首页 | 官方网站   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   1426篇
  免费   104篇
  国内免费   3篇
工业技术   1533篇
  2023年   15篇
  2022年   10篇
  2021年   33篇
  2020年   43篇
  2019年   30篇
  2018年   59篇
  2017年   53篇
  2016年   52篇
  2015年   36篇
  2014年   58篇
  2013年   89篇
  2012年   110篇
  2011年   128篇
  2010年   93篇
  2009年   83篇
  2008年   84篇
  2007年   75篇
  2006年   53篇
  2005年   47篇
  2004年   36篇
  2003年   46篇
  2002年   39篇
  2001年   32篇
  2000年   34篇
  1999年   21篇
  1998年   29篇
  1997年   18篇
  1996年   25篇
  1995年   11篇
  1994年   10篇
  1993年   11篇
  1992年   5篇
  1991年   6篇
  1990年   7篇
  1989年   6篇
  1988年   3篇
  1987年   5篇
  1986年   3篇
  1985年   3篇
  1984年   2篇
  1983年   3篇
  1982年   3篇
  1981年   4篇
  1980年   2篇
  1977年   2篇
  1976年   7篇
  1969年   1篇
  1967年   1篇
  1966年   1篇
  1959年   1篇
排序方式: 共有1533条查询结果,搜索用时 281 毫秒
61.
This paper deals with algorithms for text localization and character segmentation in images for process automation in the steel-making industry. Each character which comprises slab identification numbers may be corrupted severely before it is captured by network cameras. Therefore, proper processing is required to localize the target texts successfully. In this paper, we propose (1) a method to evaluate the closeness of an edge patch to the form of a closed contour, (2) an edge inspection method to determine character colors and estimate font thickness, and (3) three reasonable binarization methods to increase the performance of the algorithm for the detection of the left and right boundaries of the text rectangle. The experimental results show that the proposed algorithms are reliable.  相似文献   
62.
The solid solution of Pb(Mg,Nb)O3-Pb(Zr,TiO) O3 materials have high piezoelectric constant of 600 ∼650 pC/N and electromechanical coupling coefficient k p of 0.65. Due to such high piezoelectric constant and electromechanical coupling coefficient, Pb(Mg,Nb)O3-Pb(Zr,TiO)O3 materials have been attracted attentions for the applications of multilayer ceramic actuators. Actuators can be produced by staking piezoelectric ceramic materials and inner electrodes, alternatively. However, it is difficult to fabricate huge ceramic actuators without any serious problems during the process conditions. Because ceramic are easily cracked during the sintering process, due to strikingly different shrinkage rate between the ceramic materials and metal electrodes. In this research, new jointing methods will be proposed for huge ceramic actuators, and then their electrical properties were investigated. Time dependent leakage current and impedance spectroscopy were employed to expect device performances.  相似文献   
63.
We reported 94-GHz, low conversion loss, and high isolation single balanced active gate mixer based on 70-nm gate length InGaAs/InAlAs metamorphic high-electron mobility transistors (MHEMTs). This mixer showed that the conversion loss and isolation characteristics were 2.5/spl sim/3.5 dB and under -29 dB in the range of 92.95/spl sim/94.5 GHz, respectively. The low conversion loss of the mixer is mainly attributed to the high-performance of the MHEMTs exhibiting a maximum drain current density of 607 mA/mm, an extrinsic transconductance of 1015 mS/mm, a current gain cutoff frequency (f/sub t/) of 330 GHz, and a maximum oscillation frequency (f/sub max/) of 425 GHz. High isolation characteristics are due to hybrid ring coupler which adopted dielectric-supported air-gapped microstrip line structure using surface micromachined technology. To our knowledge, these results are the best performance demonstrated from 94 GHz single balanced mixer utilizing GaAs-based HEMTs in terms of conversion loss as well as isolation characteristics.  相似文献   
64.
