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   395篇
  免费   35篇
电工技术   2篇
化学工业   64篇
金属工艺   15篇
机械仪表   16篇
建筑科学   3篇
能源动力   19篇
轻工业   49篇
水利工程   3篇
石油天然气   1篇
无线电   54篇
一般工业技术   89篇
冶金工业   8篇
原子能技术   3篇
自动化技术   104篇
  2024年   3篇
  2023年   4篇
  2022年   17篇
  2021年   16篇
  2020年   20篇
  2019年   23篇
  2018年   38篇
  2017年   22篇
  2016年   26篇
  2015年   10篇
  2014年   22篇
  2013年   37篇
  2012年   15篇
  2011年   19篇
  2010年   13篇
  2009年   26篇
  2008年   18篇
  2007年   16篇
  2006年   12篇
  2005年   10篇
  2004年   6篇
  2003年   8篇
  2002年   7篇
  2001年   4篇
  2000年   4篇
  1999年   3篇
  1997年   2篇
  1996年   1篇
  1995年   2篇
  1994年   1篇
  1993年   3篇
  1992年   1篇
  1990年   2篇
  1989年   1篇
  1987年   2篇
  1986年   1篇
  1985年   3篇
  1984年   3篇
  1983年   1篇
  1979年   1篇
  1974年   1篇
  1973年   2篇
  1970年   3篇
  1956年   1篇
排序方式: 共有430条查询结果,搜索用时 625 毫秒
61.
In this article, miniaturization of the wire monopole antenna with the help of high refractive index (HRI) metamaterial is presented. For the first time, HRI medium is realized by using the array of single ring split ring resonator. By surrounding the wire monopole with the array of SR‐SRRs, the effective wavelength is squeezed in the vicinity of the near field dominance. By the loading of the monopole with such an HRI medium, the size of the antenna is reduced from 29.5 to 16 mm, without any deformation in the current distribution and radiation pattern corresponding to the fundamental resonance. The simulated and measured results are agreed to the same.  相似文献   
62.
A novel zeroth‐order resonator (ZOR) meta‐material (MTM) antenna with dual‐band is suggested using compound right/left handed transmission line as MTM. In this article, suggested antenna consists of patch through series gap, two meander line inductors, and two circular stubs. The MTM antenna is compact in size which shows dual‐band properties with first band centered at 2.47 GHz (2.05‐2.89 GHz) and second band is centered at 5.9 GHz (3.70‐8.10 GHz) with impedance bandwidth of (S11 < ? 10 dB) 34.69% and 72.45%, respectively. At ZOR mode (2.35 GHz), the suggested antenna has overall dimension of 0.197λo × 0.07λo × 0.011λo with gain of 1.65 dB for ZOR band and 3.35 dB for first positive order resonator band which covers the applications like Bluetooth (2.4 GHZ), TV/Radio/Data (3.700‐6.425 GHz), WLAN (5‐5.16 GHz), C band frequencies (5.15‐5.35, 5.47‐5.725, or 5.725‐5.875 GHz) and satellite communication (7.25‐7.9 GHz). The radiation patterns of suggested structure are steady during the operating band for which sample antenna has been fabricated and confirmed experimentally. It exhibits novel omnidirectional radiation characteristics in phi = 0° plane with lower cross‐polarization values.  相似文献   
63.
A coaxial‐fed tri‐band zeroth‐order resonance (ZOR) circularly polarized antenna with higher gains for all the excited ZORs is designed and analyzed in this paper. Epsilon negative transmission line (ENG TL) and pseudo‐open termination (P‐OT) unit cells with different series capacitances (CS and CS1 ) resonate shunt ZOR (fsh ) and two series ZORs (fse and fse1 ), respectively. Asymmetric unit cell concept is applied to ENG‐TL and P‐OT unit cells to create vertical and horizontal components, and the 90° phase shift is provided by the ZOR, resulting in circular polarization (CP). Left‐hand CP (LHCP) is achieved by creating two 90° right bends to the extended stubs in ENG TL and P‐OT unit cells. Higher gains for all the excited ZORs are achieved by shifting the shorting pins of ENG TL and P‐OT unit cells far away from the center position. After fabrication, the measured resonances occur at 4.64 GHz (fsh ), 4.04 GHz (fse ), and 3.86 GHz (fse1 ) with fractional bandwidths of 1.62%, 1.73%, and 1.6%, respectively. The measured LHCP peak gains are 4.05 dBic (fsh ), 3.85 dBic (fse ), and 3.94 dBic (fse1 ). The average axial ratio obtained is less than 3‐dB in the 10‐dB fractional bandwidth of the proposed antenna.  相似文献   
64.
