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   20958篇
  免费   1282篇
  国内免费   716篇
电工技术   669篇
技术理论   1篇
综合类   1762篇
化学工业   2555篇
金属工艺   457篇
机械仪表   807篇
建筑科学   1877篇
矿业工程   438篇
能源动力   379篇
轻工业   1829篇
水利工程   272篇
石油天然气   329篇
武器工业   77篇
无线电   1588篇
一般工业技术   2818篇
冶金工业   965篇
原子能技术   147篇
自动化技术   5986篇
  2024年   68篇
  2023年   224篇
  2022年   310篇
  2021年   403篇
  2020年   475篇
  2019年   476篇
  2018年   439篇
  2017年   556篇
  2016年   619篇
  2015年   653篇
  2014年   1205篇
  2013年   1223篇
  2012年   1430篇
  2011年   1723篇
  2010年   1327篇
  2009年   1322篇
  2008年   1156篇
  2007年   1382篇
  2006年   1180篇
  2005年   998篇
  2004年   894篇
  2003年   781篇
  2002年   655篇
  2001年   506篇
  2000年   406篇
  1999年   364篇
  1998年   304篇
  1997年   261篇
  1996年   186篇
  1995年   190篇
  1994年   131篇
  1993年   117篇
  1992年   92篇
  1991年   69篇
  1990年   68篇
  1989年   79篇
  1988年   79篇
  1987年   49篇
  1986年   46篇
  1985年   60篇
  1984年   77篇
  1983年   91篇
  1982年   91篇
  1981年   31篇
  1980年   31篇
  1979年   23篇
  1978年   19篇
  1977年   17篇
  1959年   5篇
  1955年   11篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
浙江石窗是第二批浙江省非物质文化遗产名录中的一项民间美术,它是盛开在浙江大地上的一朵建筑民俗之花,它的审美趣味与当地的民风民俗和建筑风格完全融合,它的表现手法与中国的吉祥图案一脉相连。  相似文献   
52.
The purpose was to measure the effect of a participatory ergonomics implementation strategy consisting of information, education, and facilitation on the use of new tools and working methods in the floor laying trade. Floor layers (n=292) were trained in using new working methods. The effects were evaluated by using questionnaires, interviews, and assessments of quality and productivity. Following the training, 43% had used the new working methods weekly/daily compared to 11% before. There was a reduction in the degree of self-reported pain in the knees among the floor layers using the new working methods weekly or daily compared to those using them never or occasionally. The musculoskeletal complaints did not increase from any other region and the quality and the productivity of the work were not decreased. This indicates that within a 3-months perspective the implementation strategy succeeded.  相似文献   
53.
Iterative analysis of Markov regenerative models   总被引:3,自引:0,他引:3  
Conventional algorithms for the steady-state analysis of Markov regenerative models suffer from high computational costs which are caused by densely populated matrices. In this paper, a new algorithm is suggested which avoids computing these matrices explicitly. Instead, a two-stage iteration scheme is used. An extended version of uniformization is applied as a subalgorithm to compute the required transient quantities “on-the fly”. The algorithm is formulated in terms of stochastic Petri nets. A detailed example illustrates the proposed concepts.  相似文献   
54.
An analytical study is made of the free and forced convection boundary layer flow past a porous medium bounded by a semi-infinite vertical porous plate. Locally similar solutions are then obtained by a perturbation method for large suction. Solutions for the velocity and temperature distributions are shown graphically for various suction velocities and values of the driving parameter Gr/R, where Gr is the Grashof number and Re is the Reynolds number. The corresponding values of the skin friction coefficient and the Nusselt number are finally shown in tabular form.  相似文献   
55.
Model predictive heuristic control: Applications to industrial processes   总被引:2,自引:0,他引:2  
  相似文献   
56.
In recent years, educators and students are increasingly employing online collaboration applications such as Google Docs™ and PBWorks™ for group projects and assignments. Yet, the effectiveness of these emerging technologies has not been rigorously examined. Anchoring upon and informed by the existing literature, two design characteristics – sociability and visibility, and two human characteristics – gender and age, are focused on, which are salient in online collaboration applications. A field experiment was conducted to examine the direct and moderating effects of design and human characteristics on learning outcomes. The research found that sociability improved process satisfaction and positive social environment while visibility enhanced academic performance and solution satisfaction of learners. Males had higher solution satisfaction while older learners had higher academic performance. Moderating effects were also found. Both theoretical and practical implications are drawn. In particular, a rubric for online collaboration application selection for academic performance is conceived. This study provides empirical support for online collaboration application effectiveness in education which will augur well for future adoption, use and evolution.  相似文献   
57.
New splitting iterative methods for Toeplitz systems are proposed by means of recently developed matrix splittings based on discrete sine and cosine transforms due to Kailath and Olshevsky [Displacement structure approach to discrete-trigonometric transform-based preconditioners of G. Strang type and of T. Chan type, SIAM J. Matrix Anal. Appl. 26 (2005), pp. 706–734]. Theoretical analysis shows that new splitting iterative methods converge to the unique solution of a symmetric Toeplitz linear system. Moreover, an upper bound of the contraction factor of our new splitting iterations is derived. Numerical examples are reported to illustrate the effectiveness of new splitting iterative methods.  相似文献   
58.
《国际计算机数学杂志》2012,89(10):1277-1287
Two classes of asynchronous relaxed parallel two-stage multisplitting methods based on extrapolated and AOR methods are studied for the solution of nonsingular linear systems, which are called asynchronous outer relaxed or inner relaxed parallel two-stage multisplitting methods. Convergence of these methods is studied for H-matrix. Almost all methods seen in literatures can be viewed as special cases of our methods.  相似文献   
59.
《国际计算机数学杂志》2012,89(5):1097-1121
This paper presents the mechanical quadrature methods (MQMs) for solving the boundary integral equations of steady-state anisotropic heat conduction equation on the smooth domains and polygons, respectively. The costless and high-accurate Sidi–Israeli quadrature formula are applied to deal with the integrals in which the kernels have a logarithmic singularity. Especially, the Sidi transformation is used for the polygon cases in order to obtain a rapid convergence by degrading the singularity at the corners on the boundary. The convergence and stability of the MQMs solution are proved based on Anselone's collective compact theory. In addition, asymptotic error expansion of the MQMs shows that the approximation order is of O(h3), where h is the partition size of the boundary. Finally, numerical examples are tested and results verify the theoretical analysis.  相似文献   
60.
This paper describes a probabilistic integrated object recognition and tracking framework called PIORT, together with two specific methods derived from it, which are evaluated experimentally in several test video sequences. The first step in the proposed framework is a static recognition module that provides class probabilities for each pixel of the image from a set of local features. These probabilities are updated dynamically and supplied to a tracking decision module capable of handling full and partial occlusions. The two specific methods presented use RGB color features and differ in the classifier implemented: one is a Bayesian method based on maximum likelihood and the other one is based on a neural network. The experimental results obtained have shown that, on one hand, the neural net based approach performs similarly and sometimes better than the Bayesian approach when they are integrated within the tracking framework. And on the other hand, our PIORT methods have achieved better results when compared to other published tracking methods in video sequences taken with a moving camera and including full and partial occlusions of the tracked object.  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