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   37699篇
  免费   3464篇
  国内免费   2408篇
电工技术   3373篇
技术理论   1篇
综合类   3442篇
化学工业   2064篇
金属工艺   3402篇
机械仪表   6667篇
建筑科学   1066篇
矿业工程   1921篇
能源动力   551篇
轻工业   2925篇
水利工程   374篇
石油天然气   538篇
武器工业   285篇
无线电   2494篇
一般工业技术   2390篇
冶金工业   2404篇
原子能技术   81篇
自动化技术   9593篇
  2024年   225篇
  2023年   740篇
  2022年   1306篇
  2021年   1397篇
  2020年   1396篇
  2019年   1041篇
  2018年   890篇
  2017年   1142篇
  2016年   1292篇
  2015年   1448篇
  2014年   2399篇
  2013年   1897篇
  2012年   2819篇
  2011年   2907篇
  2010年   2100篇
  2009年   2102篇
  2008年   1938篇
  2007年   2571篇
  2006年   2455篇
  2005年   2093篇
  2004年   1649篇
  2003年   1458篇
  2002年   1236篇
  2001年   1070篇
  2000年   849篇
  1999年   656篇
  1998年   476篇
  1997年   408篇
  1996年   311篇
  1995年   301篇
  1994年   230篇
  1993年   173篇
  1992年   115篇
  1991年   90篇
  1990年   81篇
  1989年   90篇
  1988年   67篇
  1987年   24篇
  1986年   26篇
  1985年   12篇
  1984年   7篇
  1983年   15篇
  1982年   12篇
  1981年   6篇
  1980年   5篇
  1979年   7篇
  1978年   5篇
  1959年   4篇
  1958年   3篇
  1957年   3篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
对机床的静压系统及其发展过程进行了综述 ,介绍了静压系统的基本结构、特点及其在机床中的各种运用。  相似文献   
92.
卢元军 《电焊机》2005,35(9):49-53
阐述了200MW汽轮机焊接隔板变形这一在国内电站中多次出现的问题,以及由于隔板变形而对机组带来的危害.强调了在隔板发生严重变形时对隔板进行焊接加固的必要性,概述了隔板检查方法,包括隔板表面缺陷、内部缺陷、通流间隙、挠曲变形等的检查,以及隔板加固的工艺要点.  相似文献   
93.
介绍了引进的辐射加热无氧化辊式热处理炉及连续辊式淬火机,有效地解决了钢板的表面质量问题,取得了满意的效果.  相似文献   
94.
一种新的变轴数控机床标定方法   总被引:1,自引:0,他引:1  
范彧  张建民 《机床与液压》2004,(11):177-179
本文论述了国内外并联数控机床所采用的标定方法,选择了序列法进行了标定试验。但在实际标定过程中,出现了部分数据误差较大的问题,本文针对所面临的问题,提出了数值逼近法,并应用到实际机床的标定中,获得了机床的相关参数。之后,通过数学模型的计算值和实际测量值对比,验证了数据的可靠性,从而验证了方法的可行性和正确性。  相似文献   
95.
谢祖锡 《铸造》2006,55(2):116-119
扼要介绍了用气冲气推成形触头造型机制造电机壳铸型的成型过程及其实砂效果,试验结果表明,在工作气压为0,4 ̄0.45MPa的条件下,气冲气推成形触头造型机对电机壳类铸型的紧实,实砂效果十分理想,砂型紧实度高而且均匀。  相似文献   
96.
分析了我国数控机床制造产业的现状以及制造水平,最后分析了我国机床制造产业的关键共性技术。  相似文献   
97.
本文对“东家宝”胶在制氧机超低温管路漏气上的应用作了简要的介绍。  相似文献   
98.
Automatic detection of a user's interest in spoken dialog plays an important role in many applications, such as tutoring systems and customer service systems. In this study, we propose a decision-level fusion approach using acoustic and lexical information to accurately sense a user's interest at the utterance level. Our system consists of three parts: acoustic/prosodic model, lexical model, and a model that combines their decisions for the final output. We use two different regression algorithms to complement each other for the acoustic model. For lexical information, in addition to the bag-of-words model, we propose new features including a level-of-interest value for each word, length information using the number of words, estimated speaking rate, silence in the utterance, and similarity with other utterances. We also investigate the effectiveness of using more automatic speech recognition (ASR) hypotheses (n-best lists) to extract lexical features. The outputs from the acoustic and lexical models are combined at the decision level. Our experiments show that combining acoustic evidence with lexical information improves level-of-interest detection performance, even when lexical features are extracted from ASR output with high word error rate.  相似文献   
99.
Breast cancer continues to be a significant public health problem in the world. Early detection is the key for improving breast cancer prognosis. Mammogram breast X-ray is considered the most reliable method in early detection of breast cancer. However, it is difficult for radiologists to provide both accurate and uniform evaluation for the enormous mammograms generated in widespread screening. Micro calcification clusters (MCCs) and masses are the two most important signs for the breast cancer, and their automated detection is very valuable for early breast cancer diagnosis. The main objective is to discuss the computer-aided detection system that has been proposed to assist the radiologists in detecting the specific abnormalities and improving the diagnostic accuracy in making the diagnostic decisions by applying techniques splits into three-steps procedure beginning with enhancement by using Histogram equalization (HE) and Morphological Enhancement, followed by segmentation based on Otsu's threshold the region of interest for the identification of micro calcifications and mass lesions, and at last classification stage, which classify between normal and micro calcifications ‘patterns and then classify between benign and malignant micro calcifications. In classification stage; three methods were used, the voting K-Nearest Neighbor classifier (K-NN) with prediction accuracy of 73%, Support Vector Machine classifier (SVM) with prediction accuracy of 83%, and Artificial Neural Network classifier (ANN) with prediction accuracy of 77%.  相似文献   
100.
Experiences applying standards in personal health devices (PHDs) show an inherent trade-off between interoperability and costs (in terms of processing load and development time). Therefore, reducing hardware and software costs as well as time-to-market is crucial for standards adoption. The ISO/IEEE11073 PHD family of standards (also referred to as X73PHD) provides interoperable communication between PHDs and aggregators. Nevertheless, the responsibility of achieving inexpensive implementations of X73PHD in limited resource microcontrollers falls directly on the developer. Hence, the authors previously presented a methodology based on patterns to implement X73-compliant PHDs into devices with low-voltage low-power constraints. That version was based on multitasking, which required additional features and resources. This paper therefore presents an event-driven evolution of the patterns-based methodology for cost-effective development of standardized PHDs. The results of comparing between the two versions showed that the mean values of decrease in memory consumption and cycles of latency are 11.59% and 45.95%, respectively. In addition, several enhancements in terms of cost-effectiveness and development time can be derived from the new version of the methodology. Therefore, the new approach could help in producing cost-effective X73-compliant PHDs, which in turn could foster the adoption of standards.  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