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   10345篇
  免费   877篇
  国内免费   24篇
电工技术   160篇
综合类   9篇
化学工业   2808篇
金属工艺   482篇
机械仪表   661篇
建筑科学   142篇
矿业工程   5篇
能源动力   427篇
轻工业   802篇
水利工程   22篇
石油天然气   11篇
无线电   1775篇
一般工业技术   2423篇
冶金工业   422篇
原子能技术   166篇
自动化技术   931篇
  2024年   12篇
  2023年   133篇
  2022年   202篇
  2021年   322篇
  2020年   257篇
  2019年   308篇
  2018年   353篇
  2017年   369篇
  2016年   443篇
  2015年   318篇
  2014年   503篇
  2013年   673篇
  2012年   779篇
  2011年   926篇
  2010年   608篇
  2009年   678篇
  2008年   554篇
  2007年   420篇
  2006年   384篇
  2005年   326篇
  2004年   312篇
  2003年   325篇
  2002年   275篇
  2001年   216篇
  2000年   197篇
  1999年   189篇
  1998年   197篇
  1997年   151篇
  1996年   120篇
  1995年   88篇
  1994年   72篇
  1993年   85篇
  1992年   56篇
  1991年   49篇
  1990年   38篇
  1989年   31篇
  1988年   31篇
  1987年   22篇
  1986年   25篇
  1985年   36篇
  1984年   26篇
  1983年   9篇
  1982年   11篇
  1981年   13篇
  1980年   22篇
  1979年   15篇
  1977年   11篇
  1976年   17篇
  1975年   10篇
  1974年   9篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
Many evolving video services and applications for intelligent security systems require reliable transmission of high quality video to diverse clients over heterogeneous networks using available system resources. Scalable video coding (SVC) is one of the emerging video compression technologies with such potential capabilities. Advances in lifting-based motion-compensated temporal filtering (MCTF) have enabled highly efficient and flexible spatial, temporal, signal-to-noise ratio (SNR), and complexity scalability to be realized over a wide range of bit rates. In this paper, we present an algorithm to improve the update step of MCTF, which serves as an important informative step for the coding performance of SVC. A novel update-step algorithm, which takes advantage of the chrominance information of the video sequence and the correlation of the motion vectors (MVs) of the neighboring blocks as well as the correlation of the derived update MVs in the low-pass frames, is proposed to improve update step of MCTF by (1) computing correct update motion information, (2) generating correct amount of energy contained in the high-pass frames. Experimental results show that the proposed algorithm can significantly improve the quality of the reconstructed video sequence in visual quality.
Xiaokang YangEmail:
  相似文献   
92.
CMOS for the mixed-mode applications has gained much interest recently. While the International Technology Roadmap for Semiconductors provides two different scaling guidelines for the analog and digital circuit operation using the bulk MOSFET, there are no well-defined scaling guidelines for improving the analog performance of silicon-on-insulator (SOI) MOSFETs. This paper presents a systematic and quantitative comparison between the analog characteristics of the bulk and SOI technology. The intrinsic gain, f/sub T/ and g/sub m//I/sub ds/ ratio are considered as a metric for this comparison. It is shown that, even for the operating frequencies in the range of gigahertz (where the ac kink effect is suppressed), analog performance of SOI devices is inferior to that of the bulk devices due to the capacitive drain-to-body coupling. Based on our study, we show that hat the gate-workfunction engineering (close to mid-gap workfunction) is essential in fully depleted SOI (FDSOI) devices for improving analog performance. The analog performance of partially depleted SOI (PDSOI) devices can be improved by using body-tied structures. An increased gate control in double-gate MOSFETs can provide very high output resistance for short-channel devices.  相似文献   
93.
Three-dimensional (3-D) localization of individual cochlear implant electrodes within the inner ear is of importance for modeling the electrical field of the cochlea, designing the electrode array, and programming the associated speech processor. A 3-D reconstruction method of cochlear implant electrodes is proposed to localize individual electrodes from two X-ray views in combination with the spiral computed tomography technique. By adapting epipolar geometry to the configuration of an X-ray imaging system, we estimate individual electrode locations in the least square sense without using a patient attachment required by an existing stereophotogrammetry technique. Furthermore, our method does not require any knowledge of the intrinsic and extrinsic parameters of the imaging system. The performance of our method is studied in numerical simulation and with patient data and is found to be sufficiently accurate for clinical use. The maximum root mean-square errors measured are 0.0445 and 0.214 mm for numerical simulation and patient data, respectively.  相似文献   
94.
With video compression standards such as MPEG‐4, a transmission error happens in a video‐packet basis, rather than in a macroblock basis. In this context, we propose a semantic error prioritization method that determines the size of a video packet based on the importance of its contents. A video packet length is made to be short for an important area such as a facial area in order to reduce the possibility of error accumulation. To facilitate the semantic error prioritization, an efficient hardware algorithm for face tracking is proposed. The increase of hardware complexity is minimal because a motion estimation engine is efficiently re‐used for face tracking. Experimental results demonstrate that the facial area is well protected with the proposed scheme.  相似文献   
95.
96.
The performance of a stochastic gradient adaptive filter can be significantly improved by introducing a forgetting factor. The complexity of the original algorithm can also be reduced by using only the signs of error signals and input signals in the gradient adaptive step size computation  相似文献   
97.
The implementation of TS MAC system for KOREASAT DBS (direct broadcast satellite) system is presented. This TS MAC controls and monitors the status of the TS equipment and gathers the alarm for them. The advantage of this system is the center-concentrated, real time processing, remote control, and object oriented module decomposing  相似文献   
98.
A new fiber-optic catheter for in vivo blood-flow measurements has been developed. The catheter is designed to measure blood flow in both the forward (toward the catheter tip) and reverse (away from the catheter tip) flow directions. It consists of two multimode optical fibers with core diameter of 50 μm and cladding diameter of 125 μm. One fiber transmits the laser beam into blood and the other receives the backscattered light from the erythrocytes within the probe volume. In the flow experiment, it was found that the flow within the boundary layer is indeed laminar and, hence, the relationship between the Doppler shift frequencies and the flow velocities is linear, thereby making the linear calibration possible for predicting the free stream flow velocity. Plots of the maximum shift frequency (frequency at which the Doppler spectrum disappeared into the noise spectrum) against the flow velocities are found to be more linear in both the forward and reverse flow directions than that of the dominant shift frequency (frequency with the highest amplitude). These results were reaffirmed by the numerical flow simulation along the catheter side wall  相似文献   
99.
The improvement of the linewidth enhancement factor in complex-coupled laser diode (CC-LD), or loss-coupled, was confirmed by measuring the spontaneous emission spectra below threshold from the sidewall of laser diodes. In addition, the serial resistance of the device was measured. The linewidth enhancement factor is improved by the presence of a light absorbing InGaAs grating for loss coupled distributed-feedback (DFB) laser diode (LD). We report the comparison of the linewidth enhancement factors of Fabry-Perot (FP) LD, conventional DFB-LD, and loss coupled DFB-LDs  相似文献   
100.
Fast DCT algorithm with fewer multiplication stages   总被引:1,自引:0,他引:1  
A novel fast DCT scheme with reduced multiplication stages and fewer additions and multiplications is proposed. The proposed algorithm is structured so that most multiplications tend to be performed at the final stage, which reduces the propagation error that could occur in the fixed-point computation. Minimisation of the multiplication stages can further decrease the error  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