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   4863篇
  免费   328篇
  国内免费   2篇
电工技术   71篇
综合类   4篇
化学工业   1189篇
金属工艺   74篇
机械仪表   88篇
建筑科学   169篇
矿业工程   18篇
能源动力   191篇
轻工业   887篇
水利工程   24篇
石油天然气   20篇
无线电   270篇
一般工业技术   789篇
冶金工业   319篇
原子能技术   21篇
自动化技术   1059篇
  2024年   10篇
  2023年   46篇
  2022年   162篇
  2021年   206篇
  2020年   132篇
  2019年   153篇
  2018年   194篇
  2017年   186篇
  2016年   190篇
  2015年   168篇
  2014年   211篇
  2013年   369篇
  2012年   353篇
  2011年   387篇
  2010年   306篇
  2009年   264篇
  2008年   277篇
  2007年   234篇
  2006年   183篇
  2005年   164篇
  2004年   116篇
  2003年   119篇
  2002年   119篇
  2001年   48篇
  2000年   53篇
  1999年   49篇
  1998年   91篇
  1997年   68篇
  1996年   41篇
  1995年   57篇
  1994年   24篇
  1993年   31篇
  1992年   19篇
  1991年   18篇
  1990年   14篇
  1989年   15篇
  1988年   11篇
  1987年   7篇
  1986年   6篇
  1985年   10篇
  1984年   11篇
  1983年   9篇
  1982年   4篇
  1980年   4篇
  1979年   7篇
  1978年   4篇
  1977年   9篇
  1976年   10篇
  1975年   9篇
  1974年   3篇
排序方式: 共有5193条查询结果,搜索用时 31 毫秒
31.
A CMOS current-mode approach for implementing the defuzzification function in analogue fuzzy controllers is proposed. The circuit computes the centre of area of the output fuzzy conclusion using switched current adders and a current divider. Simulation results of the defuzzifier show how the circuit can produce a good approximation of the centre of area even if a small number of levels are used to quantise the output variable.<>  相似文献   
32.
Acetylsalicylic acid (ASA) alone (at least 30 mg per day) in post-cerebral ischaemia patients reduces the relative risk of further vascular events by 13% compared with placebo. A meta-analysis of all studies shows that the combination of ASA with dipyridamole reduces the relative risk by 16% (95% confidence interval: 5-26%) compared with ASA alone, but confirmation by a major trial appears desirable, because of discrepant results of a recent trial and 4 previous ones. Clopidogrel might reduce the risk by 7% compared with ASA alone, but this drug is expected to be expensive. Anticoagulation therapy with an international normalized ratio (INR) of 2.0-4.0 is particularly efficacious for secondary prevention in patients with atrial fibrillation, but anticoagulation therapy with an INR of 3.0-4.5 is not safe in secondary prevention of cerebral ischaemia of presumed arterial origin. Finally, not all atherosclerotic vascular diseases are identical from the therapeutic point of view; the effect of treatment depends in part on the clinical manifestation form.  相似文献   
33.
Image segmentation towards new image representation methods   总被引:1,自引:0,他引:1  
Very low bit-rate video coding has recently become one of the most important areas of image communication and a large variety of applications have already been identified. Since conventional approaches are reaching a saturation point, in terms of coding efficiency, a new generation of video coding techniques, aiming at a deeper “understanding” of the image, is being studied. In this context, image analysis, particularly the identification of objects or regions in images (segmentation), is a very important step. This paper describes a segmentation algorithm based on split and merge. Images are first simplified using mathematical morphology operators, which eliminate perceptually less relevant details. The simplified image is then split according to a quad tree structure and the resulting regions are finally merged in three steps: merge, elimination of small regions and control of the number of regions.  相似文献   
34.
Single crystals of nylon 7 prepared by crystallization from glycerine were studied by both X-rays and electron microscopy. Electron diffraction proved that they consist of a twinned layered-structure with hydrogen bonds running parallel to their long dimension. Polyethylene decoration of such crystals showed that they are subdivided in folding domains so that both chain folding and hydrogen bonding take place along the same crystallographical planes.  相似文献   
35.

