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   3735篇
  免费   131篇
  国内免费   110篇
电工技术   70篇
综合类   152篇
化学工业   78篇
金属工艺   53篇
机械仪表   166篇
建筑科学   197篇
矿业工程   52篇
能源动力   99篇
轻工业   50篇
水利工程   42篇
石油天然气   66篇
武器工业   27篇
无线电   221篇
一般工业技术   214篇
冶金工业   172篇
原子能技术   25篇
自动化技术   2292篇
  2024年   5篇
  2023年   20篇
  2022年   36篇
  2021年   49篇
  2020年   52篇
  2019年   51篇
  2018年   56篇
  2017年   84篇
  2016年   122篇
  2015年   122篇
  2014年   165篇
  2013年   218篇
  2012年   188篇
  2011年   243篇
  2010年   170篇
  2009年   203篇
  2008年   243篇
  2007年   263篇
  2006年   220篇
  2005年   219篇
  2004年   164篇
  2003年   179篇
  2002年   140篇
  2001年   117篇
  2000年   105篇
  1999年   92篇
  1998年   71篇
  1997年   60篇
  1996年   64篇
  1995年   36篇
  1994年   33篇
  1993年   22篇
  1992年   15篇
  1991年   16篇
  1990年   11篇
  1989年   13篇
  1988年   11篇
  1987年   10篇
  1986年   7篇
  1985年   28篇
  1984年   8篇
  1983年   15篇
  1982年   4篇
  1981年   7篇
  1980年   6篇
  1979年   3篇
  1978年   2篇
  1977年   4篇
  1976年   2篇
  1971年   1篇
排序方式: 共有3976条查询结果,搜索用时 15 毫秒
41.
A Further Comparison of Splitting Rules for Decision-Tree Induction   总被引:10,自引:0,他引:10  
One approach to learning classification rules from examples is to build decision trees. A review and comparison paper by Mingers (Mingers, 1989) looked at the first stage of tree building, which uses a splitting rule to grow trees with a greedy recursive partitioning algorithm. That paper considered a number of different measures and experimentally examined their behavior on four domains. The main conclusion was that a random splitting rule does not significantly decrease classificational accuracy. This note suggests an alternative experimental method and presents additional results on further domains. Our results indicate that random splitting leads to increased error. These results are at variance with those presented by Mingers.  相似文献   
42.
网络税控系统用于监管零售行业的税收,它从零售企业的MIS和POS系统中采集税控信息,实现了销售小票与机打发票的统一,并采用传统的关系数据库来存储收集的税控数据。本文阐述了在网络税控系统的基础上应用数据仓库技术构建零售业税务决策支持系统的框架方案,并重点介绍了零售业税务决策支持系统数据仓库总体架构以及数据仓库的设计实现过程。本文作者创新点:将数据仓库技术应用到零售业税务决策支持系统中,为税务部门提供了决策支持。  相似文献   
43.
本文主要介绍数据挖掘在电子商务中的应用,文章从数据挖掘的定义、数据挖掘的常用方法出发,阐述了数据挖掘在海量信息中提取有效信息的作用,特别是数据挖掘与电子商务的结合可以给人们生活带来便利,给企业带来新的利润空间以及为企业提供决策支持。常用的数据挖掘技术主要包括支持向量机、朴素贝叶斯、聚类、决策树、神经网络和关联规则等,最后介绍了数据挖掘在电子商务的4个主要应用方面,说明了数据挖掘存在的必要性。  相似文献   
44.
高校餐饮服务相比较于社会化餐饮服务具有其独特特性,在购买原材料完全遵循市场规则而销售定价不能完全市场化的限制下,还要面对窗口自选以及餐厅点餐两种销售模式并存的影响,以及伴随着扩招带来了多校区、多食堂、多窗口的状况,如何通过信息化手段提高其工作流程和效率,成为当前迫切需要。文中提出一种符合实际工作需要的信息化解决方案,对整个高校餐饮服务过程中所涉及的人、物、财进行综合管理,并形成决策,以最大化信息系统的效用,真正做到开源节流。  相似文献   
45.
