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   207838篇
  免费   28367篇
  国内免费   9295篇
电工技术   12941篇
技术理论   13篇
综合类   13160篇
化学工业   42511篇
金属工艺   10312篇
机械仪表   11402篇
建筑科学   15911篇
矿业工程   5555篇
能源动力   5936篇
轻工业   18479篇
水利工程   3916篇
石油天然气   9602篇
武器工业   1660篇
无线电   25990篇
一般工业技术   29623篇
冶金工业   7939篇
原子能技术   2110篇
自动化技术   28440篇
  2024年   863篇
  2023年   3151篇
  2022年   5926篇
  2021年   8160篇
  2020年   7414篇
  2019年   7879篇
  2018年   8317篇
  2017年   9246篇
  2016年   8911篇
  2015年   11170篇
  2014年   12828篇
  2013年   15334篇
  2012年   14081篇
  2011年   14578篇
  2010年   13413篇
  2009年   12561篇
  2008年   11929篇
  2007年   10996篇
  2006年   10532篇
  2005年   8725篇
  2004年   6837篇
  2003年   6576篇
  2002年   7243篇
  2001年   6092篇
  2000年   4689篇
  1999年   3944篇
  1998年   2629篇
  1997年   2236篇
  1996年   2122篇
  1995年   1664篇
  1994年   1368篇
  1993年   966篇
  1992年   841篇
  1991年   515篇
  1990年   426篇
  1989年   321篇
  1988年   261篇
  1987年   165篇
  1986年   144篇
  1985年   106篇
  1984年   68篇
  1983年   60篇
  1982年   54篇
  1981年   38篇
  1980年   40篇
  1979年   19篇
  1977年   4篇
  1976年   9篇
  1959年   14篇
  1951年   10篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
实验利用数字全息干涉技术对电极反应过程中溶液浓度变化分布进行测量。运用基于直方图的自适应滤波方法和基于形态学滤波的固液界面提取方法,解决了每更换一次实验数据都要人工识别和更换滤波参数以及手动去除固侧干扰信息的难题,为实现从摄像机实时读取数据、实时处理、测量和观察提供了仿真依据。  相似文献   
992.
A new efficient image codec called embedded wavelet coding based on list structure (EWCBL) is proposed in this paper. By combining the techniques of morphological representation and quadtree partitioning, EWCBL effectively exploits both within-subband clustering and cross-subband similarity of wavelet coefficients. Based on the list structure, a fine fractional bit-plane coding is employed to achieve excellent rate-distortion performance. The patterned morphological dilation is introduced to greatly reduce the redundant test operations. Experimental results show that the proposed EWCBL outperforms state-of-the-art embedded codecs for both lossy and lossless compression. Moreover, the good performance and features of embeddedness and scalability are achieved with relatively low complexity.  相似文献   
993.
基于SIP家庭网关和Web Service的智能家居系统   总被引:1,自引:0,他引:1  
提出了一种将 SIP 家庭网关技术和 Web Service 技术相结合的智能家居系统的设计和实现方案,详细介绍了系统各功能模块,给出了在 PDA 上调用基于 SIP 家庭网关的 Web 服务来监控家中各电器状态的实现结果。该技术可以向用户提供智能家居管理、远程监控等具体服务。  相似文献   
994.
Emergency medical service (EMS) providers continually seek ways to improve system performance particularly the response time to incidents. The demand for ambulances fluctuate throughout the week, depending on the day of week, and even the time of day, therefore EMS operators can improve system performance by dynamic relocation/redeployment of ambulances in response to fluctuating demand patters. The objective of the model is to determine the minimum number of ambulances and their locations for each time cluster in which significant changes in demand pattern occur while meeting coverage requirement with a predetermined reliability. The model is further enhanced by calculating ambulance specific busy probabilities and validated by a comprehensive simulation model. Computational results on experimental data sets and data from an EMS agency are provided.  相似文献   
995.
The Makeham distribution has been used to describe human mortality and establish actuarial tables. The hazard function is defined by μ(t)=A+BCtμ(t)=A+BCt, we use the least squares type estimation to estimate the parameters of Makeham distribution in this paper. Seven cases are considered, when A, B, C are known or unknown, respectively. Also, we evaluated the mean square errors of these estimators.  相似文献   
996.
Limits of Learning-Based Superresolution Algorithms   总被引:2,自引:0,他引:2  
Learning-based superresolution (SR) is a popular SR technique that uses application dependent priors to infer the missing details in low resolution images (LRIs). However, their performance still deteriorates quickly when the magnification factor is only moderately large. This leads us to an important problem: “Do limits of learning-based SR algorithms exist?” This paper is the first attempt to shed some light on this problem when the SR algorithms are designed for general natural images. We first define an expected risk for the SR algorithms that is based on the root mean squared error between the superresolved images and the ground truth images. Then utilizing the statistics of general natural images, we derive a closed form estimate of the lower bound of the expected risk. The lower bound only involves the covariance matrix and the mean vector of the high resolution images (HRIs) and hence can be computed by sampling real images. We also investigate the sufficient number of samples to guarantee an accurate estimate of the lower bound. By computing the curve of the lower bound w.r.t. the magnification factor, we could estimate the limits of learning-based SR algorithms, at which the lower bound of the expected risk exceeds a relatively large threshold. We perform experiments to validate our theory. And based on our observations we conjecture that the limits may be independent of the size of either the LRIs or the HRIs.  相似文献   
997.
高鹏  曹先彬 《计算机工程》2008,34(5):166-168
聊天室中的聊天数据充斥着大量噪声,极大地降低了话题检测的监控效率。但聊天数据只有对话发出时间这一线索可供直接利用,因此噪声过滤是聊天室监控的一个难题。该文提出一种基于社会网络的聊天数据噪声过滤方法,通过分析聊天数据的时序关系,推断出聊天用户间的社会网络关系,根据社会网络蕴含的用户交流特点判断并过滤出噪声。实验证实了该方法能较准确地过滤出噪声,提高话题识别的准确率。  相似文献   
998.
基于XML的数据交换是一种典型的Web应用,通过分析基于服务的数据交换数据,说明在该Web应用中,存在的安全问题和需求,架构一个基于PKI/PMI的安全Web数据交换平台,实现应用层的授权和安全访问控制,并应用在实际中.  相似文献   
999.
提出了一种小型嵌入式Linux Boot Loader的设计方案,并详细介绍该方案在Arm-Linux平台上的实现过程.方案大大简化了特定应用平台下Linux Boot Loader的设计,并且大大减小了生成的可执行文件的大小,针对特定应用平台自行设计小型的Boot Loader具有一定的参考价值.  相似文献   
1000.
Network traffic classification based on ensemble learning and co-training   总被引:4,自引:0,他引:4  
Classification of network traffic is the essential step for many network researches. However,with the rapid evolution of Internet applications the effectiveness of the port-based or payload-based identifi-cation approaches has been greatly diminished in recent years. And many researchers begin to turn their attentions to an alternative machine learning based method. This paper presents a novel machine learning-based classification model,which combines ensemble learning paradigm with co-training tech-niques. Compared to previous approaches,most of which only employed single classifier,multiple clas-sifiers and semi-supervised learning are applied in our method and it mainly helps to overcome three shortcomings:limited flow accuracy rate,weak adaptability and huge demand of labeled training set. In this paper,statistical characteristics of IP flows are extracted from the packet level traces to establish the feature set,then the classification model is created and tested and the empirical results prove its feasibility and effectiveness.  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