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   5948篇
  免费   106篇
  国内免费   88篇
电工技术   44篇
综合类   130篇
化学工业   672篇
金属工艺   302篇
机械仪表   502篇
建筑科学   971篇
矿业工程   143篇
能源动力   259篇
轻工业   160篇
水利工程   47篇
石油天然气   224篇
武器工业   51篇
无线电   185篇
一般工业技术   1001篇
冶金工业   538篇
原子能技术   48篇
自动化技术   865篇
  2024年   6篇
  2023年   89篇
  2022年   104篇
  2021年   149篇
  2020年   124篇
  2019年   112篇
  2018年   114篇
  2017年   143篇
  2016年   158篇
  2015年   168篇
  2014年   281篇
  2013年   322篇
  2012年   284篇
  2011年   508篇
  2010年   362篇
  2009年   340篇
  2008年   363篇
  2007年   350篇
  2006年   275篇
  2005年   249篇
  2004年   250篇
  2003年   222篇
  2002年   181篇
  2001年   102篇
  2000年   128篇
  1999年   146篇
  1998年   130篇
  1997年   111篇
  1996年   66篇
  1995年   60篇
  1994年   58篇
  1993年   39篇
  1992年   26篇
  1991年   21篇
  1990年   21篇
  1989年   17篇
  1988年   13篇
  1987年   11篇
  1986年   5篇
  1985年   7篇
  1984年   6篇
  1983年   3篇
  1982年   5篇
  1981年   5篇
  1980年   3篇
  1978年   2篇
  1976年   1篇
  1975年   1篇
  1973年   1篇
排序方式: 共有6142条查询结果,搜索用时 0 毫秒
31.
In this study, the problem of blind signal separation for coprime planar arrays is investigated. For coprime planar arrays comprising two uniform rectangular subarrays, we link the signal separation to the tensor-based model called coupled canonical polyadic decomposition (CPD) and propose an improved coupled trilinear decomposition approach. The output data of coprime planar arrays are modeled as a coupled tensor set that can be further interpreted as a coupled CPD model, allowing a signal separation to be achieved using coupled trilinear alternating least squares (TALS). Furthermore, in the procedure of the coupled TALS, a Vandermonde structure enforcing approach is explicitly applied, which is shown to ensure fast convergence. The results of Monto Carlo simulations show that our proposed algorithm has the same separation accuracy as the basic coupled TALS but with a faster convergence speed.  相似文献   
32.
网上考试应用系统   总被引:1,自引:0,他引:1  
介绍了在Internet环境下利用活动服务器页面(ASP)技术,设计一套网上考试系统的实施方案和技术分析,具体介绍了在整个系统的实施中所需要的数据库结构、系统组成以及网页的设计。  相似文献   
33.
光电成像干扰图像质量评估   总被引:1,自引:0,他引:1  
曾凯  杨华  翟月  张红 《电子与信息学报》2011,33(9):2164-2168
干扰图像质量评估是光电成像干扰的一个难点问题,评估结果应与人类主观视觉感受相匹配.该文分析了光电干扰图像的特点和普通图像质量评估方法的局限性.然后,依据人眼主观视觉特性,利用四叉树数据结构划分方法,将干扰图像划分为边缘部分和非边缘部分.对于边缘部分,构造边缘比较函数评估干扰前后图像边缘变化的情况;对于非边缘部分,引入基...  相似文献   
34.
No-reference image quality assessment using structural activity   总被引:2,自引:0,他引:2  
Presuming that human visual perception is highly sensitive to the structural information in a scene, we propose the concept of structural activity (SA) together with a model of SA indicator in a new framework for no-reference (NR) image quality assessment (QA) in this study. The proposed framework estimates image quality based on the quantification of the SA information of different visual significance. We propose some alternative implementations of SA indicator in this paper as examples to demonstrate the effectiveness of the SA-motivated framework. Comprehensive testing demonstrates that the model of SA indicator exhibits satisfactory performance in comparison with subjective quality scores as well as representative full-reference (FR) image quality measures.  相似文献   
35.
