Author Keywords: Radiation detection; Long-lasting phosphor; Luminescence; Temperature dependence; Fade-out effect 相似文献
全文获取类型
收费全文 | 49181篇 |
免费 | 8500篇 |
国内免费 | 5153篇 |
专业分类
电工技术 | 4603篇 |
技术理论 | 2篇 |
综合类 | 4316篇 |
化学工业 | 1938篇 |
金属工艺 | 981篇 |
机械仪表 | 3528篇 |
建筑科学 | 1900篇 |
矿业工程 | 958篇 |
能源动力 | 402篇 |
轻工业 | 4552篇 |
水利工程 | 420篇 |
石油天然气 | 1020篇 |
武器工业 | 773篇 |
无线电 | 11189篇 |
一般工业技术 | 3223篇 |
冶金工业 | 724篇 |
原子能技术 | 482篇 |
自动化技术 | 21823篇 |
出版年
2024年 | 544篇 |
2023年 | 1490篇 |
2022年 | 2416篇 |
2021年 | 2615篇 |
2020年 | 2546篇 |
2019年 | 1967篇 |
2018年 | 1678篇 |
2017年 | 2167篇 |
2016年 | 2291篇 |
2015年 | 2597篇 |
2014年 | 3977篇 |
2013年 | 3416篇 |
2012年 | 4161篇 |
2011年 | 4367篇 |
2010年 | 3282篇 |
2009年 | 3235篇 |
2008年 | 3272篇 |
2007年 | 3532篇 |
2006年 | 2830篇 |
2005年 | 2370篇 |
2004年 | 1759篇 |
2003年 | 1444篇 |
2002年 | 1070篇 |
2001年 | 736篇 |
2000年 | 601篇 |
1999年 | 462篇 |
1998年 | 395篇 |
1997年 | 285篇 |
1996年 | 278篇 |
1995年 | 194篇 |
1994年 | 133篇 |
1993年 | 116篇 |
1992年 | 113篇 |
1991年 | 100篇 |
1990年 | 79篇 |
1989年 | 38篇 |
1988年 | 47篇 |
1987年 | 24篇 |
1986年 | 31篇 |
1985年 | 28篇 |
1984年 | 25篇 |
1983年 | 23篇 |
1982年 | 17篇 |
1981年 | 20篇 |
1980年 | 17篇 |
1979年 | 7篇 |
1978年 | 6篇 |
1976年 | 4篇 |
1975年 | 4篇 |
1951年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Chia-Jung Pai Author Vitae Author Vitae Yu-Ming Liang Author Vitae Author Vitae Sei-Wang Chen Author Vitae 《Pattern recognition》2004,37(5):1025-1034
This paper presents a system that can perform pedestrian detection and tracking using vision-based techniques. A very important issue in the field of intelligent transportation system is to prevent pedestrians from being hit by vehicles. Recently, a great number of vision-based techniques have been proposed for this purpose. In this paper, we propose a vision-based method, which combines the use of a pedestrian model as well as the walking rhythm of pedestrians to detect and track walking pedestrians. Through integrating some spatial and temporal information grabbed by a vision system, we are able to develop a reliable system that can be used to prevent traffic accidents happened at crossroads. In addition, the proposed system can deal with the occlusion problem. Experimental results obtained by executing some real world cases have demonstrated that the proposed system is indeed superb. 相似文献
32.
V. Rodin Author Vitae A. Benzinou Author VitaeAuthor Vitae P. Ballet Author VitaeAuthor Vitae J. Tisseau Author VitaeAuthor Vitae 《Pattern recognition》2004,37(4):631-645
In this article, we present a parallel image processing system based on the concept of reactive agents. Our system lies in the oRis language, which allows to describe finely and simply the agents’ behaviors to detect image features. We also present a method of segmentation using a multi-agent system, and two biological applications made with oRis. The stopping of this multi-agent system is implemented through a technique issued from immunology: the apoptosis. 相似文献
33.
Kernel Spectral Matched Filter for Hyperspectral Imagery 总被引:1,自引:0,他引:1
In this paper a kernel-based nonlinear spectral matched filter is introduced for target detection in hyperspectral imagery,
which is implemented by using the ideas in kernel-based learning theory. A spectral matched filter is defined in a feature
space of high dimensionality, which is implicitly generated by a nonlinear mapping associated with a kernel function. A kernel
version of the matched filter is derived by expressing the spectral matched filter in terms of the vector dot products form
and replacing each dot product with a kernel function using the so called kernel trick property of the Mercer kernels. The proposed kernel spectral matched filter is equivalent to a nonlinear matched filter in the original input space,
which is capable of generating nonlinear decision boundaries. The kernel version of the linear spectral matched filter is
implemented and simulation results on hyperspectral imagery show that the kernel spectral matched filter outperforms the conventional
linear matched filter. 相似文献
34.
