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   384篇
  免费   17篇
  国内免费   3篇
电工技术   4篇
综合类   4篇
化学工业   72篇
金属工艺   7篇
机械仪表   19篇
建筑科学   12篇
矿业工程   3篇
能源动力   26篇
轻工业   39篇
水利工程   6篇
无线电   44篇
一般工业技术   59篇
冶金工业   17篇
原子能技术   18篇
自动化技术   74篇
  2024年   1篇
  2023年   10篇
  2022年   34篇
  2021年   39篇
  2020年   28篇
  2019年   30篇
  2018年   37篇
  2017年   15篇
  2016年   25篇
  2015年   17篇
  2014年   17篇
  2013年   24篇
  2012年   18篇
  2011年   10篇
  2010年   15篇
  2009年   18篇
  2008年   15篇
  2007年   12篇
  2006年   8篇
  2005年   3篇
  2004年   1篇
  2003年   1篇
  2002年   3篇
  2001年   1篇
  2000年   1篇
  1999年   2篇
  1998年   3篇
  1997年   3篇
  1996年   3篇
  1995年   1篇
  1994年   1篇
  1993年   1篇
  1992年   1篇
  1991年   3篇
  1985年   1篇
  1983年   1篇
  1977年   1篇
排序方式: 共有404条查询结果,搜索用时 0 毫秒
131.
Conducting polymers represent a promising platform toward coating materials for implant technologies in recent years. In this investigation, copolymers based on pyrrole (Py) and 3,4-ethylenedioxythiophene (EDOT) were electrodeposited on 316L SS with various feed ratio of Py/EDOT through cyclic voltammetric technique. The surface and chemical structure of the synthesized copolymers were analyzed by SEM, AFM, FT-IR, and 1H NMR spectroscopic analysis. The influence of comonomer feed ratio on electrochemical corrosion behavior was investigated in stimulated body fluid. A significant lower corrosion current with nobler shift in corrosion potential and higher charge transfer resistance values of copolymer-coated 316L SS were obtained and the comparisons were made with uncoated as well as their homo polymers. Furthermore, in vitro cell culture studies were performed on MG63 osteoblast human cells to confirm the biocompatibility of copolymer coatings. Quantum chemical approach was employed to verify the obtained experimental outcomes. As a result of this investigation, it was concluded that the performance of coatings was strongly dependent to the monomer feed ratio and the copolymer synthesized with 50:50 feed ratio showed high corrosion protection efficiency with improved cell growth on MG63 osteoblast cell.  相似文献   
132.
The effects of using high density low enriched uranium on the dynamics of a material test research reactor were studied. For this purpose, the low density LEU fuel of an MTR was replaced with high density LEU fuels currently being developed under the RERTR program. Since the alloying elements have different properties affecting the reactor in different ways, fuels U–Mo (9w/o) which contain the same elements in same ratio were selected for analysis. Simulations were carried out to determine the reactor performance under reactivity insertion and loss of flow transients. Nuclear reactor analysis code PARET was employed to carry out these calculations. It is observed that during the fast reactivity insertion transient, the maximum reactor power is achieved and the energy released till the power reaches its maximum increases by 45% and 18.5%, respectively, as uranium density increases from 6.57 gU/cm3 to 8.90 gU/cm3. This results in increased maximum temperatures of fuel, clad and coolant outlet, achieved during the transient, by 27.7 K, 19.7 K and 7.9 K, respectively. The time required to reach the peak power decreases. During the slow reactivity insertion transient, the maximum reactor power achieved increases slightly by 0.3% as uranium density increases from 6.57 gU/cm3 to 8.90 gU/cm3 but the energy generated till the power reaches its maximum decreases by 5.7%. The temperatures of fuel, clad and coolant outlet remain almost the same for all types of fuels. During the loss of flow transients, no appreciable difference in the power and temperature profiles was observed and the graph plots overlapped each other.  相似文献   
133.
In the present study, an attempt is made to enhance the performance of heat pump by utilizing two types of nanofluids namely, copper and alumina nanofluids. These nanofluids were employed around the evaporator coil of the heat pump. The nanofluids were used to enhance the heat input to the system by means of providing an external jacket around the evaporator coil. Both the nanofluids were prepared in three volume fractions 1%, 2% and 5%. Water was chosen as the base fluid. The performance of the heat pump was assessed by calculating the coefficient of performance of the system when it was operated with and without nanofluid jacket. A significant enhancement in the coefficient of performance was noticed when copper and alumina nanofluids were employed in the system. Also, the coefficient of performance was found to have a direct relationship with the tested volume fractions. For the highest volume fraction of 5%, the performance of the heat pump was found to enhance by 23% with alumina nanofluid, while for copper nanofluid, a very significant enhancement in performance by 72% was observed. Thus, utilizing of nanofluids in heat pumps can be very beneficial towards performance enhancement and the idea can also be extended to other thermal systems such as steam power plant, automobile radiator, industrial heat exchangers and refrigeration systems.  相似文献   
134.
This paper explores the effect of electrodeposition time on microstructure, optical, and photoelectrochemical properties of CuO films. CuO films were electrochemically deposited on tin-doped indium oxide (ITO) substrates using a Cu2O electrodeposition method followed by annealing at 550 °C for 2 h. The electrochemical deposition was carried out at different times (300, 600, 1200, and 1800 s) utilizing a copper sulfate pentahydrate and lactic acid solution. X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) were used to perform phase and microstructure analysis. Photoluminescence (PL) studies confirmed an increase in emission intensities with increasing deposition time. In addition, a significant change was observed in photoelectrochemical properties of the film by varying the deposition time. The film deposited for 600 s showed a high photocurrent density of ?0.55 mA cm?2 at ?0.5 V. Moreover, a lowest resistance from electrochemical impedance spectroscopy (EIS) was recorded for the films electrochemically deposited for 600 s.  相似文献   
135.
Chen  Jiongwei  Jin  Yi  Akram  Muhammad Waqar  Li  Kuan  Chen  Enhong 《Multimedia Tools and Applications》2019,78(12):15887-15907
Multimedia Tools and Applications - The smile is one of the most common human facial expressions encountered in our daily lives. Smile recognition can be used in many scenarios, such as emotion...  相似文献   
136.
Multimedia Tools and Applications - We propose a novel automatic photographic painting style technique with a single example image by using Convolutional Neural Networks (CNN). The photographic...  相似文献   
137.

With the popularity of software-defined radio and cognitive radio-technologies in wireless communication, radio frequency devices have to adapt to changing conditions and adjust its transmitting parameters such as transmitting power, operating frequency, and modulation schemes. Thus, automatic modulation classification becomes an essential feature for such scenarios where the receiver has a little or no knowledge about the transmitter parameters. This paper presents kth nearest neighbor (KNN)-based classification of M-QAM and M-PSK modulation schemes using higher-order cumulants as input features set. Genetic programming is used to enhance the performance of the KNN classifier by creating super features from the data set. Simulation result shows improved accuracy at comparatively lower signal-to-noise ratio for all the considered modulations.

  相似文献   
138.
139.
Water Resources Management - Increased groundwater accessibility resulting from the expansion of deep and shallow tube wells helped Bangladesh attain near self-sufficiency in rice, with national...  相似文献   
140.
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