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   46120篇
  免费   6003篇
  国内免费   3220篇
电工技术   10169篇
技术理论   2篇
综合类   5073篇
化学工业   1752篇
金属工艺   942篇
机械仪表   3770篇
建筑科学   7024篇
矿业工程   1256篇
能源动力   1790篇
轻工业   3085篇
水利工程   1450篇
石油天然气   1746篇
武器工业   486篇
无线电   3030篇
一般工业技术   3573篇
冶金工业   1122篇
原子能技术   269篇
自动化技术   8804篇
  2024年   216篇
  2023年   780篇
  2022年   1472篇
  2021年   1671篇
  2020年   1805篇
  2019年   1509篇
  2018年   1427篇
  2017年   1773篇
  2016年   1815篇
  2015年   2042篇
  2014年   3139篇
  2013年   2723篇
  2012年   3582篇
  2011年   3903篇
  2010年   2874篇
  2009年   2933篇
  2008年   2732篇
  2007年   3205篇
  2006年   2809篇
  2005年   2271篇
  2004年   1833篇
  2003年   1592篇
  2002年   1310篇
  2001年   1054篇
  2000年   889篇
  1999年   741篇
  1998年   523篇
  1997年   499篇
  1996年   407篇
  1995年   342篇
  1994年   286篇
  1993年   197篇
  1992年   152篇
  1991年   126篇
  1990年   121篇
  1989年   112篇
  1988年   97篇
  1987年   55篇
  1986年   42篇
  1985年   29篇
  1984年   41篇
  1983年   27篇
  1982年   36篇
  1981年   28篇
  1980年   33篇
  1979年   18篇
  1978年   15篇
  1977年   9篇
  1961年   5篇
  1959年   8篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
借助现场采集装置,在计算机上获取每一分钟的冶炼工艺电能需求量,显示当前15分钟时段已发生的电耗量,调整用户设定,实现需量自动刷新、报警和专家分析推荐后续用量;实现平稳用电并减少对电网冲击,同时降低电能最大需用量以减少成本。  相似文献   
62.
应用SPC技术对机械零件加工过程的管理和控制   总被引:4,自引:0,他引:4  
介绍了SPC(统计过程控制)技术原理,以某传动轴外径φ45 0.50^0.90 mm为控制对象,提出应用SPC技术,对机械零件加工过程进行管理和控制,从而达到过程失控预警、过程不断改进、过程能力不断提高的目的,继而保证产品质量的稳定和不断提高。  相似文献   
63.
A stochastic realization problem of a stationary stochastic process is re-visited, and a new stochastically balanced realization algorithm is derived in a Hilbert space generated by second-order stationary processes. The present algorithm computes a stochastically balanced realization by means of the singular value decomposition of a weighted block Hankel matrix derived by a “block LQ decomposition”. Extension to a stochastic subspace identification method explains how the proposed abstract algorithm is implemented in system identification.  相似文献   
64.
冯明光  谢安国 《冶金能源》2004,23(1):6-8,26
利用寿命周期评价的思想,计算了炼铁生产过程中的环境负荷,并分析了各因素对环境负荷的影响,运用神经网络对炼铁生产过程环境负荷进行了预测。  相似文献   
65.
We study the stressed state of an inhomogeneous welded joint containing an interlayer of a more high-strength material under the action of tensile loads. It is assumed that the contact boundary has a cracklike defect. We deduce analytic dependences of the fracture load on the mechanical inhomogeneity of the joint, thickness of the interlayer, and depth of the defect. The maximum depth of the defect to which the joint is insensitive is established. The proposed theoretical results are innovative and agree with the experimental data obtained for specimens cut out from a pipe of 14KhGS steel.  相似文献   
66.
This paper proposes a frequency domain algorithm for Wiener model identifications based on exploring the fundamental frequency and harmonics generated by the unknown nonlinearity. The convergence of the algorithm is established in the presence of white noise. No a priori knowledge of the structure of the nonlinearity is required and the linear part can be nonparametric.  相似文献   
67.
董世坚 《电力电容器》2003,(2):41-42,48
就我公司动力厂给水车间155kW水泵电机无功就地补偿的可行性及经济效益进行了分析和研究,对工厂用电如何节能降耗有一定的参考价值。  相似文献   
68.
An increasing amount of laser beam welded T‐joints (e.g. skin‐stringer) of aluminium alloys are now in use in advanced fuselage applications designed as ‘integral structures’ for weight and cost savings. It is known that weld joints generally show lower strength (undermatching) than base metal in both laser beam and friction stir welded joints of 6xxx series Al‐alloys. Damage tolerance considerations in terms of the residual strength of such joints require limit load solutions to be used in engineering fitness‐for‐service (FFS) analysis. The paper, therefore, provides an upper bound limit load solution in closed form for welded T‐joints (idealized) with strength undermatching and subject to a bending moment. In addition to the necessary requirements of the upper bound theorem, the kinematically admissible velocity field chosen leads to a stress field, which satisfies the equilibrium equations and some stress boundary conditions in the plastic zone. This is an advantage of the solution and, therefore, it is expected that the upper bound obtained is close to the exact limit load of such joints.  相似文献   
69.
A method for constructing an approximation of the critical excitation that drives an elastoplastic system from rest to a target threshold at a specified time instant, referred to as the “suboptimal excitation,” is presented in this paper. It is based on the observations gained from study of the critical excitations in the companion paper. Essentially, for the usual case of interest where the failure time is not small compared to the natural period, the duration of the positive and negative pulses of the critical excitation are roughly equal to half of the natural period. This consideration allows for a simple intuitive approximation of the critical excitation. The amplitudes of the positive and negative pulses are obtained in closed forms using energy balance. Numerical investigations show that the critical excitations are well approximated by the suboptimal excitations.  相似文献   
70.
In this work, simple modifications on the cost index of particular local-model fuzzy clustering algorithms are proposed in order to improve the readability of the resulting models. The final goal is simultaneously providing local linear models (reasonably close to the plant’s Jacobian) and clustering in the input space so that desirable characteristics (regarding final model accuracy, and convexity and smoothness of the cluster membership functions) are improved with respect to other proposals in literature. Some examples illustrate the proposed approach.  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