全文获取类型
收费全文 | 541篇 |
免费 | 13篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 4篇 |
综合类 | 34篇 |
化学工业 | 83篇 |
金属工艺 | 17篇 |
机械仪表 | 18篇 |
建筑科学 | 91篇 |
矿业工程 | 10篇 |
能源动力 | 19篇 |
轻工业 | 179篇 |
水利工程 | 2篇 |
石油天然气 | 6篇 |
武器工业 | 4篇 |
无线电 | 11篇 |
一般工业技术 | 30篇 |
冶金工业 | 12篇 |
原子能技术 | 4篇 |
自动化技术 | 33篇 |
出版年
2024年 | 2篇 |
2023年 | 4篇 |
2022年 | 5篇 |
2021年 | 9篇 |
2020年 | 10篇 |
2019年 | 9篇 |
2018年 | 11篇 |
2017年 | 8篇 |
2016年 | 12篇 |
2015年 | 13篇 |
2014年 | 42篇 |
2013年 | 42篇 |
2012年 | 39篇 |
2011年 | 43篇 |
2010年 | 31篇 |
2009年 | 28篇 |
2008年 | 34篇 |
2007年 | 41篇 |
2006年 | 34篇 |
2005年 | 22篇 |
2004年 | 18篇 |
2003年 | 16篇 |
2002年 | 17篇 |
2001年 | 9篇 |
2000年 | 11篇 |
1999年 | 7篇 |
1998年 | 5篇 |
1997年 | 9篇 |
1996年 | 6篇 |
1995年 | 6篇 |
1994年 | 5篇 |
1993年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1986年 | 2篇 |
排序方式: 共有557条查询结果,搜索用时 0 毫秒
1.
The origin of magnetoconductance (MC) in organic light-emitting diodes under bipolar injection conditions was investigated using devices containing pristine Super-Yellow poly(phenylene vinylene) (SY-PPV) or SY-PPV:phenyl-C61-butyric acid methyl ester (PCBM) (x wt%) blends as the active layers. In pristine SY-PPV device, it was found that the low-field component of MC was always larger than the high-field component. Additionally, the low-field component increased and then saturated with increasing the electrical stressing time, whereas the high-field component remained unchanged. These behaviors were analyzed using empirical formula (containing a Lorentzian and a non-Lorentzian function), which suggested that the dominant mechanism in the MC response was hyperfine mixing between single and triplet polaron pairs that occurred on trap sites. The specific role of these traps, providing interaction sites for hyperfine mixing, was confirmed by controlling the lifetime of the trapped polaron-pairs states by doping the active layer with PCBM. 相似文献
2.
本文主要讨论了剩余类环Z/(m)上线性递归序列的周期,计数,分布以及与其相关联的Z/(m)[x]中多项式的有关问题。 相似文献
3.
Natural plant fibre composites have been developed for the production of a variety of industrial products, with benefits including biodegradability and environmental protection. Bamboo fibre materials have attracted broad attention as reinforcement polymer composites due to their environmental sustainability, mechanical properties, and recyclability, and they can be compared with glass fibres. This review classifies and describes the various procedures that have been developed to extract fibres from raw bamboo culm. There are three main types of procedures: mechanical, chemical and combined mechanical and chemical extraction. Composite preparation from extracted bamboo fibres and various thermal analysis methods are also classified and analysed. Many parameters affect the mechanical properties and composite characteristics of bamboo fibres and bamboo composites, including fibre extraction methods, fibre length, fibre size, resin application, temperature, moisture content and composite preparation techniques. Mechanical extraction methods are more eco-friendly than chemical methods, and steam explosion and chemical methods significantly affect the microstructure of bamboo fibres. The development of bamboo fibre-reinforced composites and interfacial adhesion fabrication techniques must consider the type of matrix, the microstructure of bamboo and fibre extraction methods. 相似文献
4.
Jiong Zheng Fusheng Zhang Jiaxin Song Mao Lin Jianquan Kan 《International Journal of Food Science & Technology》2014,49(2):531-540
The enzymes activity, texture, pectin, microstructure and colour change in bamboo shoots (Dendrocalamus latiflorus) were examined to evaluate the effect of blanching and drying treatments on quality of bamboo shoot slices (BSS). Peroxidase (POD), phenylalanine ammonia‐lyase and polyphenol oxidase in BSS will become completely inactive at 95 °C for 6‐, 9‐ and 12‐min blanching treatments, respectively. The hardness and protopectin (PP) content decreased after the blanching treatment. Meanwhile, the content of water‐soluble pectin increased initially and then decreased gradually during the blanching. After the blanching treatment, the L* and a* of BSS decreased, while b* increased, ΔE > 2. The hardness of rehydrated BSS decreased by 43.57% after freeze drying (FD), which, however, decreased more after hot air drying (HAD). The pectin of rehydrated BSS was also determined to explain the hardness change in BSS. The BSS acquired similar microstructure of fresh samples after FD, while microstructure of BSS was severely damaged after HAD. The colour of BSS changes significantly after drying treatment. However, FD can maintain better colour of BSS than HAD. The results may provide a reference for industrial production of BSS. 相似文献
5.
6.
探讨竹浆纤维赛络纺纱的生产工艺。针对竹浆纤维的性能特点,通过对原料进行预处理,优选各工序工艺参数,实现了提高产品质量的目的。开清棉工序多松少打、尽量少落、慢车速,以减少对纤维的损伤;梳棉中大定量、低速度、小张力,以利于成网;并条头并、二并均采用6根喂入,减少总牵伸倍数,以减少棉结的产生;粗纱工序重加压、大隔距、轻定量、低车速、小张力、大捻度,以改善粗纱条干不匀;细纱工序采用喇叭口两眼距离为3.0 mm的双喇叭口,优选牵伸工艺及胶辊、上销、钢领、钢丝圈等配件,以降低管纱毛羽。通过采取以上措施,使所纺制的竹浆纤维14.8 tex赛络纺针织纱成纱质量达到了使用要求。 相似文献
7.
8.
9.
10.