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   2844篇
  免费   179篇
  国内免费   2篇
电工技术   21篇
综合类   3篇
化学工业   519篇
金属工艺   34篇
机械仪表   68篇
建筑科学   127篇
矿业工程   4篇
能源动力   78篇
轻工业   213篇
水利工程   31篇
石油天然气   6篇
无线电   242篇
一般工业技术   642篇
冶金工业   436篇
原子能技术   11篇
自动化技术   590篇
  2024年   4篇
  2023年   24篇
  2022年   41篇
  2021年   73篇
  2020年   58篇
  2019年   64篇
  2018年   91篇
  2017年   86篇
  2016年   82篇
  2015年   81篇
  2014年   126篇
  2013年   206篇
  2012年   205篇
  2011年   278篇
  2010年   196篇
  2009年   216篇
  2008年   181篇
  2007年   193篇
  2006年   150篇
  2005年   138篇
  2004年   95篇
  2003年   83篇
  2002年   73篇
  2001年   44篇
  2000年   38篇
  1999年   39篇
  1998年   28篇
  1997年   30篇
  1996年   14篇
  1995年   13篇
  1994年   9篇
  1993年   13篇
  1992年   5篇
  1991年   3篇
  1990年   9篇
  1989年   6篇
  1988年   3篇
  1987年   3篇
  1986年   3篇
  1985年   4篇
  1984年   2篇
  1983年   1篇
  1982年   4篇
  1981年   2篇
  1980年   2篇
  1979年   2篇
  1977年   1篇
  1973年   1篇
  1972年   1篇
  1969年   1篇
排序方式: 共有3025条查询结果,搜索用时 536 毫秒
81.
We describe a general probabilistic framework for matching patterns that experience in-plane nonlinear deformations, such as iris patterns. Given a pair of images, we derive a maximum a posteriori probability (MAP) estimate of the parameters of the relative deformation between them. Our estimation process accomplishes two things simultaneously: it normalizes for pattern warping and it returns a distortion-tolerant similarity metric which can be used for matching two nonlinearly deformed image patterns. The prior probability of the deformation parameters is specific to the pattern-type and, therefore, should result in more accurate matching than an arbitrary general distribution. We show that the proposed method is very well suited for handling iris biometrics, applying it to two databases of iris images which contain real instances of warped patterns. We demonstrate a significant improvement in matching accuracy using the proposed deformed Bayesian matching methodology. We also show that the additional computation required to estimate the deformation is relatively inexpensive, making it suitable for real-time applications  相似文献   
82.
A Logic of Access Control   总被引:2,自引:0,他引:2  
  相似文献   
83.
Collaboration among businesses is needed to successfully fulfill a given task and goal. Service-Oriented Architecture (SOA) has been regarded as an efficient platform to support flexible interoperability among various enterprises by discovering, selecting and composing services. However, since a large number of enterprises have been participating in this SOA platform, relationships among these enterprises are getting too complicated to obtain flexibility and scalability for efficient collaboration. Thereby, in this paper, we propose a dynamic SOA platform to discover service chains for building ad hoc enterprise alliances where the only relevant enterprises are sorted out and merged. As a result, given an event, decision makers can find out which enterprises (and services from the enterprises) might be selected for their collaboration. The proposed SOA platform has been applied to mobile advertisement application as a case study. With respect to two indicators (i.e., precision and agility), we have shown that the proposed SOA outperforms traditional enterprise collaboration schemes.  相似文献   
84.
This study examined the relationship between three of the “Big Five” traits (neuroticism, extraversion, and openness), self-esteem, loneliness and narcissism, and Facebook use. Participants were 393 first year undergraduate psychology students from a medium-sized Australian university who completed an online questionnaire. Negative binomial regression models showed that students with higher openness levels reported spending more time on Facebook and having more friends on Facebook. Interestingly, students with higher levels of loneliness reported having more Facebook friends. Extraversion, neuroticism, self-esteem and narcissism did not have significant associations with Facebook use. It was concluded that students who are high in openness use Facebook to connect with others in order to discuss a wide range of interests, whereas students who are high in loneliness use the site to compensate for their lack of offline relationships.  相似文献   
85.
Metadata about information sources (e.g., databases and repositories) can be collected by Query Sampling (QS). Such metadata can include topics and statistics (e.g., term frequencies) about the information sources. This provides important evidence for determining which sources in the distributed information space should be selected for a given user query. The aim of this paper is to find out the semantic relationships between the information sources in order to distribute user queries to a large number of sources. Thereby, we propose an evolutionary approach for automatically conducting QS using multiple crawlers and obtaining the optimized semantic network from the sources. The aim of combining QS and evolutionary methods is to collaboratively extract metadata about target sources and optimally integrate the metadata, respectively. For evaluating the performance of contextualized QS on 122 information sources, we have compared the ranking lists recommended by the proposed method with user feedback (i.e., ideal ranks), and also computed the precision of the discovered subsumptions in terms of the semantic relationships between the target sources.  相似文献   
86.
Most of previous studies in picker-to-parts warehousing systems investigated only single-picker operations and are therefore adequate to evaluate order picking efficiency by travel distance as aisle congestion never takes place in such systems. In real world applications, the congestion inevitably occurs when a system has multiple pickers working together within the same region. This paper presents an approximation method based on a GI/G/1 closed queueing network by using self-correcting approximation technique algorithm to evaluate the throughput time of an order picking system with multiple pickers and aisle congestion considerations for different routing policies. The results generated by the proposed method are compared and validated via simulation model using eM-plant simulator for different sizes of warehouses. The results indicate that the approximation method appears to be sufficiently accurate for practical purposes. The sensitivity analysis of the throughput time with respect to order sizes, number of pickers and number of aisles are conducted and the performance of different item storage policies are also evaluated using the proposed approximation model.  相似文献   
87.
88.
There have been many kinds of association rule mining (ARM) algorithms, e.g., Apriori and FP-tree, to discover meaningful frequent patterns from a large dataset. Particularly, it is more difficult for such ARM algorithms to be applied for temporal databases which are continuously changing over time. Such algorithms are generally based on repeating time-consuming tasks, e.g., scanning databases. To deal with this problem, in this paper, we propose a constraint graph-based method for maintaining frequent patterns (FP) discovered from the temporal databases. Particularly, the constraint graph, which is represented as a set of constraint between two items, can be established by temporal persistency of the patterns. It means that some patterns can be used to build the constraint graph, when the patterns have been shown in a set of the FP. Two types of constraints can be generated by users and adaptation. Based on our scheme, we find that a large number of dataset has been efficiently reduced during mining process and the gathering information while updating.  相似文献   
89.
The motivation for this paper is to investigate the use of two promising classes of artificial intelligence models, the Psi Sigma Neural Network (PSI) and the Gene Expression algorithm (GEP), when applied to the task of forecasting and trading the EUR/USD exchange rate. This is done by benchmarking their results with a Multi-Layer Perceptron (MLP), a Recurrent Neural Network (RNN), a genetic programming algorithm (GP), an autoregressive moving average model (ARMA) plus a naïve strategy. We also examine if the introduction of a time-varying leverage strategy can improve the trading performance of our models.  相似文献   
90.
分辨率增强技术(RET)设计流程中聚集了各式各样的点工具和方法。当前对深亚波长可制造性(DFM)设计的要求迫使设计与制造行业必须建立十分密切的合作关系。同时也促使EDA行业提供一种平台,以促进这些行业间的密切交流。合理利用这一平台将会对产能和品质产生直接的影响。  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