灾害决策系统中,核心安置点的选择对救灾工作效率影响重大;分析常用的最短路径搜索方法,选用Dijkstra算法并对其进行改进,计算选取到达最远安置点最近的安置点作为核心安置点。实验结果表明,该方法具有良好的实用性。  相似文献   
46.
数字电路的可靠性有着至关重要的影响,测试是其重要保证,测试向量的自动生成(ATPG)在数字电路的测试中占有重要地位;逻辑表达式图(Boolean Expression Diagrams,BED)是用于逻辑函数与逻辑电路表达与运算一种数据结构,能够将逻辑电路在线性空间复杂度内表达,是二元判决图(Binary Decision Diagrams, BDD)在概念上的推广且保留着BDD的许多有用的性质。讨论了BED的性质与实现方法,并将BED用于逻辑电路呆滞型故障测试向量的自动生成中,基于BED的测试算法直接将原电路与故障电路做异或运算后用BED表达再化简或判断其可满足性,算法能充分使用逻辑代数的化简规则和利用电路与故障电路的相似性。实验结果表明,基于BED的测试方法具有较低的复杂度。  相似文献   
47.
Y. Jin  M. Geslin  S.C.-Y. Lu 《CIRP Annals》2007,56(1):181-184
Engineering of complex systems involves multiple disciplinary design teams with diversified skills. The team members must work together to make joint decisions, but are often faced with difficulties when trying to reach agreements. Negotiation has been studied as a method for facilitating information exchange, mutual understanding, and joint decision-making. In our previous work, we introduced an argumentative negotiation model to support collaborative engineering. In this paper, we present an experiment study that was conducted to assess the impact of this negotiation support system on the process and the outcome of collaborative design. The results of the experiment have demonstrated the positive effects of the approach.  相似文献   
48.
介绍用水煤浆代替轻油原料,改造年产30万吨合成氨装置,重点论述其制氨工艺单元的合理组合和国产化措施。  相似文献   
49.
This article provides a comprehensive review of research articles related to the application of decision support and intelligent systems in the textile and apparel supply chains. Data were obtained from 77 articles published from 1994 to 2009 in 35 journals. The articles were categorized according to their applicability into three basic sectors – textile production, apparel manufacture, and distribution/sales. They were further categorized into 16 subsectors based on their operational and management/control processes. A comprehensive list of categorized journal articles identified in this study provides insights and relevant references for both researchers and practitioners on the application of decision support and intelligent systems to various stages of a textile and apparel supply chain. In light of the developed classification framework, we identify gaps in extending the use of the decision support and artificial intelligent systems in the industry and suggest potential and applicable research areas for further consideration in this subject area.  相似文献   
50.
A goal of this study is to develop a Composite Knowledge Manipulation Tool (CKMT). Some of traditional medical activities are rely heavily on the oral transfer of knowledge, with the risk of losing important knowledge. Moreover, the activities differ according to the regions, traditions, experts’ experiences, etc. Therefore, it is necessary to develop an integrated and consistent knowledge manipulation tool. By using the tool, it will be possible to extract the tacit knowledge consistently, transform different types of knowledge into a composite knowledge base (KB), integrate disseminated and complex knowledge, and complement the lack of knowledge. For the reason above, I have developed the CKMT called as K-Expert and it has four advanced functionalities as follows. Firstly, it can extract/import logical rules from data mining (DM) with the minimum of effort. I expect that the function can complement the oral transfer of traditional knowledge. Secondly, it transforms the various types of logical rules into database (DB) tables after the syntax checking and/or transformation. In this situation, knowledge managers can refine, evaluate, and manage the huge-sized composite KB consistently with the support of the DB management systems (DBMS). Thirdly, it visualizes the transformed knowledge in the shape of decision tree (DT). With the function, the knowledge workers can evaluate the completeness of the KB and complement the lack of knowledge. Finally, it gives SQL-based backward chaining function to the knowledge users. It could reduce the inference time effectively since it is based on SQL query and searching not the sentence-by-sentence translation used in the traditional inference systems. The function will give the young researchers and their fellows in the field of knowledge management (KM) and expert systems (ES) more opportunities to follow up and validate their knowledge. Finally, I expect that the approach can present the advantages of mitigating knowledge loss and the burdens of knowledge transformation and complementation.  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