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   278680篇
  免费   22792篇
  国内免费   14100篇
电工技术   18113篇
技术理论   52篇
综合类   38201篇
化学工业   29766篇
金属工艺   9945篇
机械仪表   14584篇
建筑科学   41486篇
矿业工程   16918篇
能源动力   8529篇
轻工业   14597篇
水利工程   16145篇
石油天然气   13668篇
武器工业   2631篇
无线电   17920篇
一般工业技术   18724篇
冶金工业   16062篇
原子能技术   2761篇
自动化技术   35470篇
  2024年   765篇
  2023年   2550篇
  2022年   5117篇
  2021年   6288篇
  2020年   6730篇
  2019年   5525篇
  2018年   5127篇
  2017年   6285篇
  2016年   7600篇
  2015年   8539篇
  2014年   15761篇
  2013年   14101篇
  2012年   18763篇
  2011年   19893篇
  2010年   15819篇
  2009年   16381篇
  2008年   15394篇
  2007年   20019篇
  2006年   18979篇
  2005年   16580篇
  2004年   14045篇
  2003年   12718篇
  2002年   10472篇
  2001年   8849篇
  2000年   7424篇
  1999年   6032篇
  1998年   4560篇
  1997年   3983篇
  1996年   3655篇
  1995年   3127篇
  1994年   2775篇
  1993年   2084篇
  1992年   1841篇
  1991年   1348篇
  1990年   1196篇
  1989年   1042篇
  1988年   831篇
  1987年   563篇
  1986年   435篇
  1985年   372篇
  1984年   346篇
  1983年   256篇
  1982年   225篇
  1981年   181篇
  1980年   135篇
  1979年   114篇
  1978年   62篇
  1977年   72篇
  1976年   55篇
  1975年   55篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
以电信用户入网协议为切入点,电信用户的携号转网行为应受到《合同法》《消费者权益保护法》等私法规范的保护与限制。该行为引起的格式条款解释、合同终止、违约责任、损失赔偿等问题,不能仅靠《电信条例》等公法规范来调整。应当积极引导广大消费者用户以私法领域相关规定为依据,转变争议解决思维,拓宽纠纷处理途径,合理选择维权手段,以保护自身合法民事权益,与行业监管部门共同推动电信行业有序发展。  相似文献   
53.
54.
55.
56.
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   
57.
58.
A series of methacrylate-acrylonitrile-butadiene-styrene (MABS) resins was prepared using bulk polymerization. The polarity of the continuous phase and the compatibility of two phases were changed by adjusting the methyl methacrylate (MMA) content, choosing values that were close to styrene-butadiene rubber solubility value. The possibility of controlling the microstructure of the MABS resin by changing the polarity of the components and the compatibility of two phases was assessed. The dynamic mechanical analysis shows that the compatibility of two phases varies with the MMA content. The morphological analysis shows that increasing MMA contents results in a gradual decrease in the sub-inclusion structure with a network skeleton of rubber particles, and that all the particles become solid rubber when the MMA content reaches 75%. The sub-inclusion structure reappears but does not have a network skeleton when the MMA content is 90%. The impact strength and morphological analysis indicate that the solid rubber particles and the sub-inclusion structure with a network skeleton provide excellent toughness, while the sub-inclusion structure without a network skeleton does not. In contrast, the transmittance of the ABS resin first increased and then decreased with increasing MMA content.  相似文献   
59.
Reliability based criteria are quite popular for optimal sensor network design. We present a modified definition of system reliability for sensor network design for two applications: reliable estimation of variables in a steady state linear flow process, and reliable fault detection and diagnosis for any process. Unlike the weakest-link based definition of system reliability in the literature, the proposed definition considers the entire system and is consistent with the reliability concept used in classical reliability literature. For each application, dual approaches for defining system reliability are proposed, and their analogy with the reliability problem in the classical reliability literature is established. Using examples and stochastic simulations, the advantage of using the proposed system reliability in contrast to the existing definition is illustrated. Part II of this series of articles presents methods for efficient generation of the system reliability function and its use in optimization-based approaches for designing optimal sensor networks.  相似文献   
60.
与传统比例-积分-微分(PID)控制方法相比,滑模控制(SMC)方法可以比较容易地将不确定性纳入控制器设计中,从而增强系统的鲁棒性。探索了SMC技术在运载器主动段姿态控制中的工程应用,首先通过分析基于趋近律的SMC系统,提出了降低不连续切换项系数的需求,然后研究了基于干扰上界的SMC方法。三通道小偏差仿真结果验证了两种方法的控制效果,表明第2种控制器的鲁棒性更好,稳态误差小,同时发动机喷管摆角需求较小。  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