全文获取类型
收费全文 | 436991篇 |
免费 | 7333篇 |
国内免费 | 1395篇 |
专业分类
电工技术 | 7803篇 |
综合类 | 345篇 |
化学工业 | 66005篇 |
金属工艺 | 17004篇 |
机械仪表 | 14122篇 |
建筑科学 | 9443篇 |
矿业工程 | 2217篇 |
能源动力 | 12214篇 |
轻工业 | 33052篇 |
水利工程 | 4574篇 |
石油天然气 | 8041篇 |
武器工业 | 21篇 |
无线电 | 51230篇 |
一般工业技术 | 88944篇 |
冶金工业 | 83361篇 |
原子能技术 | 9325篇 |
自动化技术 | 38018篇 |
出版年
2022年 | 2848篇 |
2021年 | 4632篇 |
2020年 | 3546篇 |
2019年 | 4385篇 |
2018年 | 7780篇 |
2017年 | 7742篇 |
2016年 | 8262篇 |
2015年 | 5246篇 |
2014年 | 8327篇 |
2013年 | 22349篇 |
2012年 | 13390篇 |
2011年 | 17090篇 |
2010年 | 13640篇 |
2009年 | 14998篇 |
2008年 | 15578篇 |
2007年 | 15120篇 |
2006年 | 13425篇 |
2005年 | 11956篇 |
2004年 | 11282篇 |
2003年 | 11114篇 |
2002年 | 10422篇 |
2001年 | 10119篇 |
2000年 | 9530篇 |
1999年 | 9999篇 |
1998年 | 26931篇 |
1997年 | 18293篇 |
1996年 | 13832篇 |
1995年 | 10146篇 |
1994年 | 8907篇 |
1993年 | 8904篇 |
1992年 | 6226篇 |
1991年 | 5883篇 |
1990年 | 5871篇 |
1989年 | 5505篇 |
1988年 | 5208篇 |
1987年 | 4563篇 |
1986年 | 4462篇 |
1985年 | 5002篇 |
1984年 | 4586篇 |
1983年 | 4116篇 |
1982年 | 3802篇 |
1981年 | 3886篇 |
1980年 | 3568篇 |
1979年 | 3443篇 |
1978年 | 3432篇 |
1977年 | 3920篇 |
1976年 | 5227篇 |
1975年 | 2926篇 |
1974年 | 2727篇 |
1973年 | 2800篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
Lucas Portela Oliveira Camila Cristina de Foggi Bruna Natália Alves da Silva Pimentel Marcelo Assis Juan Andrés Elson Longo Carlos Eduardo Vergani 《Ceramics International》2021,47(16):22604-22614
The present study reports for the first time the performance of silver phosphate (Ag3PO4) microcrystals as photocatalyst (degradation of Rodamine B-RhB) and antifungal agent (against Candida albicans–C. albicans) under visible-light irradiation (455 nm). Ag3PO4 microcrystals were synthesized by a simple co-precipitation (CP) method at room temperature. The structural and electronic properties of the as-synthetized Ag3PO4 have been investigated before and after 4 cycles of RhB degradation under visible light using X-ray diffraction (XRD), micro-Raman spectroscopy, UV–Vis spectrophotometer and field emission scanning electron microscopy (FE-SEM) images. The antifungal activity was analyzed in planktonic cells and 48h-biofilm of C. albicans by colony forming units (CFU) counting, confocal laser and FE-SE microscopies. Statistical analysis was carried out using SPSS software. Morphological and structural modifications of Ag3PO4 were observed upon recycling. After 4 recycles, the material maintained its photodegradation property; an eightfold increase in the efficiency of Ag3PO4 was observed in planktonic cells and a two fold increase in biofilm when irradiated under visible light. Thus, higher antifungal effectiveness against C. albicans was obtained when associated with visible-light irradiation. 相似文献
42.
Wireless Personal Communications - Multiple inputs multiple outputs (MIMO) is a reliable technique which can manage the increased wireless data traffic in the future generation of wireless... 相似文献
43.
Romero-Garcés A. Salles De Freitas R. Marfil R. Vicente-Chicote C. Martínez J. Inglés-Romero J. F. Bandera A. 《Multimedia Tools and Applications》2022,81(3):3603-3628
Multimedia Tools and Applications - The design of robots capable of operating autonomously in changing and unstructured environments, requires using complex software architectures in which,... 相似文献
44.
