排序方式： 共有43条查询结果，搜索用时 31 毫秒
31.
MOHAMMAD Tariqul Islam ZAINOL Abidin Abdul Rashid 《浙江大学学报(A卷英文版)》2006,7(10):1709-1716
INTRODUCTION The demand for mobile communication services is increasing at a rapid pace throughout the globe. The increasing demand for mobile communication ser- vices in a limited RF spectrum motivates the need for better techniques to improve spectrum utilization. Smart antenna system was adopted by ITU for the IMT-2000 or the Third Generation (3G) wireless networks due to its capability to improve channel capacity and interference suppression. A smart an- tenna system combines mult… 相似文献
32.
Training paraprofessionals such as teachers is one of many significant challenges facing Afghanistan??s educational system. This case study focuses on the innovations offered in that regard by BRAC, a large NGO based in Bangladesh that brought its many years of development experience to Afghanistan in 2002 and established itself there as the premier change agent on multiple developmental fronts. Through the use of structured and semi-structured interviews with stakeholders, classroom observations, and extensive document analysis, the authors conclude that by successfully modifying its teacher training programme in Bangladesh, BRAC has been able to develop an approach to teacher training in Afghanistan that may become a showcase example of effective South-South partnership in education. The article concludes by urging adoption of BRAC??s innovations in teacher training and recruitment by other developing nations facing similar challenges. 相似文献
33.
Jiajun Guo Islam A. Y. M. Atiquil Teo Timothy Spector Jonathan Michael 《Instructional Science》2019,47(5):609-625
Instructional Science - This study focuses on visual creativity and how it can be supported with computer technologies and thereby be used to support learning and instruction. However, studies... 相似文献
34.
Three studies examined the links between psychological control and prosociality in middle childhood, and the role of religiosity as a moderator. Study 1 (101 Israeli Jewish families, ages 6–9, 50% girls) found a significant interaction, with a negative association between maternal psychological control and children's prosociality in secular but not in religious families. Study 2 (161 Israeli Jewish families, ages 6–12, 48% girls) replicated this interaction for mothers using a continuous religiosity measure. Study 3 (64 Arab Muslim Israeli families, ages 6–8.5, 50% girls) also found a significant interaction, with a positive link between psychological control and prosociality seen at higher, but not at lower, religiosity levels. The findings suggest that religiosity may alter the meaning and consequences of parenting practices. 相似文献
35.
The objective of perforating the petroleum wells is to maximize well productivity. A good connectivity between the wellbore and formation can lead up to achieve that goal. However, the conventional method of perforation, which basically involves the use of explosive charges, rarely meets the expected well productivity. It is mainly because of the formation of a region of reduced permeability around the perforation tunnel. To offset such and several other shortcomings of present practices, a new technique is required, the highlight of this paper. Described as the ‘perforation by drilling’ (PD), this new technique is examined and compared for its performance with that of another technique, ‘Perforation by Shooting’ (PS). For this, the experimental and numerical results of the PS technique on cylindrical sand samples of varying amounts of strength and porosity are studied. Moreover, in order to achieve a so-called ‘perfect perforation’, results are compared with the ‘Casting technique’. Three different samples were selected for the measurement of fluid flow rate and differential pressure across the perforation using a ‘geotechnical digital system’ (GDS), which is a triaxial testing device. Profiles such as fluid flow rate with a change in differential pressure and pressure build-up data with time, signify that the PD technique can achieve maximum wellbore productivity when compared to the PS technique. Results also indicate that at a 100 kPa differential pressure, the PS, PD and Casting techniques can achieve 0.20, 0.65 and 1.00 mL/s fluid flow rates respectively across a sample. The paper also implements a 1-D time dependent porous media flow model to simulate flow across the perforated cylindrical samples created by the PS, PD and Casting techniques. Results show a good consistency between the experimental and numerical approaches. 相似文献
36.
37.
