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   4169篇
  免费   466篇
  国内免费   306篇
电工技术   128篇
技术理论   2篇
综合类   388篇
化学工业   153篇
金属工艺   31篇
机械仪表   112篇
建筑科学   10篇
矿业工程   21篇
能源动力   66篇
轻工业   21篇
水利工程   2篇
石油天然气   7篇
武器工业   50篇
无线电   1781篇
一般工业技术   186篇
冶金工业   10篇
原子能技术   11篇
自动化技术   1962篇
  2024年   23篇
  2023年   153篇
  2022年   187篇
  2021年   207篇
  2020年   248篇
  2019年   147篇
  2018年   208篇
  2017年   381篇
  2016年   301篇
  2015年   267篇
  2014年   410篇
  2013年   358篇
  2012年   392篇
  2011年   367篇
  2010年   248篇
  2009年   288篇
  2008年   153篇
  2007年   183篇
  2006年   122篇
  2005年   59篇
  2004年   26篇
  2003年   16篇
  2002年   30篇
  2001年   26篇
  2000年   25篇
  1999年   21篇
  1998年   6篇
  1997年   7篇
  1996年   6篇
  1995年   3篇
  1994年   2篇
  1993年   4篇
  1992年   2篇
  1991年   2篇
  1990年   4篇
  1989年   1篇
  1988年   11篇
  1987年   20篇
  1986年   15篇
  1985年   3篇
  1983年   1篇
  1982年   2篇
  1981年   2篇
  1980年   2篇
  1979年   2篇
排序方式: 共有4941条查询结果,搜索用时 0 毫秒
51.
Based on advantages of basic non-negative sparse coding (NNSC) model, and considered the prior class constraint of image features, a novel NNSC model is discussed here. In this NNSC model, the sparseness criteria is selected as a two-parameter density estimation model and the dispersion ratio of within-class and between-class is used as the class constraint. Utilizing this NNSC model, image features can be extracted successfully. Further, the feature recognition task by using different classifiers can be implemented well. Simulation results prove that our NNSC model proposed is indeed effective in extracting image features and recognition task in application.  相似文献   
52.
Visual tracking, as a popular computer vision technique, has a wide range of applications, such as camera pose estimation. Conventional methods for it are mostly based on vision only, which are complex for image processing due to the use of only one sensor. This paper proposes a novel sensor fusion algorithm fusing the data from the camera and the fiber-optic gyroscope. In this system, the camera acquires images and detects the object directly at the beginning of each tracking stage; while the relative motion between the camera and the object measured by the fiber-optic gyroscope can track the object coordinate so that it can improve the effectiveness of visual tracking. Therefore, the sensor fusion algorithm presented based on the tracking system can overcome the drawbacks of the two sensors and take advantage of the sensor fusion to track the object accurately. In addition, the computational complexity of our proposed algorithm is obviously lower compared with the existing approaches(86% reducing for a 0.5 min visual tracking). Experiment results show that this visual tracking system reduces the tracking error by 6.15% comparing with the conventional vision-only tracking scheme(edge detection), and our proposed sensor fusion algorithm can achieve a long-term tracking with the help of bias drift suppression calibration.  相似文献   
53.
The success of an artificial neural network (ANN) strongly depends on the variety of the connection weights and the network structure. Among many methods used in the literature to accurately select the network weights or structure in isolate; a few researchers have attempted to select both the weights and structure of ANN automatically by using metaheuristic algorithms. This paper proposes modified bat algorithm with a new solution representation for both optimizing the weights and structure of ANNs. The algorithm, which is based on the echolocation behaviour of bats, combines the advantages of population-based and local search algorithms. In this work, ability of the basic bat algorithm and some modified versions which are based on the consideration of the personal best solution in the velocity adjustment, the mean of personal best and global best solutions through velocity adjustment and the employment of three chaotic maps are investigated. These modifications are aimed to improve the exploration and exploitation capability of bat algorithm. Different versions of the proposed bat algorithm are incorporated to handle the selection of the structure as well as weights and biases of the ANN during the training process. We then use the Taguchi method to tune the parameters of the algorithm that demonstrates the best ability compared to the other versions. Six classifications and two time series benchmark datasets are used to test the performance of the proposed approach in terms of classification and prediction accuracy. Statistical tests demonstrate that the proposed method generates some of the best results in comparison with the latest methods in the literature. Finally, our best method is applied to a real-world problem, namely to predict the future values of rainfall data and the results show satisfactory of the method.  相似文献   
54.

