全文获取类型
收费全文 | 506篇 |
免费 | 21篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 1篇 |
综合类 | 1篇 |
化学工业 | 86篇 |
金属工艺 | 11篇 |
机械仪表 | 64篇 |
建筑科学 | 24篇 |
矿业工程 | 1篇 |
能源动力 | 7篇 |
轻工业 | 175篇 |
无线电 | 15篇 |
一般工业技术 | 67篇 |
冶金工业 | 10篇 |
原子能技术 | 1篇 |
自动化技术 | 66篇 |
出版年
2024年 | 1篇 |
2023年 | 7篇 |
2022年 | 20篇 |
2021年 | 16篇 |
2020年 | 12篇 |
2019年 | 13篇 |
2018年 | 8篇 |
2017年 | 12篇 |
2016年 | 15篇 |
2015年 | 11篇 |
2014年 | 15篇 |
2013年 | 116篇 |
2012年 | 47篇 |
2011年 | 46篇 |
2010年 | 36篇 |
2009年 | 15篇 |
2008年 | 21篇 |
2007年 | 13篇 |
2006年 | 15篇 |
2005年 | 17篇 |
2004年 | 6篇 |
2003年 | 10篇 |
2002年 | 14篇 |
2001年 | 5篇 |
2000年 | 1篇 |
1999年 | 5篇 |
1998年 | 2篇 |
1997年 | 4篇 |
1996年 | 4篇 |
1995年 | 5篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 3篇 |
1981年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有529条查询结果,搜索用时 15 毫秒
1.
2.
3.
We analyze the classic board game of Mastermind with n holes and a constant number of colors. The classic result of Chvátal (Combinatorica 3:325–329, 1983) states that the codebreaker can find the secret code with Θ(n/logn) questions. We show that this bound remains valid if the codebreaker may only store a constant number of guesses and answers. In addition to an intrinsic interest in this question, our result also disproves a conjecture of Droste, Jansen, and Wegener (Theory Comput. Syst. 39:525–544, 2006) on the memory-restricted black-box complexity of the OneMax function class. 相似文献
4.
5.
Prediction of parking space availability in real time 总被引:1,自引:0,他引:1
Intelligent parking reservation (IPR) systems allow customers to select a parking facility according to their preferences, rapidly park their vehicle without searching for a free stall, and pay their reservation in advance avoiding queues. Some IPR systems interact with in-vehicle navigation systems and provide users with information in real time such as capacity, parking fee, and current parking utilization. However, few of these systems provide information on the forecast utilization at specific hours - a process that requires the study of the competition between parking alternatives for the market share. This paper proposes a methodology for predicting real-time parking space availability in IPR architectures. This methodology consists of three subroutines to allocate simulated parking requests, estimate future departures, and forecast parking availability. Parking requests are allocated iteratively using an aggregated approach as a function of simulated drivers’ preferences, and parking availability. This approach is based on a calibrated discrete choice model for selecting parking alternatives. A numerical comparison between a one-by-one simulation-based forecast and the proposed aggregated approach indicates that no significant discrepancies exists, validating and suggesting the use of the less time consuming proposed aggregated methodology. Results obtained from contrasting predictions with real data yielded small average error availabilities. The forecast improves as the system registers arrivals and departures. Thus, the forecast is adequate for potential distribution in real-time using different media such as Internet, navigation systems, cell phones or GIS. 相似文献
6.
J. T. TIAN J. M. MOLINA J. NARCISO C. GARCÍA-CORDOVILLA E. LOUIS 《Journal of Materials Science》2005,40(9-10):2537-2540
Oxidizing SiC particles is a common practice in the fabrication of SiC/Al composites through direct mixing of the liquid metal and the ceramic particles. This practice is addressed to reduce the reaction between the two materials. In a previous work it was concluded that oxidizing SiC particles scarcely affected the threshold pressure for infiltration of pure Al into compacts made of those particles. In this work we present a detailed study of this problem for infiltration of pure Al and the eutectic Al-Si alloy. Our results indicate that oxidizing of SiC particles does not affect significantly either the threshold pressure or the infiltration kinetics. This conclusion is equally valid for both pure Al and the eutectic alloy. 相似文献
7.
8.
ABSTRACT
Over two subsequent seasons, emission of volatile compounds, consumer acceptability and quality parameters were analyzed in “Fuji” apples. In both seasons, apples were harvested at the same maturity stage and stored for 19 or 30 weeks at 1C and 92% relative humidity under an ultralow oxygen (ULO) atmosphere (1% O2 + 1% CO2) or under an ULO atmosphere followed by different periods (2 or 4 weeks) in cold air. The results revealed, for both seasons, that 4 weeks of cold air storage after ULO storage helped to increase the emission of some volatile compounds for both storage period, including characteristic volatile compounds for the variety, and did not have a negative effect on quality parameters. Additionally, the consumer acceptability was superior for those fruits.PRACTICAL APPLICATIONS
It is well known for various apple varieties that long‐term storage under ULO conditions reduces volatile production resulting in poor flavor and aroma compared with fruits stored in air. Consequently, there is often dissatisfaction among consumers with the flavor of fruits which have been subjected to cold storage. The strategy that is proposed in the present work could be recommended to enhance the aromatic quality of fruit provided by the apple industry and, in consequence, increase its acceptability by consumers. 相似文献9.
10.
Everton Barbosa Nunes Nathália Escóssio Cavalcante Alexandre Sousa Barreto Antônio Ítalo Neves da Silva Marcelo Ferreira Motta 《Welding International》2017,31(3):173-183
Plasma powder surfacing is one of the latest processes for application of coatings, with control of dilution as its main feature. Surfacing with superduplex stainless steels is an interesting option for the construction and repair of equipment for applications in a highly corrosive environment, allowing the desired characteristics to be achieved: corrosion resistance and good mechanical properties. The aim of this work is to assess the ferrite content in the weld metal and the mechanical characteristics via microhardness profiles in surfacing of C-Mn steel pipes with deposition of UNS S32760 by plasma powder surfacing. Welding operations were carried out on pipes with deposition of SDSS, employing three welding heat input levels, varying the welding speed or the welding current. Then the geometry was analysed, the ferrite content in the weld metal was quantified and the microhardness profile was recorded. Variation in welding heat input caused changes in weld bead geometry, with variation in the welding current producing the most significant changes. Increase in heat input caused decrease in ferrite content of the weld metal. Regarding microhardness, only the condition with a higher level of welding current gave sufficiently high levels of microhardness in the weld metal. 相似文献