Parallel Programming skills may require a long time to acquire. “Think in parallel” is a skill that requires time, effort, and experience. In this work, we propose to facilitate the students’ learning process in parallel programming by using instant messaging. Our aim was to find out whether students’ interaction through instant messaging tools is beneficial for the learning process. In order to do so, we asked several students of an HPC course of the Master’s degree in Computer Science of the University of León to develop a specific parallel application, each of them using a different application program interface: OpenMP, MPI, CUDA, or OpenCL. Even though the used APIs are different, there are common points in the design process. We encouraged students to interact with each other by using Gitter, an instant messaging tool for GitHub users. Our analysis of the communications and results demonstrate that the direct interaction of students through the Gitter tool has a positive impact on the learning process.

  相似文献   
36.
Applied Intelligence - The17 Sustainable Development Goals (SDGs) established by the United Nations Agenda 2030 constitute a global blueprint agenda and instrument for peace and prosperity...  相似文献   
37.
Neural Computing and Applications - Preserving red-chili quality is of utmost importance in which the authorities demand quality techniques to detect, classify, and prevent it from impurities. For...  相似文献   
38.
We focus on two aspects of the face recognition, feature extraction and classification. We propose a two component system, introducing Lattice Independent Component Analysis (LICA) for feature extraction and Extreme Learning Machines (ELM) for classification. In previous works we have proposed LICA for a variety of image processing tasks. The first step of LICA is to identify strong lattice independent components from the data. In the second step, the set of strong lattice independent vector are used for linear unmixing of the data, obtaining a vector of abundance coefficients. The resulting abundance values are used as features for classification, specifically for face recognition. Extreme Learning Machines are accurate and fast-learning innovative classification methods based on the random generation of the input-to-hidden-units weights followed by the resolution of the linear equations to obtain the hidden-to-output weights. The LICA-ELM system has been tested against state-of-the-art feature extraction methods and classifiers, outperforming them when performing cross-validation on four large unbalanced face databases.  相似文献   
39.
Membrane Computing is a discipline aiming to abstract formal computing models, called membrane systems or P systems, from the structure and functioning of the living cells as well as from the cooperation of cells in tissues, organs, and other higher order structures. This framework provides polynomial time solutions to NP-complete problems by trading space for time, and whose efficient simulation poses challenges in three different aspects: an intrinsic massively parallelism of P systems, an exponential computational workspace, and a non-intensive floating point nature. In this paper, we analyze the simulation of a family of recognizer P systems with active membranes that solves the Satisfiability problem in linear time on different instances of Graphics Processing Units (GPUs). For an efficient handling of the exponential workspace created by the P systems computation, we enable different data policies to increase memory bandwidth and exploit data locality through tiling and dynamic queues. Parallelism inherent to the target P system is also managed to demonstrate that GPUs offer a valid alternative for high-performance computing at a considerably lower cost. Furthermore, scalability is demonstrated on the way to the largest problem size we were able to run, and considering the new hardware generation from Nvidia, Fermi, for a total speed-up exceeding four orders of magnitude when running our simulations on the Tesla S2050 server.  相似文献   
40.
Nowadays, the impact of technological developments on improving human activities is becoming more evident. In e-learning, this situation is no different. There are common to use systems that assist the daily activities of students and teachers. Typically, e-learning recommender systems are focused on students; however, teachers can also benefit from these type of tools. A recommender system can propose actions and resources that facilitate teaching activities like structuring learning strategies. In any case, a complete user’s representation is required. This paper shows how a fuzzy ontology can be used to represent user profiles into a recommender engine and enhances the user’s activities into e-learning environments. A fuzzy ontology is an extension of domain ontologies for solving the problems of uncertainty in sharing and reusing knowledge on the Semantic Web. The user profile is built from learning objects published by the user himself into a learning object repository. The initial experiment confirms that the automatically obtained fuzzy ontology is a good representation of the user’s preferences. The experiment results also indicate that the presented approach is useful and warrants further research in recommending and retrieval information.  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