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   514篇
  免费   14篇
  国内免费   1篇
教育   319篇
科学研究   129篇
各国文化   4篇
体育   29篇
综合类   4篇
文化理论   5篇
信息传播   39篇
  2023年   9篇
  2022年   10篇
  2021年   22篇
  2020年   11篇
  2019年   30篇
  2018年   30篇
  2017年   43篇
  2016年   23篇
  2015年   22篇
  2014年   33篇
  2013年   63篇
  2012年   37篇
  2011年   20篇
  2010年   26篇
  2009年   22篇
  2008年   25篇
  2007年   14篇
  2006年   9篇
  2005年   11篇
  2004年   10篇
  2003年   9篇
  2002年   11篇
  2001年   6篇
  2000年   7篇
  1999年   1篇
  1997年   1篇
  1996年   2篇
  1995年   1篇
  1993年   2篇
  1992年   2篇
  1991年   3篇
  1990年   2篇
  1989年   2篇
  1988年   1篇
  1987年   1篇
  1985年   1篇
  1984年   1篇
  1980年   1篇
  1978年   1篇
  1976年   1篇
  1975年   1篇
  1970年   1篇
  1967年   1篇
排序方式: 共有529条查询结果,搜索用时 15 毫秒
101.
The present study was conducted to investigate the oxidant–antioxidant status in iron deficient pregnant anemic women. One hundred thirty pregnant women with iron deficiency anemia (IDA) were divided into three groups, namely mild (50), moderate (50) and severe (30) anemic along with pregnant healthy women as controls (50). The complete blood count, plasma lipid peroxidation products, enzymatic and non-enzymatic antioxidants were measured according to respective protocols. The levels of complete blood count, iron, ferritin along with antioxidant enzymes namely catalase, superoxide dismutase, glutathione peroxidase, glutathione reductase and reduced glutathione were significantly reduced in all IDA groups. However, the level of oxidized glutathione, lipid peroxides, protein carbonyls, conjugated dienes were found significantly increased in all anemic patients. Antioxidant vitamins, namely C, E and A were also found significantly decreased in IDA patients. On the basis of our results, it may be concluded that IDA tends to increase the pro-oxidant components, which may result in various complications including peroxidation of vital body molecules resulting in increased risk for pregnant women as well as fetus.  相似文献   
102.
103.
A microfluidic device that is able to perform dielectric spectroscopy is developed. The device consists of a measurement chamber that is 250 μm thick and 750 μm in radius. Around 1000 cells fit inside the chamber assuming average quantities for cell radius and volume fraction. This number is about 1000 folds lower than the capacity of conventional fixtures. A T-cell leukemia cell line Jurkat is tested using the microfluidic device. Measurements of deionized water and salt solutions are utilized to determine parasitic effects and geometric capacitance of the device. Physical models, including Maxwell-Wagner mixture and double shell models, are used to derive quantities for sub-cellular units. Clausius-Mossotti factor of Jurkat cells is extracted from the impedance spectrum. Effects of cellular heterogeneity are discussed and parameterized. Jurkat cells are also tested with a time domain reflectometry system for verification of the microfluidic device. Results indicate good agreement of values obtained with both techniques. The device can be used as a unique cell diagnostic tool to yield information on sub-cellular units.  相似文献   
104.
105.
This research examines the learning preferences of students in UAE University (UAEU). The uniqueness of this research emanates from the fact that no prior research examined this area from the UAE’s perspective. Thus, this research embarks on the fact that student learning strategies vary from one country to another due to many factors. This research utilizes six learning strategies extended from the literature and attempts to examine their importance on UAEU students using survey research. The selected learning strategies were students” motivation, time-poorness, mastery effort, assessment focus, competitiveness, and listening. This research provided interesting insights and contrasts pertaining to the learning strategies of UAEU students. Implications are discussed highlighting different theoretical as well as professional contributions and contentions and portrayed a path where pending issues could be addressed by future research.  相似文献   
106.
In this special issue of Biomicrofluidics, a wide variety of applications of microfluidics to tissue engineering and cell biology are presented. The articles illustrate the benefits of using microfluidics for controlling the cellular environment in a precise yet high rate manner using minimum reagents. The topic is very timely and takes a stab at portraying a glimpse of what is to come in this exciting and emerging field of research.  相似文献   
107.
This paper is devoted to the non-fragile exponential synchronization problem of complex dynamical networks with time-varying coupling delays via sampled-data static output-feedback controller involving a constant signal transmission delay. The dynamics of the nodes contain s quadratically restricted nonlinearities, and the feedback gain is allowed to have norm-bounded time-varying uncertainty. The control design is based on a Lyapunov–Krasovskii functional, which consists of the sum of terms assigned to the individual nodes, i.e., it is constructed without merging the complex dynamical network’s nodes into a single large-scale system. In this way, the proposed design method has substantially reduced computational complexity and improved conservativeness, and guaranties non-fragile exponential stability of the error system. The sufficient stability condition is expressed in terms of linear matrix inequalities that are solvable by standard tools. The efficiency of the proposed method is illustrated by numerical examples.  相似文献   
108.
本文给出了一种有效的余弦调制滤波器组的设计方法。这种算法采用了内插法和迭代算法相结合设计原型滤波器,目标函数表示为滤波器系数的四次方,用迭代算法来优化滤波器的系数。这种方法使需要优化的参数大大减少。最后的实例仿真,验证了此算法的有效性。  相似文献   
109.
田阿利 《科教文汇》2012,(31):32-33
力学教学对当代大学生的创新能力和素质的培养有着重要的作用.该文结合教学实践和体会,通过力学史的渗透、多种教学手段相结合、“一题多解”的训练、使用力学知识解决生活实际问题和鼓励学生参加课程实践活动等方式,不断激发学生学习兴趣,提高思维积极性,培养创新精神,加强创新能力和科学素质.  相似文献   
110.
The use of Bluetooth Low Energy (BLE) beacons is becoming widespread for context-aware learning environments. This technology can be used in indoor and outdoor settings such as museums, shops, home and schools in order to identify the location of learners and their contexts. Specifically, in the constructivist view of learning, learners can use such sensing technology for constructing knowledge and experiencing learning at any time, anywhere. However, exploration of such technology has been limited in the constructivist context-aware ubiquitous learning (U-learning) literature. For this purpose, the authors evaluated two android-based U-learning applications: one was an outdoor learning environment in a garden, the other was about locating books in a library. The applications were implemented and tested with school and university students. The qualitative results are presented in this article, and show how such sensing technology is promising for both pedagogical environments.  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