Detection-based pedestrian counting methods produce results of considerable accuracy in non-crowded scenes. However, the detection-based approach is dependent on the camera viewpoint. On the other hand, map-based pedestrian counting methods are performed by measuring features that do not require separate detection of each pedestrian in the scene. Thus, these methods are more effective especially in high crowd density. In this paper, we propose a hybrid map-based model that is a new directional pedestrian counting model. Our proposed model is composed of direction estimation module with classified foreground motion vectors, and pedestrian counting module with principal component analysis. Our contributions in this paper have two aspects. First, we present a directional moving pedestrian counting system that does not depend on object detection or tracking. Second, the number and major directions of pedestrian movements can be detected, by classifying foreground motion vectors. This representation is more powerful than simple features in terms of handling noise, and can count the moving pedestrians in images more accurately.

  相似文献   
55.
OMAP4430是TI公司推出的开放式多媒体可扩展应用平台,对于移动通信开发应用具有一定的价值。本文主要从硬件结构、软件架构两个方面进行阐述,突出OMAP4430的低能耗、高性能、高集成度以及在现代通信与多媒体技术中的相关应用。  相似文献   
56.
给出了采用ADXL335加速度传感器来采集五个手指和手背的加速度三轴信息,并通过ZigBee无线网络传输来提取手势特征量,同时利用BP神经网络算法进行误差分析来实现手势识别的设计方法。最后,通过Matlab验证,结果表明,该系统在测试中识别率较高,系统稳定。  相似文献   
57.
Qi, the wireless power standard, has been proposed to allow low power systems to receive power through wireless inductive power transfer. The standard outlines the essential, desired and optional requirements for developing the wireless power transfer platform. In this paper, we present the design and implementation results of communication controller for guided positioning single transmitter–single receiver wireless power transfer platform. Apart from the basic design, additional processing and data storage capability is introduced to make the design adaptive in terms of response time and the size of control data transfer. The method of estimating the amount of power transfer is modified to reduce design complexity and internal power consumption of power transmitter and receiver. The implementation results help to access the ratio of power transferred to resource utilization and the ratio of power transferred to power consumed in simplistic wireless power transfer platform.  相似文献   
58.
Low-density parity-check (LDPC) codes have become the part of various communication standards due to their excellent error correcting performance. Existing methods require matrix inverse computation for obtaining a systematic generator matrix from parity check matrix. With the change in code rate or code length the process is repeated and hence, a large number of pre-processing computations time and resources are required. In the existing methods, the complexity of encoding is essentially quadratic with respect to the block length. In this paper, it is shown that the parity check matrix can be constructed using patterned sub-matrix structure such that the matrix inverse operation is replaced by matrix multiplication of sparse matrices. The sparseness of matrices is then utilized to obtain efficient encoders which can achieve encoding in real time with reduced pre-computation complexity. Hardware implementation of encoder and simulation results show that the proposed encoder achieves throughput in excess of 1 Gbps with the same error correcting performance as the conventional designs.  相似文献   
59.
This paper addresses new and significant research issues in web page design in relation to the use of graphics. The original findings include that (a) graphics play an important role in enhancing the appearance and thus users' feelings (aesthetics) about web pages and that (b) the effective use of graphics is crucial in designing web pages. In addition, we have developed a web page design support database based on a user-centered experimental procedure and a neural network model. This design support database can be used to examine how a specific combination of design elements, particularly the ratio of graphics to text, will affect the users' feelings about a web page. As a general rule, the ratio of graphics to text between 3:1 and 1:1 will give the users the best feelings of ease-to-use and clear-to-follow. A web page with a ratio of 1:1 will have the most realistic look, while a ratio of over 3:1 will have the fanciest appearance. The result provides useful insights in using graphics on web pages that help web designers best meet users' specific expectations and aesthetic consistency.  相似文献   
60.
In this paper, we propose a novel tracking algorithm, boosted color distribution (BCD), for tracking color objects. There exist three contributions in this paper. First, we propose a novel online gentle boost (OGB) algorithm for online learning. The essential idea of OGB is composed of two aspects: online updating candidate weak classifiers, and then choosing and combining them in a boosting way. Second, we design a novel weak classifier, log color feature distribution ratio, which focuses on the difference of color distributions rather than individual samples and provides a simple yet effective manner of mining color features for object tracking. Third, by combining our OGB algorithm and our log color features, we develop a fast yet effective color-based object tracking algorithm. Numerous experiments demonstrate that our tracking algorithm is better than or not worse than some state-of-the-art tracking algorithms on some public sequences.Overall, this paper presents a novel BCD algorithm for color object tracking that achieves good results at a fast speed.  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