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   1587299篇
  免费   29757篇
  国内免费   7087篇
电工技术   34933篇
综合类   6508篇
化学工业   273687篇
金属工艺   66339篇
机械仪表   46338篇
建筑科学   47462篇
矿业工程   11575篇
能源动力   51897篇
轻工业   120658篇
水利工程   15850篇
石油天然气   37426篇
武器工业   151篇
无线电   203479篇
一般工业技术   299477篇
冶金工业   197728篇
原子能技术   34608篇
自动化技术   176027篇
  2021年   16618篇
  2020年   12735篇
  2019年   15509篇
  2018年   18279篇
  2017年   17587篇
  2016年   23394篇
  2015年   18524篇
  2014年   30342篇
  2013年   90552篇
  2012年   39650篇
  2011年   53830篇
  2010年   46213篇
  2009年   54098篇
  2008年   49078篇
  2007年   45935篇
  2006年   47305篇
  2005年   42067篇
  2004年   43796篇
  2003年   43389篇
  2002年   42330篇
  2001年   39252篇
  2000年   37385篇
  1999年   37091篇
  1998年   56421篇
  1997年   46143篇
  1996年   39818篇
  1995年   33410篇
  1994年   30924篇
  1993年   30815篇
  1992年   26384篇
  1991年   23549篇
  1990年   23842篇
  1989年   22807篇
  1988年   21288篇
  1987年   19602篇
  1986年   18998篇
  1985年   22274篇
  1984年   22210篇
  1983年   20134篇
  1982年   19178篇
  1981年   19327篇
  1980年   17953篇
  1979年   18368篇
  1978年   17684篇
  1977年   17869篇
  1976年   19550篇
  1975年   15852篇
  1974年   15354篇
  1973年   15473篇
  1972年   13005篇
排序方式: 共有10000条查询结果,搜索用时 119 毫秒
21.
Multimedia Tools and Applications - Mammograms are the images used by radiologists to diagnose breast cancer. Breast cancer is one of the most common cancers in women. The early detection of breast...  相似文献   
22.
The effect of microwave roasting parameters (300, 450 and 600 W; 5, 10 and 15 min) on acrylamide content in sorghum grain was determined using High Pressure Liquid Chromatography (HPLC)-photo diode array (PDA) detector coupled with C-18 column. Samples roasted at 300 and 450 W did not possess acrylamide, whereas 600 W (15 min) favoured formation of 2740.19 µg/kg of acrylamide, levels far exceeding the defined European Union (EU) limits. The chronic daily intake (CDI) for acrylamide through consumption of such grain flour was 3.25–9.5-fold higher to Joint FAO/WHO Expert Committee on Food Additives (JECFA) defined high exposure limits. The margin of exposure (MOE) values ranged from 4.3 to 12.76 and from 11.07 to 32.27 for neoplastic and neurological effects, respectively, demonstrating high exposure and serious health concerns associated with dietary intake of this toxicant. This study assesses the risk for the Indian population and highlights the importance of optimising process parameters for food product to minimise such exposure risks.  相似文献   
23.
Refractories and Industrial Ceramics - The paper introduces a promising technology for utilizing a traditional scheme for implementing a flow-through micro-arc oxidation method to restore localized...  相似文献   
24.
Theoretical Foundations of Chemical Engineering - On the basis of the classic concepts of the theory of solid-phase combustion, for the first time, a model with a detailed scheme of chemical...  相似文献   
25.
26.
Multimedia Tools and Applications - Recently, many concepts in technology has been changed. According to the digital transformation trends, Internet of Things (IoT) represents an interested...  相似文献   
27.
In this study, dilute chemical bath deposition technique has been used to deposit CdZnS thin films on soda-lime glass substrates. The structural, morphological, optoelectronic properties of as-grown films have been investigated as a function of different Zn2+ precursor concentrations. The X-ray diffractogram of CdS thin-film reveals a peak corresponding to (002) plane with wurtzite structure, and the peak shift has been observed with the increase of the Zn2+ concentration upon formation of CdZnS thin film. From morphological studies, it has been revealed that the diluted chemical bath deposition technique provides homogeneous distribution of film on the substrate even at a lower concentration of Zn2+. Optical characterization has shown that the transparency of the film is influenced by Zn2+ concentration and when the Zn2+ concentration is varied from 0 M to 0.0256 M, bandgap values of resulting films range from 2.42 eV to 3.90 eV while. Furthermore, electrical properties have shown that with increasing zinc concentration the resistivity of the film increases. Finally, numerical simulation validates and suggests that CdZnS buffer layer with composition of 0.0032 M Zn2+ concentration would be a promising candidate in CIGS solar cell.  相似文献   
28.
Combustion, Explosion, and Shock Waves - Results of a numerical study of mixing, ignition, and combustion of a cold hydrogen jet propagating along the lower wall of a channel parallel to a...  相似文献   
29.
Multimedia Tools and Applications - In this work, a new fuzzy logic-based algorithm is proposed for the enhancement of low light color images. A generalization of a fuzzy set known as an...  相似文献   
30.
Multimedia Tools and Applications - The three-dimensional models of brain tumors serve as diagnostic assistance for physicians, surgeons, and radiologists. The proposed system establishes an...  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