全文获取类型
收费全文 | 19805篇 |
免费 | 1729篇 |
国内免费 | 896篇 |
专业分类
电工技术 | 1061篇 |
综合类 | 1086篇 |
化学工业 | 3661篇 |
金属工艺 | 1643篇 |
机械仪表 | 1103篇 |
建筑科学 | 839篇 |
矿业工程 | 1899篇 |
能源动力 | 628篇 |
轻工业 | 1674篇 |
水利工程 | 193篇 |
石油天然气 | 582篇 |
武器工业 | 85篇 |
无线电 | 1007篇 |
一般工业技术 | 3019篇 |
冶金工业 | 1992篇 |
原子能技术 | 298篇 |
自动化技术 | 1660篇 |
出版年
2024年 | 82篇 |
2023年 | 353篇 |
2022年 | 550篇 |
2021年 | 696篇 |
2020年 | 734篇 |
2019年 | 651篇 |
2018年 | 621篇 |
2017年 | 766篇 |
2016年 | 723篇 |
2015年 | 708篇 |
2014年 | 1141篇 |
2013年 | 1245篇 |
2012年 | 1210篇 |
2011年 | 1508篇 |
2010年 | 1034篇 |
2009年 | 1088篇 |
2008年 | 987篇 |
2007年 | 1097篇 |
2006年 | 1074篇 |
2005年 | 959篇 |
2004年 | 796篇 |
2003年 | 717篇 |
2002年 | 630篇 |
2001年 | 484篇 |
2000年 | 471篇 |
1999年 | 372篇 |
1998年 | 325篇 |
1997年 | 301篇 |
1996年 | 222篇 |
1995年 | 200篇 |
1994年 | 153篇 |
1993年 | 117篇 |
1992年 | 97篇 |
1991年 | 80篇 |
1990年 | 65篇 |
1989年 | 42篇 |
1988年 | 41篇 |
1987年 | 30篇 |
1986年 | 14篇 |
1985年 | 9篇 |
1984年 | 8篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 5篇 |
1980年 | 8篇 |
1979年 | 2篇 |
1964年 | 1篇 |
1962年 | 1篇 |
1959年 | 1篇 |
1951年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
42.
The strength of agglomerates of nickel flash furnace concentrate and dust was determined from experimental observations of agglomerates forming under controlled conditions, combined with mathematical equations from the literature. It was found that the agglomerates had a tensile strength ranging from 0.01 Pa to 38.7 Pa, while inter-particle forces ranged from 2.2 × 10− 12 N to 1.5 × 10− 10 N. These values were compared to the expected magnitude of van der Waals, electrostatic, magnetic and capillary forces within the agglomerates, and it was found that both electrostatic and van der Waals forces are likely to contribute to the cohesion of agglomerates, although sub-micron particles and the presence of sufficiently large asperities on the surface of particles limit the magnitude of van der Waals forces. Magnetic forces are large enough to contribute to the cohesion of dust agglomerates, which is in keeping with the high magnetite content of the recycle dust. It is postulated that electrostatic forces, acting over a longer range than van der Waals forces, may be responsible for initially bringing particles together. The methodology for determining inter-particle forces can be applied to the computer modelling of flash smelting systems, as well as other gas/particle systems such as fluidized beds. 相似文献
43.
44.
本文提出采用高分子有机材料配合,生产石膏制品防水防潮剂的生产方法和工艺。该剂还可以应用到氧化镁系列板材,同时提出开发珠光或彩色防水防潮剂,能达到满足的装饰效果,值提开发推广。 相似文献
45.
通过对制冷压缩机功耗的模拟和对实际运行数据的分析,比较了乙烯装置中的复迭多级制冷系统和混合冷剂制冷系统的用能状况,分析了混合冷剂制冷的优点和不足。采用AspenPlus10.2软件模拟的结果表明,采用混合冷剂制冷技术的丙烯-混合冷剂复迭制冷系统比传统的丙烯-乙烯复迭制冷系统节省功耗4.3GJ/h,制冷压缩机损系数则从47.6%减小到43.3%,而系统效率由25.0%提高到26.6%。虽混合冷剂在换热过程中出现的气液两相流,会在一定程度上抵消其在热力学效率上的优势,但混合制冷技术用于乙烯装置仍可降低能耗、提高热力学效率。 相似文献
46.
47.
提出了一种以FPGA为核心控制器的高灰度级TFT-LCD显示系统的设计方案。该系统采用幅值-帧速率控制调制-空间混合灰度调制方法,首先将10 bit的R、G、B信号分割成高8 bit数据和低2 bit数据,低2 bit数据经过空间处理后平均分到4个相邻的8 bit数据上,然后把这8 bit数据继续分割成高6 bit数据和低2 bit数据,其中高6 bit数据用于幅值调制,低2 bit数据用于帧速率控制调制,从而实现1 024个灰度等级显示。试验结果表明,该系统具有良好的显示效果和较高的显示灰度等级。 相似文献
48.
This paper is concerned with the neutral‐delay‐dependent and discrete‐delay‐dependent stability for uncertain neutral systems with mixed delays and norm‐bounded uncertainties. Through constructing a new augmented Lyapunov‐Krasovskii functional and proving its positive definiteness, introducing some slack matrices and using integral inequality, the improved delay‐dependent stability criteria are derived in terms of linear matrix inequalities. Numerical examples are given to illustrate the significant improvement on the conservatism of the delay bound over some existing results. Copyright © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society 相似文献
49.
V Chandrasekaran Ch Sreerama Murthy P Subrahmaniam G Venkateswarlu 《Bulletin of Materials Science》1986,8(1):39-48
Iron-chromium-cobalt alloys possess attractive magnetic properties combined with good formability and hence are identified as technologically important magnetic materials. Alloys with compositions Fe-28·9 Cr-15·6 Co and Fe-28·4 Cr-20·1Co (weight percent) have been studied. Heat-treatment parameters during thermomagnetic treatment viz temperature, time and external magnetic field were optimized with reference to magnetic properties. The fully treated anisotropic alloys develop remanence=11·5–12·0 kilo Gauss, coercivity=600–650 Oersted and energy product=4–4·5 million Gauss Oersted. Electron microscopic and Mössbauer spectroscopic techniques were used to identify the original and transformed phases. During the various stages of the development of the alloy, the changes in mechanical hardness were correlated with magnetic hardness. 相似文献
50.
The attack of nickel, cobalt, iron, and alloys of these metals containing chromium and aluminum, by gases containing sulfur-oxygen,
carbon-oxygen, and nitrogen-oxygen has been studied at temperatures of 600 and 900°C. The degradation of these metals and
alloys was characterized by using standard analytical techniques with emphasis on optical metallography. Three types of accelerated
degradation were identified for the attack of alloys by gases containing another oxidant in addition to oxygen. One type of
degradation occurred because of the formation of reaction products composed of mixtures of phases involving both of the oxidants.
Another type resulted from the reaction of second oxidant phases with oxygen. The third form of degradation involved the development
of less protective phases due to thermodynamic instabilities. Thermodynamic stability diagrams are used to help account for
the effects produced by different elements in the alloys. 相似文献