65.

The forecasting of bus passenger flow is important to the bus transit system’s operation. Because of the complicated structure of the bus operation system, it’s difficult to explain how passengers travel along different routes. Due to the huge number of passengers at the bus stop, bus delays, and irregularity, people are experiencing difficulties of using buses nowadays. It is important to determine the passenger flow in each station, and the transportation department may utilize this information to schedule buses for each region. In Our proposed system we are using an approach called the deep learning method with long short-term memory, recurrent neural network, and greedy layer-wise algorithm are used to predict the Karnataka State Road Transport Corporation (KSRTC) passenger flow. In the dataset, some of the parameters are considered for prediction are bus id, bus type, source, destination, passenger count, slot number, and revenue These parameters are processed in a greedy layer-wise algorithm to make it has cluster data into regions after cluster data move to the long short-term memory model to remove redundant data in the obtained data and recurrent neural network it gives the prediction result based on the iteration factors of the data. These algorithms are more accurate in predicting bus passengers. This technique handles the problem of passenger flow forecasting in Karnataka State Road Transport Corporation Bus Rapid Transit (KSRTCBRT) transportation, and the framework provides resource planning and revenue estimation predictions for the KSRTCBRT.

  相似文献   
66.
Wireless Personal Communications - The proposed beamforming model exploits the underlying sparseness of the adaptive filter as impulse response of wireless channel shows some extent of sparse...  相似文献   
67.
The objective of this paper is to present some series of geometric‐aggregated operators under Pythagorean fuzzy environment by relaxing the condition that the sum of the degree of membership functions is less than one with the square sum of the degree of membership functions is less than one. Under these environments, aggregator operators, namely, Pythagorean fuzzy Einstein weighted geometric, Pythagorean fuzzy Einstein ordered weighted geometric, generalized Pythagorean fuzzy Einstein weighted geometric, and generalized Pythagorean fuzzy Einstein ordered weighted geometric operators, are proposed in this paper. Some of its properties have also been investigated in details. Finally, an illustrative example for multicriteria decision‐making problems of alternatives is taken to demonstrate the effectiveness of the approach.  相似文献   
68.
69.
Incremental sheet forming (ISF) is a recently developed manufacturing technique. In ISF, forming is done by applying deformation force through the motion of Numerically controlled (NC) single point forming tool on the clamped sheet metal blank. Single Point Incremental sheet forming (SPISF) is also known as a die-less forming process because no die is required to fabricate any component by using this process. Now a day it is widely accepted for rapid manufacturing of sheet metal components. The formability of SPISF process improves by adding some intermediate stages into it, which is known as Multi-stage SPISF (MSPISF) process. However during forming in MSPISF process because of intermediate stages stepped features are generated. This paper investigates the generation of stepped features with simulation and experimental results. An effective MSPISF strategy is proposed to remove or eliminate this generated undesirable stepped features.  相似文献   
70.
Dynamic voltage and frequency scaling (DVFS) is an efficient method to reduce the power consumption in system on-chip. To support DVFS, multiple supply voltages are generated based on different work load frequencies and currents using on-chip DC–DC voltage converter. In this paper a frequency tunable multiple output voltage switched capacitor based dc–dc converter is presented. An analog to digital converter and phase controller is used in the feedback to change the switching frequency and duty cycle of the converter. An input voltage of 1.8 V is converted to 0.6 and 0.8 V for low and high signal frequency respectively. The proposed 2-phase switched capacitor architecture with gain setting of 1:2 is designed with the 90 nm technology. An output ripple of 45 mV is observed and the maximum transient response time of the converter is 17.3 ns (= 58 MHz).  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