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   422545篇
  免费   5898篇
  国内免费   1399篇
电工技术   7694篇
综合类   432篇
化学工业   65015篇
金属工艺   16818篇
机械仪表   13819篇
建筑科学   9019篇
矿业工程   2207篇
能源动力   12109篇
轻工业   32886篇
水利工程   4437篇
石油天然气   8069篇
武器工业   18篇
无线电   50054篇
一般工业技术   85767篇
冶金工业   76555篇
原子能技术   9275篇
自动化技术   35668篇
  2022年   3217篇
  2021年   4729篇
  2020年   3441篇
  2019年   4373篇
  2018年   7195篇
  2017年   7193篇
  2016年   7693篇
  2015年   4881篇
  2014年   7967篇
  2013年   21575篇
  2012年   12666篇
  2011年   16653篇
  2010年   13192篇
  2009年   14705篇
  2008年   14946篇
  2007年   14597篇
  2006年   13058篇
  2005年   11591篇
  2004年   10948篇
  2003年   10873篇
  2002年   10201篇
  2001年   10025篇
  2000年   9386篇
  1999年   9764篇
  1998年   24933篇
  1997年   17122篇
  1996年   13110篇
  1995年   9727篇
  1994年   8536篇
  1993年   8501篇
  1992年   6125篇
  1991年   5745篇
  1990年   5721篇
  1989年   5367篇
  1988年   5095篇
  1987年   4469篇
  1986年   4330篇
  1985年   4860篇
  1984年   4460篇
  1983年   4032篇
  1982年   3688篇
  1981年   3754篇
  1980年   3463篇
  1979年   3340篇
  1978年   3348篇
  1977年   3776篇
  1976年   4894篇
  1975年   2857篇
  1974年   2674篇
  1973年   2747篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
In this paper, we present a novel memory access reduction scheme (MARS) for two-dimension fast cosine transform (2-D FCT). It targets programmable DSPs with high memory-access latency. It reduces the number of memory accesses by: 1) reducing the number of weighting factors and 2) combining butterflies in vector-radix 2-D FCT pruning diagram from two stages to one stage with an efficient structure. Hardware platform based on general purpose processor is used to verify the effectiveness of the proposed method for vector-radix 2-D FCT pruning implementation. Experimental results validate the benefits of the proposed method with reduced memory access, less clock cycle and fewer memory space compared with the conventional implementation.  相似文献   
2.
3.
4.
5.
6.
Lobster krill (Munida genus) represents an under‐valued crustacean frequently caught on European fishing banks. In this work, its sensory, microbiological and biochemical qualities were evaluated during chilled storage. Additionally, the effects of a prestorage antimelanosic treatment consisting of soaking in sodium metabisulphite (SMB) solutions at two different concentrations (0.25% and 0.75%) were also studied. SMB prestorage treatment provided lobster specimens that still exhibited acceptable sensory quality after 10 days of storage, while control specimens were unacceptable at that time. SMB treatment also resulted in a significant (P < 0.05) inhibition of microbial growth, mainly of Enterobacteriaceae, psychrotrophes and proteolytic bacteria. Low lipid oxidation levels were observed for all batches; however, a significantly higher (P < 0.05) retention of polyunsaturated fatty acids was found in SMB‐treated lobster, especially in the 0.75% SMB batch. The results presented here open the way to the potential commercialisation of currently under‐utilised lobster krill as a chilled product.  相似文献   
7.
8.
9.

To increase the efficiency of designing systems intended for monitoring surface cracks in aluminum structures during their working life, we have analyzed a two-dimensional symmetric problem on uniaxial extension of an Al-polyimide-Cu layered structure with ideal adhesion between layers and a model crack in the aluminum base. The problem has been first solved for a sample with the crack modeled by a zero-thickness notch using the ANSYS engineering simulation program package. It is shown that this setting of the problem can lead to inadequate results as manifested, in particular, by significantly overstated mechanical stresses in aluminum in the region of crack emergence on the surface. In order to eliminate this difficulty, we propose to use the structure with a model defect in the form of a notch of nonzero thickness in the initial unstressed state of the structure. Recommendations for selecting the thickness of a notch used in the model structure are given.

  相似文献   
10.
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