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   2997篇
  免费   99篇
  国内免费   19篇
电工技术   59篇
综合类   3篇
化学工业   578篇
金属工艺   95篇
机械仪表   67篇
建筑科学   45篇
矿业工程   1篇
能源动力   169篇
轻工业   120篇
水利工程   26篇
石油天然气   21篇
无线电   374篇
一般工业技术   757篇
冶金工业   328篇
原子能技术   20篇
自动化技术   452篇
  2023年   45篇
  2022年   82篇
  2021年   115篇
  2020年   90篇
  2019年   91篇
  2018年   124篇
  2017年   102篇
  2016年   100篇
  2015年   66篇
  2014年   105篇
  2013年   190篇
  2012年   121篇
  2011年   181篇
  2010年   134篇
  2009年   137篇
  2008年   112篇
  2007年   99篇
  2006年   80篇
  2005年   70篇
  2004年   58篇
  2003年   64篇
  2002年   48篇
  2001年   51篇
  2000年   40篇
  1999年   40篇
  1998年   68篇
  1997年   56篇
  1996年   42篇
  1995年   43篇
  1994年   49篇
  1993年   42篇
  1992年   26篇
  1991年   32篇
  1990年   22篇
  1989年   19篇
  1988年   29篇
  1987年   24篇
  1986年   19篇
  1985年   33篇
  1984年   34篇
  1983年   28篇
  1982年   23篇
  1981年   22篇
  1980年   26篇
  1979年   15篇
  1978年   11篇
  1977年   21篇
  1976年   27篇
  1975年   12篇
  1973年   14篇
排序方式: 共有3115条查询结果,搜索用时 250 毫秒
1.
Wireless Personal Communications - This research work explores the neural network learning capabilities by using a multi-layer perceptron artificial neural network to predict signal power loss by...  相似文献   
2.
Wireless Personal Communications - IoT-based smart farming techniques have come up as one of the solutions to tackle the effect of climate change, water scarcity, etc. which are the prime reason...  相似文献   
3.
Srivastava  Vivek 《Catalysis Letters》2021,151(12):3704-3720
Catalysis Letters - We gave an effective protocol to support Ru NPs on amine-functionalized SBA-15 mesoporous silica to catalyze the CO2 hydrogenation reaction. The amine groups present in the...  相似文献   
4.
Wireless Personal Communications - Authentication is a term very important for data communication security. We see many frauds due to authentication failure. The problem manifolds when...  相似文献   
5.
SiC based composites filled with graphene nano-platelets (GNPs) or graphene oxide (GO) prepared by rapid hot-pressing exhibit sufficient electrical conductivity for their machinability by wire electro-discharge machining (WEDM). Composites microstructure anisotropy caused by graphene alignment as a consequence of rapid hot pressing was confirmed by measuring of electrical conductivity and thermal diffusivity. Electrical conductivity increased significantly with increased weight fraction of graphene in both measured directions. Highest value of 2031 S/m was obtained for composites with 15 wt. % of GNPs in parallel direction and only 1246 S/m in perpendicular direction to aligned GNPs. Thermal diffusivity is 63.3 mm2/s in parallel and only 23.3 mm2/s in perpendicular direction. The increase of the electrical conductivity has resulted in successful WEDM. The MRR was almost doubled when the filler concentration increased from 5 wt. % GNPs/GO to 15 wt. % GNPs. At the same time, the surface roughness decreased.  相似文献   
6.
Sharma  Deepak  Bhushan  Rajesh Kumar 《SILICON》2020,12(5):1211-1211
Silicon - The original version of this paper was unfortunately published with an error in the order of authors and their corresponding affiliations. The correct data is shown above.  相似文献   
7.
Verma  Priyanshu  Punetha  Deepak  Pandey  Saurabh Kumar 《SILICON》2020,12(11):2663-2671
Silicon - Silicon carbide piezoresistive pressure sensor is more suitable for harsh environment due to its wide bandgap, corrosion tolerance, excellent chemical inertness, high Young’s...  相似文献   
8.
9.
Herein, nanocrystals of Er3+ and Er3+, Yb3+ co-doped NaYF4 upconversion (UC) phosphor were prepared via the reverse-microemulsion method. The impact of different concentrations of Er3+ ions on the UC emission intensity after 980?nm diode laser excitation is discussed. The structure, morphology and composition of the nanophosphors were confirmed by X-ray diffraction, transmission electron microscopy, scanning electron microscopy and the results showed the presence of NaYF4 nanocrystals with hexagonal phases of NaYF4. The UC spectra revealed two emission bands including a green and a red emission band and the CIE coordinate for the samples were estimated. The present research revealed that the reverse-microemulsion approach will be suitable for the synthesis of efficient upconversion nanophosphors.  相似文献   
10.
Synthesis of mono-crystalline Ga2O3 Nanorods was done by sol-gel transformation of gallium(III) isopropoxide (Ga(OPri)3). XRD studies were done to determine the planes and crystal structure of synthesized nanorods that showed the synthesis of β-Ga2O3(a). TEM studies of synthesized Ga2O3 confirmed the synthesis of monocrystalline β-Ga2O3 nanorods. To study the effect of precursor chemistry and to determine role of precursor structures on the crystal structure, phase and morphology of the Ga2O3, a new modified precursor complex was synthesized. The reaction of Ga(OPri)3 with N-phenylsalicylaldimine, [C6H4(OH)CH=N(C6H5)] in 1:1?M ratio yielded [{(H5C6)N?=?CH-C6H4O}Ga(OPri)2]. The newly synthesized complex was characterized by elemental analyses, molecular weight measurement, FT-IR and NMR (1H and 13C) spectral studies. Spectral studies of the modified complex suggest the presence of bi-dentate mode of attachment of Schiff's base in the solution state. Sol-gel transformations of [{(H5C6)N?=?CH-C6H4O}Ga(OPri)2] in organic medium, yielded γ-Ga2O3(b), as found by XRD studies. TEM image of the sample (a) revealed the formation of nano-rods of oxide with average diameter of ~100?nm whereas the TEM image of sample (b) showed presence of nano-sized particles of oxide with average particle size of 10?nm. Morphological and compositional studies of synthesized samples (a) and (b) were carried out using SEM and EDX. The method provides a possibility of large scale synthesis of dissimilar shaped and pure Ga2O3 nanoparticles.  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