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   2051篇
  免费   92篇
  国内免费   3篇
电工技术   19篇
综合类   11篇
化学工业   437篇
金属工艺   50篇
机械仪表   49篇
建筑科学   90篇
矿业工程   8篇
能源动力   57篇
轻工业   123篇
水利工程   4篇
石油天然气   5篇
无线电   140篇
一般工业技术   404篇
冶金工业   370篇
原子能技术   15篇
自动化技术   364篇
  2024年   5篇
  2023年   22篇
  2022年   33篇
  2021年   66篇
  2020年   50篇
  2019年   55篇
  2018年   49篇
  2017年   40篇
  2016年   63篇
  2015年   53篇
  2014年   54篇
  2013年   128篇
  2012年   97篇
  2011年   137篇
  2010年   97篇
  2009年   88篇
  2008年   103篇
  2007年   111篇
  2006年   75篇
  2005年   67篇
  2004年   50篇
  2003年   55篇
  2002年   50篇
  2001年   38篇
  2000年   25篇
  1999年   36篇
  1998年   75篇
  1997年   35篇
  1996年   48篇
  1995年   43篇
  1994年   15篇
  1993年   25篇
  1992年   19篇
  1991年   17篇
  1990年   17篇
  1989年   16篇
  1988年   15篇
  1987年   22篇
  1986年   11篇
  1984年   11篇
  1983年   13篇
  1982年   12篇
  1980年   10篇
  1979年   11篇
  1978年   11篇
  1977年   8篇
  1976年   20篇
  1975年   5篇
  1972年   4篇
  1971年   6篇
排序方式: 共有2146条查询结果,搜索用时 8 毫秒
231.
On the basis of taxometric analyses of data sets that they created to pose interpretive challenges, S. R. H. Beach, N. Amir, and J. J. Bau (2005) cautioned that using comparison data simulated by J. Ruscio's programs can lead to inaccurate conclusions. Careful examination of S. R. H. Beach et al.'s methods and results plus reanalysis of their data fails to substantiate this concern: Using comparison data identified the taxonic structure of S. R. H. Beach et al.'s data sets, even when the taxon base rate was very low. The authors show that J. Ruscio's simulation programs generate comparison data appropriately and that analyzing these data provides a useful interpretive aid. Additionally, the authors discuss and illustrate the effective use of the inchworm consistency test to disambiguate taxometric results for small taxa and dimensional constructs with positively skewed indicators. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
232.
233.
We describe a framework for designing encoders that transform arbitrary data sequences into two-dimensional arrays satisfying certain constraints, in particular, constraints that guarantee arrays with limited high spatial frequency content. We also exhibit specific codes that produce such arrays. Such codes are useful for holographic recording systems  相似文献   
234.
Three children with adrenoleukodystrophy (ALD) underwent allogeneic bone marrow transplantation (BMT) between 1992 and 1993. The first boy had attention deficits, marked neuropsychological deficits and widespread demyelination in the frontal lobes on MRI before transplantation. Four years later he has mentally deteriorated and the demyelination on MRI has progressed. The second boy had no symptoms but had white matter lesions on MRI when diagnosed. He was regularly followed with MRI and neuropsychological investigations until BMT 18 months later. A progress of the lesions was noted on the initial MRI investigations, and 4 months before BMT a worsening of deficits in attention and kinaesthetic praxis could be observed. He rapidly deteriorated after the transplantation and died 18 months later. Both PCR and in situ hybridization confirmed the presence of donor cells in the brain. The third boy had no symptoms but white matter lesions on MRI when diagnosed. The neuropsychological tests remained normal but a slight progress was observed on MRI just before transplantation. This boy is still healthy 3.5 years after BMT. BMT as treatment for ALD has to be considered very early, even if a child without symptoms but signs of demyelination on MRI, if a suitable donor is available.  相似文献   
235.
A longitudinal study examined the relationship between teacher-rated behaviors (the Devereux Elementary School Behavior Rating Scale) in kindergarten through Grade 3 and delinquency and school misconduct throughout adolescence. 659 children who were at risk because of their urban minority living conditions were initially assessed in 1968, and 380 were successfully followed up in 1982. An early high-risk pattern was identified in both sexes that indicated that Ss who were overly and disruptively involved socially and who failed to modulate their own behavior to accommodate others were likely to come into conflict with authority quite early in life and into adolescence. Results are discussed in relationship to other research on temperament, parent–child interaction, and possible preventive intervention. (47 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
236.
237.
Editorial     
Ohne Zusammenfassung  相似文献   
238.
239.
240.
Macroporous TiO2 (anatase) thin films are fabricated by an all low‐temperature process in which substrates are dip‐coated in suspensions of mixed anatase nanoparticles and polystyrene beads, and the templating agents are removed by ultraviolet (UV) irradiation at a temperature below 50 °C. Scanning electron microscopy (SEM) and Raman spectroscopy show that the templating polymer beads are removed by UV irradiation combined with the photocatalytic activity of TiO2. X‐Ray diffraction reveals that nanoparticle growth is negligible in UV irradiated films, while nanoparticle size increases by almost 10 times in calcined films that are prepared for comparison. The macroporous films are prepared on FTO‐(fluorine‐doped tin oxide) coated glass and ITO (indium tin oxide) coated flexible plastics and thereby used as working electrodes. In both cases, the films are electrochemically addressable, and cyclic voltammetry is consistent with the response of bulk TiO2 for calcined films and of nanoscale‐TiO2 for UV‐irradiated films.  相似文献   
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