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   18773篇
  免费   958篇
  国内免费   137篇
电工技术   326篇
综合类   27篇
化学工业   4018篇
金属工艺   601篇
机械仪表   638篇
建筑科学   374篇
矿业工程   45篇
能源动力   1358篇
轻工业   1184篇
水利工程   147篇
石油天然气   85篇
武器工业   1篇
无线电   2344篇
一般工业技术   4350篇
冶金工业   1445篇
原子能技术   175篇
自动化技术   2750篇
  2024年   23篇
  2023年   419篇
  2022年   867篇
  2021年   1132篇
  2020年   917篇
  2019年   959篇
  2018年   1238篇
  2017年   969篇
  2016年   951篇
  2015年   615篇
  2014年   852篇
  2013年   1524篇
  2012年   901篇
  2011年   1089篇
  2010年   869篇
  2009年   817篇
  2008年   720篇
  2007年   574篇
  2006年   476篇
  2005年   366篇
  2004年   271篇
  2003年   242篇
  2002年   185篇
  2001年   164篇
  2000年   151篇
  1999年   148篇
  1998年   268篇
  1997年   221篇
  1996年   199篇
  1995年   168篇
  1994年   156篇
  1993年   152篇
  1992年   101篇
  1991年   124篇
  1990年   98篇
  1989年   97篇
  1988年   79篇
  1987年   88篇
  1986年   74篇
  1985年   84篇
  1984年   73篇
  1983年   71篇
  1982年   60篇
  1981年   70篇
  1980年   48篇
  1979年   31篇
  1978年   27篇
  1977年   27篇
  1976年   35篇
  1975年   13篇
排序方式: 共有10000条查询结果,搜索用时 186 毫秒
21.
Neural Processing Letters - Part of Speech (POS) tagging is a sequential labelling task and one of the core applications of Natural Language Processing. It has been a challenging problem for the...  相似文献   
22.
23.
24.
In this study, MgO nanoparticles were successfully fabricated and incubated inside ZnO NPs to form MgO/ZnO nanocomposite for biomedical applications. The x-ray diffraction analysis of MgO, ZnO, and MgO/ZnO has shown the single-phase x-ray diffraction patterns through X'pert High score. The crystallite sizes were calculated as 18 nm, 42 nm, and 53 nm, respectively. The average particle size of MgO, ZnO, and MgO/ZnO nanopowders depicted from secondary electron images of field emission electron microscopy were 56 nm, 400 nm, and 450 nm, respectively. The presence of MgO NPs inside ZnO NPs was confirmed by transmission electron microscopy. The elemental dispersive spectroscopy of MgO, given the peaks of oxygen and magnesium, also showed only zinc and oxygen peaks in ZnO, which confirms no other impurities in MgO and ZnO powders. The elemental analysis of MgO/ZnO nanocomposite showed the peaks of Zinc and Oxygen, along with a tiny peak of Mg. The photoluminescence and UV–vis spectroscopy revealed the absorbance fluorescence limit of the nanomaterials. Fourier transform infrared spectroscopy confirmed the several groups present in the nanocomposite. The biocompatibility of MgO, ZnO, and MgO/ZnO was observed with human peripheral blood mononuclear cells. The cytotoxicity studies were also performed against human cancer (liver and breast) cell lines. The MgO, ZnO, and MgO/ZnO exhibited the antimicrobial properties against Escherichia coli and Staphylococcus aureus.  相似文献   
25.
Wireless Personal Communications - A Delay Tolerant Network (DTN) is a network capable of handling long delays and data loss efficiently in various challenged scenarios and environments. Owing to...  相似文献   
26.
Telecommunication Systems - Wireless sensor networks (WSNs) and Internet of Things domain comprise of numerous small sized battery powered sensor nodes. Energy efficiency and energy balancing are...  相似文献   
27.
In the present study we made an effort to deploy eco-friendly synthesized reduced graphene oxide/Lanthanum Alluminate nanocomposites (RGO-LaAlO3) and Lanthanum Alluminate (LaAlO3) as adsorbents to remove dye from the synthetic media. XRD, SEM, BET surface area and EDX have been used to characterize the above-mentioned adsorbents. The impacts of different factors like adsorbent dosage, the concentration of adsorbate and PH on adsorption were studied. The best fit linear and nonlinear equations for the adsorption isotherms and kinetic models had been examined. The sum of the normalized errors and the coefficient of determination were used to determine the best fit model. The experimental data were more aptly fitted for nonlinear forms of isotherms and kinetic equations. Pseudo-second-order and Freundlich isotherm model fits the equilibrium data satisfactorily. Methyl orange (MO) has been used as model dye pollutant and maximum adsorption capacity was found to be 469.7 and 702.2 mg g?1 for LaAlO3 and RGO-LaAlO3, respectively.  相似文献   
28.
Reddy  N. Nagendra  Panda  Deepak Kumar 《SILICON》2021,13(9):3085-3100
Silicon - In this fast-growing technological world biosensors become more substantial in human life and the extensive use of biosensors creates enormous research interest among researchers to...  相似文献   
29.
Photonic Network Communications - Performance of underwater wireless optical communication (UWOC) with different vertical water channel conditions is experimentally analyzed. Experiment has been...  相似文献   
30.
ZnO rice like nonarchitects are grafted on the graphene carbon core via a rapid microwave synthesis route. The prepared grafted systems are characterized via XRD, SEM, RAMAN, and XPS to examined the structural and morphological parameters. Zinc oxide grafted graphene sheets (ZnO-G) are further doped in β-phase of polyvinylidene fluoride (PVDF) to prepare the polymer nanocomposites (PNCs) via mixed solvent approach (THF/DMF). β-phase confirmation of PVDF PNCs is done by FTIR studies. It is observed that ZnO-G filler enhances the β-phase content in the PNCs. Non-doped PVDF and PNCs are further studied for rheological behavior under the shear rate of 1–100 s−1. Doping of ZnO-G dopant to the PVDF matrix changes its discontinuous shear thickening (DST) behavior to continues shear thickening behavior (CST). Hydrocluster formation and their interaction with the dopant could be the reason for this striking DST to CST behavioral change. Strain amplitude sweep (10−3% -10%) oscillatory test reveals that the PNCs shows extended linear viscoelastic region with high elastic modulus and lower viscous modulus. Effective shear thickening behavior and strong elastic strength of these PNCs present their candidature for various fields including mechanical and soft body armor applications.  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