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   986篇
  免费   35篇
  国内免费   3篇
电工技术   25篇
综合类   3篇
化学工业   261篇
金属工艺   47篇
机械仪表   34篇
建筑科学   24篇
矿业工程   4篇
能源动力   66篇
轻工业   86篇
水利工程   3篇
石油天然气   6篇
无线电   65篇
一般工业技术   168篇
冶金工业   69篇
原子能技术   4篇
自动化技术   159篇
  2024年   2篇
  2023年   10篇
  2022年   17篇
  2021年   34篇
  2020年   23篇
  2019年   36篇
  2018年   32篇
  2017年   36篇
  2016年   32篇
  2015年   20篇
  2014年   44篇
  2013年   82篇
  2012年   57篇
  2011年   68篇
  2010年   60篇
  2009年   65篇
  2008年   56篇
  2007年   47篇
  2006年   45篇
  2005年   29篇
  2004年   36篇
  2003年   25篇
  2002年   22篇
  2001年   13篇
  2000年   8篇
  1999年   9篇
  1998年   22篇
  1997年   9篇
  1996年   14篇
  1995年   6篇
  1994年   7篇
  1993年   7篇
  1992年   11篇
  1991年   3篇
  1990年   3篇
  1989年   4篇
  1988年   4篇
  1987年   2篇
  1986年   1篇
  1985年   1篇
  1984年   1篇
  1983年   4篇
  1982年   2篇
  1980年   2篇
  1979年   2篇
  1978年   3篇
  1976年   2篇
  1974年   2篇
  1973年   3篇
  1971年   1篇
排序方式: 共有1024条查询结果,搜索用时 31 毫秒
1.
The study aims to evaluate the technological properties of autochthonous strains (Lactobacillus sakei S15, Lactobacillus plantarum S24, L. plantarum S91, Pediococcus pentosaceus S128b and Staphylococcus carnosus G109) in Turkish dry fermented sausage (sucuk). After 24 h of fermentaPtion, all lactic acid bacteria strains reduced the pH to below 5.0, while the pH in the control group was above 5.3. The number of lactic acid bacteria strains reached 108–109 cfu g−1 during fermentation. Staphylococcus carnosus G109 remained at the inoculation level of 106 cfu g−1 during ripening. Lactobacillus sakei S15 as mono-culture showed higher TBARS values compared to other strains. The control group had the lowest L* value and autochthonous strains caused no significant difference for a* value. According to principal component analysis results, most volatile compounds were positively correlated with the group containing only L. sakei S15.  相似文献   
2.
Journal of Materials Science: Materials in Electronics - In this study, zinc oxide (ZnO) nanowires (NWs) were successfully produced on Zn plates through electrochemical anodization in potassium...  相似文献   
3.
4.
Multimedia Tools and Applications - Hotel recommendation is one of the most used application areas in recommendation systems. So far, many hotel recommendation systems have been proposed. Most of...  相似文献   
5.
6.
7.
In the present study, a Mn-supported catalyst material developed from Microcystis aeruginosa microalgae for hydrogen generation was tested as a supercapacitor electrode material for the first time. The catalyst material (MA-HCl-Mn) was examined for hydrogen generation through methanolysis of NaBH4, and it demonstrated good catalytic activity. Symmetric and asymmetric supercapacitor cells were prepared using MA-HCl-Mn as the electrode material. The electrochemical performance of the cells were evaluated by a two-electrode system using 2 M KOH as the electrolyte. The gravimetric capacitance of the symmetric and asymmetric cells found to be 40 F/g and 71 F/g, respectively. It was concluded that MA-HCl-Mn served as a sustainable, dual functional material showing a high catalytic activity for the hydrogen generation and a promising electrochemical performance as the supercapacitor electrode.  相似文献   
8.
ABSTRACT

Wind turbine control is an important task to make the electricity generation secure in terms of energy demand and machine safety. It also yields to control the desired power level and optimized energy because of the assignment of turbine speed. The contactless piezoelectric wind energy harvester (CPWEH) used in this study has three piezoelectric layers located around the shaft with 120 degrees apart and they are buckled by the magnetic force without any physical contact. The superiority of this device is to generate energy for low wind speeds such as 1.5 m/s. However, for high speeds, high total harmonic distortions (THDs) govern the waveforms, thus controlling the turbine speed becomes necessary for optimizing the output power. Encouraged by this, a small low inertia dc generator is coupled with the wind turbine, and the generator terminals are connected to a resistor through a power switch to generate a braking torque that opposes to wind speed direction. By controlling the switch properly, turbine speed is ensured to remain within a certain band, which accordingly prevents the turbine from rotating very fast at damaging wind speeds. Several experiments are performed on the developed CPWEH with/without the presented control scheme which prove the existence of promising performance of our proposal.  相似文献   
9.
A new series of poly(azomethine-imide)s having siloxane moities in backbone was prepared using different dianhydrides.Thermal, optical, and morphological properties of these polymers were clarified. Also, bulky  CO and  CF3 group effects and meta or para-substituted aldeyhde effects on the mentioned properties were evaluated. The structural characterization of poly(azomethine-imide)s was carried out using a FT-IR spectroscopy. The optical properties of the polymers were performed via an UV–Vis spectrophotometer. Optical band gap of the poly(imide)s containing azomethine was calculated between 2.20 and 2.33 eV. Thermal behavior of poly(azomethine-imide)s was also studied using TG-DTA, DSC, and DMA techniques. The onset degradation temperature and percentage char values of the polyimides were found in the range from 429 to 545 °C and 22 to 35%, respectively. Thermal stability results demonstrated that benzophenone bearing poly(azomethine-imide)s have higher onset temperature, percentage char, and the glass transition temperature than poly(azomethine-imide)s derived from hexafluoroisopropylidene. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48364.  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