应用功率控制、波束赋形和多用户检测可以有效地消除和减少CDMA系统中的干扰。本文结合波束赋形和多用户检测的特性,提出一种应用波束赋形增益和多用户相关矩阵的解相关算法。基于算法的复杂性,提出一种区分聚集用户进行多用户检测的的算法。由于波束赋形能够消减主瓣波束之外的多用户干扰,对聚集移动台采用解相关检测达到减少运算量和消除多用户干扰的目的。对算法进行了仿真分析,证明了本算法的优越性。 相似文献
35.
Abstract: This paper presents a novelty detection-based technique to identify core material properties of honeycombs and cellular structures. A numerical model (finite element) representing full scale and/or reduced size of the cellular solid is used to generate transmissibilities between topological homologous points at cells in different locations. In order to make the procedure robust against noise, these transmissibilities are artificially corrupted. This step is representative of a series of experimentally obtained measurements which automatically return information relating to the size and shape of data noise along with the mean measurement. The next stage, both in this paper and in the proposal for the experimental approach, is to generate several further sets of transmissibilities from the finite element model; the only difference being that the core material properties are altered from the original values. A novelty detection framework is then adopted to find a similarity measure between each of these 'test' transmissibilities and the original set thereby identifying the material properties. Although this work is concerned with identifying only one material property, the methodology extends to identifying several properties. 相似文献
36.
电梯门机控制系统的运行曲线设计 总被引:1,自引:0,他引:1
为了实现电梯轿厢门的开门和关门快速且平稳地运行,介绍了一种基于高性能微型机的门机控制系统结构和门位移的检测原理,以门位移量作为控制系统的反馈量,对门机运行速度进行了分区设计。在高速附近的变化区,门机速度匀速变化时,进行了门机开门和关门控制曲线的计算,推导出运行位移与门机速度具有二次曲线的关系,进而对微型机控制的软件流程进行了设计,达到了门机高低速运行的平稳过渡。最后,给出了实际运行系统的主电路电压波形。 相似文献
37.
38.
Munehiko Kowatari Daisuke Koyama Yoshiyuki Satoh Kouichi Iinuma Shunsuke Uchida 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2002,480(2-3):431-439
The temperature dependence of luminescence from a long-lasting phosphor (LLP), SrAl2O4 : Eu2+,Dy3+, exposed to ionizing radiation has been measured to understand the LLP luminescence mechanism. Evaluation of the decay constants of the LLP exposed to -, β- or γ-rays at temperatures from 200 to 390 K showed that the decay constant is divided into four components ranging from 10−4 to 10−1 s−1 with activation energies of 0.02–0.35 eV.
Total luminous intensity from the LLP with changing irradiation temperature has its maximum value around the room temperature. Irradiation at elevated temperature (390 K) has the total luminescence pattern with monotonous decrease as temperature rises. As a result of evaluating the temperature dependence of luminescence, the luminescence mechanism is considered as follows:
39.
R. GRAY† M. HILARY STEVENSON‡ 《International Journal of Food Science & Technology》1991,26(6):669-672
One hundred and twenty-five pairs of chicken drumsticks were randomly allocated to one of five dose rates: 5, 10, 15, 20 or 600 kGyh-. The highest dose rate was obtained using a linear accelerator whilst the remaining dose rates were provided using a 60 Co gamma source. Each batch of 25 pairs was further divided into groups five of which were stored at 4°C for 0, 7, 14, 21 or 28 days. ESR spectroscopy was used to measure the intensity of the radiation-induced signal. There was a quadratic relationship between ESR signal strength and dose rate, which although statistically significant is unlikely to be of practical importance. The magnitude of the ESR signal declined by about 20% over the first 14 days of storage at 4°C and thereafter the decrease was minimal. 相似文献
40.
J. Balakrishnan W. A. Sethares C. R. Johnson 《International Journal of Adaptive Control and Signal Processing》2002,16(4):309-323
A method of approximate channel identification is proposed that is based on a simplification of the correlation estimator. Despite the numerical simplification (no multiplications or additions are required, only comparisons and an accumulator), the performance of the proposed estimator is not significantly worse than that of the standard correlation estimator. A free (user selectable) parameter moves ‘smoothly’ from a situation with small sum‐squared channel estimation error but hard‐to‐identify channel peaks, to one with a larger sum‐squared estimation error but easy‐to‐identify channel peaks. The proposed estimator is shown to be biased and its behaviour is analysed in a number of situations. Applications of the proposed estimator to sparsity detection, symbol timing recovery and to the initialization of blind equalizers are suggested. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献