Md. Mofakkarul Islam David Gray Janet Reid Peter Kemp 《The Journal of Agricultural Education and Extension》2013,19(5):425-443
Abstract The limited effectiveness and fiscal unsustainability of professional-led public sector extension systems in developing countries have aroused considerable interest in Farmer-led Extension (FLE) approaches in the recent decades. A key challenge facing these initiatives is a lack of sustainability of the farmer groups developed through project or programme assistance. This not only makes FLE initiatives costly, but also creates dependency among farmers. Despite this, the knowledge of what can make externally-initiated FLE groups sustainable is scant and largely anecdotal. In this paper we provide an empirically-drawn and theoretically-informed framework to fill this knowledge gap. The framework is based on a comparative case study of six non-sustained and four sustained FLE groups initiated through an innovative extension reform project in Bangladesh and a comparison of the results with the theories of collective action. We have identified four sets of inter-related factors called ‘capitals’ affecting group sustainability: ‘financial capital’ accumulated through group-based microcredit activities, an effective governance mechanism called ‘institutional capital’ devised by the members themselves, good quality group leaders and facilitators called ‘human capital’, and past relations of exchange, reciprocity, trust and respect called ‘social capital’ among members and between members and professional facilitators. While microcredit can benefit sustainability, it suits women rather than men farmers. Good quality leaders and facilitators are not only technically competent, but also fair, innovative, tenacious, self-sacrificing, trustworthy, honest, and sincere. All forms of social capital are not useful for group sustainability and social capital can make a positive impact only when the other types of capital—human and institutional—are present within a group. To improve group sustainability, FLE programmes should take a holistic approach and address the four kinds of capitals proposed in this paper. Key strategies may include: combining extension (information or advisory functions) with economic activities but avoiding a one-size-fits-all solution, recruiting group leaders and facilitators by going beyond technical considerations (e.g. taking into account the personality traits identified in this study), adopting a bottom-up approach in devising group rules and regulations, and taking into account both the positive and negative aspects of social capital. The originality of our research lies in the explanatory framework that we provide in this paper. Our study also contributes to the intellectual debates on social capital by exhibiting the dual roles that social capital plays and its complex interrelationships with other forms of capital. 相似文献
38.
Assessing potential dietary toxicity of heavy metals in selected vegetables and food crops 总被引：3，自引：0，他引：3
Heavy metals, such as cadmium, copper, lead, chromium and mercury, are important environmental pollutants, particularly in areas with high anthropogenic pressure. Their presence in the atmosphere, soil and water, even in traces can cause serious problems to all organisms, and heavy metal bioaccumulation in the food chain especially can be highly dangerous to human health. Heavy metals enter the human body mainly through two routes namely： inhalation and ingestion, ingestion being the main route of exposure to these elements in human population. Heavy metals intake by human populations through food chain has been reported in many countries. Soil threshold for heavy metal toxicity is an important factor affecting soil environmental capacity of heavy metal and determines heavy metal cumulative loading limits. For soil-plant system, heavy metal toxicity threshold is the highest permissible content in the soil （total or bioavailable concentration） that does not pose any phytotoxic effects or heavy metals in the edible parts of the crops does not exceed food hygiene standards. Factors affecting the thresholds of dietary toxicity of heavy metal in soil-crop system include： soil type which includes soil pH, organic matter content, clay mineral and other soil chemical and biochemical properties; and crop species or cultivars regulated by genetic basis for heavy metal transport and accumulation in plants. In addition, the interactions of soil-plant root-microbes play important roles in regulating heavy metal movement from soil to the edible parts of crops. Agronomic practices such as fertilizer and water managements as well as crop rotation system can affect bioavailability and crop accumulation of heavy metals, thus influencing the thresholds for assessing dietary toxicity of heavy metals in the food chain. This paper reviews the phytotoxic effects and bioaccumulation of heavy metals in vegetables and food crops and assesses soil heavy metal thresholds for potential dietary toxicity. 相似文献
39.
This study explored the usage and applications of barcode technologies through a survey carried out in eight libraries in Dhaka City of Bangladesh. The survey included the following: Inception year, software used to barcode, areas in which barcodes are being used in libraries, training of library staff, and satisfaction of users and information professionals. The merits and demerits of barcode technologies are presented. 相似文献
40.
Nasreen Noor Najmul Islam Shagufta Moin Abbas Ali Mahdi Sapna Jaiswal Farzana Bano 《Indian journal of clinical biochemistry : IJCB》2008,23(3):227-232
To probe the glutathione peroxidase (GPx) activity coupled to ROS and TNF-α levels in younger versus elderly primigravidas.
Monocytes were isolated from blood of young and elderly primigravidas after 12 hrs, 24 hrs and 14 days postpartum. Age-matched
healthy female donors served as controls. Thereafter, the above monocytes were subjected to evaluation of GPx activity, levels
of pro-inflammatory cytokine TNF-α and reactivity/specificity towards anti-TNF-α antibody. Suppression in GPx activity with
simultaneous enhancement of TNF-α levels in monocytes was observed after 12 hrs and 24 hrs of spontaneous labor pain-induced
maternal delivery through normal vaginal route. Conversely, an enhancement of GPx activity and decrease in TNF-α levels were
observed on day 14 of postpartum, thereby indicating reversal of the impaired neutralizing mechanisms. The antioxidant network
combating ROS was stronger in younger primigravidas. Capability of TNF-α and ROS suppression was somewhat lesser in elderly
primigravidas even 14 days of postpartum via normal vaginal route. The capability of GPx activity enhancement with simultaneous
suppression in ROS and TNF-α, decreases in elderly primigravidas. This may act as one of the important parameters leading
to a variety of complications encountered by elderly primigravidas. 相似文献