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   12086篇
  免费   2381篇
  国内免费   1448篇
电工技术   1035篇
技术理论   1篇
综合类   1594篇
化学工业   665篇
金属工艺   577篇
机械仪表   763篇
建筑科学   1044篇
矿业工程   549篇
能源动力   500篇
轻工业   286篇
水利工程   496篇
石油天然气   312篇
武器工业   150篇
无线电   1430篇
一般工业技术   1111篇
冶金工业   421篇
原子能技术   51篇
自动化技术   4930篇
  2024年   126篇
  2023年   374篇
  2022年   623篇
  2021年   694篇
  2020年   659篇
  2019年   578篇
  2018年   487篇
  2017年   557篇
  2016年   591篇
  2015年   681篇
  2014年   981篇
  2013年   835篇
  2012年   1064篇
  2011年   1030篇
  2010年   860篇
  2009年   834篇
  2008年   742篇
  2007年   791篇
  2006年   617篇
  2005年   537篇
  2004年   416篇
  2003年   345篇
  2002年   267篇
  2001年   197篇
  2000年   206篇
  1999年   155篇
  1998年   115篇
  1997年   100篇
  1996年   76篇
  1995年   64篇
  1994年   63篇
  1993年   35篇
  1992年   38篇
  1991年   26篇
  1990年   31篇
  1989年   18篇
  1988年   11篇
  1987年   19篇
  1986年   12篇
  1985年   11篇
  1984年   7篇
  1983年   6篇
  1982年   7篇
  1980年   4篇
  1979年   4篇
  1978年   2篇
  1977年   3篇
  1976年   2篇
  1975年   3篇
  1951年   4篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
We consider the minimization over probability measures of the expected value of a random variable, regularized by relative entropy with respect to a given probability distribution. In the general setting we provide a complete characterization of the situations in which a finite optimal value exists and the situations in which a minimizing probability distribution exists. Specializing to the case where the underlying probability distribution is Wiener measure, we characterize finite relative entropy changes of measure in terms of square integrability of the corresponding change of drift. For the optimal change of measure for the relative entropy weighted optimization, an expression involving the Malliavin derivative of the cost random variable is derived. The theory is illustrated by its application to several examples, including the case where the cost variable is the maximum of a standard Brownian motion over a finite time horizon. For this example we obtain an exact optimal drift, as well as an approximation of the optimal drift through a Monte-Carlo algorithm.  相似文献   
102.
《Chemical engineering science》2003,58(12):2515-2518
The paper presents an attempt to define the physical entropy of the dense phase of a fluidized bed, based on liquid-like properties of fluidized systems. The quantity U was used as the analogy of temperature in classical thermodynamics. The obtained expression for physical entropy was compared to the correlation suggested for the Kolmogorov entropy in bubbling bed.  相似文献   
103.
《Graphical Models》2014,76(5):507-521
The 2.1D sketch is a layered image representation, which assigns a partial depth ordering of over-segmented regions in a monocular image. This paper presents a global optimization framework for inferring the 2.1D sketch from a monocular image. Our method only uses over-segmented image regions (i.e., superpixels) as input, without any information of objects in the image, since (1) segmenting objects in images is a difficult problem on its own and (2) the objective of our proposed method is to be generic as an initial module useful for downstream high-level vision tasks. This paper formulates the inference of the 2.1D sketch using a global energy optimization framework. The proposed energy function consists of two components: (1) one is defined based on the local partial ordering relations (i.e., figure-ground) between two adjacent over-segmented regions, which captures the marginal information of the global partial depth ordering and (2) the other is defined based on the same depth layer relations among all the over-segmented regions, which groups regions of the same object to account for the over-segmentation issues. A hybrid evolution algorithm is utilized to minimize the global energy function efficiently. In experiments, we evaluated our method on a test data set containing 100 diverse real images from Berkeley segmentation data set (BSDS500) with the annotated ground truth. Experimental results show that our method can infer the 2.1D sketch with high accuracy.  相似文献   
104.
According to the pulverized coal combustion flame image texture features of the rotary-kiln oxide pellets sintering process,a combustion working condition recognition method based on the generalized learning vector(GLVQ) neural network is proposed.Firstly,the numerical flame image is analyzed to extract texture features,such as energy,entropy and inertia,based on grey-level co-occurrence matrix(GLCM) to provide qualitative information on the changes in the visual appearance of the flame.Then the kernel principal component analysis(KPCA) method is adopted to deduct the input vector with high dimensionality so as to reduce the GLVQ target dimension and network scale greatly.Finally,the GLVQ neural network is trained by using the normalized texture feature data.The test results show that the proposed KPCA-GLVQ classifer has an excellent performance on training speed and correct recognition rate,and it meets the requirement for real-time combustion working condition recognition for the rotary kiln process.  相似文献   
105.
106.
基于计算机实训教学的需求,重点探讨高可用性计算机实训室的搭建要求、配置特点与管理策略。  相似文献   
107.
王凯  刘海英 《中国陶瓷》2005,41(6):61-63
中华民族是个古老的、有着悠久历史和灿烂文明的伟大民族,远在八千年前,中国的文明在世界就已初露曙光。漫步在漫长的历史长河边,流连于丰富的博物馆展厅里,对我国悠久的历史和灿烂的文明作一次美的巡礼该是使人感到无比的欣慰和自豪的了。美学特征乃艺术的属性,总结它不是为了停留于前人的成果上,而是为了新的创造和新的开拓。  相似文献   
108.
The aim of this study is to predict automatic trading decisions in stock markets. Comprehensive features (CF) for predicting future trend are very difficult to generate in a complex environment, especially in stock markets. According to related work, the relevant stock information can help investors formulate objects that may result in better profits. With this in mind, we present a framework of an intelligent stock trading system using comprehensive features (ISTSCF) to predict future stock trading decisions. The ISTSCF consists of stock information extraction, prediction model learning and stock trading decision. We apply three different methods to generate comprehensive features, including sentiment analysis (SA) that provides sensitive market events from stock news articles for sentiment indices (SI), technical analysis (TA) that yields effective trading rules based on trading information on the stock exchange for technical indices (TI), as well as the trend-based segmentation method (TBSM) that raises trading decisions from stock price for trading signals (TS). Experiments on the Taiwan stock market show that the results of employing comprehensive features are significantly better than traditional methods using numeric features alone (without textual sentiment features).  相似文献   
109.
基于灰熵关联分析的流水车间多目标调度优化及算法实现   总被引:1,自引:0,他引:1  
求解流水车间多目标调度优化问题及算法适应度值分配问题, 结合灰色关联度分析方法及信息熵理论提出灰熵关联度适应值分配策略, 利用灰关联系数结合熵值权重计算适应度值, 以灰熵关联度值引导启发式算法进化. 将该方法应用到差分算法及遗传算法中解决三目标流水车间调度问题. 实验表明: 灰熵关联度适应值分配策略能够解决该问题, 可以得到分布均匀的Pareto 前端; 同时, 基于此策略的差分算法得到的解好于遗传算法的解.  相似文献   
110.
熊文涛  余胜平 《控制与决策》2014,29(9):1715-1718

针对带有间接偏好信息的多准则决策问题, 首先利用加性效用函数理论提出一种排序方法, 该方法通过构建一个简单的优化模型, 得到与间接偏好信息相容的各评价值的效用; 然后, 利用线性插值方法计算出剩下方案各评价值的效用, 进而得到所有方案的综合效用及排序; 最后, 通过实例验证了该方法的有效性和可行性.

  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