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   974篇
  免费   68篇
  国内免费   5篇
电工技术   17篇
综合类   1篇
化学工业   310篇
金属工艺   15篇
机械仪表   21篇
建筑科学   32篇
矿业工程   3篇
能源动力   52篇
轻工业   122篇
水利工程   15篇
石油天然气   19篇
无线电   99篇
一般工业技术   170篇
冶金工业   45篇
原子能技术   6篇
自动化技术   120篇
  2024年   4篇
  2023年   16篇
  2022年   49篇
  2021年   52篇
  2020年   42篇
  2019年   27篇
  2018年   50篇
  2017年   37篇
  2016年   51篇
  2015年   51篇
  2014年   51篇
  2013年   128篇
  2012年   60篇
  2011年   75篇
  2010年   53篇
  2009年   40篇
  2008年   35篇
  2007年   22篇
  2006年   14篇
  2005年   31篇
  2004年   20篇
  2003年   11篇
  2002年   8篇
  2001年   7篇
  2000年   6篇
  1999年   11篇
  1998年   19篇
  1997年   9篇
  1996年   7篇
  1995年   8篇
  1994年   2篇
  1993年   5篇
  1992年   1篇
  1991年   5篇
  1990年   4篇
  1989年   3篇
  1988年   3篇
  1987年   5篇
  1986年   5篇
  1985年   2篇
  1984年   2篇
  1983年   1篇
  1981年   1篇
  1980年   4篇
  1979年   1篇
  1978年   2篇
  1977年   2篇
  1976年   2篇
  1975年   2篇
  1974年   1篇
排序方式: 共有1047条查询结果,搜索用时 15 毫秒
31.
Two modified electrodes (Pb/PbO2 and C/PbO2) were prepared by electrodepositing a lead oxide layer on lead and carbon sub-strates. These modified electrodes were used as anodes for the generation of sodium hypochlorite (NaOCl) from sodium chloride solution. Different operating conditions and factors affecting the treatment process of NaOCl generation, including current density, pH values, con-ductive electrolytes, and electrolysis time, were studied and optimized. By comparison the C/PbO2 electrode shows a higher efficiency than the Pb/PbO2 electrode for the generation of NaOCl.  相似文献   
32.
International Journal on Document Analysis and Recognition (IJDAR) - Optical character recognition (OCR) is the process of recognizing characters automatically from scanned documents for editing,...  相似文献   
33.
Composite biomaterials are in high demand in the medical field of today. The combination of bioactive wollastonite (WA) glass ceramic with the biocompatibility of alloy titanium (Ti6Al4V) could be a good candidate for implant applications. The rheological properties of Ti6Al4V/WA feedstock show a pseudoplastic behaviour with low activation energy. The feedstock was successfully injected as a green part with no defects. The green part was solvent debound for 6?h in heptane and thermal debound in an argon environment for 1?h. The brown part was successfully sintered at 1300?°C for 3?h with 5?°C/min heating and cooling rates. The average sintered density was 4.12?g/cm3; which is 97.5% from the theoretical density. The highest Young's modulus obtained was 18.10?GPa; which is in the range of human bone strength. EDX analysis shows that by increasing sintering temperature, the level of oxygen decreased. Cell viability test shown an absorbance increased with days increasing indicated that the cellular were proliferated on the composite Ti6Al4V/WA composite which also proved that the composite was non-toxic. This indicates that the Ti6Al4V/WA composite is suitable for bone implant applications.  相似文献   
34.
35.
Engineering with Computers - Vast research works implementing feature-based technology have successfully been devoted. However, work on recognition of revolved regular-freeform surfaces is still...  相似文献   
36.
37.
Brown seaweeds contain a number of bioactive compounds. The xanthophyll, fucoxanthin, has in vivo efficacy against disorders such as type 2 diabetes, obesity and cancer. Organic solvents are traditionally employed to extract fucoxanthin, but carry a toxic chemical and environmental burden. The aim of this study was to optimise a fucoxanthin extraction method using enzymes, water, low‐temperature dehydration and mechanical blending, to produce yields comparable to those achieved with an organic solvent (acetone). Response surface methodology was applied, using Fucus vesiculosus as a model species. A fucoxanthin yield of 0.657 mg g?1 (dry mass) was obtained from F. vesiculosus blade using the enzymatic method, equivalent to 94% of the acetone‐extracted yield. Optimum extraction parameters were determined to be enzyme‐to‐water ratio 0.52%, seaweed‐to‐water ratio 5.37% and enzyme incubation time 3.05 h. These findings may be applied to the development of value‐added nutraceutical products from seaweed.  相似文献   
38.
Catalysis Letters - To avoid the aggregation problem and activity loss of nickel oxide (NiO) nanoparticles (NPs) in organic reactions, NiO NPs were incorporated into TUD-1 mesoporous material....  相似文献   
39.
40.
Obtained results of micro and nano studies reveal that bismuth refines the silicon in which the flake silicon changed to lamellar structure with reduction in twin spacing from 160 to 75 nm. Bismuth segregates towards the inter-dendritic regions and decreases the Al-Si contact angle resulting in suppression of the silicon growth causing refinement of the eutectic structure. Increased recalescence temperature and time confirmed that the refinement effect is attributed to the growth stage.  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