全文获取类型
收费全文 | 665篇 |
免费 | 21篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 6篇 |
综合类 | 5篇 |
化学工业 | 186篇 |
金属工艺 | 10篇 |
机械仪表 | 7篇 |
建筑科学 | 8篇 |
矿业工程 | 1篇 |
能源动力 | 30篇 |
轻工业 | 53篇 |
水利工程 | 3篇 |
石油天然气 | 2篇 |
无线电 | 73篇 |
一般工业技术 | 150篇 |
冶金工业 | 57篇 |
原子能技术 | 8篇 |
自动化技术 | 89篇 |
出版年
2024年 | 3篇 |
2023年 | 19篇 |
2022年 | 38篇 |
2021年 | 33篇 |
2020年 | 37篇 |
2019年 | 30篇 |
2018年 | 48篇 |
2017年 | 30篇 |
2016年 | 20篇 |
2015年 | 7篇 |
2014年 | 25篇 |
2013年 | 39篇 |
2012年 | 30篇 |
2011年 | 44篇 |
2010年 | 22篇 |
2009年 | 35篇 |
2008年 | 25篇 |
2007年 | 21篇 |
2006年 | 10篇 |
2005年 | 9篇 |
2004年 | 8篇 |
2003年 | 15篇 |
2002年 | 11篇 |
2001年 | 7篇 |
2000年 | 4篇 |
1999年 | 5篇 |
1998年 | 14篇 |
1997年 | 11篇 |
1996年 | 9篇 |
1995年 | 10篇 |
1994年 | 6篇 |
1993年 | 10篇 |
1992年 | 5篇 |
1991年 | 4篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1988年 | 4篇 |
1987年 | 4篇 |
1986年 | 4篇 |
1985年 | 7篇 |
1984年 | 6篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1971年 | 1篇 |
排序方式: 共有688条查询结果,搜索用时 78 毫秒
1.
Wireless Networks - Spectrum handoff has an undesirable effect in utilizing the space for Secondary user (SU) in the spectrum, which causes a handoff delay in cognitive radio network. The SU... 相似文献
2.
Bhupendra Singh Nitika Devi Lakshya Mathur Rajesh K. Singh Aman Bhardwaj Sun-Ju Song Dirk Henkensmeier 《Ceramics International》2018,44(6):6170-6175
In the present work, we report a method of fabrication of dense 10 mol% Mg2+-doped cerium pyrophosphate-phosphate (Ce0.9Mg0.1P2O7-PmOn; CMP-P) composites by microwave heat-treatment of the preformed Ce0.9Mg0.1P2O7 substrates in the presence of phosphoric acid. The composite was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). The microwave heating at 375 °C for 5 min resulted in the formation of dense CMP-P composites which retained most of the pyrophosphate phase. The electrical conductivity was extracted from the EIS data and for the CMP-P composite prepared by H3PO4 loading for 10 h and microwave heat-treatment for 5 min it was found to be >10?2 S m?1 in 100–250 °C range with a maximum of 0.062 S cm?1 at 190 °C, which was significant for its application as electrolyte in intermediate temperature fuel cells. 相似文献
3.
Kalavathi Devi T. Priyanka E. B. Sakthivel P. Stephen Sagayaraj A. 《Analog Integrated Circuits and Signal Processing》2021,109(3):487-499
Analog Integrated Circuits and Signal Processing - Remarkable progress in the field of wireless communication has created a research interest for Viterbi decoder with long duration of battery life,... 相似文献
4.
5.
6.
Twitter, the social network which evolving faster and regular usage by millions of people and who become addicted to it. So spam playing a major role for Twitter users to distract them and grab their attention over them. Spammers actually detailed like who send unwanted and irrelevant messages or websites and promote them to several users. To overcome the problem many researchers proposed some ideas using some machine learning algorithms to detect the spammers. In this research work, a new hybrid approach is proposed to detect the streaming of Twitter spam in a real-time using the combination of a Decision tree, Particle Swarm Optimization and Genetic algorithm. Twitter has given access to the researchers to get tweets from its Twitter-API for real-time streaming of tweet data which they can get direct access to public tweets. Here 600 million tweets are created by using URL based security tool and further some features are extracted for representation of tweets in real-time detection of spam. In addition, our research results are compared with other hybrid algorithms which a better detection rate is given by our proposed work. 相似文献
7.
Multimedia Tools and Applications - Recently, the attention mechanism has been effectively implemented in convolutional neural networks to boost performance of several computer vision tasks.... 相似文献
8.
An attempt is made to examine the effect of hybrid nanocoolant in microchannel heat sink for computer cooling.Two-hybrid coolants with graphene as one of the prime components are synthesized and images of the particles are shown using scanning electron microscopy(SEM) and transmission electron microscopy(TEM). Heat transfer properties like thermal conductivity of the hybrid fluid, specific heat, density, and viscosity are evaluated experimentally and theoretically. The heat transfer characteristics are also studied in heat sink channels of micro level in the processors of personal computers. The parameters like internal heat transfer coefficient, thermal resistances and base temperature representing the processor temperature are examined for the applied heater power of 325 W. The coolant dilution was varied in the range of 0.05 vol%, 0.075 vol% and 0.1 vol% and the base temperature is noted. The recorded lowest base temperature is 310.01 K for the concentration of 0.1 vol%graphene-iron oxide(GFO) system for 0.5 mm fin spacing for the graphene-iron oxide hybrid coolant and for graphene oxide–iron oxide(GOFO) hybrid coolant it is 311.24 K for the same operating conditions. 相似文献
9.
Europium doped calcium orthosilicate (Ca2SiO4) phosphors have been synthesized by the conventional high temperature solid-state reaction method in various concentrations from agricultural waste (egg shell as a CaO and rice husk as a SiO2). These phosphors structure from X-ray diffraction and morphology from scanning electron microscopy have been examined. Concentration dependent Eu3+ ions luminescent properties in Ca2SiO4 phosphors have been studied from the excitation, emission and decay curves analysis. The 5D0 → 7FJ transitions observed in luminescence spectrum allows to determine the site symmetry of the Eu3+ ion. A charge transfer band (CTB) at around 260?nm which is due to the Eu–O interaction in the host along with the 4f – 4f excitation bands due to Eu3+ ions in UV and blue regions are observed. The color co-ordinates determined from emission spectra varies with concentrations of Eu3+ ions and are found to fall in the red region. The decay curves show single exponential behavior for all concentrations of Eu3+ ions (0.01–0.4?mol%) and the lifetimes varied from 2.67 to 2.78?ms. It is worth noting that the present material is found to be far better than many red phosphors synthesized by using agricultural waste as raw materials. 相似文献
10.
Mishra Devi Prasad Panigrahi Durga Charan Kumar Pradeep Kumar Abhijeet Sinha Pritam Kumar 《Neural computing & applications》2021,33(1):181-190
Neural Computing and Applications - Dispersing methane to a safer level is crucial for mines safety as methane has been the greatest contributor of explosion hazard in underground coal mines... 相似文献