Micromachined jets for liquid impingement cooling of VLSI chips   总被引:2,自引:0,他引:2  
Two-phase microjet impingement cooling is a potential solution for removing heat from high-power VLSI chips. Arrays of microjets promise to achieve more uniform chip temperatures and very high heat transfer coefficients. This paper presents the design and fabrication of single-jets and multijet arrays with circular orifice diameters ranging from 40 to 76 /spl mu/m, as well as integrated heater and temperature sensor test devices. The performance of the microjet heat sinks is studied using the integrated heater device as well as an industry standard 1 cm/sup 2/ thermal test chip. For single-phase, the silicon temperature distribution data are consistent with a model accounting for silicon conduction and fluid advection using convection coefficients in the range from 0.072 to 4.4 W/cm/sup 2/K. For two-phase, the experimental results show a heat removal of up to 90 W on a 1 cm/sup 2/ heated area using a four-jet array with 76 /spl mu/m diameter orifices at a flowrate of 8 ml/min with a temperature rise of 100/spl deg/C. The data indicate convection coefficients are not significantly different from coefficients for pool boiling, which motivates future work on optimizing flowrates and flow regimes. These microjet heat sinks are intended for eventual integration into a closed-loop electroosmotically pumped cooling system.  相似文献   
65.
The decomposition of CHF3 in a mixture with O2 and Ar was investigated in a coaxial dielectric barrier discharge at atmospheric pressure. CHF3 decomposition increased linearly in regard to specific energy input (SEI), whereas energy efficiency decreased. The main product was CO2, and its selectivity increased with high SEI and the presence of O2 in the feed, but an increase of O2 in the feed led to a decrease in decomposition rate. An increase in total flow rate led to an increase of the absolute amount of CHF3 decomposition and energy efficiency; however, the decomposition of CHF3 decreased. A complete CHF3 decomposition occurred under an SEI of 1.54 kJ/L with the selectivity of CO2 and CO as 89.87% and 7.00%, respectively. Optical emission spectroscopic analysis could explain the available reaction pathways for CHF3 decomposition in the CHF3/O2/Ar atmospheric plasma and show the possibility of F2 and HF formation.  相似文献   
66.
67.
A long‐lasting particle‐based fluorescent label is designed for extended cell imaging studies. This onion‐like nanoprobe is constructed through layer‐by‐layer fabrication technology. The nanoprobes are assembled with multiple layers of optically quenched polyelectrolytes, the fluorescence signal of which can be released later by intracellular proteolysis. Upon incubation with cells, the assembled nanoprobes are taken up efficiently. The tight packing and layered assembly of the quenched polyelectrolytes slow subsequent intracellular degradation, and then result in a prolonged intracellular fluorescence signal for up to 3 weeks with no noticeable toxicity.  相似文献   
68.
For elevated temperature design evaluations by the ASME-NH rules, the most important material data is the isochronous stress-strain curves, which can provide design creep information. The main purpose of this paper is to investigate appropriate formulations to be able to generate the isochronous stress-strain curves and implement it to the computer program which is coded the ASME-NH design evaluation procedures. To do this, formulations by the strain-time relationship are investigated in detail and the sensitivity studies for rapid initial transient creep contributions, slower and longer transient creep contribution, and secondary creep contributions are carried out for type 316 austenitic stainless steel. From the results of this study, it is found that the strain-time relationship formulations can well describe the isochronous stress-strain curves with the transient creep contributions.  相似文献   
69.
A continuous screening procedure interchangeably using the performance and surrogate variables is proposed. At the start of the inspection, the performance variable is measured for all items. As soon as i consecutive items are found to be free of defects, the surrogate variable is measured instead of the performance variable. If an item is rejected, the inspection based on the performance variable is resumed. All non-conforming items found in the inspection are either reworked or replaced with conforming items. The average outgoing quality (AOQ) expression is derived, and methods of finding the inspection procedure with a specified average outgoing quality limit (AOQL) are presented.  相似文献   
70.
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-23

京公网安备 11010802026262号