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   420576篇
  免费   5621篇
  国内免费   1440篇
电工技术   7997篇
综合类   373篇
化学工业   61929篇
金属工艺   17103篇
机械仪表   13979篇
建筑科学   8811篇
矿业工程   2201篇
能源动力   11928篇
轻工业   29969篇
水利工程   4427篇
石油天然气   8035篇
武器工业   18篇
无线电   51101篇
一般工业技术   85939篇
冶金工业   79848篇
原子能技术   9444篇
自动化技术   34535篇
  2021年   3980篇
  2020年   3032篇
  2019年   3903篇
  2018年   6634篇
  2017年   6622篇
  2016年   7102篇
  2015年   4440篇
  2014年   7326篇
  2013年   20647篇
  2012年   11770篇
  2011年   15779篇
  2010年   12518篇
  2009年   14149篇
  2008年   14540篇
  2007年   14326篇
  2006年   12851篇
  2005年   11657篇
  2004年   10934篇
  2003年   10899篇
  2002年   10347篇
  2001年   10270篇
  2000年   9599篇
  1999年   9985篇
  1998年   25978篇
  1997年   17775篇
  1996年   13651篇
  1995年   10101篇
  1994年   8853篇
  1993年   8896篇
  1992年   6351篇
  1991年   5983篇
  1990年   5963篇
  1989年   5600篇
  1988年   5291篇
  1987年   4650篇
  1986年   4514篇
  1985年   5035篇
  1984年   4602篇
  1983年   4157篇
  1982年   3816篇
  1981年   3928篇
  1980年   3615篇
  1979年   3469篇
  1978年   3460篇
  1977年   4004篇
  1976年   5184篇
  1975年   2967篇
  1974年   2761篇
  1973年   2824篇
  1972年   2359篇
排序方式: 共有10000条查询结果,搜索用时 218 毫秒
31.
Deshmukh  P.  Sar  S. K.  Smječanin  N.  Nuhanović  M.  Lalwani  R. 《Radiochemistry》2022,64(4):532-542
Radiochemistry - Magnetically modified waste bark of the Aegle marmelos tree was prepared by using green synthesis method and was used in a batch system for U(VI) removal from aqueous solution. The...  相似文献   
32.
Kamar  M. S.  Shalan  A. S.  Youssef  W. M.  Hussein  A. E. M.  Khawassek  Y. M.  Taha  M. H. 《Radiochemistry》2022,64(2):244-256
Radiochemistry - Ferrugination, sericitization, desulfitization, chloritization, and kaolinitization of hydrothermal origin are the main wall rock alterations occurring within the NNW shear zones...  相似文献   
33.

Modern metrics for evaluating agreement coefficients between the experimental results and expert opinion are compared, and the possibility of using these metrics in experimental research in automatic text processing by machine learning methods is assessed. The choice of Cohen’s kappa coefficient as a measure of expert opinion agreement in the NLP and Text Mining problems is justified. An example of using Cohen’s kappa coefficient for evaluating the level of agreement between the opinion of an expert and the results of ML classification and the measure of agreement of expert opinions in the alignment of sentences of the Kazakh-Russian parallel corpus is given. Based on this analysis, it is proved that Cohen’s kappa coefficient is one of the best statistical methods for determining the level of agreement in experimental studies due to its ease of use, computing simplicity, and high accuracy of the results.

  相似文献   
34.
Wireless Personal Communications - Multiple inputs multiple outputs (MIMO) is a reliable technique which can manage the increased wireless data traffic in the future generation of wireless...  相似文献   
35.
Multimedia Tools and Applications - Discovering the relevant web services for specific applications in the dynamically changing business world becomes very critical. Researchers have used many...  相似文献   
36.
Mobile Networks and Applications - 5G/6G communication are first generation high speed wireless communication network which integrates the aerial data, terrestrial data and maritime data via...  相似文献   
37.
Theoretical Foundations of Chemical Engineering - The effect of the electrolyte composition, mass-transfer conditions, pore diameter, interpore distance, and electric parameters on the formation of...  相似文献   
38.
The influence of the microstructure on the corrosion rate of three monolithic SiC samples in FLiNaK salt at 900 °C for 250 h was studied. The SiC samples, labeled as SiC-1, SiC-2, and SiC-3, had corrosion rates of 0.137, 0.020, and 0.043 mg/cm2h, respectively. Compared with grain size and the presence of special grain boundaries (i.e., Σ3), the content of high-angle grain boundaries (HAGBs) appeared to have the strongest influence on the corrosion rate of SiC in FLiNaK salt, since the corrosion rate increased six times as the concentration of high-angle grain boundaries increased from 19 to 32% for SiC-2 and SiC-1, respectively. These results stress the importance of controlling the content of HAGBs during the production process of SiC.  相似文献   
39.
Theoretical Foundations of Chemical Engineering - The corona onset voltage is an important operating parameter in the electrostatic precipitation of nanoparticulate, however, its experimental...  相似文献   
40.
Herein, we report the photosensing property of CdS thin films. CdS thin films were coated onto glass substrates via a spray pyrolysis method using different spray pressures. Prepared films were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and optical and photoluminescence spectroscopy. XRD analysis demonstrated the growth of crystalline CdS films with crystallite sizes varying from 26 to 29 nm depending on the pressure. The SEM and EDAX analyses revealed nearly-stoichiometric CdS films with smooth surfaces and slight variation in grain morphology due to pressure changes. Optical measurements showed a direct bandgap varying from 2.37 eV to 2.42 eV due to pressure changes. A photodetector was also fabricated using the grown CdS films; the fabricated photodetector exhibited good performance depending on the spray pressure. A spray pressure of 1.5 GPa resulted in high photoresponsivity and external quantum efficiency.  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