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   7133篇
  免费   324篇
  国内免费   53篇
电工技术   133篇
综合类   26篇
化学工业   1796篇
金属工艺   120篇
机械仪表   211篇
建筑科学   277篇
矿业工程   6篇
能源动力   469篇
轻工业   725篇
水利工程   76篇
石油天然气   115篇
无线电   656篇
一般工业技术   1159篇
冶金工业   337篇
原子能技术   83篇
自动化技术   1321篇
  2024年   24篇
  2023年   151篇
  2022年   317篇
  2021年   408篇
  2020年   296篇
  2019年   335篇
  2018年   420篇
  2017年   359篇
  2016年   358篇
  2015年   240篇
  2014年   324篇
  2013年   651篇
  2012年   357篇
  2011年   506篇
  2010年   350篇
  2009年   326篇
  2008年   292篇
  2007年   217篇
  2006年   202篇
  2005年   141篇
  2004年   111篇
  2003年   117篇
  2002年   91篇
  2001年   64篇
  2000年   73篇
  1999年   50篇
  1998年   77篇
  1997年   41篇
  1996年   49篇
  1995年   40篇
  1994年   36篇
  1993年   44篇
  1992年   36篇
  1991年   32篇
  1990年   30篇
  1989年   20篇
  1988年   35篇
  1987年   30篇
  1986年   20篇
  1985年   15篇
  1984年   27篇
  1983年   22篇
  1982年   22篇
  1981年   16篇
  1980年   20篇
  1979年   16篇
  1978年   17篇
  1976年   18篇
  1975年   19篇
  1974年   12篇
排序方式: 共有7510条查询结果,搜索用时 0 毫秒
101.
This paper proposes a holistic lexicon-reduction method for ancient and modern handwritten Arabic documents. The word shape is represented by the weighted topological signature vector (W-TSV), which encodes graph data into a low-dimensional vector space. Three directed acyclic graph (DAG) representations are proposed for Arabic word shapes, based on topological and geometrical features. Lexicon reduction is achieved by a nearest neighbors search in the W-TSV space. The proposed framework has been tested on the IFN/ENIT and the Ibn Sina databases, achieving respectively a degree of reduction of 83.5% and 92.9% for an accuracy of reduction of 90%.  相似文献   
102.
Several biclustering algorithms have been proposed in different fields of microarray data analysis. We present a new approach that improves their performance in using the ensemble methods. An ensemble biclustering is considered and formalized by a problem of binary triclustering. We propose a simple and efficient algorithm to solve it. To illustrate the interest of our ensemble approach, numerical experiments are performed on both artificial and real datasets with two biclustering algorithms commonly used in bioinformatics.  相似文献   
103.
This paper addresses the field of stereophonic acoustic echo cancellation (SAEC) by adaptive filtering algorithms. Recently, we have proposed a new version of the fast Newton transversal FNTF algorithm for SAEC applications. In this paper, we propose an efficient modification of this algorithm for the same applications. This new algorithm uses a new proposed and simplified numerical stabilization technique and takes into account the cross-correlation between the inputs of the channels. The basic idea is to introduce a small nonlinearity into each channel that has the effect of reducing the inter-channel coherence while not being noticeable for speech due to self masking. The complexity of the proposed algorithm does not alter the complexity of the original version and is kept less than half the complexity of the fastest two-channel FTF filter version. Simulation results and comparisons with the extended two-channel normalized least mean square NLMS and FTF algorithms are presented.  相似文献   
104.
105.
There is an increasing recognition for the need to develop high quality use case models from the professional and academic communities. Quality in use case models is of particular importance when they are utilized within a use case driven development process, whereby every aspect of development is driven by the models and influenced by their quality. Many practitioners and researchers have provided guidelines, suggestions and techniques to construct high quality use case models. This invaluable body of knowledge is disseminated across numerous literature resources. Without unifying this knowledge into one resource, it cannot be expected that a use case modeler would be fully aware of the entire body of knowledge and benefitting from it. This paper presents a systematic review that was conducted in order to identify and amalgamate this knowledge. The amalgamated knowledge is presented in a unified form, specifically as a set of 26 anti-patterns, which modelers can use to improve the quality of their models.  相似文献   
106.
107.
108.
Etch-pit (EP) technique and transmission electron microscopy (TEM) have been used to investigate the subgrain size, , as a function of applied shear stress, , during high-temperature creep of aluminium. Examination of thin foils, prepared from deformed specimens, in the electron microscope shows the presence of very large equiaxed sub-grains that approximate those observed in etch-pit photographs. By measuring the average subgrain size from transmission micrographs of representative areas of the foils, two observations are made. First, the average subgrain size is smaller than that determined from etch-pit procedure, but exhibits the same stress dependence: /b (/G) where b is the Burgers vector and G is the shear modulus. Second, the TEM subgrain size data of aluminium and those of other metals and alloys, when plotted in the normalized form of /Gb against /Gb on a logarithmic scale, where is the stacking-fault energy of the material, fall within a narrow, horizontal band, confirming earlier reports that the subgrain size is insensitive to stacking-fault energy.  相似文献   
109.
The dynamical behavior for two parallel reactions in a continuous stirred tank reactor (CSTR) is considered. The global maximum number of steady states is five. Stability conditions are obtained. When the steady state is unique and unstable, a circulating attractor is proven to exist. The orbit structure is numerically found to consist of periodic orbits and chaotic behavior.  相似文献   
110.
This study considers the content of the papers published by ASCE’s Journal of Management in Engineering, which has witnessed a growth in number of papers and breadth of participation, particularly of international origin, during the 1985–2002 period. The content is analyzed in two main dimensions: the type of subject and its composing topics, and the type of contributors to the journal. The analysis shows the evolution of the engineering management discipline as represented in the journal. Over the years the discipline has been enriched by an increasing number of contributions on corporate strategies and programs, organizational change, and cultures issues, as well as a growing interest in project management topics, such as quality planning and evaluation of alternative project delivery systems. The number of papers by practitioners, initially the largest contributing group to the journal, has declined significantly over the years.  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