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   309113篇
  免费   4924篇
  国内免费   2102篇
电工技术   6583篇
技术理论   5篇
综合类   2226篇
化学工业   49597篇
金属工艺   13343篇
机械仪表   10029篇
建筑科学   8165篇
矿业工程   2269篇
能源动力   6030篇
轻工业   28206篇
水利工程   3548篇
石油天然气   7178篇
武器工业   256篇
无线电   34336篇
一般工业技术   57236篇
冶金工业   53982篇
原子能技术   6062篇
自动化技术   27088篇
  2022年   4653篇
  2021年   6172篇
  2020年   4429篇
  2019年   5506篇
  2018年   4508篇
  2017年   4086篇
  2016年   4089篇
  2015年   3155篇
  2014年   4967篇
  2013年   12229篇
  2012年   8305篇
  2011年   11833篇
  2010年   9423篇
  2009年   10134篇
  2008年   10284篇
  2007年   10391篇
  2006年   9337篇
  2005年   8426篇
  2004年   8690篇
  2003年   8120篇
  2002年   8224篇
  2001年   7912篇
  2000年   6995篇
  1999年   6781篇
  1998年   14230篇
  1997年   10569篇
  1996年   8138篇
  1995年   6170篇
  1994年   5833篇
  1993年   5570篇
  1992年   4425篇
  1991年   4127篇
  1990年   4224篇
  1989年   4267篇
  1988年   3957篇
  1987年   3359篇
  1986年   3489篇
  1985年   3790篇
  1984年   3589篇
  1983年   3433篇
  1982年   2983篇
  1981年   3147篇
  1980年   2833篇
  1979年   3013篇
  1978年   3012篇
  1977年   3188篇
  1976年   4047篇
  1975年   2692篇
  1974年   2506篇
  1973年   2463篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
Refractories and Industrial Ceramics - The paper introduces a promising technology for utilizing a traditional scheme for implementing a flow-through micro-arc oxidation method to restore localized...  相似文献   
2.
Theoretical Foundations of Chemical Engineering - On the basis of the classic concepts of the theory of solid-phase combustion, for the first time, a model with a detailed scheme of chemical...  相似文献   
3.
Combustion, Explosion, and Shock Waves - Results of a numerical study of mixing, ignition, and combustion of a cold hydrogen jet propagating along the lower wall of a channel parallel to a...  相似文献   
4.
Journal of Chemical Ecology - Biocontrol agents such as parasitic wasps use long-range volatiles and host-associated cues from lower trophic levels to find their hosts. However, this chemical...  相似文献   
5.
Noncentrosymmetric (NCS) tetrel pnictides have recently generated interest as nonlinear optical (NLO) materials due to their second harmonic generation (SHG) activity and large laser damage threshold (LDT). Herein nonmetal-rich silicon phosphides RuSi4P4 and IrSi3P3 are synthesized and characterized. Their crystal structures are reinvestigated using single crystal X-ray diffraction and 29Si and 31P magic angle spinning NMR. In agreement with previous report RuSi4P4 crystallizes in NCS space group P1, while IrSi3P3 is found to crystallize in NCS space group Cm, in contrast with the previously reported space group C2. A combination of DFT calculations and diffuse reflectance measurements reveals RuSi4P4 and IrSi3P3 to be wide bandgap (Eg) semiconductors, Eg = 1.9 and 1.8 eV, respectively. RuSi4P4 and IrSi3P3 outperform the current state-of-the-art infrared SHG material, AgGaS2, both in SHG activity and laser inducer damage threshold. Due to the combination of high thermal stabilities (up to 1373 K), wide bandgaps (≈2 eV), NCS crystal structures, strong SHG responses, and large LDT values, RuSi4P4 and IrSi3P3 are promising candidates for longer wavelength NLO materials.  相似文献   
6.
Glass and Ceramics - Ceramic bricks based on low-melting clay and ferro-dust from self-disintegrating, low-carbon, ferrochrome slags, graded from M100 to M175, respectively, were obtained in the...  相似文献   
7.
Automation and Remote Control - A linear-quadratic positional differential game of three persons is considered. Coefficient criteria are established under which there is no Nash equilibrium...  相似文献   
8.
Water contamination is a global challenge impacting both the environment and human health with significant economic and social costs. The growing scarcity of usable water resources requires effective treatment of wastewater. In this context, developing cheaper, safer and more efficient wastewater treatment technologies are the need of the hour. One promising approach that several studies have reported success has been the usage of nanomaterials in water and waste water management. The rapid progress of research in nanomaterial sciences has shown their growing potential; however, there has not been a great amount of information available on their implementation. This review focuses on developments in nanotechnology that hold strong potential for wastewater treatment. The review covers key techniques in nanomaterial‐based water treatments including adsorption, filtration and photocatalysis with recent examples showing how to improve their properties and efficiencies according to the need.  相似文献   
9.
Russian Journal of Nondestructive Testing - The results of amplitude analysis of discrete acoustic emission signals from developing sources such as fatigue cracks are presented. The studies were...  相似文献   
10.
Russian Engineering Research - Digital tools for managing improvements in automobile production are developed. An operative tool provides warnings regarding the operational quality of the vehicles...  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