全文获取类型
收费全文 | 1580448篇 |
免费 | 36769篇 |
国内免费 | 12481篇 |
专业分类
电工技术 | 41185篇 |
技术理论 | 9篇 |
综合类 | 15591篇 |
化学工业 | 282579篇 |
金属工艺 | 69669篇 |
机械仪表 | 47806篇 |
建筑科学 | 53434篇 |
矿业工程 | 14054篇 |
能源动力 | 52852篇 |
轻工业 | 118703篇 |
水利工程 | 17141篇 |
石油天然气 | 42203篇 |
武器工业 | 1160篇 |
无线电 | 205505篇 |
一般工业技术 | 288307篇 |
冶金工业 | 162768篇 |
原子能技术 | 34885篇 |
自动化技术 | 181847篇 |
出版年
2021年 | 19795篇 |
2020年 | 15053篇 |
2019年 | 17054篇 |
2018年 | 17271篇 |
2017年 | 16882篇 |
2016年 | 23437篇 |
2015年 | 21451篇 |
2014年 | 34066篇 |
2013年 | 93873篇 |
2012年 | 41887篇 |
2011年 | 54007篇 |
2010年 | 48663篇 |
2009年 | 56768篇 |
2008年 | 50205篇 |
2007年 | 46628篇 |
2006年 | 50053篇 |
2005年 | 43214篇 |
2004年 | 44174篇 |
2003年 | 43605篇 |
2002年 | 42946篇 |
2001年 | 39340篇 |
2000年 | 37343篇 |
1999年 | 36206篇 |
1998年 | 44681篇 |
1997年 | 39157篇 |
1996年 | 35705篇 |
1995年 | 31076篇 |
1994年 | 29107篇 |
1993年 | 28744篇 |
1992年 | 26302篇 |
1991年 | 23417篇 |
1990年 | 23588篇 |
1989年 | 22674篇 |
1988年 | 21127篇 |
1987年 | 19407篇 |
1986年 | 18713篇 |
1985年 | 22038篇 |
1984年 | 22231篇 |
1983年 | 20216篇 |
1982年 | 19254篇 |
1981年 | 19340篇 |
1980年 | 17954篇 |
1979年 | 18478篇 |
1978年 | 17749篇 |
1977年 | 17534篇 |
1976年 | 18770篇 |
1975年 | 16006篇 |
1974年 | 15516篇 |
1973年 | 15575篇 |
1972年 | 13051篇 |
排序方式: 共有10000条查询结果,搜索用时 218 毫秒
151.
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
152.
153.
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
154.
Dr. Timo Broese Dr. Peter Ehlers Dr. Peter Langer Dr. Jan von Langermann 《Chembiochem : a European journal of chemical biology》2021,22(23):3314-3318
Fluoro-substituted and heteroaromatic compounds are valuable intermediates for a variety of applications in pharma- and agrochemistry and synthetic chemistry. This study investigates the chemoenzymatic preparation of chiral alcohols bearing a heteroaromatic ring with an increasing degree of fluorination in α-position. Starting from readily available picoline derivatives prochiral α-halogenated acyl moieties were introduced with excellent selectivity and 64–95 % yield. The formed carbonyl group was subsequently reduced to the corresponding alcohols using the alcohol dehydrogenase from Lactobacillus kefir, yielding an enantiomeric excess of 95–>99 % and up to 98 % yield. 相似文献
155.
Vasanthapriya R. Neelakandeswari N. Uthayarani K. Chitra M. 《Journal of Inorganic and Organometallic Polymers and Materials》2021,31(11):4272-4280
Journal of Inorganic and Organometallic Polymers and Materials - This paper reports the performance of alizarin based SnO2 dye-sensitized solar cells. A novel template assisted method has been... 相似文献
156.
Applied Composite Materials - Determining the impact behavior of adhesive joints allows the designing of high-strength joints. Therefore, the dynamic behavior of adhesive joints has recently become... 相似文献
157.
Cuiping Yu Shuang Sun Sihui Li Huijia Yan Henan Zou 《International Journal of Food Science & Technology》2022,57(2):1173-1185
In this study, the effect of high-intensity ultrasound (HIUS) (200 and 400 W for 0, 5, 10 and 15 min respectively) on conformational changes, physicochemical, rheological and emulsifying properties of scallop (Patinopecten yessoensis) myofibrillar protein (SMP) was investigated. HIUS-treated SMP had lower α-helix content and higher β-sheet content compared with the native SMP. HIUS treatment induced the unfolding of SMP and increased the surface hydrophobicity. The particle size of SMP decreased and the absolute zeta-potential increased after ultrasonication, which in turn increased the solubility of SMP. The conformational changes and the improvement of physicochemical properties of SMP increased the ability for SMP to lower the interfacial tension at the oil–water interface and increased the percentage of adsorbed protein. As a result, the emulsifying properties, rheological properties of SMP and storage stability of emulsions were also improved. In conclusion, HIUS treatment has future potential for improving the emulsifying properties of SMP. 相似文献
158.
159.
Yan He Kangren Kong Zhengxi Guo Weifeng Fang Zaiqiang Ma Haihua Pan Ruikang Tang Zhaoming Liu 《Advanced functional materials》2021,31(26):2101291
Sensitivity and multi-directional motivation are major two factors for developing optimized humidity-response materials, which are promising for sensing, energy production, etc. Organic functional groups are commonly used as the water sensitive units through hydrogen bond interactions with water molecules in actuators. The multi-coordination ability of inorganic ions implies that the inorganic ionic compounds are potentially superior water sensitive units. However, the particle forms of inorganic ionic compounds produced by classical nucleation limit the number of exposed ions to interact with water. Recent progress on the inorganic ionic oligomers has broken through the limitation of classical nucleation, and realized the molecular-scaled incorporation of inorganic ionic compounds into an organic matrix. Here, the incorporation of hydrophilic calcium carbonate ionic oligomers into hydrophobic poly(vinylidene fluoride) (PVDF) is demonstrated. The ultra-small calcium carbonate oligomers within a PVDF film endow it with an ultra-sensitive, reversible, and bidirectional response. The motivation ability is superior to other bidirectional humidity-actuators at present, which realizes self-motivation on an ice surface, converting the chemical potential energy of the humidity gradient from ice to kinetic energy. 相似文献
160.
Carolyn A. Grimley Stephen Funni Christopher Green Elizabeth C. Dickey 《Journal of the European Ceramic Society》2021,41(4):2807-2817
In flash sintering experiments, the thermal history of the sample is key to understanding the mechanisms underlying densification rate and final properties. By combining robust temperature measurements with current-ramp-rate control, this study examined the effects of the thermal profile on the flash sintering of yttria-stabilized zirconia, with experiments ranging from a few seconds to several hours. The final density was maximized at slower heating rates, although processes slower than a certain threshold led to grain growth. The amount of grain growth observed was comparable to a similar conventional thermal process. The bulk electrical conductivity correlated with the maximum temperature and cooling rate. The only property that exhibited behavior that could not be attributed to solely the thermal profile was the grain boundary conductivity, which was consistently higher than conventional in flash sintered samples. These results suggest that, during flash sintering, athermal electric field effects are relegated to the grain boundary. 相似文献