全文获取类型
收费全文 | 8828篇 |
免费 | 1853篇 |
国内免费 | 256篇 |
专业分类
电工技术 | 39篇 |
综合类 | 484篇 |
化学工业 | 1360篇 |
金属工艺 | 493篇 |
机械仪表 | 192篇 |
建筑科学 | 498篇 |
矿业工程 | 1096篇 |
能源动力 | 54篇 |
轻工业 | 428篇 |
水利工程 | 12篇 |
石油天然气 | 60篇 |
武器工业 | 18篇 |
无线电 | 792篇 |
一般工业技术 | 1340篇 |
冶金工业 | 3779篇 |
原子能技术 | 52篇 |
自动化技术 | 240篇 |
出版年
2024年 | 34篇 |
2023年 | 151篇 |
2022年 | 252篇 |
2021年 | 305篇 |
2020年 | 380篇 |
2019年 | 311篇 |
2018年 | 337篇 |
2017年 | 405篇 |
2016年 | 506篇 |
2015年 | 477篇 |
2014年 | 581篇 |
2013年 | 682篇 |
2012年 | 635篇 |
2011年 | 636篇 |
2010年 | 500篇 |
2009年 | 480篇 |
2008年 | 380篇 |
2007年 | 466篇 |
2006年 | 367篇 |
2005年 | 332篇 |
2004年 | 266篇 |
2003年 | 284篇 |
2002年 | 234篇 |
2001年 | 255篇 |
2000年 | 238篇 |
1999年 | 229篇 |
1998年 | 200篇 |
1997年 | 135篇 |
1996年 | 128篇 |
1995年 | 125篇 |
1994年 | 140篇 |
1993年 | 99篇 |
1992年 | 89篇 |
1991年 | 87篇 |
1990年 | 64篇 |
1989年 | 74篇 |
1988年 | 20篇 |
1987年 | 18篇 |
1986年 | 7篇 |
1985年 | 6篇 |
1984年 | 8篇 |
1983年 | 3篇 |
1982年 | 5篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Stefano Mariani Antonino Amedeo La Mattina Alessandro Paghi Lucanos Strambini Giuseppe Barillaro 《Advanced functional materials》2021,31(26):2100774
Here, a fluoride-assisted route for the controlled in-situ synthesis of metal nanoparticles (NPs) (i.e., AgNPs, AuNPs) on polydimethylsiloxane (PDMS) is reported. The size and coverage of the NPs on the PDMS surface are modulated with time and over space during the synthetic process, leveraging the improved yield (10×) and faster kinetics (100×) of NP formation in the presence of F− ions, compared to fluoride-free approaches. This enables the maskless preparation of both linear and step gradients and patterns of NPs in 1D and 2D on the PDMS surface. As an application in flexible plasmonics/photonics, continuous and step-wise spatial modulations of the plasmonic features of PDMS slabs with 1D and 2D AgNP gradients on the surface are demonstrated. An excellent spatially resolved tuning of key optical parameters, namely, optical density from zero to 5 and extinction ratio up to 100 dB, is achieved with AgNP gradients prepared in AgF solution for 12 minutes; the performance are comparable to those of commercial dielectric/interference filters. When used as a rejection filter in optical fluorescence microscopy, the AgNP-PDMS slabs are able to reject the excitation laser at 405 nm and retain the green fluorescence of microbeads (100 µm) used as test cases. 相似文献
2.
3.
4.
5.
以用户为中心的可见光通信协作传输是近年来出现的新架构,这导致虚拟小区之间出现重叠。为避免导频污染问题,每个虚拟小区中的光接入点(AP)或者虚拟小区中选择相同AP的用户发送的训练序列应该是正交的。针对可见光通信中以用户为中心的协作网络,研究训练资源的正交分配问题,提出了一种新的导频分配算法,联合导频分配和用户选择问题,以期最大限度地增加虚拟小区内可被接入的用户数。分析和仿真结果表明,该导频分配方案可以有效改善导频污染问题,提高训练资源利用率,并且相比已有的导频分配方案,性能有所改进。 相似文献
6.
7.
Bart J Kemps Flip R Bamelis Bart De Ketelaere Kristof Mertens Kokou Tona Eddy M Decuypere Josse G De Baerdemaeker 《Journal of the science of food and agriculture》2006,86(9):1399-1406
The objective of this research was to investigate the feasibility of visible transmission spectroscopy for the non‐destructive assessment of the freshness of an individual egg. A total of 600 intact white‐shelled eggs of the same flock (Lohmann, 40 weeks of age) were measured. To obtain a considerable variation in freshness, groups consisting of 60 eggs were stored (18 °C, 55% RH) for 0, 2, 4, 6, 8, 10, 12, 14, 16 and 18 days. The non‐destructive spectral measurements were compared with the two most widely used destructive freshness parameters, namely Haugh units and albumen pH. A partial least squares (PLS1) model was built in order to predict Haugh units and pH of the albumen based on the transmission spectra. The correlation coefficients between the predicted value and the measured value were 0.842 and 0.867 for Haugh unit and pH of the albumen, respectively. These results show that the light transmission spectrum of an egg provides quantitative information about egg freshness. Relevant information concerning egg freshness is restricted to the interval between 570 and 750 nm. Furthermore, the models obtained for both destructive parameters were strikingly similar, indicating that Haugh unit and pH have the same physico‐chemical background. Copyright © 2006 Society of Chemical Industry 相似文献
8.
Removal of gold from basic solutions containing [Au(CN)2]? has been demonstrated using the inherently conducting polymer polypyrrole. Polymers containing sulfonated aromatic dopants have been found to display a significant ability to remove gold from such solutions. Experiments performed in solutions containing both gold and copper cyanide complexes indicate that the recovery process is not highly selective. However, the polypyrroles used display significantly faster rates of gold recovery than activated carbon. © 2003 Society of Chemical Industry 相似文献
9.
10.
低光照和抗晕CCD的设计和制作 总被引:2,自引:1,他引:1
针对帧转移可见光CCD低光照响应、抗电晕能力和动态范围,较详细讨论了CCD光响应灵敏度、动态范围和抗电晕的设计与计算。设计的具有抗晕功能CCD,采用2μm工艺制作,达到了设计技术指标要求,满足了工程应用需求。 相似文献