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   186篇
  免费   3篇
  国内免费   1篇
教育   133篇
科学研究   42篇
各国文化   3篇
体育   3篇
信息传播   9篇
  2023年   3篇
  2022年   8篇
  2021年   8篇
  2020年   3篇
  2019年   11篇
  2018年   19篇
  2017年   6篇
  2016年   19篇
  2015年   8篇
  2014年   4篇
  2013年   20篇
  2012年   12篇
  2011年   8篇
  2010年   8篇
  2009年   8篇
  2008年   6篇
  2007年   7篇
  2006年   7篇
  2005年   2篇
  2004年   1篇
  2003年   3篇
  2001年   2篇
  1998年   3篇
  1997年   1篇
  1996年   1篇
  1994年   1篇
  1993年   1篇
  1987年   1篇
  1986年   1篇
  1984年   1篇
  1982年   2篇
  1979年   2篇
  1978年   1篇
  1975年   2篇
排序方式: 共有190条查询结果,搜索用时 15 毫秒
171.
The paper presents a stochastic calculations algorithm that mimics the photon polarization experiments of quantum mechanics. This experiment is usually used to introduce the quantum computing approach. Stochastic filters that operate on stochastic numbers in a mode similar to that of polarized filter operation on random polarized photons are introduced.  相似文献   
172.
A series of interviews and classroom observations were conducted with a group of in-service science teachers, students, school principal, and computer lab supervisors, from a “Discovery” female school in Jordan to assess their utilization of information and communication technology (ICT) in teaching science. The study also intended to determine how these participants were using ICT and if they had any internal and external impediments in the way of the effective integration of ICT in the teaching of science. Results showed that some participants were using ICT creatively in their science teaching. However, despite considerable political pressure to increase ICT use in the classroom, most expressed frustration at the lack of ICT tools, support from the school, from the Ministry of Education, and from the surrounding community. The article proposes possible resolutions to help these participants overcome their impediments. Some of the suggested resolutions for the internal impediments include involving teachers in preparing the school’s time-table, equipping the school with more ICT tools and offering more training courses for teachers. However, the suggested resolutions for the external impediments involve (1) The Ministry of Education to rethink the administration of board examinations, (2) The school to sacrifice scoring higher in board examinations for preparing more creative and more versatile students’ perspectives.  相似文献   
173.
In this study, an adaptive interval type-2 Takagi-Sugeno-Kang fuzzy logic controller based on reinforcement learning (AIT2-TSK-FLC-RL) is proposed. The proposed controller consists of an actor, a critic and a reward signal. The actor is represented by the IT2-TSK-FLC in which the antecedents and the consequents are interval type-2 fuzzy sets (IT2FSs) and type-1 fuzzy sets (T1FSs), respectively, which are named A2-C1. The critic is represented by a neural network, which approximates the optimal guaranteed cost in the control design to ensure the system stability for all admissible uncertainties and noise. The use of a reward signal to formalize the idea of a goal is one of the most distinctive features of RL. Thus, the proposed controller evolves in time as a result of the online learning algorithm. The parameters of the proposed controller are learned online based on the Lyapunov theorem to guarantee the stability, overcome the shortcomings of the gradient descent, such as the local minima and instability, and determine the learning rate of the IT2-TSK-FLC controller. Furthermore, the critic stability is discussed for determining the optimal learning rate. The proposed controller is applied to uncertain nonlinear systems to show its robustness in reducing the effect of system uncertainties and external disturbances and is compared to other controllers.  相似文献   
174.
Chronic myeloid leukemia is a myeloproliferative disorder with a unique rearrangement, the Philadelphia chromosome. Oxidative stress, a pervasive condition of an increased number of reactive oxygen species, is now recognized to be prominent feature of various diseases and their progression. Thus antioxidants, which control the oxidative stress state, represent a major line of defense regulating overall true state of health. The relationship between antioxidants status and levels of well-known markers of oxidative stress that are measured as lipid peroxides and oxidized proteins reflect better health indices and postures. The aim of this study was to evaluate the role of oxidative stress in pathophysiology of Chronic myeloid leukemia by measuring the circulating plasma lipid peroxide levels in terms of malonyldialdehyde, total lipid hydroperoxide and oxidized proteins as protein carbonyl whereas antioxidant status were estimated in terms of reduced glutathione and total thiol in plasma of Chronic myeloid leukemia patients. The present study included 47 Chronic myeloid leukemia patients and 20 age-and sex-matched healthy subjects. Out of 47 Chronic myeloid leukemia patients, 31 were in chronic phase (CML-CP) and 16 in accelerated phase (CML-AP). The median age of Chronic myeloid leukemia patients was 33 years and that of controls was 32 years. Oxidative stress and antioxidant status in plasma were evaluated by spectrophotometric procedures. There was a significant increase (p<0.05) in plasma malonyldialdehyde, total lipid hydroperoxide and protein carbonyl levels in Chronic myeloid leukemia patients as compared to healthy subjects. Our results also showed that plasma malonyldialdehyde and protein carbonyl levels were markedly elevated (p<0.05) in both chronic phase (CML-CP) and accelerated phase (CML-AP) as compared to healthy volunteers. Antioxidant status was found to be significantly decreased (p<0.05) in Chronic myeloid leukemia patients and its phases as compared to healthy participants. It could be concluded that oxidative stress may be associated with the pathophysiology of Chronic myeloid leukemia.  相似文献   
175.
