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   299篇
  免费   17篇
  国内免费   7篇
教育   204篇
科学研究   45篇
体育   22篇
综合类   30篇
文化理论   4篇
信息传播   18篇
  2024年   1篇
  2023年   2篇
  2022年   12篇
  2021年   13篇
  2020年   18篇
  2019年   16篇
  2018年   7篇
  2017年   4篇
  2016年   6篇
  2015年   2篇
  2014年   24篇
  2013年   29篇
  2012年   25篇
  2011年   35篇
  2010年   16篇
  2009年   10篇
  2008年   16篇
  2007年   17篇
  2006年   12篇
  2005年   18篇
  2004年   12篇
  2003年   9篇
  2001年   7篇
  2000年   2篇
  1999年   2篇
  1998年   2篇
  1997年   3篇
  1995年   1篇
  1992年   1篇
  1991年   1篇
排序方式: 共有323条查询结果,搜索用时 15 毫秒
31.
Imaging Analysis by Means of Fractional Fourier Transform   总被引:2,自引:0,他引:2  
Starting from the diffraction imaging process,we have discussed the relationship between optical imaging system and tional Fourier transform,and proposed a specific system which can form an inverse amplified image of input function.  相似文献   
32.
社会美主要指的是人的美。人美包括外貌美和心灵美。语文课文中成功地塑造了一系列美的人,如何充分利用这些美的人教育学生,让学生学习这些美的人,模仿这引起美的人,从而造就新一代美的人,是我们语文教学的首要任务,也是教育的宗旨。该文试图通过分析课文中社会美的内涵和形式,探索社会美的审美教育,更好地完成社会美的审美教育目的。  相似文献   
33.
Body-scanning exploiting 3-D imaging has revolutionised diagnostics and treatment in medicine. Process engineers would like to be similarly able to image chemical process units in 3-D, but without the £multi-million price tag. UMIST and Leeds University have together, through the Virtual Centre for Industrial Process Tomography (http://www. vcipt.org), pioneered several electrical process tomography techniques and used them in a variety of applications. Illustrations are presented to show how electrical resistance tomography (ERT) has been developed for typical stirred vessels widely encountered in batch process manufacturing. The technique is potentially fast and inexpensive and capable of imaging both dynamic and pseudo-stationary processes. Examples from UMIST's two-tonne vessel will be presented for miscible tracer mixing, as well as gas-liquid and solid-liquid mixing.  相似文献   
34.
Radiative imaging of combustion flame in furnace of power plant plays an increasingly important role in combustion diagnosis. This paper presents a new method for calculating the radiative imaging of three-dimensional (3D) combustion flame based on Monte Carlo method and optical lens imaging. Numerical simulation case was used in this study. Radiative images were calculated and images obtained can not only present the energy distribution on the charge-coupled device (CCD) camera target plane but also reflect the energy distribution condition in the simulation furnace. Finally the relationships between volume ele- ments and energy shares were also discussed.  相似文献   
35.
Incorporating metacognitive strategies in the classroom helps students monitor and adjust their learning strategies throughout the semester, and helps students progress from novice to expert learners in a subject. Journaling (i.e., reflective writing) is one metacognitive task that allows students to contemplate and articulate their skill development as they learn a new subject. The research reported here examines the use of ‘blogs’ (i.e., online journals) in an upper level undergraduate human anatomy course. The blogs both facilitated development of students' metacognitive skills and provided researchers insight into student metacognitive process. Data were examined from 92 students from three successive semesters (spring 2010, 2012 and 2014). Each student reviewed 10 radiology online cases throughout the semester and then reflected on their understanding of anatomy and radiology in an online blog for each case. A total of 927 blogs were examined for this research. The researchers used a grounded theory approach to analyze the blog narratives and develop a codebook based on common themes. The 927 blogs yielded 11,082 statements that were coded with the codebook. As the semester progressed, the blog entries showed that students demonstrated greater self-confidence in their abilities to understand the subject matter, expressed greater enthusiasm for anatomy in general, and they improved their metacognitive skills. This research illustrates that reflective writing in an undergraduate anatomy course not only facilitates improvement in student metacognitive skills, but also provides the instructor with evidence how a student progresses from novice to more experienced learner in anatomy.  相似文献   
36.
提出一种可见光域的相干衍射成像方法.该方法在待测样品面引入一个已知的标准物体作为先验信息,并通过控制激光光束的照明范围得到2幅不同输入信息下的衍射图.依据这2幅衍射图和已知的先验信息,使用本文提出的相位恢复算法,在计算机数值模拟和光学实验中重建待测样品的复振幅信息.该方法仅需2幅衍射图即可进行无透镜成像,因此其成像过程较为简便,具有一定的实用价值.  相似文献   
37.
Marmosets are highly social non-human primates that live in families. They exhibit rich vocalization, but the neural basis underlying this complex vocal communication is largely unknown. Here we report the existence of specific neuron populations in marmoset A1 that respond selectively to distinct simple or compound calls made by conspecific marmosets. These neurons were spatially dispersed within A1 but distinct from those responsive to pure tones. Call-selective responses were markedly diminished when individual domains of the call were deleted or the domain sequence was altered, indicating the importance of the global rather than local spectral-temporal properties of the sound. Compound call-selective responses also disappeared when the sequence of the two simple-call components was reversed or their interval was extended beyond 1 s. Light anesthesia largely abolished call-selective responses. Our findings demonstrate extensive inhibitory and facilitatory interactions among call-evoked responses, and provide the basis for further study of circuit mechanisms underlying vocal communication in awake non-human primates.  相似文献   
38.
磁共振成像技术依据原子核能级跃迁释放能量在物质不同结构环境中不同的衰减,通过外加梯度磁场检测所发射的电磁波,获得构成物体的原子核种类和位置,从而绘制出物体内部的结构图像.近年来,随着快速变化的梯度磁场的应用,核磁共振成像技术不仅在医学,而且在其他科研领域都得到了广泛的应用.  相似文献   
39.
基于雷达成像的熵函数优化方法(英文)   总被引:1,自引:0,他引:1  
对ISAR成像的最小熵自聚焦(MEA)算法进行了收敛性分析. 仿真结果表明, MEA算法存在局部最优问题, 作为其代价函数的ISAR像熵函数并非多维补偿相位的下凸函数. 只有当该补偿相位矢量的初值选取合适, 使其处于像熵函数的全局最小点附近时, MEA算法才能收敛到全局最优解. 针对MEA算法的最优化问题, 给出了一种基于雷达成像的熵函数优化方法. 该方法首先采用改进的多普勒中心跟踪法估计补偿相位初值. 该初值是最大似然准则下的估计结果, 可以使初始相位位于最优解附近. 然后, 利用快速MEA 算法进行局部搜索, 得到全局最优解. 仿真结果表明, 该算法不仅实现了MEA算法的全局最优求解, 还可避免步长、阈值等参数的选择与调整.  相似文献   
40.
工作记忆:人类高级认知活动的核心   总被引:2,自引:0,他引:2  
工作记忆是个体在执行认知任务过程中,对信息暂时保持与操作的能力。近年来的诸多研究指出,工作记忆在人类智力、学习、推理、创造力等高级认知活动中起重要的作用。潜变量分析揭示了工作记忆的中央执行系统与高级认知活动之间存在着密切关系;而脑成像研究显示,工作记忆与高级认知活动的共享脑机制可能是两者关系紧密的主要原因;通过对个体工作记忆能力的训练,提升其阅读能力、智力水平等高级认知能力的干预研究,则进一步证明了工作记忆在人类高级认知活动中的核心影响。  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