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   3107篇
  免费   135篇
  国内免费   32篇
电工技术   47篇
综合类   59篇
化学工业   495篇
金属工艺   108篇
机械仪表   98篇
建筑科学   86篇
矿业工程   10篇
能源动力   140篇
轻工业   182篇
水利工程   15篇
石油天然气   14篇
武器工业   2篇
无线电   464篇
一般工业技术   695篇
冶金工业   391篇
原子能技术   15篇
自动化技术   453篇
  2023年   22篇
  2022年   24篇
  2021年   57篇
  2020年   39篇
  2019年   43篇
  2018年   52篇
  2017年   58篇
  2016年   65篇
  2015年   50篇
  2014年   87篇
  2013年   243篇
  2012年   176篇
  2011年   184篇
  2010年   149篇
  2009年   173篇
  2008年   147篇
  2007年   138篇
  2006年   151篇
  2005年   113篇
  2004年   97篇
  2003年   81篇
  2002年   71篇
  2001年   64篇
  2000年   60篇
  1999年   65篇
  1998年   108篇
  1997年   95篇
  1996年   108篇
  1995年   68篇
  1994年   62篇
  1993年   49篇
  1992年   45篇
  1991年   36篇
  1990年   33篇
  1989年   38篇
  1988年   34篇
  1987年   23篇
  1986年   28篇
  1985年   16篇
  1984年   12篇
  1983年   9篇
  1982年   14篇
  1981年   19篇
  1980年   9篇
  1979年   12篇
  1977年   11篇
  1976年   15篇
  1975年   5篇
  1972年   6篇
  1970年   2篇
排序方式: 共有3274条查询结果,搜索用时 46 毫秒
1.
The influences of atmosphere during processes of melting and heat treatment, heat treatment temperature, Fe3O4 content and basicity on the magnetic properties of magnetite-based glass ceramics were investigated. For sample containing 20 % Fe3O4 melted in different atmospheres, the highest saturation magnetisation was realized in 20vol% air + 80 vol% Ar, due to the fact that ratio of Fe3+ to Fe2+ in melt obtained in this atmosphere was close to 2. However, it was found that the coercivity of glass ceramics was not affected by the melting atmosphere. A high sintering temperature led to the decrease of saturation magnetisation and the increase of coercivity. As increasing Fe3O4 content, the main crystal phase transformed from CaSiO3 to CaFe0.6Al1.3Si1.08O6 and finally to magnetite phase, accompanied by the increase of saturation magnetisation and coercivity. In addition, the increase of basicity caused the decrease of saturation magnetisation and the increase of coercivity.  相似文献   
2.
3.
Kuo  Shu-Chun  Chien  Tsair-Wei  Chou  Willy 《Scientometrics》2022,127(2):1191-1194
Scientometrics - The article published on 5 July 2021 is well-written and of interest. However, some improvements could be made, such as ten Tables/Figures can be shortened to highlight the focused...  相似文献   
4.
The late-onset type of Fabry disease (FD) with GLA IVS4 + 919G > A mutation has been shown to lead to cardiovascular dysfunctions. In order to eliminate variations in other aspects of the genetic background, we established the isogenic control of induced pluripotent stem cells (iPSCs) for the identification of the pathogenetic factors for FD phenotypes through CRISPR/Cas9 genomic editing. We adopted droplet digital PCR (ddPCR) to efficiently capture mutational events, thus enabling isolation of the corrected FD from FD-iPSCs. Both of these exhibited the characteristics of pluripotency and phenotypic plasticity, and they can be differentiated into endothelial cells (ECs). We demonstrated the phenotypic abnormalities in FD iPSC-derived ECs (FD-ECs), including intracellular Gb3 accumulation, autophagic flux impairment, and reactive oxygen species (ROS) production, and these abnormalities were rescued in isogenic control iPSC-derived ECs (corrected FD-ECs). Microarray profiling revealed that corrected FD-derived endothelial cells reversed the enrichment of genes in the pro-inflammatory pathway and validated the downregulation of NF-κB and the MAPK signaling pathway. Our findings highlighted the critical role of ECs in FD-associated vascular dysfunctions by establishing a reliable isogenic control and providing information on potential cellular targets to reduce the morbidity and mortality of FD patients with vascular complications.  相似文献   
5.
Chrysanthemum flower is among one of the highly sought after and widely planted flower crops, in particular for cultural and religious ceremonies. However, the chrysanthemum stem and stalk have little value and usually discard as by‐product waste from floristry. The objective of this research is to investigate the potential value of utilizing chrysanthemum stem and stalk as reinforcing fillers for thermoplastic composites. In this study, 2‐mm thick composite sheet containing predefined formulations of polylactic acid (PLA), chrysanthemum waste filler (CWF) ranging from 15 to 60 phr, and maleated polyethylene (MAPE) coupling agent up to 5 phr were prepared with the aid of Haake internal mixer and compression molding. The effect of MAPE loading on tensile, thermal, and morphological properties of PLA/CWF composites was investigated. The findings revealed that PLA/CWF composite attained improved tensile modulus compared to the neat PLA, and the tensile modulus increases with higher concentration of CWF. However, both tensile strength and elongation at break reduces with increase loading of CWF. Overall, PLA/CWF composites with MAPE shows better performance compared to those without MAPE, where an optimum strength of 21.8 MPa can be achieved with 60 phr CW and 3 phr MAPE. The measured tensile strength is comparable to alternatives natural fiber thermoplastic composites demonstrating its potential to be used in non‐structurally demanding application. J. VINYL ADDIT. TECHNOL., 26:10–16, 2020. © 2019 Society of Plastics Engineers  相似文献   
6.
Molybdenum boride is an ideal hard and wear-resistant material. In this study, a new method is proposed for preparing molybdenum boride, by which Mo first reacts with B4C to generate the mixture of molybdenum boride and C, and then the product is decarburized by molten Ca to generate CaC2. Pure molybdenum boride could be obtained after acid leaching to remove the by-product CaC2. According to the experimental and thermodynamic calculation results, it is concluded that the single-phase MoB could be successfully prepared, while Mo2B, Mo2B5, and MoB4 could not be synthesized by this method. Moreover, it was found that the particle size of finally prepared MoB is determined by particle size of raw Mo powder. The residual carbon content of the product could be decreased to 0.10 wt% after first reaction at 1673 K for 6 hours and then decarburization reaction at 1673 K for 6 hours.  相似文献   
7.
8.
9.
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