Image quality assessment (IQA) attempts to quantify the quality-aware visual attributes perceived by humans. They can be divided into subjective and objective image quality assessment. Subjective IQA algorithms rely on human judgment of image quality, where the human visual perception functions as the dominant factor However, they cannot be widely applied in practice due to the heavy reliance on different individuals. Motivated by the fact that objective IQA largely depends on image structural information, we propose a structural cues-based full-reference IPTV IQA algorithm. More specifically, we first design a grid-based object detection module to extract multiple structural information from both the reference IPTV image (i.e., video frame) and the test one. Afterwards, we propose a structure-preserved deep neural networks to generate the deep representation for each IPTV image. Subsequently, a new distance metric is proposed to measure the similarity between the reference image and the evaluated image. A test IPV image with a small calculated distance is considered as a high quality one. Comprehensive comparative study with the state-of-the-art IQA algorithms have shown that our method is accurate and robust.  相似文献   
36.
37.
网上营销的难点是如何寻找潜在客户。识别用户行为是一个复杂的过程,建议采用二维模型来寻找相关的项目,然后推荐给用户。但太多不相干的建议转化为用户信息过载问题。本研究的目的是在每个维度中找出已被用户搜索的项目/对象,最受好评的每个维度中的项目可给予建议。要做到这一点,我们采用张量,它可以有效地模拟多维Web日志中的用户搜索数据,然后确定在每一个搜索维度上的用户模型。所有的评估均基于真实数据集,这清晰地显示出比其他广泛使用的向量和矩阵方法的有效性。  相似文献   
38.
Analysis Expression of Rate Equation for Vertical Cavity Lasers   总被引:1,自引:0,他引:1  
An analysis solution of rate equation is derived for vertical cavity surface-emitting lasers.Based on the enhanced spontaneous emission caused by VCSELs and influence of nonradiative recombination, the relation between output properties and structural parametersof multi-quantum wells(MQWs) is obtanined.It was found that the characteristic curve of a “thresholdless“ laser is strongly nonradiative depopulation-dependent.When the nonradiative depopulation is no zero,the light-current characteristic is not linearly even for an ideal closed microcavity.The light output is increased by the enhanced well number and by the reduced width.In particular, a lower threshold current density for MQWs structure in the short cavity is realized by us, meanwhile the sharpness of the variation depends on spontaneous emission factor.  相似文献   
39.
This paper presents a Distributed compressive video sensing scheme with Adaptive measurements (DCVS-AM). In this approach, the key frame in each Group of pictures (GOP) is coded by Compressive sensing (CS) with a fixed measurement rate; whereas other frames in the same GOP are compressed by an adaptive random projection in two stages, yielding the Adaptive compressive sensing (ACS) frames. The first stage uses a small and fixed measurement rate and recovers a coarse version. In the second stage, each coarse-version ACS-frame together with its proceeding and following key frames will go through a joint analysis at the decoder side and the analysis result - Structural similarity (SSIM) that is based on a motion-guided interpolation and calculated in a multilevel discrete wavelet transform domain - is sent back to the encoder side to facilitate a re-sampling of the ACS-frame with an adaptive measurement rate. Experimental results show that our proposed DCVS-AM consistently outperforms the state-of-the-art DCVS with a fixed measurement.  相似文献   
40.
A simple method to decorate mutliwalled carbon nanotubes (MWCNTs) with silver nanoparticles (Ag NPs) to enhance the structural properties is reported in the present study. The Ag NPs of average size 9 nm were deposited uniformly on MWCNTs network by RF sputtering technique. X-ray diffraction (XRD), Raman spectroscopy and Scanning electron microscopy (SEM) are used to compare the structural properties of Ag NPs sputtered nanotubes with those containing functionalized tubes. In addition, effect of these Ag NPs on the surface of nanotubes and optimization of the experimental parameter for uniform deposition of Ag NPs are also discussed.  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