首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   156篇
  免费   5篇
教育   117篇
科学研究   26篇
各国文化   5篇
体育   6篇
文化理论   2篇
信息传播   5篇
  2023年   2篇
  2022年   3篇
  2021年   3篇
  2020年   1篇
  2019年   8篇
  2018年   16篇
  2017年   12篇
  2016年   10篇
  2015年   2篇
  2014年   9篇
  2013年   27篇
  2012年   5篇
  2011年   7篇
  2010年   8篇
  2009年   9篇
  2008年   5篇
  2007年   4篇
  2006年   8篇
  2005年   1篇
  2004年   3篇
  2003年   2篇
  2002年   2篇
  2001年   1篇
  1999年   2篇
  1996年   1篇
  1995年   2篇
  1994年   1篇
  1992年   1篇
  1991年   2篇
  1988年   2篇
  1983年   1篇
  1980年   1篇
排序方式: 共有161条查询结果,搜索用时 15 毫秒
101.
ABSTRACT

The aim of education is to ensure a holistic development towards knowledge and well-being. Despite exhaustive effort on embedding twenty-first century skills in science teaching, students show lack of interest to learn and pursue their science careers. This present study has attempted to develop an instrument for measuring attitude towards science learning. The purpose was to ensure valid items were identified to measure all aspects of attitude namely affect, behaviour and cognitive. The study of attitude in science will determine the direction on how teaching strategies can be successful in promoting interest in learning. The study has been underpinned from the theories related to Theory of Reasoned Action, Constructivist learning and Connectivism. Samples from three secondary schools were selected based on proportionate stratified random sampling. 350 samples were targeted to respond to self-constructed questionnaires. Confirmatory Factor Analysis (CFA) was employed to prove the hypothesised 5-factor measurement model. The results have supported a model fit with positive interactions between the factors are evident. The study has proven the theoretical contributions which embark on holistic development of an individual to ensure attitude is moulded. The emotional and spiritual aspects of learning are needed to ensure positive contribution to the social dynamic. In this paper, the discussions are elaborated from the standpoints of theories and practical importance. The results have contributed to a theoretical model of science teaching method.  相似文献   
102.
The Routine Activities Theory suggests that when there is the presence of a motivated offender, a suitable target, and the absence of a capable guardian, crime has the opportunity to occur. Large sporting events accompanied by massive tourists bring these ingredients of crime together. The purpose of this study is to find out whether the crime rates spike in the host cities during the high tourist month of the Super Bowl. Twenty-four months of crime rates on eight types of crimes were obtained for every American city that has hosted the Super Bowl. Panel Data Analysis is used to test the Hypotheses of this study. The findings do not show a spike in crime rates during the month of Super Bowl for any of the crimes examined in this study. It is in the economic interests of all stakeholders to provide a safe and secure venue free of crimes for sports tourists.  相似文献   
103.
This study describes the development and testing of a magnetic microfluidic chip (MMC) for trapping and isolating cells tagged with superparamagnetic beads (SPBs) in a microfluidic environment for selective treatment and analysis. The trapping and isolation are done in two separate steps; first, the trapping of the tagged cells in a main channel is achieved by soft ferromagnetic disks and second, the transportation of the cells into side chambers for isolation is executed by tapered conductive paths made of Gold (Au). Numerical simulations were performed to analyze the magnetic flux and force distributions of the disks and conducting paths, for trapping and transporting SPBs. The MMC was fabricated using standard microfabrication processes. Experiments were performed with E. coli (K12 strand) tagged with 2.8 μm SPBs. The results showed that E. coli can be separated from a sample solution by trapping them at the disk sites, and then isolated into chambers by transporting them along the tapered conducting paths. Once the E. coli was trapped inside the side chambers, two selective treatments were performed. In one chamber, a solution with minimal nutrition content was added and, in another chamber, a solution with essential nutrition was added. The results showed that the growth of bacteria cultured in the second chamber containing nutrient was significantly higher, demonstrating that the E. coli was not affected by the magnetically driven transportation and the feasibility of performing different treatments on selectively isolated cells on a single microfluidic platform.  相似文献   
104.
This paper presents a new implementation of discrete multi-tone (DMT) systems based on different discrete transforms that include the discrete sine transform (DST), discrete cosine transform (DCT), and discrete wavelet transform (DWT). The implementation also considers time-domain equalization to mitigate channel distortion. Compared to the fast Fourier transform discrete multi-tone (FFT-DMT) system, the proposed implementations have an advantage in that their energy-compaction property helps in reducing the channel effects. The performance of the DST-DMT, DCT-DMT, DWT-DMT, and FFT-DMT systems, employing a time-domain equalizer (TEQ), is investigated in the paper. It has been demonstrated by computer simulations that the proposed implementations outperform the FFT-DMT system and that the utilization of the TEQ can lead to higher bit rates  相似文献   
105.