The thirsty bird     
Z. Ahmad 《Resonance》1997,2(6):86-88
  相似文献   
176.
In this study, the pre-service teachers’ attitudes towards the educational inclusion for students with Autism Spectrum Disorder (ASD) were investigated to identify their attitudinal patterns and predictors. An attitudinal survey was conducted with 264 pre-service teachers in a teacher training programme in Malaysia. The study involved 151 special education pre-service teachers and 181 pre-service teachers in Special Education, Sciences, and in English teacher training programmes, in order to identify the effects of teaching specialisations and societal attitude on their inclusive education attitudinal measures. The findings revealed that the special education pre-service teachers were less in favour of the total inclusion of students with ASD in the mainstream, when compared with the non-special education pre-service teachers. The findings also revealed the combined effects of societal attitude and a categorical teacher training model in shaping the pre-service teachers’ attitudes towards inclusive education for the students with ASD in Malaysia. Such combined effects offered a perspective to explain the delay in the implementation of inclusive education, and also the prospect of its future development in the Southeast Asian region.  相似文献   
177.
在国家自然科学基金和国家重点基础研究专项经费(“973”项目) 资助下,自2003年以来,中国科学院半导体研究所固态量子信息课题组在固态量子信息研究 中取得了一些新进展。本文对这些进展作一些简单介绍。  相似文献   
178.
In this paper necessary and sufficient conditions are derived for a two-variable positive real function to be the driving-point impedance of certain classes of doubly-terminated lossless ladder networks. Specifically, two classes of networks are studied: (a) the class of networks in which the lossless structure is a cascade of p1- and p2-variable two-ports, each two-port having its transmission zeros at the origin and/or at infinity; (b) the class of networks in which the lossless structure is a lowpass or highpass ladder network with series arms having p1- and p2-type elements in series and shunt arms having the p1- and p2-type elements in parallel. It is indicated that via suitable transformations of the variables, conditions for many other types of ladder structures can be derived.  相似文献   
179.
A mathematical theory is developed for the nonlinear flexural response of an elastic, infinitely long, thin cylindrical shell submerged in an acoustic medium. The non- linearities examined pertain solely to the elastic field. Application of the theory is displayed in the context of a specific interaction problem. Inadequacies resulting from the use of existing interaction theories which employ a linear shell theory are displayed and critically examined.  相似文献   
180.
This study reports the utilization of serum fructosamine and blood glucose for the screening of gestational diabetes mellitus (GDM). Blood samples from 165 pregnant women were analyzed for fasting blood glucose (FBG), random blood glucose (RBG) and serum fructosamine. The actual fructosamine levels were corrected for serum protein (c-Fruct) for more precise presentation. Two cut-off values of FBG (>5.3 mmol/L and >7.0 mmol/L) and RBG (>7.8 mmol/L and >11.0 mmol/L) were used to classify hyperglycemic subjects for subsequent evaluation. The average values±standard deviations for FBG, RBG and cFruct were 5.865±1.95, 7.767±3.21 and 2.387±0.47 mmol/L, respectively. FBG levels were significantly correlated with RBG (Pearson correlation=0.597, P<0.001). Significant correlations were also observed between cFruct and FBG (Pearson correlation=0.673, P<0.001) or RBG (Pearson correlation=0.641, P<0.001). Out of 165 subjects, 24 (14.5%) cases were classified as hyperglycemic on the basis of FBG>7.0 mmol/L or RBG>11.0 mmol/L; use of lower cut-off values resulted higher frequencies of hyperglycemia. Whereas, a combined criteria of FBG>5.3 mmol/L and cFruct >2.5 mmol/L predicted 35 patients as the most probable hyperglycemic as compared to 32 patients identified using the criteria of RBG >7.8 mmol/L and cFruct >2.5 mmol/L. These criteria were associated with 4.8% and 3.6% false-positivity at the expense of 3.6% and 3.0% false-negative outcomes, respectively. The levels of FBG, RBG and cFruct were significantly higher in hyperglycemic groups (irrespective of grouping criteria) as compared to the respective normal groups. In conclusion, these findings clearly indicate that the paired values of cFruct with FBG or RBG could help in filtering high-risk individuals for OGTT and therefore avoiding a unnecessary OGTT.  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