全文获取类型
收费全文 | 636243篇 |
免费 | 8261篇 |
国内免费 | 2457篇 |
专业分类
电工技术 | 12022篇 |
综合类 | 944篇 |
化学工业 | 89793篇 |
金属工艺 | 24745篇 |
机械仪表 | 19055篇 |
建筑科学 | 14543篇 |
矿业工程 | 3003篇 |
能源动力 | 15613篇 |
轻工业 | 50612篇 |
水利工程 | 6279篇 |
石油天然气 | 10868篇 |
武器工业 | 111篇 |
无线电 | 80379篇 |
一般工业技术 | 123106篇 |
冶金工业 | 127972篇 |
原子能技术 | 13853篇 |
自动化技术 | 54063篇 |
出版年
2021年 | 4639篇 |
2019年 | 4594篇 |
2018年 | 7803篇 |
2017年 | 7909篇 |
2016年 | 8312篇 |
2015年 | 5488篇 |
2014年 | 9360篇 |
2013年 | 27096篇 |
2012年 | 15323篇 |
2011年 | 21148篇 |
2010年 | 16713篇 |
2009年 | 19165篇 |
2008年 | 20237篇 |
2007年 | 20282篇 |
2006年 | 18035篇 |
2005年 | 16683篇 |
2004年 | 16502篇 |
2003年 | 16022篇 |
2002年 | 15458篇 |
2001年 | 15723篇 |
2000年 | 14924篇 |
1999年 | 15901篇 |
1998年 | 40630篇 |
1997年 | 28354篇 |
1996年 | 21894篇 |
1995年 | 16660篇 |
1994年 | 14598篇 |
1993年 | 14577篇 |
1992年 | 10663篇 |
1991年 | 10080篇 |
1990年 | 9780篇 |
1989年 | 9453篇 |
1988年 | 8801篇 |
1987年 | 7676篇 |
1986年 | 7698篇 |
1985年 | 8750篇 |
1984年 | 7973篇 |
1983年 | 7233篇 |
1982年 | 6850篇 |
1981年 | 7046篇 |
1980年 | 6725篇 |
1979年 | 6301篇 |
1978年 | 6183篇 |
1977年 | 7207篇 |
1976年 | 9412篇 |
1975年 | 5449篇 |
1974年 | 5292篇 |
1973年 | 5337篇 |
1972年 | 4417篇 |
1971年 | 3948篇 |
排序方式: 共有10000条查询结果,搜索用时 125 毫秒
41.
Radchenko P. A. Batuev S. P. Radchenko A. V. 《Journal of Engineering Physics and Thermophysics》2022,95(1):90-96
Journal of Engineering Physics and Thermophysics - A numerical investigation has been made into the interaction of slender (5–20 calibers) steel cylinder strikers with orthotropic compost... 相似文献
42.
Rudenko A. I. Nishchik A. P. Otrokh E. A. Terekh A. M. 《Journal of Engineering Physics and Thermophysics》2022,95(1):206-212
Journal of Engineering Physics and Thermophysics - Results of investigation into the influence of a corrosion process on thermotechnical characteristics of heat pipes of low-temperature range are... 相似文献
43.
Radiochemistry - Magnetically modified waste bark of the Aegle marmelos tree was prepared by using green synthesis method and was used in a batch system for U(VI) removal from aqueous solution. The... 相似文献
44.
Laís D. Silva Fernanda C. Puosso Viviane O. Soares Oscar Peitl Filho Simone do R.F. Sabino Francisco C. Serbena Murilo C. Crovace Edgar D. Zanotto 《Ceramics International》2021,47(13):18720-18731
Bioactive glasses and glass-ceramics (GCs) effectively regenerate bone tissue, however most GCs show improved mechanical properties. In this work, we developed and tested a rarely studied bioactive glass composition (24.4K2O-26.9CaO-46.1SiO2-2.6P2O5 mol%, identified as 45S5-K) with different particle sizes and heating rates to obtain a sintered GC that combines good fracture strength, low elastic modulus, and bioactivity. We analyzed the influence of the sintering processing conditions in the elastic modulus, Vickers microhardness, density, and crystal phase formation in the GC. The best GC shows improved properties compared with its parent glass. This glass achieves a good densification degree with a two-step viscous flow sintering approach and the resulting GC shows as high bioactivity as that of the standard 45S5 Bioglass®. Furthermore, the GC elastic modulus (56 GPa) is relatively low, minimizing stress shielding. Therefore, we unveiled the glass sintering behavior with concurrent crystallization of this complex bioactive glass composition and developed a potential GC for bone regeneration. 相似文献
45.
Bilal Alashkar Alhamwe Daniel P. Potaczek Sarah Miethe Fahd Alhamdan Lukas Hintz Arslan Magomedov Holger Garn 《International journal of molecular sciences》2021,22(9)
Extracellular vesicles (EVs) are membranous structures, which are secreted by almost every cell type analyzed so far. In addition to their importance for cell-cell communication under physiological conditions, EVs are also released during pathogenesis and mechanistically contribute to this process. Here we summarize their functional relevance in asthma, one of the most common chronic non-communicable diseases. Asthma is a complex persistent inflammatory disorder of the airways characterized by reversible airflow obstruction and, from a long-term perspective, airway remodeling. Overall, mechanistic studies summarized here indicate the importance of different subtypes of EVs and their variable cargoes in the functioning of the pathways underlying asthma, and show some interesting potential for the development of future therapeutic interventions. Association studies in turn demonstrate a good diagnostic potential of EVs in asthma. 相似文献
46.
Wireless Personal Communications - This paper summarizes the ongoing research initiatives based on the advanced multiple access techniques towards the fifth generation (5G) wireless communication... 相似文献
47.
Belov M. I. Anashin D. V. Kabdin N. E. Storchevoy V. F. Sudnik Yu. A. 《Russian Engineering Research》2022,42(11):1110-1116
Russian Engineering Research - The stability of robot-mower motion in a specific direction is considered. The direction is regulated by means of an angular sensor and a programmable controller... 相似文献
48.
Precipitation of calcium deficient hydroxyapatite nanoparticles in an environmentally benign manner by using only dilute solutions of calcium hydroxide and phosphoric acid without pH adjustment and addition of other chemicals, and water, being the only by-product was investigated by using continuous flow Vortex Reactor (VR) and Semi-Batch Reactor (SBR). The effect of hydrodynamics by changing the Reynolds number of the jets providing residence times of 8.4 ms to 4.37 s for VR, and by changing the stirrer speed between 100 rpm (Re = 2656) and 1000 rpm (Re = 26560) for SBR, on the particle size, particle size distribution, and morphology of the particles was investigated for both systems. It has been shown that it is possible to produce pure phase hydroxyapatite nanoparticles in the desired morphology by changing production system, without resorting to additives. While VR produced rod-like particles with the crystallite size around 4 nm, SBR produced spherical particles with the crystallite size of around 5 nm. 相似文献
49.
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
50.
Belcher Calvin H. Zheng Baolong MacDonald Benjamin E. Langlois Eric D. Lehman Benjamin Pearce Charles Delaney Robert Apelian Diran Lavernia Enrique J. Monson Todd C. 《Journal of Materials Science》2022,57(9):5518-5532
Journal of Materials Science - For transformers and inductors to meet the world’s growing demand for electrical power, more efficient soft magnetic materials with high saturation magnetic... 相似文献