全文获取类型
收费全文 | 365296篇 |
免费 | 4757篇 |
国内免费 | 1035篇 |
专业分类
电工技术 | 5720篇 |
综合类 | 2497篇 |
化学工业 | 54347篇 |
金属工艺 | 19973篇 |
机械仪表 | 14752篇 |
建筑科学 | 8696篇 |
矿业工程 | 3337篇 |
能源动力 | 7136篇 |
轻工业 | 19358篇 |
水利工程 | 5066篇 |
石油天然气 | 9071篇 |
武器工业 | 27篇 |
无线电 | 36696篇 |
一般工业技术 | 78641篇 |
冶金工业 | 47122篇 |
原子能技术 | 7852篇 |
自动化技术 | 50797篇 |
出版年
2021年 | 2714篇 |
2020年 | 2006篇 |
2019年 | 2608篇 |
2018年 | 22732篇 |
2017年 | 22190篇 |
2016年 | 16650篇 |
2015年 | 3853篇 |
2014年 | 5061篇 |
2013年 | 11267篇 |
2012年 | 11690篇 |
2011年 | 23108篇 |
2010年 | 20139篇 |
2009年 | 17738篇 |
2008年 | 18842篇 |
2007年 | 20944篇 |
2006年 | 7287篇 |
2005年 | 10224篇 |
2004年 | 8203篇 |
2003年 | 7907篇 |
2002年 | 6353篇 |
2001年 | 5307篇 |
2000年 | 4991篇 |
1999年 | 4860篇 |
1998年 | 10846篇 |
1997年 | 7796篇 |
1996年 | 6085篇 |
1995年 | 4730篇 |
1994年 | 4153篇 |
1993年 | 4382篇 |
1992年 | 3492篇 |
1991年 | 3325篇 |
1990年 | 3302篇 |
1989年 | 3244篇 |
1988年 | 3189篇 |
1987年 | 2864篇 |
1986年 | 2881篇 |
1985年 | 3273篇 |
1984年 | 3098篇 |
1983年 | 2861篇 |
1982年 | 2595篇 |
1981年 | 2550篇 |
1980年 | 2613篇 |
1979年 | 2631篇 |
1978年 | 2624篇 |
1977年 | 2712篇 |
1976年 | 3086篇 |
1975年 | 2380篇 |
1974年 | 2240篇 |
1973年 | 2332篇 |
1972年 | 2059篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
2.
3.
Kuznetsov Yu. A. Markov M. A. Kravchenko I. N. Krasikov A. V. Bykova A. D. 《Refractories and Industrial Ceramics》2021,62(4):421-425
Refractories and Industrial Ceramics - The paper introduces a promising technology for utilizing a traditional scheme for implementing a flow-through micro-arc oxidation method to restore localized... 相似文献
4.
Combustion, Explosion, and Shock Waves - Results of a numerical study of mixing, ignition, and combustion of a cold hydrogen jet propagating along the lower wall of a channel parallel to a... 相似文献
5.
Deepika M. Malini Raajan N. R. Srinivasan A. 《Multimedia Tools and Applications》2022,81(9):12701-12724
Multimedia Tools and Applications - The three-dimensional models of brain tumors serve as diagnostic assistance for physicians, surgeons, and radiologists. The proposed system establishes an... 相似文献
6.
Brian Lawn David Marshall Rishi Raj Greg Hirth Trevor Page Julie Yeomans 《Journal of the American Ceramic Society》2021,104(1):23-26
Crystalline quartz has long been identified as among the weakest of abundant crustal minerals. This weakness is particularly evident around the α–β phase inversion at 573°C, in which Si–O bonds undergo a displacive structural transformation from trigonal to hexagonal symmetry. Here we present data using indentation testing methodologies that highlight the precipitous extent of the transformational weakening. Although the indentations are localized over relatively small specimen contact areas, the data quantify the essential deformation and fracture properties of quartz in a predominantly (but not exclusively) compressive stress field, at temperatures and pressures pertinent to conditions in the earth's crust. 相似文献
7.
