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   1723篇
  免费   66篇
  国内免费   11篇
电工技术   71篇
综合类   2篇
化学工业   316篇
金属工艺   34篇
机械仪表   39篇
建筑科学   32篇
矿业工程   1篇
能源动力   141篇
轻工业   135篇
水利工程   13篇
石油天然气   13篇
武器工业   1篇
无线电   174篇
一般工业技术   332篇
冶金工业   198篇
原子能技术   11篇
自动化技术   287篇
  2023年   27篇
  2022年   59篇
  2021年   97篇
  2020年   56篇
  2019年   70篇
  2018年   84篇
  2017年   60篇
  2016年   67篇
  2015年   41篇
  2014年   54篇
  2013年   118篇
  2012年   59篇
  2011年   84篇
  2010年   55篇
  2009年   62篇
  2008年   58篇
  2007年   54篇
  2006年   33篇
  2005年   25篇
  2004年   38篇
  2003年   27篇
  2002年   24篇
  2001年   21篇
  2000年   23篇
  1999年   19篇
  1998年   63篇
  1997年   39篇
  1996年   37篇
  1995年   27篇
  1994年   32篇
  1993年   24篇
  1992年   14篇
  1991年   30篇
  1990年   26篇
  1989年   25篇
  1988年   18篇
  1987年   13篇
  1986年   11篇
  1985年   12篇
  1984年   12篇
  1983年   13篇
  1982年   12篇
  1981年   10篇
  1979年   9篇
  1978年   9篇
  1976年   6篇
  1973年   4篇
  1972年   7篇
  1968年   3篇
  1966年   4篇
排序方式: 共有1800条查询结果,搜索用时 31 毫秒
21.
22.
Artificial Intelligence Review - Nowadays we see huge amount of information is available on both, online and offline sources. For single topic we see hundreds of articles are available, containing...  相似文献   
23.
Like the electrocardiographic inverse problem, the object of which is the algorithmical analysis and diagnosis of the electrocardiogram (ECG), the pacemaker inverse problem is the analysis of the ECG in order to establish details of heart-pacemaker interaction (HPI) with special reference to the diagnosis of pacemaker failure. The solution to this problem is of practical importance, since it is often difficult to evaluate such records clinically. The ECG patterns of natural cardiac depolarizations and paced events may not be distinguishable and many combinations of potential pacemaker response must be taken into account. A computer system providing automatic analysis of the HPI, based on ECG data, has been developed and implemented on an IBM PC AT computer. The system uses a complex algorithm which enables the evaluation of all possible combinations of HPI events, and establishes for each of these combinations its correspondence to the specified pacemaker algorithm. The system is written in Pascal and its source text has approximately 11,000 lines. The first version of the system has been tested with algorithms of the dual chamber cardiac pulse generator AUTIMA-II (Telectronics). The interactive input of the system allows the pacemaker algorithm and the ECG, in the form of timing of "definite" and "possible" sensing events and pacemaker pulses, to be specified. The analysis establishes whether the device operates correctly within permitted error. Should one or more correct explanations of the specified case be found, the system prints simplified patterns of the ECG accompanied by a simulated marker channel tracing the possible HPIs.  相似文献   
24.
25.
The present work is focusing on the synthesization and physico-chemical properties of Jatropha curcas biodiesel with diesel and alcohols.The densities of binary diesel (2)+1-alkanols (C_3 or C_4)(3) and ternary Jatropha curcas biodiesel (1)+diesel (2)+1-alkanols (C_3or C_4)(3) blends have been reported over full range of composition at temperatures within range 288.15 to 313.15 K.Also densities of Jatropha curcas biodiesel (1)+diesel or 1-alkanols (C_3 or C_4)(2) blends have been measured at 313.15 K.Excess molar volumes,V~E,V~E_(123)of binary and ternary blends were calculated from the measured data and the derived properties were correlated to composition using Redlich–Kister equation.A reasonable agreement was found between the measured and estimated values.Further,densities and excess molar volumes data were reasoned to discuss molecular interactions taking into consideration effect of composition and temperature.  相似文献   
26.
Mechanical properties of high density polyethylene (HDPE) extended to draw ratios in the 20–40 range have been determined and compared with corresponding properties of the polymers containing particulates including rutile, carbon black, iron oxide, and mica. Shrinkage of drawn structures was studied to temperatures near the fusion of the polymer host. The degree of interaction at polymer/additive interfaces was varied by surface coating certain of the solids with standard coupling agents. Solids were found to increase tensile moduli and to decrease shrinkage, particularly at higher exposure temperatures. The magnitude of changes due to the presence of solids was shown to depend on the apparent interaction at contacts between host and additive. In a dispersion–force matrix, like HDPE, benefits were optimized when the particulates were amphoteric or neutral, rather than having pronounced acid or base interaction potentials.  相似文献   
27.
28.
In this paper, a simple technique is proposed for face recognition among many human faces. It is based on the polynomial coefficients, covariance matrix and algorithm on common eigenvalues. The main advantage of the proposed approach is that the identification of similarity between human faces is carried out without computing actual eigenvalues and eigenvectors. A symmetric matrix is calculated using the polynomial coefficients-based companion matrices of two compared images. The nullity of a calculated symmetric matrix is used as similarity measure for face recognition. The value of nullity is very small for dissimilar images and distinctly large for similar face images. The feasibility of the propose approach is demonstrated on three face databases, i.e., the ORL database, the Yale database B and the FERET database. Experimental results have shown the effectiveness of the proposed approach for feature extraction and classification of the face images having large variation in pose and illumination.  相似文献   
29.
This paper presents a gravity optimised particle filter (GOPF) where the magnitude of the gravitational force for every particle is proportional to its weight. GOPF attracts nearby particles and replicates new particles as if moving the particles towards the peak of the likelihood distribution, improving the sampling efficiency. GOPF is incorporated into a technique for hand features tracking. A fast approach to hand features detection and labelling using convexity defects is also presented. Experimental results show that GOPF outperforms the standard particle filter and its variants, as well as state-of-the-art CamShift guided particle filter using a significantly reduced number of particles.  相似文献   
30.
Morphological studies of high density polyethylene (HDPE) reinforced by mica flakes has been investigated. The mica flakes were surface treated by silane and titanate coupling agents. Effects of these treatments on the polymer-mica interface is discussed. It is found that surface treatment, particularly silane treated composites, have better adhesion between the reinforcing agent and the polymer matrix. This effect can only be detected when the mica concentration is higher than 20 weight percent. This interfacial adhesion could not be seen across the surface of the sample but only when the measurements were made parallel to the surface.  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