全文获取类型
收费全文 | 679094篇 |
免费 | 11559篇 |
国内免费 | 1971篇 |
专业分类
电工技术 | 11809篇 |
综合类 | 515篇 |
化学工业 | 105136篇 |
金属工艺 | 26123篇 |
机械仪表 | 20699篇 |
建筑科学 | 15938篇 |
矿业工程 | 3725篇 |
能源动力 | 17920篇 |
轻工业 | 57468篇 |
水利工程 | 7183篇 |
石油天然气 | 13060篇 |
武器工业 | 37篇 |
无线电 | 75222篇 |
一般工业技术 | 134625篇 |
冶金工业 | 128986篇 |
原子能技术 | 14452篇 |
自动化技术 | 59726篇 |
出版年
2021年 | 6669篇 |
2020年 | 5217篇 |
2019年 | 6388篇 |
2018年 | 11173篇 |
2017年 | 11068篇 |
2016年 | 11944篇 |
2015年 | 7792篇 |
2014年 | 12242篇 |
2013年 | 33414篇 |
2012年 | 19605篇 |
2011年 | 25174篇 |
2010年 | 20275篇 |
2009年 | 22447篇 |
2008年 | 23094篇 |
2007年 | 22397篇 |
2006年 | 19615篇 |
2005年 | 17789篇 |
2004年 | 16747篇 |
2003年 | 16488篇 |
2002年 | 15767篇 |
2001年 | 15229篇 |
2000年 | 14369篇 |
1999年 | 14922篇 |
1998年 | 39496篇 |
1997年 | 27792篇 |
1996年 | 21149篇 |
1995年 | 15646篇 |
1994年 | 13869篇 |
1993年 | 13825篇 |
1992年 | 9815篇 |
1991年 | 9397篇 |
1990年 | 9275篇 |
1989年 | 8990篇 |
1988年 | 8700篇 |
1987年 | 7457篇 |
1986年 | 7432篇 |
1985年 | 8427篇 |
1984年 | 7821篇 |
1983年 | 7088篇 |
1982年 | 6687篇 |
1981年 | 6838篇 |
1980年 | 6427篇 |
1979年 | 6204篇 |
1978年 | 6306篇 |
1977年 | 7425篇 |
1976年 | 9907篇 |
1975年 | 5504篇 |
1974年 | 5165篇 |
1973年 | 5323篇 |
1972年 | 4478篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
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
72.
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
73.
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
74.
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
75.
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
76.
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
77.
Silicon - The products of solid-phase mechanochemical interaction between pyrocatechol and silicon dioxide yielding a powdered composite were studied using a number of physicochemical methods. This... 相似文献
78.
Young Been Kim Sung Hyeon Jung Dong Su Kim Nishad G. Deshpande Hee Won Suh Hak Hyeon Lee Ji Hoon Choi Ho Seong Lee Hyung Koun Cho 《Advanced functional materials》2021,31(38):2102439
Antimony triselenide (Sb2Se3) nanoflake-based nitrogen dioxide (NO2) sensors exhibit a progressive bifunctional gas-sensing performance, with a rapid alarm for hazardous highly concentrated gases, and an advanced memory-type function for low-concentration (<1 ppm) monitoring repeated under potentially fatal exposure. Rectangular and cuboid shaped Sb2Se3 nanoflakes, comprising van der Waals planes with large surface areas and covalent bond planes with small areas, can rapidly detect a wide range of NO2 gas concentrations from 0.1 to 100 ppm. These Sb2Se3 nanoflakes are found to be suitable for physisorption-based gas sensing owing to their anisotropic quasi-2D crystal structure with extremely enlarged van der Waals planes, where they are humidity-insensitive and consequently exhibit an extremely stable baseline current. The Sb2Se3 nanoflake sensor exhibits a room-temperature/low-voltage operation, which is noticeable owing to its low energy consumption and rapid response even under a NO2 gas flow of only 1 ppm. As a result, the Sb2Se3 nanoflake sensor is suitable for the development of a rapid alarm system. Furthermore, the persistent gas-sensing conductivity of the sensor with a slow decaying current can enable the development of a progressive memory-type sensor that retains the previous signal under irregular gas injection at low concentrations. 相似文献
79.
Chemical and Petroleum Engineering - The processes of separation of impurities of particles of different sizes are analyzed under conditions of irregularity of structural and kinematic parameters... 相似文献
80.
A. Kathalingam S. Valanarasu Tansir Ahamad Saad M. Alshehri Hyun-Seok Kim 《Ceramics International》2021,47(6):7608-7616
Herein, we report the photosensing property of CdS thin films. CdS thin films were coated onto glass substrates via a spray pyrolysis method using different spray pressures. Prepared films were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and optical and photoluminescence spectroscopy. XRD analysis demonstrated the growth of crystalline CdS films with crystallite sizes varying from 26 to 29 nm depending on the pressure. The SEM and EDAX analyses revealed nearly-stoichiometric CdS films with smooth surfaces and slight variation in grain morphology due to pressure changes. Optical measurements showed a direct bandgap varying from 2.37 eV to 2.42 eV due to pressure changes. A photodetector was also fabricated using the grown CdS films; the fabricated photodetector exhibited good performance depending on the spray pressure. A spray pressure of 1.5 GPa resulted in high photoresponsivity and external quantum efficiency. 相似文献