Population growth, trophic level, and some aspects of reproductive biology of two congeneric archer fish species, Toxotes chatareus and Toxotes jaculatrix, collected from Johor coastal waters, Malaysia, were studied. Growth pattern by length-weight relationship (W=aL~b) for the sexes differed, and exhibited positive allometric growth (male, female and combined sexes of T. chatareus; female and combined sexes of T. jaculatrix) and isometric growth (male samples of T. jaculatrix only). Trophic levels of both species were analyzed based on 128 specimens. The results show that, in both species, crustaceans and insects were the most abundant prey items, and among crustaceans the red clawed crab Sesarma bidens and Formicidae family insects were the most represented taxa. The estimated mean trophic levels for T. chatareus and T. jaculatrix were 3.422±0.009 and 3.420±0.020, respectively, indicating that they are largely carnivores. Fecundity of T. chatareus ranged from 38354 to 147185 eggs for females with total length ranging from 14.5 to 22.5 cm and total body weight from 48.7 to 270.2 g, and T. jaculatrix 25 251 to 150456 eggs for females with total length ranging from 12.2 to 23.0 cm and total body weight from 25.7 to 275.0 g. Differences in values of gonadosomatic and hepatosomatic indexes calculated for both species in this study may have resulted from uneven sample size ranges.  相似文献   
106.
In this paper, a novel on-line observer-based trajectory tracking strategy for leader-follower formation of multiple nonholonomic mobile robots is developed. In the proposed strategy, a leader robot follows a certain trajectory whereas a number of followers track the leader as specified by a formation protocol. Unlike other techniques in the literature, a predefined trajectory is not required, and it can be changed on-line. Moreover, this strategy aims to have a fast transient response without showing undesired overshoots. To achieve this feature, a new observer is introduced. Based on the output of that observer, a control strategy with two components is derived. The first control component is responsible for tracking the desired trajectory, whereas the second control component is used to regulate the robot to its desired steady state position. The stability of the closed loop control system is investigated. Applications of the proposed observer-based controller to different case studies are presented to illustrate the effectiveness, robustness and applicability of the developed technique. To show the superiority of proposed controller, its performance in a trajectory tracking application is compared to that of a Lyapunov-based controller.  相似文献   
107.
It is well known that dietary intakes play a pivotal role in pathogenesis of nonalcoholic fatty liver disease (NAFLD)/nonalcoholic steatohepatitis (NASH); however, the role of each component of diet has not yet been elucidated. Our objective was to evaluate the effects of onion consumption on prevention of NAFLD/NASH development. Sprague–Dawley rats were fed either high-fat, high sugar diet (model group), or high-fat, high sugar diet plus 7% onion powder (model + onion), or chow diet ad libitum for 7 weeks. Serum levels of fasting glucose, triglyceride, cholesterol, liver enzymes, insulin, and hepatic tumor necrosis factor-alpha (TNF-α) gene expression were determined. Hepatic histology was examined by H&E stain. Model + onion group had significantly lower hepatic steatosis, ballooning, lobular inflammation, and portal inflammation (p < 0.001), lower hepatic TNF-α gene expression (p < 0.001), lower plasma levels of ALT (p = 0.026), AST (p = 0.041), insulin (p < 0.001), TG (p = 0.041), and glucose (p = 0.009) compared with model group; however, weight gain, food intake, plasma total cholesterol and LDL levels were not significantly different between these two groups. Our data indicate that regular consumption of onion can prevent NAFLD even in the presence of the other risk factors such as obesity, hypercholesterolemia, and high energy, fat, and sugar intakes.  相似文献   
108.
Mouth rinsing using a carbohydrate (CHO) solution has been suggested to improve physical performance in fasting participants. This study examined the effects of CHO mouth rinsing during Ramadan fasting on running time to exhaustion and on peak treadmill speed (Vpeak). In a counterbalanced crossover design, 18 sub-elite male runners (Age: 21?±?2 years, Weight: 68.1?±?5.7?kg, VO2max: 55.4?±?4.8?ml/kg/min) who observed Ramadan completed a familiarization trial and three experimental trials. The three trials included rinsing and expectorating a 25?mL bolus of either a 7.5% sucrose solution (CHO), a flavour and taste matched placebo solution (PLA) for 10?s, or no rinse (CON). The treatments were performed prior to an incremental treadmill test to exhaustion. Three-day dietary and exercise records were obtained on two occasions and analysed. Anthropometric characteristics were obtained and recorded for all participants. A main effect for mouth rinse on peak velocity (Vpeak) (CHO: 17.6?±?1.5?km/h; PLA: 17.1?±?1.4?km/h; CON: 16.7?±?1.2?km/h; P?ηp2?=?0.49) and time to exhaustion (CHO: 1282.0?±?121.3?s; PLA: 1258.1?±?113.4?s; CON: 1228.7?±?98.5?s; P?=?.002, ηp2?=?0.41) was detected, with CHO significantly higher than PLA (P?P?P?>?.05). Energy availability from dietary analysis, body weight, and fat-free mass did not change during the last two weeks of Ramadan (P?>?.05). This study concludes that carbohydrate mouth rinsing improves running time to exhaustion and peak treadmill speed under Ramadan fasting conditions.  相似文献   
109.
110.
College students have often been surveyed about their general information seeking behaviors. However, little has been done to explore what specific system features they use to find and save information when they are working on their real-life tasks. In this study, 32 college students were invited to an information interaction lab for a session in which they recalled a recently finished task and worked on a to-be-finished task using a computer in the lab. They were asked to complete questionnaires regarding what systems they used to finish their tasks and what features were helpful for searching and for saving information. Results showed that college students rely more heavily on the Internet sources than on library sources, even for their course related work. The study identified fourteen categories of system features helpful for information search and eight categories helpful for information saving. The findings have implications for designing systems that will better help people accomplish their tasks.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号