全文获取类型
收费全文 | 573篇 |
免费 | 33篇 |
国内免费 | 12篇 |
专业分类
电工技术 | 14篇 |
综合类 | 6篇 |
化学工业 | 117篇 |
金属工艺 | 17篇 |
机械仪表 | 32篇 |
建筑科学 | 15篇 |
能源动力 | 25篇 |
轻工业 | 35篇 |
水利工程 | 8篇 |
石油天然气 | 16篇 |
无线电 | 87篇 |
一般工业技术 | 94篇 |
冶金工业 | 26篇 |
原子能技术 | 4篇 |
自动化技术 | 122篇 |
出版年
2024年 | 1篇 |
2023年 | 11篇 |
2022年 | 19篇 |
2021年 | 37篇 |
2020年 | 30篇 |
2019年 | 38篇 |
2018年 | 55篇 |
2017年 | 47篇 |
2016年 | 45篇 |
2015年 | 16篇 |
2014年 | 25篇 |
2013年 | 51篇 |
2012年 | 42篇 |
2011年 | 42篇 |
2010年 | 39篇 |
2009年 | 29篇 |
2008年 | 18篇 |
2007年 | 19篇 |
2006年 | 15篇 |
2005年 | 9篇 |
2004年 | 7篇 |
2003年 | 5篇 |
2002年 | 2篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1995年 | 1篇 |
1994年 | 5篇 |
排序方式: 共有618条查询结果,搜索用时 15 毫秒
1.
Jafar Baseri Rahim Naghizadeh Hamid Reza Rezaie Farhad Golestanifard Mohammad Golmohammad 《International Journal of Applied Ceramic Technology》2020,17(6):2709-2715
CoAl2O4 spinel was successfully synthesized by combustion synthesis method using glycine and urea by 1:1 molar ratio as fuels and sol-gel process using citric acid as a chelating agent. The as-synthesized powders were calcined at desired temperatures to obtain CoAl2O4 spinel as a single phase. X-ray diffraction, thermogravimetric, and differential thermal analysis results revealed that the formation of CoAl2O4 spinel in combustion method needs 300°C higher temperatures than those of sol-gel. Scanning electron microscopy and transmission electron microscopy analysis results revealed that “sol-gel spinel” had nanometric particle size which was smaller than those of “combustion spinel.” Temperature programed reduction with hydrogen and Fourier transform infrared spectroscopy results declared that there was a little residual cobalt oxide in combustion spinel while there is no oxide resided in “sol-gel spinel.” Consequently, the sol-gel method has more benefit in synthesizing spinel with sulfate precursors than combustion. 相似文献
2.
Silicon - Magnetic stirring is considered to be the most useful stirring method in semi-solid casting processes which doesn’t have the restrictions of the mechanical stirring. In this... 相似文献
3.
Seyedeh Nooshin Banitaba Dariush Semnani Elahe Heydari‐Soureshjani Behzad Rezaei Ali A Ensafi Ahmadreza Taghipour‐Jahromi 《Polymer International》2020,69(8):675-687
In this study, solvent‐free nanofibrous electrolytes were fabricated through an electrospinning method. Polyethylene oxide (PEO), lithium perchlorate and ethylene carbonate were used as polymer matrix, salt and plasticizer respectively in the electrolyte structures. Keggin‐type hetero polyoxometalate (Cu‐POM@Ru‐rGO, Ni‐POM@Ru‐rGO and Co‐POM@Ru‐rGO (POM, polyoxometalate; rGO, reduced graphene oxide)) nanoparticles were synthesized and inserted into the PEO‐based nanofibrous electrolytes. TEM and SEM analyses were carried out for further evaluation of the synthesized filler structures and the electrospun nanofibre morphologies. The fractions of free ions and crystalline phases of the as‐spun electrolytes were estimated by obtaining Fourier transform infrared and XRD spectra, respectively. The results showed a significant improvement in the ionic conductivity of the nanofibrous electrolytes by increasing filler concentrations. The highest ionic conductivity of 0.28 mS cm?1 was obtained by the introduction of 0.49 wt% Co‐POM@Ru‐rGO into the electrospun electrolyte at ambient temperature. Compared with solution‐cast polymeric electrolytes, the electrospun electrolytes present superior ionic conductivity. Moreover, the cycle stability of the as‐spun electrolytes was clearly improved by the addition of fillers. Furthermore, the mechanical strength was enhanced with the insertion of 0.07 wt% fillers to the electrospun electrolytes. The results implied that the prepared nanofibres are good candidates as solvent‐free electrolytes for lithium ion batteries. © 2020 Society of Chemical Industry 相似文献
4.
Sahar Hashemi Daryan Jafar Javadpour Alireza Khavandi Mohammad Erfan 《Ceramics International》2018,44(16):19743-19750
Well-ordered and surface engineered hierarchical hydroxyapatite microspheres (HAM) were prepared via a template free hydrothermal process. Ethylene diamine tetra (methylene phosphonic acid) (EDTMP) was used as chelating or regulating agent for the first time in this study. The results indicated the formation of sheet-like particles in the absence of EDTMP. On the other hand, microspheres with radially grown nanorods (HAMNR) or nanosheets (HAMNS) on the surface were obtained (with average diameter of 5?µm) in the presence of EDTMP. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy were used to characterize the crystalline phases in the synthesized samples. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed that EDTMP concentration played an important part in regulating the morphology to form well organized microspheres with nanosheets or nanorods on the surface. Brunauer-Emmett-Teller (BET) revealed an increase in the specific surface area with the change in morphology from the HAMNS to HAMNR. Possible mechanisms are proposed to account for the formation of different morphologies based upon thermodynamic and kinetic theories. 相似文献
5.
Knowledge and Information Systems - The standard machine learning tasks often assume that the training (source domain) and test (target domain) data follow the same distribution and feature space.... 相似文献
6.
Cheraghi Alireza Yoozbashizadeh Hossein Ringdalen Eli Safarian Jafar 《Metallurgical and Materials Transactions B》2019,50(4):1566-1580
Metallurgical and Materials Transactions B - The calcination and the reduction behaviors of a low-grade manganese ore by methane was studied at 973 K to 1273 K by several techniques. The onset... 相似文献
7.
8.
Wireless Networks - Source localization based on the received signal strength (RSS) has received great interest due to its low cost and simple implementation. In this paper we consider the source... 相似文献
9.
10.