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   101555篇
  免费   19813篇
  国内免费   3221篇
电工技术   5024篇
技术理论   3篇
综合类   4536篇
化学工业   26260篇
金属工艺   4081篇
机械仪表   5151篇
建筑科学   6920篇
矿业工程   1947篇
能源动力   2591篇
轻工业   12215篇
水利工程   1692篇
石油天然气   3194篇
武器工业   619篇
无线电   14648篇
一般工业技术   18301篇
冶金工业   3398篇
原子能技术   809篇
自动化技术   13200篇
  2024年   956篇
  2023年   1420篇
  2022年   2338篇
  2021年   3411篇
  2020年   4432篇
  2019年   4863篇
  2018年   4914篇
  2017年   5593篇
  2016年   5798篇
  2015年   6734篇
  2014年   7317篇
  2013年   8983篇
  2012年   7006篇
  2011年   7174篇
  2010年   6846篇
  2009年   6599篇
  2008年   6075篇
  2007年   5449篇
  2006年   4925篇
  2005年   4015篇
  2004年   3036篇
  2003年   2655篇
  2002年   2509篇
  2001年   2239篇
  2000年   2035篇
  1999年   1421篇
  1998年   844篇
  1997年   703篇
  1996年   648篇
  1995年   579篇
  1994年   475篇
  1993年   378篇
  1992年   258篇
  1991年   233篇
  1990年   163篇
  1989年   124篇
  1988年   110篇
  1987年   72篇
  1986年   71篇
  1985年   41篇
  1983年   42篇
  1982年   35篇
  1917年   58篇
  1916年   48篇
  1912年   40篇
  1911年   46篇
  1907年   33篇
  1906年   44篇
  1905年   45篇
  1904年   51篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
The SRM (Spatial Rich Model) is a very effective steganalysis method. It uses statistics of neighboring noise residual samples as features to capture the dependency changes caused by embedding. Because the noise residuals are the high-frequency components of image and closely tied to image content, the residuals of different types of image regions have different statistical properties and effectiveness for steganalysis. In this paper, the effectiveness of the residuals is investigated. Then the effectiveness of the statistics collected from different types of neighboring residual samples is investigated from the FLD (Fisher Linear Discriminant) viewpoint, and ineffective, effective and high-effective neighboring residual samples are defined. The ineffective neighboring residual samples are not likely to change during embedding, and if they are counted in statistics, they may mix the features with noise and make the features impure. Pure SRM features are extracted based on neighboring noise residual sample selection strategy. Furthermore, multi-order statistical features are proposed to increase the statistical diversity. Steganalysis performances of the statistical features collected from different types of neighboring residual samples are investigated on three content adaptive steganographic algorithms. Experimental results demonstrate that the proposed method can achieve a more accurate detection than SRM.  相似文献   
132.
In this work, we have put forth two different protocols to address a concrete secure multi-party computational (MPC) problem related to a triangle, of which the coordinates of the three vertices are confidentially kept by the three participants, respectively. The three parties wish to collaboratively compute the area of this triangle while preserving their own coordinate privacy. As one of the merits, our protocols employ weaker assumptions of the existence of pseudorandom generators. In particular, unlike massive secure MPC protocols that rely a lot on oblivious transfer, ours utilize a new computing idea called “pseudorandom-then-rounding” method to avoid this burdensome obstacle. The two protocols are based on different theorems, while they both make use of the same underlying idea. At last, we provide a detailed proof for the first protocol by a series of security reductions of our newly defined games, which seems somewhat stronger than the previous simulation-based proofs and a proof sketch for the second one. Analysis and discussion about the reasons are provided as well to round off our work.  相似文献   
133.
在经济的推动下,商业区数量日益增多,空间布局更加紧凑,用电量也随之大幅增加,管理更为困难。因此,要重视商业区建筑的供电配电。介绍了商业区建筑的特点,然后结合实际案例对其供配电进行了设计。  相似文献   
134.
Converting unconstrained video sequences into videos that loop seamlessly is an extremely challenging problem. In this work, we take the first steps towards automating this process by focusing on an important subclass of videos containing a single dominant foreground object. Our technique makes two novel contributions over previous work: first, we propose a correspondence‐based similarity metric to automatically identify a good transition point in the video where the appearance and dynamics of the foreground are most consistent. Second, we develop a technique that aligns both the foreground and background about this transition point using a combination of global camera path planning and patch‐based video morphing. We demonstrate that this allows us to create natural, compelling, loopy videos from a wide range of videos collected from the internet.  相似文献   
135.
136.
137.
Abstract

The shape and content of science education has always been articulated from the scientist's perspective. Recently, an increasing number of science educators have recognized the serious limitations of this perspective and have proposed to define scientific literacy from societal or citizenship perspectives. In this article, I argue that these alternatives will remain as limited as their predecessors unless the very structures of schooling are called into question. Furthermore, I argue that alternatives cannot be designed at the drawing board by theoreticians, but have to be grounded in praxis, thereby providing concrete trajectories along which science education can actually change.  相似文献   
138.
This article considers stabilization of a one‐dimensional Schrödinger equation with variable coefficient and boundary observation which suffers from an arbitrary given time delay. We design an observer and predictor to stabilize the system. The state is estimated in the time span where the observation is available, and also predicted in the time interval where the observation is not available. It is shown that the estimated state feedback stabilizes the system exponentially. A numerical simulation is presented to illustrate the effect of the stabilizing controller.  相似文献   
139.
Image preview is a convenient way to browse large or multiple images on small displays. However, current signal-level image resampling algorithms may remove many features of interest in the preview image. In this paper, we propose perceptual image preview which retains more perceptual features such that users can inspect features of interest by viewing the preview image only and without zooming in. This technology has two components, structure enhancement and perceptual feature visualization. Structure enhancement enhances the image structure while suppressing subtle details using a gradient modulation method, thus making the succedent perceptual features more apparent. For perceptual feature visualization, features of interest detected in the picture is visualized on the structure enhanced preview image. We demonstrate with two examples of most commonly used image quality features, image blur and noise. The effectiveness of the proposed method is validated by experimental results.  相似文献   
140.
基于ARCGis9.2的安徽省地震会商系统不仅需要强大的技术功能,还需要友好和一目了然的界面,这样不仅让会商报告者思路清晰,也能使会商观众更加清晰了解地震预报会商内容,从而为决策者更好应对不同地点和不同大小的地震发生可能性做出科学的决策;引入flash8作为软件系统的界面,用flash调用各个模块,无论从界面和功能上都较好的解决了这一问题。  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