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   3262篇
  免费   3篇
电工技术   6篇
综合类   3篇
化学工业   93篇
金属工艺   5篇
机械仪表   7篇
建筑科学   20篇
矿业工程   1篇
能源动力   8篇
轻工业   77篇
水利工程   7篇
无线电   35篇
一般工业技术   52篇
冶金工业   2860篇
原子能技术   2篇
自动化技术   89篇
  2021年   4篇
  2020年   5篇
  2019年   8篇
  2018年   7篇
  2017年   11篇
  2016年   7篇
  2015年   5篇
  2014年   10篇
  2013年   20篇
  2012年   16篇
  2011年   25篇
  2010年   10篇
  2009年   21篇
  2008年   14篇
  2007年   18篇
  2006年   22篇
  2005年   13篇
  2004年   13篇
  2003年   19篇
  2002年   9篇
  2001年   12篇
  2000年   8篇
  1999年   94篇
  1998年   840篇
  1997年   519篇
  1996年   313篇
  1995年   211篇
  1994年   162篇
  1993年   179篇
  1992年   32篇
  1991年   60篇
  1990年   46篇
  1989年   64篇
  1988年   50篇
  1987年   37篇
  1986年   37篇
  1985年   35篇
  1984年   4篇
  1983年   10篇
  1982年   22篇
  1981年   16篇
  1980年   22篇
  1979年   3篇
  1978年   10篇
  1977年   76篇
  1976年   101篇
  1975年   10篇
  1974年   3篇
  1973年   6篇
  1970年   3篇
排序方式: 共有3265条查询结果,搜索用时 0 毫秒
41.
We performed intraoperative arthrography of the knee in 12 children with congenital short femur, Blount's disease or Ollier's disease in whom the Ilizarov technique was used for correction of deformity, leg lengthening or both. In each case, arthrography revealed a joint surface considerably different from that assumed from plain radiographs, and resulted in a change in the placement of our reference wires before application of the frame. This gave significant improvement in the mechanical axis obtained at the time of removal of the frame. The technique is safe, cheap and easy to perform. It is a useful adjunct to the application of the Ilizarov frame when used for complex lengthening and correction of deformity in the leg.  相似文献   
42.
43.
The online version of the original article can be found at  相似文献   
44.
In this study the desizing, scouring, bleaching and slack mercerising of cotton fabric by a one–step process at different sodium hydroxide concentrations, impregnation temperatures and curing times were examined. The results indicate that when the fabrics are mercerised at lower temperature, the strength retention and colour strength are enhanced. When the sodium hydroxide concentration is increased, these properties also increase. When cotton fabrics are mercerised for 3 min at 40C and cured for 30 s at 120C, their physical properties are similar to those obtained using a conventional two–step approach.  相似文献   
45.
46.
47.
INTRODUCTION: Global amnesia (AG) is a dysfunction of memory, in which there is a sudden incapacity to remember recent events and assimilate new information. The aetiology is currently under discussion. The main hypotheses under consideration are an ischemic mechanism and an epileptic mechanism. OBJECTIVE: To study the cerebral blood flow in patients with temporary global amnesia (AGT) or permanent global amnesia (AGP) using functional neuroimaging techniques. MATERIAL AND METHODS: Four patients were studied. Two had severe alterations of fixation memory which had been present for months. The other two had a sudden loss of recent memory, although space-person orientation and immediate memory remained normal. In all cases the cerebral blood flow (FSC), was assessed by single photon emission tomography (SPECT), using Tc-HMPAO as the radio tracer. RESULTS: We describe 4 patients, 2 men and 2 women aged between 42 and 64.2 with AGT and the others with AGP. On SPECT there was temporal hypoperfusion in all 4 patients. In 2 cases there was associated parietal hypoperfusion and in 1 case there was frontal hypoperfusion. CONCLUSIONS: These findings suggest that AGT and AGP are of vascular origin and that SPECT is a useful diagnostic technique in patients with AG.  相似文献   
48.
49.
Integrated fieldwork and modelling has been undertaken to assess the vulnerability of riverside wells to pollution when river water is contaminated. Results highlight the importance of streambed sediments as a barrier to groundwater pollution by river water. The bed of the River Thames is lined with brown and grey organic-rich silts of low hydraulic conductivity (about 0.002 m/d). A 3-D model for solute transport in stream-aquifer systems was developed and applied to two riverside sites in the middle Thames valley. Model results indicate that well-water quality would only breach EC limits if the river was heavily polluted for a week or even a month (clearly an unlikely scenario). Sensitivity analyses showed the models to be far more sensitive to streambed parameters than to aquifer parameters. Thus it would be more sensible to focus fieldwork on the measurement of streambed properties than on the more usually measured aquifer parameters.  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