首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   120612篇
  免费   8182篇
  国内免费   2877篇
电工技术   4549篇
技术理论   6篇
综合类   4471篇
化学工业   22548篇
金属工艺   6023篇
机械仪表   7991篇
建筑科学   6238篇
矿业工程   2406篇
能源动力   4292篇
轻工业   8557篇
水利工程   1259篇
石油天然气   5325篇
武器工业   462篇
无线电   15206篇
一般工业技术   19655篇
冶金工业   7645篇
原子能技术   1398篇
自动化技术   13640篇
  2024年   250篇
  2023年   1724篇
  2022年   2606篇
  2021年   4292篇
  2020年   3178篇
  2019年   3042篇
  2018年   3623篇
  2017年   3833篇
  2016年   3754篇
  2015年   3931篇
  2014年   5441篇
  2013年   7126篇
  2012年   7512篇
  2011年   8639篇
  2010年   6916篇
  2009年   6802篇
  2008年   6593篇
  2007年   5850篇
  2006年   5772篇
  2005年   5129篇
  2004年   3814篇
  2003年   3554篇
  2002年   3160篇
  2001年   2748篇
  2000年   2792篇
  1999年   2952篇
  1998年   3301篇
  1997年   2392篇
  1996年   2192篇
  1995年   1727篇
  1994年   1391篇
  1993年   1112篇
  1992年   827篇
  1991年   692篇
  1990年   581篇
  1989年   487篇
  1988年   424篇
  1987年   304篇
  1986年   220篇
  1985年   200篇
  1984年   151篇
  1983年   98篇
  1982年   80篇
  1981年   66篇
  1980年   52篇
  1979年   44篇
  1978年   33篇
  1977年   45篇
  1976年   69篇
  1975年   24篇
排序方式: 共有10000条查询结果,搜索用时 453 毫秒
41.
42.
43.
Science China Technological Sciences - Accurate modelling of lithium ion batteries is crucial for battery management in electric vehicles. Recent studies have revealed the fractional order nature...  相似文献   
44.
Multimedia Systems - The preferences of Web information purchasers are changing. Cost-effectiveness (i.e., an emphasis on performance with respect to price) is becoming less regarded than...  相似文献   
45.
46.
This study investigates the impact of lighting colors on subjective judgments of fabric: in particular, whether the influence of lighting varies depending on fabric types and color combinations. We conducted two visual assessments. In Study 1 (N = 44), eight illuminants and six types of fabric were presented as cloth stimuli. Derived from the literature review, four sets of adjectives (humble-luxurious, cool-warm, old-new, and not preferred-preferred) were used as metrics. In Study 2 (N = 41), five sets of fabric color combination swatches were assessed under lighting conditions that were identical to those of Study 1. Three bipolar scales (ordinary-characterful, classic-modern, and soft-rigid), were employed from factor analysis along with three unipolar scales (luxurious, preferred, harmonious with lighting). The results showed that hue characteristics of lighting and cloth types influenced participants' perceptions of the fabric. Overall, white lighting with 4000 K was the most preferred and luxurious lighting across various types of clothes, while a pinkish white with 4700 K (duv = −0.0127) was the best matched in every color combination. In addition, there were interaction effects between lighting colors, clothes types, and fabric color combinations with regard to each of the perceptual qualities. This study provides empirical evidence for optimally match lighting colors with fabric in the presentation of fabric goods.  相似文献   
47.
48.
Sun  Yue  Zhu  Yu  Li  Ying  Zhang  Mingyu 《Wireless Personal Communications》2020,111(1):83-96
Wireless Personal Communications - The existing long term evolution networks originally designed for human-to-human communications are hard to tackle numerous and bursty random access requests from...  相似文献   
49.
A series of anionic conjugated polyelectrolytes (CPEs) is synthesized based on poly(fluorene-co-phenylene) by varying the side-chain ionic density from two to six per repeat units (MPS2-TMA, MPS4-TMA, and MPS6-TMA). The effect of MPS2, 4, 6-TMA as interlayers on top of a hole-extraction layer of poly(bis(4-phenyl)-2,4,6-trimethylphenylamine (PTAA) is investigated in inverted perovskite solar cells (PeSCs). Owing to the improved wettability of perovskites on hydrophobic PTAA with the CPEs, the PeSCs with CPE interlayers demonstrate a significantly enhanced device performance, with negligible device-to-device dependence relative to the reference PeSC without CPEs. By increasing the ionic density in the MPS-TMA interlayers, the wetting, interfacial defect passivation, and crystal growth of the perovskites are significantly improved without increasing the series resistance of the PeSCs. In particular, the open-circuit voltage increases from 1.06 V for the PeSC with MPS2-TMA to 1.11 V for the PeSC with MPS6-TMA. The trap densities of the PeSCs with MPS2,4,6-TMA are further analyzed using frequency-dependent capacitance measurements. Finally, a large-area (1 cm2) PeSC is successfully fabricated with MPS6-TMA, showing a power conversion efficiency of 18.38% with negligible hysteresis and a stable power output under light soaking for 60 s.  相似文献   
50.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号