Kumar S. Ganesh Sridhar S. S. Hussain Azham Manikanthan S. V. Padmapriya T. 《Multimedia Tools and Applications》2022,81(7):9091-9109
Multimedia Tools and Applications - Discovering the relevant web services for specific applications in the dynamically changing business world becomes very critical. Researchers have used many... 相似文献
45.
Mohammed Amin Salih Venkatachalam K. Hubálovský S. Trojovský P. Prabu P. 《Mobile Networks and Applications》2022,27(3):1050-1059
Mobile Networks and Applications - 5G/6G communication are first generation high speed wireless communication network which integrates the aerial data, terrestrial data and maritime data via... 相似文献
46.
Nicolas Larché Benoit Emo Audrey Allion Elisabeth Johansson Dominique Thierry 《工业材料与腐蚀》2021,72(8):1338-1349
With lower alloying cost and higher mechanical properties, lean duplex stainless steels can be an alternative to the more commonly used austenitic stainless steels. However, these alloys are still not the preferred choice, probably due to a lack of field experience. A study was thus initiated in view of defining the limits of use of selected (lean) duplexes for urban wastewater treatment units. The present paper shows the localized corrosion performance of selected lean duplexes in chloride contaminated solutions. The results are compared with austenitic S30403 and S31603 and with the more standard duplexes S82441 and S32205. The effect of welding was also investigated. Exposures in field municipal wastewater plants were conducted for 1 year in low and high chloride content units. The results show that lean duplexes S32101 and S32202 can be used as alternatives to S30403 and S31603 in low chloride electrolytes. At 500 ppm of chloride content, duplex stainless steel S32304 showed better corrosion resistance than S30403 and S31603. For higher chloride contents (1000 ppm and above) the standard duplexes S82441 and S32205 shall be preferred. 相似文献
47.
Kruglikov S. S. Zagorskii D. L. Kolesnikov V. A. Doludenko I. M. Bedin S. A. 《Theoretical Foundations of Chemical Engineering》2021,55(5):942-951
Theoretical Foundations of Chemical Engineering - The effect of the electrolyte composition, mass-transfer conditions, pore diameter, interpore distance, and electric parameters on the formation of... 相似文献
48.
Erwan Diler Vanessa Leblanc Hervé Gueuné Nicolas Larché Valerie Deydier Yannick Linard Didier Crusset Dominique Thierry 《工业材料与腐蚀》2021,72(1-2):218-234
In the context of the high-level radioactive waste disposal CIGEO, the corrosion rate due to microbially influenced corrosion (MIC) has to be evaluated. In France, it is envisaged to dispose of high- and intermediate-level long-lived radioactive waste at a depth of 500 m in a deep geological disposal, drilled in the Callovo-Oxfordian claystone (Cox) formation. To do so, a carbon steel casing will be inserted inside disposal cells, which are horizontal tunnels drilled in the Cox. A specific cement grout will be injected between the carbon steel casing and the claystone. A study was conducted to evaluate the possibility of MIC on carbon steel in the foreseeable high radioactive waste disposal. The corrosiveness of various environments was investigated at 50°C and 80°C with or without microorganisms enriched from samples of Andra's underground research laboratory. The monitoring of corrosion during the experiments was ensured using gravimetric method and real-time corrosion monitoring using sensors based on the measurements of the electrical resistance. The corrosion data were completed with microbiological analyses including cultural and molecular characterizations. 相似文献
49.
L.J. Espinoza-Pérez S. Esquivel-Medina E. López-Honorato 《Ceramics International》2021,47(11):15527-15532
The influence of the microstructure on the corrosion rate of three monolithic SiC samples in FLiNaK salt at 900 °C for 250 h was studied. The SiC samples, labeled as SiC-1, SiC-2, and SiC-3, had corrosion rates of 0.137, 0.020, and 0.043 mg/cm2h, respectively. Compared with grain size and the presence of special grain boundaries (i.e., Σ3), the content of high-angle grain boundaries (HAGBs) appeared to have the strongest influence on the corrosion rate of SiC in FLiNaK salt, since the corrosion rate increased six times as the concentration of high-angle grain boundaries increased from 19 to 32% for SiC-2 and SiC-1, respectively. These results stress the importance of controlling the content of HAGBs during the production process of SiC. 相似文献
50.
Andrade R. G. S. A. de Oliveira A. E. Guerra V. G. 《Theoretical Foundations of Chemical Engineering》2022,56(4):504-512
Theoretical Foundations of Chemical Engineering - The corona onset voltage is an important operating parameter in the electrostatic precipitation of nanoparticulate, however, its experimental... 相似文献