David Diaz Elisa Lopez-Dolado Sergio Haro Jorge Monserrat Carlos Martinez-Alonso Dimitrios Balomeros Agustín Albillos Melchor Alvarez-Mon 《International journal of molecular sciences》2021,22(2)
Our aim was to investigate the subset distribution and function of circulating monocytes, proinflammatory cytokine levels, gut barrier damage, and bacterial translocation in chronic spinal cord injury (SCI) patients. Thus, 56 SCI patients and 28 healthy donors were studied. The levels of circulating CD14+highCD16−, CD14+highCD16+, and CD14+lowCD16+ monocytes, membrane TLR2, TLR4, and TLR9, phagocytic activity, ROS generation, and intracytoplasmic TNF-α, IL-1, IL-6, and IL-10 after lipopolysaccharide (LPS) stimulation were analyzed by polychromatic flow cytometry. Serum TNF-α, IL-1, IL-6 and IL-10 levels were measured by Luminex and LPS-binding protein (LBP), intestinal fatty acid-binding protein (I-FABP) and zonulin by ELISA. SCI patients had normal monocyte counts and subset distribution. CD14+highCD16− and CD14+highCD16+ monocytes exhibited decreased TLR4, normal TLR2 and increased TLR9 expression. CD14+highCD16− monocytes had increased LPS-induced TNF-α but normal IL-1, IL-6, and IL-10 production. Monocytes exhibited defective phagocytosis but normal ROS production. Patients had enhanced serum TNF-α and IL-6 levels, normal IL-1 and IL-10 levels, and increased circulating LBP, I-FABP, and zonulin levels. Chronic SCI patients displayed impaired circulating monocyte function. These patients exhibited a systemic proinflammatory state characterized by enhanced serum TNF-α and IL-6 levels. These patients also had increased bacterial translocation and gut barrier damage. 相似文献
8.
Seredin P. V. Radam Ali Obaid Goloshchapov D. L. Len’shin A. S. Buylov N. S. Barkov K. A. Nesterov D. N. Mizerov A. M. Timoshnev S. N. Nikitina E. V. Arsentyev I. N. Sharafidinov Sh. Kukushkin S. A. Kasatkin I. A. 《Semiconductors》2022,56(4):253-258
Semiconductors - Abstract—In our work, we carry out a structural-spectroscopic study of AlGaN/GaN epitaxial layers grown by molecular-beam epitaxy with nitrogen-plasma activation on a hybrid... 相似文献
9.
Boltar K. O. Burlakov I. D. Iakovleva N. I. Vlasov P. V. Lazarev P. S. 《Journal of Communications Technology and Electronics》2022,67(9):1175-1184
Journal of Communications Technology and Electronics - In recent years, there has been a rapid improvement in photonics products due to the use of multilayer heterostructures grown on the basis of... 相似文献
10.
Golam Haider Krishna Sampathkumar Tim Verhagen Lukáš Nádvorník Farjana J. Sonia Václav Valeš Jan Sýkora Peter Kapusta Petr Němec Martin Hof Otakar Frank Yang-Fang Chen Jana Vejpravová Martin Kalbáč 《Advanced functional materials》2021,31(29):2102196
Recent advancements in isolation and stacking of layered van der Waals materials have created an unprecedented paradigm for demonstrating varieties of 2D quantum materials. Rationally designed van der Waals heterostructures composed of monolayer transition-metal dichalcogenides (TMDs) and few-layer hBN show several unique optoelectronic features driven by correlations. However, entangled superradiant excitonic species in such systems have not been observed before. In this report, it is demonstrated that strong suppression of phonon population at low temperature results in a formation of a coherent excitonic-dipoles ensemble in the heterostructure, and the collective oscillation of those dipoles stimulates a robust phase synchronized ultra-narrow band superradiant emission even at extremely low pumping intensity. Such emitters are in high demand for a multitude of applications, including fundamental research on many-body correlations and other state-of-the-art technologies. This timely demonstration paves the way for further exploration of ultralow-threshold quantum-emitting devices with unmatched design freedom and spectral tunability. 相似文献