全文获取类型
收费全文 | 12261篇 |
免费 | 328篇 |
国内免费 | 12篇 |
专业分类
电工技术 | 92篇 |
综合类 | 10篇 |
化学工业 | 1562篇 |
金属工艺 | 184篇 |
机械仪表 | 326篇 |
建筑科学 | 129篇 |
矿业工程 | 3篇 |
能源动力 | 314篇 |
轻工业 | 1074篇 |
水利工程 | 20篇 |
石油天然气 | 8篇 |
武器工业 | 1篇 |
无线电 | 1080篇 |
一般工业技术 | 1319篇 |
冶金工业 | 5592篇 |
原子能技术 | 59篇 |
自动化技术 | 828篇 |
出版年
2023年 | 83篇 |
2022年 | 117篇 |
2021年 | 208篇 |
2020年 | 157篇 |
2019年 | 150篇 |
2018年 | 181篇 |
2017年 | 181篇 |
2016年 | 214篇 |
2015年 | 190篇 |
2014年 | 297篇 |
2013年 | 484篇 |
2012年 | 432篇 |
2011年 | 468篇 |
2010年 | 347篇 |
2009年 | 339篇 |
2008年 | 369篇 |
2007年 | 279篇 |
2006年 | 224篇 |
2005年 | 224篇 |
2004年 | 190篇 |
2003年 | 165篇 |
2002年 | 150篇 |
2001年 | 117篇 |
2000年 | 116篇 |
1999年 | 248篇 |
1998年 | 1718篇 |
1997年 | 995篇 |
1996年 | 701篇 |
1995年 | 414篇 |
1994年 | 366篇 |
1993年 | 389篇 |
1992年 | 89篇 |
1991年 | 126篇 |
1990年 | 94篇 |
1989年 | 119篇 |
1988年 | 128篇 |
1987年 | 122篇 |
1986年 | 98篇 |
1985年 | 74篇 |
1984年 | 36篇 |
1983年 | 45篇 |
1982年 | 52篇 |
1981年 | 53篇 |
1980年 | 78篇 |
1978年 | 60篇 |
1977年 | 171篇 |
1976年 | 372篇 |
1975年 | 43篇 |
1974年 | 31篇 |
1972年 | 35篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
The photonic quantum ring (PQR) laser is a three dimensional whispering gallery (WG) mode laser and has anomalous quantum wire properties, such as microampere to nanoampere range threshold currents and √T‐dependent thermal red shifts. We observed uniform bottom emissions from a 1‐kb smart pixel chip of a 32×32 InGaAs PQR laser array flip‐chip bonded to a 0.35 µm CMOS‐based PQR laser driver. The PQR‐CMOS smart pixel array, now operating at 30 MHz, will be improved to the GHz frequency range through device and circuit optimization. 相似文献
82.
83.
84.
85.
86.
87.
JaeHyunKim JounHoLee JiChulLim ChangHoonLee MooHyoungSong JuYeonYoon HeeDongChoi JeomJaeKim ChangHoOh SangDeogYeo 李路海 《现代显示》2004,31(5):31-33
薄膜晶体管液晶电视(TFT-LCD TV)因为具有薄、轻、紧凑和可随意放置的特点,已经占据了大部分电视机市场。除了这些物理特性以外,最重要的特性是已具有了良好像质的对比度。为了将对比度提高到1:600以上,对偏振片膜、背光源板、滤色片树脂、电极锥角和摩擦条件等都进行了研究。优化的背光板组合,光滑的电极锥角和摩擦方法的控制是提高对比度的主要控制因素。应用新开发的滤色片树脂,对获得高对比度最为有效。 相似文献
88.
Friction and wear of Inconel 690 and Inconel 600 for steam generator tube in room temperature water 总被引:1,自引:0,他引:1
In the steam generators of nuclear power plants, the flow of cooling water can cause the tubes to vibrate, resulting in fretting wear damage due to contacts between these tubes and their supports. The tubes are made of Inconel 690 and Inconel 600 and the supports are made of STS 304. In this paper, fretting wear tests in water were performed using the materials Inconel 690 and Inconel 600 in contact with STS 304. Fretting tests using a cross-cylinder type set up were conducted under various vibrating amplitudes and applied normal loads in order to measure friction forces and wear volumes. Also, conventional sliding tests using a pin-on-disk type set up were carried out to compare these test results.In the fretting tests, friction force was found to be strongly dependent on normal load and vibrating amplitude. Coefficients of friction decreased with an increase in the normal load and a decrease in the vibrating amplitude applied. Also, the wear of Inconel 600 and Inconel 690 was predicted using a work rate model. Depending on the normal load and vibrating amplitude applied, distinctively different wear mechanisms and often drastically different wear rates occurred. It was found that the fretting wear coefficients for Inconel 600 and Inconel 690 were 9.3×10−15 and 16.2×10−15 Pa−1, respectively. This study shows that Inconel 690 can result in lesser friction forces and exhibits less wear resistance than Inconel 600 in room temperature water. 相似文献
89.
Mou Weimin; Biocca Frank; Owen Charles B.; Tang Arthur; Xiao Fan; Lim Lynette 《Canadian Metallurgical Quarterly》2004,10(4):238
In 3 experiments, the authors investigated spatial updating in augmented reality environments. Participants learned locations of virtual objects on the physical floor. They were turned to appropriate facing directions while blindfolded before making pointing judgments (e.g., "Imagine you are facing X. Point to Y"). Experiments manipulated the angular difference between the learning heading and the imagined heading and between the actual heading and the imagined heading. The effect of actual-imagined on pointing latency was observed for naive users but not for users with brief training or instructions concerning the fact that objects can move with body movements. The results indicated that naive users used an environment-stabilized reference frame to access information arrays, but with experience and instruction the nature of the representation changed from an environment stabilized to a body stabilized reference frame. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
90.
A novel positive‐working photosensitive polyimide (PSPI) based on a poly(hydroxyimide) (PHI), a crosslinking agent having vinyl ether groups, and a photoacid generator (PAG) was prepared. The PHI as a base resin of the three‐component PSPI was synthesized from 4,4′‐oxydiphthalic anhydride and 2,2′‐bis(3‐amino‐4‐hydroxyphenyl)hexafluoropropane through ring‐opening polymerization and subsequent thermal cyclization. 2,2′‐bis(4‐(2‐(vinyloxy)ethoxy)phenyl)propane (BPA‐DEVE) was used as a vinylether compound and diphenyliodonium 5‐hydroxynaphthalene‐1‐sulfonate was used as a PAG. The phenolic hydroxyl groups of the PHI and the vinyl ether groups of BPA‐DEVE are thermally crosslinked with acetal structures during prebake step, and the crosslinked PHI becomes completely insoluble in an aqueous basic solution. Upon exposure to UV light (365 nm) and subsequent postexposure bake (PEB), a strong acid generated from the PAG cleaves the crosslinked structures, and the exposed area is effectively solubilized in the alkaline developer. The dissolution behavior of the PSPI containing each 11.5 wt % of BPA‐DEVE and of the PAG was studied after UV exposure (365 nm) and PEB. It was found that the difference in dissolution rates between exposed and unexposed areas was enough to get high resolution. A fine positive pattern with a resolution of 5 μm in a 3.7‐μm‐thick film was obtained from the three‐component PSPI. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献