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   325505篇
  免费   28012篇
  国内免费   17795篇
电工技术   22669篇
技术理论   57篇
综合类   42492篇
化学工业   35515篇
金属工艺   12497篇
机械仪表   16964篇
建筑科学   46123篇
矿业工程   17684篇
能源动力   10095篇
轻工业   17283篇
水利工程   16862篇
石油天然气   16228篇
武器工业   3069篇
无线电   24530篇
一般工业技术   22902篇
冶金工业   18711篇
原子能技术   3373篇
自动化技术   44258篇
  2024年   1126篇
  2023年   3402篇
  2022年   6556篇
  2021年   7766篇
  2020年   8250篇
  2019年   6895篇
  2018年   6558篇
  2017年   8039篇
  2016年   9324篇
  2015年   10555篇
  2014年   18771篇
  2013年   17256篇
  2012年   22208篇
  2011年   23690篇
  2010年   18554篇
  2009年   19116篇
  2008年   18034篇
  2007年   23246篇
  2006年   21893篇
  2005年   19045篇
  2004年   16168篇
  2003年   14577篇
  2002年   11979篇
  2001年   10126篇
  2000年   8516篇
  1999年   6870篇
  1998年   5142篇
  1997年   4431篇
  1996年   4072篇
  1995年   3412篇
  1994年   3037篇
  1993年   2241篇
  1992年   2010篇
  1991年   1482篇
  1990年   1310篇
  1989年   1123篇
  1988年   909篇
  1987年   606篇
  1986年   484篇
  1985年   402篇
  1984年   380篇
  1983年   281篇
  1982年   230篇
  1981年   179篇
  1980年   143篇
  1979年   118篇
  1978年   70篇
  1977年   77篇
  1975年   59篇
  1959年   57篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
The sensitivity of a monitoring scheme depends on many factors including the variance of the charting statistic which is very important in the computation of the control limits. This paper discusses the computation of the variance of the recently proposed hybrid homogeneously weighted moving average (HHWMA) X¯ scheme which was based on an incorrect assumption. The correct variance is used to evaluate the run-length characteristics of the HHWMA X¯ scheme. It is observed that the incorrect variance has a significant impact on the sensitivity (or performance) of the HHWMA X¯ scheme.  相似文献   
2.
高素质人才培养是我国可持续发展战略、科教兴国战略以及人才强国战略等多项发展战略的一项基础性工程。本文针对中医药类院校程序设计类课程实践教学模式单一等教学实际,以“学科竞赛”为平台,“赛教结合”为理念,以《C语言程序设计》为例,从现存问题、赛教结合模式的引入、建立实施及其评价机制4个方面展开阐述,旨在提高学生学习积极性和能力。  相似文献   
3.
本文以云杉八齿小蠹Ips typographus Linnaeus为例,经标本选取,观察虫体整体形态,绘制整体结构草图,电子显微镜观察局部、得到局部数字图像,分别建立虫体每一部分的高精度细节。把模型每部分拼装在一起组成整体模型,构建出了云杉八齿小蠹三维虚拟昆虫数字化模型。  相似文献   
4.
5.
6.
7.
We investigate the effect of dopant random fluctuation on threshold voltage and drain current variation in a two-gate nanoscale transistor. We used a quantum-corrected technology computer aided design simulation to run the simulation (10000 randomizations). With this simulation, we could study the effects of varying the dimensions (length and width), and thicknesses of oxide and dopant factors of a transistor on the threshold voltage and drain current in subthreshold region (off) and overthreshold (on). It was found that in the subthreshold region the variability of the drain current and threshold voltage is relatively fixed while in the overthreshold region the variability of the threshold voltage and drain current decreases remarkably, despite the slight reduction of gate voltage diffusion (compared with that of the subthreshold). These results have been interpreted by using previously reported models for threshold current variability, load displacement, and simple analytical calculations. Scaling analysis shows that the variability of the characteristics of this semiconductor increases as the effects of the short channel increases. Therefore, with a slight increase of length and a reduction of width, oxide thickness, and dopant factor, we could correct the effect of the short channel.  相似文献   
8.
A small handful of recent studies have addressed a phenomenon known as “phantom vibration syndrome”. This refers to when phone users perceive their device to vibrate, indicating that a call or text is incoming, when in fact the phone did not vibrate at all. Though these studies show that most users do not find phantom vibration hallucinations to be very bothersome, they also find that a large majority of users experience this phenomenon. This paper explores what the striking prevalence of phantom vibration syndrome means for our contemporary relationships with technology. I begin with a review of the theories purporting to explain these data, which largely rely on particular understandings of the brain. Next I develop an alternative theory of phantom vibration syndrome based on insights from the philosophical tradition of phenomenology. This account considers the ways users develop bodily and perceptual habits regarding how the phone is understood and used. By critically contrasting these different theories, we can refine our questions about what the high prevalence of phantom vibration syndrome implies about our contemporary technological situation.  相似文献   
9.
Rectangular section control technology(RSCT)was introduced to achieve high-precision profile control during silicon steel rolling.The RSCT principle and method were designed,and the whole RSCT control strategy was developed.Specifically,RSCT included roll contour design,rolling technology optimization,and control strategy development,aiming at both hot strip mills(HSMs)and cold strip mills(CSMs).Firstly,through the high-performance variable crown(HVC)work roll optimization design in the upper-stream stands and the limited shifting technology for schedule-free rolling in the downstream stands of HSMs,a hot strip with a stable crown and limited wedge,local spot,and single wave was obtained,which was suitable for cold rolling.Secondly,an approximately rectangular section was obtained by edge varying contact(EVC)work roll contour design,edge-drop setting control,and closed loop control in the upper-stream stands of CSMs.Moreover,complex-mode flatness control was realized by coordinating multiple shape-control methods in the downstream stands of CSMs.In addition,the RSCT approach was applied in several silicon-steel production plants,where an outstanding performance and remarkable economic benefits were observed.  相似文献   
10.
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