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   313257篇
  免费   9303篇
  国内免费   4158篇
电工技术   8883篇
技术理论   2篇
综合类   4669篇
化学工业   45019篇
金属工艺   13137篇
机械仪表   11820篇
建筑科学   11192篇
矿业工程   2705篇
能源动力   8899篇
轻工业   25180篇
水利工程   3581篇
石油天然气   6297篇
武器工业   633篇
无线电   41988篇
一般工业技术   56767篇
冶金工业   51491篇
原子能技术   5798篇
自动化技术   28657篇
  2022年   3211篇
  2021年   5018篇
  2020年   3741篇
  2019年   3663篇
  2018年   5086篇
  2017年   5474篇
  2016年   5351篇
  2015年   5063篇
  2014年   7451篇
  2013年   15658篇
  2012年   10674篇
  2011年   13516篇
  2010年   11241篇
  2009年   12112篇
  2008年   12540篇
  2007年   11932篇
  2006年   10715篇
  2005年   9201篇
  2004年   8031篇
  2003年   7961篇
  2002年   7346篇
  2001年   7694篇
  2000年   6990篇
  1999年   7391篇
  1998年   17362篇
  1997年   12131篇
  1996年   9458篇
  1995年   7187篇
  1994年   6365篇
  1993年   6217篇
  1992年   4384篇
  1991年   4251篇
  1990年   4019篇
  1989年   3765篇
  1988年   3665篇
  1987年   3089篇
  1986年   3008篇
  1985年   3247篇
  1984年   2953篇
  1983年   2854篇
  1982年   2662篇
  1981年   2567篇
  1980年   2489篇
  1979年   2279篇
  1978年   2091篇
  1977年   2569篇
  1976年   3525篇
  1975年   1737篇
  1974年   1705篇
  1973年   1633篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
At the hydroelectric unit No. 11 of the Nizhnekamsk hydroelectric power plant, the filling wedges of a rotor were investigated by ultrasound in the free st  相似文献   
52.
The bromodomain and extra terminal (BET) family of bromodomain-containing proteins (BCPs) have been the subject of extensive research over the past decade, resulting in a plethora of high-quality chemical probes for their tandem bromodomains. In turn, these chemical probes have helped reveal the profound biological role of the BET bromodomains and their role in disease, ultimately leading to a number of molecules in active clinical development. However, the BET subfamily represents just 8/61 of the known human bromodomains, and attention has now expanded to the biological role of the remaining 53 non-BET bromodomains. Rapid growth of this research area has been accompanied by a greater understanding of the requirements for an effective bromodomain chemical probe and has led to a number of new non-BET bromodomain chemical probes being developed. Advances since December 2015 are discussed, highlighting the strengths/caveats of each molecule, and the value they add toward validating the non-BET bromodomains as tractable therapeutic targets.  相似文献   
53.
54.
单片机原理与应用作为电子技术类学科中的必修课程具有很强实践性,要求学生掌握实际应用能力,为此研制了基于单片机系统通信为基础的实验板,依据单片机应用系统特点,可完成SPI、I^2C、UART串行通信以及并行总线方式通信。实验板有利于学生更好地了解和掌握单片机应用系统设计的方法,有利于学生进行自主设计和内容拓展。做到培养学生的学习能力、提高学生的学习兴趣、发挥学生的创造性。  相似文献   
55.
Metallurgical and Materials Transactions B - The process of obtaining titanium tetrachloride (TiCl4) from the quartz-leucoxene concentrate (QLC) from the Yaregskoe oil-titanium field was studied....  相似文献   
56.
Hassan  Lovelu  Khan  K. A. 《Microsystem Technologies》2020,26(3):1031-1041

The efficiency of any electric cell or battery is very important. To keep it in mind it has been studied the columbic efficiency, voltaic efficiency and energy efficiency of a PKL (Pathor Kuchi Leaf) Quasi Voltaic Cell or Modified Voltaic Cell. It was found that the columbic efficiency data illustrated that this efficiency was lower comparing to other efficiencies may be the absence of salt bridge or separator between the electrodes. Because, our designed and fabricated PKL cell does not have any salt bridge. So that the internal resistance is lower than the traditional voltaic cell and as a result more current was found. The voltage and current changes with time and I–V characteristics for PKL unit cell, module, panel and array have also been studied. It is shown that the voltaic and energy efficiency have been studied. However, the highest efficiency was obtained for 40% PKL sap with 5% secondary salt in 55% aqueous solution, which implies that the concentration of PKL juice can play an important role regarding efficiency. It was also found that the average energy efficiency was 97.43% and it was also found that the average voltaic efficiency was 57.29%. Finally, morphological study FESEM (Field Emission Scanning Electron Microscopy) has also been performed. It is seen that the results confirmed that Zn was deposited on the Cu surface during the electro deposition process in PKL solution. Using AAS, it has been measured the concentration of [Cu2+] as a reactant ion and the concentration of [Zn2+] as a product ion those have been tabulated and graphically discussed. The variation of pH has also been studied with time and which was also tabulated and graphically discussed.

  相似文献   
57.
58.
A layer-by-layer analysis of the structures, the phase compositions, and the defect substructures of differentially hardened rails has been carried by optical and transmission electron microscopy. It is found that the material volume of the rail head fillet is cooled faster than the volume located along the central axis.  相似文献   
59.
Wu  Li  Li  Jing  Fu  Caixia  Kühn  Bernd  Wang  Xiaolin 《Magma (New York, N.Y.)》2019,32(4):501-509
Magnetic Resonance Materials in Physics, Biology and Medicine - To investigate the value of using diffusion-weighted imaging (DWI) and intravoxel incoherent motion DWI (IVIM-DWI) to assess the...  相似文献   
60.
Metallurgical and Materials Transactions A - The influence of the chemical composition on the crystallization process, amorphous phase formation, and the anticorrosion properties of Al-Zr-Ni-Fe-Y...  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