probe incubation samples. Evidence for reversible mixed-competitive inhibition was apparent. Addition and/or replenishment of NADPH were important factors in maintaining control activity. -naphthoflavone increased desethylamiodarone formation only in lung and kidney microsomes. Desethylamiodarone formation in liver, intestine and heart microsomes was not altered. Body-weight-normalized liver mass was significantly increased (27%) by -naphthoflavone. In conclusion, human CYP1A1 was more efficient in forming desethylamiodarone than rat isoenzyme. Exposure to PAH increased desethylamiodarone levels in vivo. Increased desethylamiodarone levels were partly caused by CYP1A1 induction, and by increased liver mass. Desethylamiodarone did not inactivate CYP1A1 activity. / Pharmaceutical sciences

Page generated in 0.0859 seconds