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   504篇
  免费   16篇
  国内免费   1篇
电工技术   8篇
综合类   5篇
化学工业   121篇
金属工艺   7篇
机械仪表   16篇
建筑科学   5篇
能源动力   37篇
轻工业   32篇
无线电   61篇
一般工业技术   107篇
冶金工业   16篇
原子能技术   3篇
自动化技术   103篇
  2024年   4篇
  2023年   15篇
  2022年   26篇
  2021年   33篇
  2020年   31篇
  2019年   35篇
  2018年   35篇
  2017年   24篇
  2016年   36篇
  2015年   13篇
  2014年   15篇
  2013年   60篇
  2012年   28篇
  2011年   31篇
  2010年   35篇
  2009年   13篇
  2008年   17篇
  2007年   16篇
  2006年   16篇
  2005年   10篇
  2004年   8篇
  2003年   4篇
  2002年   3篇
  2001年   2篇
  2000年   1篇
  1999年   1篇
  1997年   1篇
  1996年   4篇
  1994年   1篇
  1993年   1篇
  1980年   1篇
  1976年   1篇
排序方式: 共有521条查询结果,搜索用时 0 毫秒
1.
Present paper deals with fractional version of a dynamical system introduced by C. Liu, L. Liu and T. Liu [C. Liu, L. Liu, T. Liu, A novel three-dimensional autonomous chaos system, Chaos Solitons Fractals 39 (4) (2009) 1950–1958]. Numerical investigations on the dynamics of this system have been carried out. Properties of the system have been analyzed by means of Lyapunov exponents. Furthermore the minimum effective dimensions have been identified for chaos to exist in commensurate and incommensurate orders. It is noteworthy that the results obtained are consistent with the analytical conditions given in the literature.  相似文献   
2.
Journal of Signal Processing Systems - Segmentation of thigh tissues (muscle, fat, inter-muscular adipose tissue (IMAT), bone, and bone marrow) from magnetic resonance imaging (MRI) scans is useful...  相似文献   
3.
Differential-difference equations with multiple delays have applications in a variety of applied fields. We propose a prototype delay model introduced by Uçar involving two delays. Sufficient conditions for the stability of the model are given and used to study chaos. It is observed first time in the literature that the Uçar system shows not only two-scroll but also one-scroll chaotic attractors.  相似文献   
4.
We demonstrate ultra-thin (<150 nm) Si1−x Ge x dislocation blocking layers on Si substrates used for the fabrication of tensile-strained Si N channel metal oxide semiconductor (NMOS) and Ge P channel metal oxide semiconductor (PMOS) devices. These layers were grown using ultra high vacuum chemical vapor deposition (UHVCVD). The Ge mole fraction was varied in rapid, but distinct steps during the epitaxial layer growth. This results in several Si1−x Ge x interfaces in the epitaxially grown material with significant strain fields at these interfaces. The strain fields enable a dislocation blocking mechanism at the Si1−x Ge x interfaces on which we were able to deposit very smooth, atomically flat, tensile-strained Si and relaxed Ge layers for the fabrication of high mobility N and P channel metal oxide semiconductor (MOS) devices, respectively. Both N and P channel metal oxide semiconductor field effect transister (MOSFETs) were successfully fabricated using high-k dielectric and metal gates on these layers, demonstrating that this technique of using ultra-thin dislocation blocking layers might be ideal for incorporating high mobility channel materials in a conventional CMOS process.  相似文献   
5.
An electrically switchable graphene terahertz (THz) modulator with a tunable-by-design optical bandwidth is presented and it is exploited to compensate the cavity dispersion of a quantum cascade laser (QCL). Electrostatic gating is achieved by a metal grating used as a gate electrode, with an HfO2/AlOx gate dielectric on top. This is patterned on a polyimide layer, which acts as a quarter wave resonance cavity, coupled with an Au reflector underneath. The authors achieve 90% modulation depth of the intensity, combined with a 20 kHz electrical bandwidth in the 1.9–2.7 THz range. The modulator is then integrated with a multimode THz QCL. By adjusting the modulator operational bandwidth, the authors demonstrate that the graphene modulator can partially compensate the QCL cavity dispersion, resulting in an integrated laser behaving as a stable frequency comb over 35% of the operational range, with 98 equidistant optical modes and a spectral coverage ~1.2 THz. This paves the way for applications in the terahertz, such as tunable transformation-optics devices, active photonic components, adaptive and quantum optics, and metrological tools for spectroscopy at THz frequencies.  相似文献   
6.
Wireless Personal Communications - In this paper, we have proposed a lightweight blockchain based model to provide distributed authentication and anonymous authorization in IoD. We have proposed...  相似文献   
7.
This paper presents effect of the weather impairments on a high altitude platform (HAP) broadband wireless communication system. It is shown that attenuation due to oxygen, water vapor, fog, cloud, and rain has significant effect on a radio link which is operating in a millimeter frequency range. Channel capacity is calculated for different seasons using Shannon’s channel capacity theorem. The location of HAP is taken to be Delhi (India). Further, it is considered that a user and the HAP platform are stationary.  相似文献   
8.
This paper presents an approach to solve coupled systems where electrical/mechanical devices, whose behaviour is governed by a PDE or a system of PDEs, are connected together through an electrical circuit. In an earlier paper [1], it had been shown that PDEs can be modeled by an electrical equivalent circuit generated from the complete set of equations arising from the Finite Element Method (FEM). In this paper, the approach is extended to solve a system of PDEs. The approach allows the simulation of coupled systems with circuit simulation tools alone since the resultant system becomes an electrical circuit after an application of electrical analogy. The coupled system is solved by directly replacing PDE devices with the equivalent circuits. Further, a special circuit simulation technique, viz. multiport decomposition is used in order to solve a large coupled system. A sequential as well as a parallel simulator is built for coupled problems based on the proposed approach. A circuit with 100 linear PDE devices (the equivalent circuit contains 8 million nodes) has been simulated using the parallel simulator in less than 1 h. We have achieved a speedup of 5 over the sequential simulator using 8 processors on distributed memory architecture. The characteristic of p–n junction diode (drift–diffusion equation) is analyzed by our circuit simulator to show that the proposed approach can be used to build a circuit-cum-device simulator.  相似文献   
9.
触摸屏在移动设备中越来越受欢迎。但触摸屏消耗的平均电流可能很大,从而会导致系统电池的电量快速耗尽。本文将主要探讨以下内容:功耗的基础知识、影响功耗的不同因素以及为需要提供强大性能同时节省电池使用寿命的器件设计低功耗触摸屏系统。  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