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   4840篇
  免费   157篇
  国内免费   13篇
电工技术   58篇
综合类   5篇
化学工业   939篇
金属工艺   84篇
机械仪表   117篇
建筑科学   182篇
矿业工程   23篇
能源动力   120篇
轻工业   308篇
水利工程   28篇
石油天然气   17篇
无线电   581篇
一般工业技术   844篇
冶金工业   928篇
原子能技术   38篇
自动化技术   738篇
  2022年   47篇
  2021年   88篇
  2020年   65篇
  2019年   50篇
  2018年   67篇
  2017年   76篇
  2016年   113篇
  2015年   87篇
  2014年   106篇
  2013年   309篇
  2012年   165篇
  2011年   257篇
  2010年   185篇
  2009年   192篇
  2008年   175篇
  2007年   169篇
  2006年   151篇
  2005年   149篇
  2004年   152篇
  2003年   123篇
  2002年   102篇
  2001年   73篇
  2000年   89篇
  1999年   93篇
  1998年   181篇
  1997年   132篇
  1996年   112篇
  1995年   84篇
  1994年   77篇
  1993年   99篇
  1992年   75篇
  1991年   60篇
  1990年   56篇
  1989年   67篇
  1988年   60篇
  1987年   56篇
  1986年   59篇
  1985年   66篇
  1984年   63篇
  1983年   41篇
  1982年   42篇
  1981年   58篇
  1980年   38篇
  1979年   41篇
  1978年   39篇
  1977年   57篇
  1976年   63篇
  1975年   23篇
  1974年   28篇
  1973年   22篇
排序方式: 共有5010条查询结果,搜索用时 15 毫秒
21.
This paper proposes a probabilistic variant of the SOM-kMER (Self Organising Map-kernel-based Maximum Entropy learning Rule) model for data classification. The classifier, known as pSOM-kMER (probabilistic SOM-kMER), is able to operate in a probabilistic environment and to implement the principles of statistical decision theory in undertaking classification problems. A distinctive feature of pSOM-kMER is its ability in revealing the underlying structure of data. In addition, the Receptive Field (RF) regions generated can be used for variable kernel and non-parametric density estimation. Empirical evaluation using benchmark datasets shows that pSOM-kMER is able to achieve good performance as compared with those from a number of machine learning systems. The applicability of the proposed model as a useful data classifier is also demonstrated with a real-world medical data classification problem.  相似文献   
22.
23.
The lead free Sn–Ag–y%Cu (y = 0.0, 0.5, 1.0 and 2.0) interconnect interfacial microstructures and the microstructure evolution under thermal treatment (isothermal aging, 150 °C/1000 h) were studied in detail by using surface microetching microscopy and cross section microscopy. The corresponding mechanical and reliability behaviors were evaluated by performing shear test and fracture mode analysis before and after the thermal treatment. The results indicate: (i) The interconnects could have different microstructures and intermetallic compound (IMC), depending on the Cu content. The Cu–Sn IMC could have microstructures that were clusters or protrusion-like, Augustine grass leaf-like, scissor-like, tweezers-like, etc. (ii) Ag3Sn IMCs were not observed at time zero for any interconnect groups, but they occurred after the aging for all groups. The Ag3Sn IMC could have different microstructures, again depending on Cu content. For low Cu content, the Ag3Sn IMCs were granules or nodules; for higher Cu content, Ag3Sn IMCs were plate-like. (iii) The growth of Ag3Sn plates was promoted by the growth of Cu–Sn IMCs, but indirectly linked to the Cu content. (iv) High Cu content (1.0 wt% and higher) could degrade the mechanical and reliability performances of the LF interconnect by providing a brittle joint, which was mainly achieved through the substantial growth of Cu–Sn IMCs and Ag3Sn plates.  相似文献   
24.
In 1984, computing firms saw integrated voice/data terminals (IVDTs) as the solution to the proliferation of new forms of executive communication. The Sydis VoiceStation was hailed as the best of this new class of office machine but, like all IVDTs, it failed. Sydis succumbed to "integration stress," one danger of product development driven by the urge to integrate traditionally discrete functions. Sydis also failed from poor integration of financial and market actors.  相似文献   
25.
Fabrication process of open surfaces by robotic fibre placement   总被引:3,自引:2,他引:3  
Composite materials are being used extensively in many industrial sectors. They offer excellent material properties compared to other structural materials available. However, the traditional fabrication process using manual hand lay-up is time consuming and labour intensive. Therefore, robotic fibre placement has been introduced to overcome these drawbacks. This approach may greatly reduce cycle time and manufacturing costs. This paper describes the overall strategy for the establishment of a flexible robotic fibre placement technique. The fabrication process planning of this new technique is presented. Three different types of fibre placement for open surfaces are discussed. These include simulation-based fibre path generation, fibre steering, and sensory-based contour following methodologies. The system architecture for the process control is also presented.  相似文献   
26.
Henry 《程序员》2004,(8):13-13
当证监会第二天就找上门来希望合作之前,中科院软件学院院长潘辛平博士并没有预料到他写的“建设金融科技中心”的提案会有这么强的反馈。潘辛平说:“他们希望我们能够在科研、测试、认证和监管方面和我们全面合作,并且提供足够的人才和项目。”事实上,从担任中科院软件学院院长的那一天起,在中国金融科技界享有盛誉的潘辛平就明确了自己的工程化人才教育模式。他认为,工程教育应该比工学教育更加关注流程化、标准化、团队作  相似文献   
27.
28.
美国火电厂烟气排放限值及控制技术在过去的37年内不断发展进步.受限制的排放物越来越多,而且对每种污染物的限值日益严格.总结了当今美国使用的排放限值及控制技术,并展望了未来的排放限值及潜在的排放控制技术.  相似文献   
29.
30.
Chee Tsai  Ludwik Kurz 《Automatica》1983,19(3):279-288
The performance of a linear Kalman filter will degrade when the dynamic noise is not Gaussian. A robust Kalman filter based on the m-interval polynomial approximation (MIPA) method for unknown non-Gaussian noise is proposed. Two situations are considered: (a) the state is Gaussian and the observation noise is non-Gaussian; (b) the state is non-Gaussian and the observation noise is Gaussian. It is shown, as compared with other non-Gaussian filters, the MIPA Kalman filter is computationally feasible, unbiased, more efficient and robust. For the scalar model, Monte Carlo simulations are given to demonstrate the ideas involved.  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