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   249813篇
  免费   1684篇
  国内免费   268篇
电工技术   4052篇
综合类   192篇
化学工业   40446篇
金属工艺   15153篇
机械仪表   10077篇
建筑科学   4365篇
矿业工程   3766篇
能源动力   3885篇
轻工业   9722篇
水利工程   4093篇
石油天然气   13012篇
武器工业   29篇
无线电   20225篇
一般工业技术   62866篇
冶金工业   32264篇
原子能技术   11134篇
自动化技术   16484篇
  2021年   2764篇
  2019年   2737篇
  2018年   5443篇
  2017年   5722篇
  2016年   6050篇
  2015年   3060篇
  2014年   5346篇
  2013年   10131篇
  2012年   7332篇
  2011年   8996篇
  2010年   7319篇
  2009年   8153篇
  2008年   8194篇
  2007年   7886篇
  2006年   6387篇
  2005年   5582篇
  2004年   5507篇
  2003年   5321篇
  2002年   5157篇
  2001年   4970篇
  2000年   4952篇
  1999年   4269篇
  1998年   7217篇
  1997年   5856篇
  1996年   4447篇
  1995年   3672篇
  1994年   3435篇
  1993年   3658篇
  1992年   3260篇
  1991年   3376篇
  1990年   3496篇
  1989年   3371篇
  1988年   3270篇
  1987年   3262篇
  1986年   3158篇
  1985年   3316篇
  1984年   3259篇
  1983年   3149篇
  1982年   2995篇
  1981年   3051篇
  1980年   3073篇
  1979年   3257篇
  1978年   3491篇
  1977年   3463篇
  1976年   3919篇
  1975年   3211篇
  1974年   3294篇
  1973年   3341篇
  1972年   2988篇
  1971年   2755篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
In this paper, effects of particles on the subgrid scales of turbulence are properly accounted for during the modeling of subgrid scale stresses in the large-eddy simulation (LES) of fluid phase. In doing so, we propose closed filtered kinetic equations for phase space density of the particle. The various moments of these equations give the `fluid' equations which can be considered as the LES equations for the particle phase. The influence of subgrid scales motion on the particles is included in these `fluid' equations.  相似文献   
73.
74.
Validity on the well-known Onsager reciprocal relations L 12=L 21 is verified in the kinetic theory of gases taking into account mass and heat transfer near the surface. Using an analytical solution to the ellipsoidal statistical equation (providing for the true Prandtl number), it is demonstrated that the Onsager relations are obeyed, at least to within exponential corrections of the type exp(−1/Kn) in the Knudsen number.  相似文献   
75.
It is established that the capillary rise of a liquid has an oscillatory character, in contrast to the commonly accepted opinion that a vertical capillary is filled at a monotonically varying velocity. The value of the tangential shear stress arising in an ascending liquid is evaluated for ethyl alcohol and distilled water.  相似文献   
76.
The purpose and current construction status, at the Institute of Theoretical and Experimental Physics, of an experimental electronuclear setup, combining a pulsed proton linear accelerator (36 MeV, 0.5 mA) and a subcritical blanket thermal-power assembly 100 kW, are discussed. The main equipment is already available or is being built in industry. The setup can be used to investigate the dynamics of the interaction of a linac–driver and a subcritical reactor and problems concerning the accelerator–driver and the target–blanket assembly. The proton beams and neutron fluxes will be used for applied purposes. In the future it will be possible to increase substantially the current and energy of the proton beam.  相似文献   
77.
A.V. Kolobov  P. Fons 《Thin solid films》2007,515(19):7534-7537
We discuss specific features of Te-based compounds that made them the best materials for the phase-change data storage. It is demonstrated that the phase-change recording is due to a switch of Ge atoms between octahedral and tetrahedral symmetry positions within the Te face-centered cubic lattice. It is this nature of the transition that makes the Te-based media fast and stable. The driving force for this transition is also discussed. The chapter is concluded by introduction of a concept of the super-resolution near-field structure (super-RENS) disc that allows to reduce a bit size well below the diffraction limit and makes 100 GB/disc storage a reality.  相似文献   
78.
79.
80.
With the creation of balancing authorities by the North American Reliability Council that span large portions of the North American interconnection, and stringent requirements for real time monitoring of power system evolution, faster and more accurate state estimation algorithms that can efficiently handle systems of very large sizes are needed in the present environment. This paper presents a distributed state estimation algorithm suitable for large-scale power systems. Synchronized phasor measurements are applied to aggregate the voltage phase angles of each decomposed subsystem in the distributed state estimation solution. The aggregated state estimation solution is obtained from the distributed solution using a sensitivity analysis based update at chosen boundary buses. Placement of synchronized phasor measurements in the decomposed subsystems is also investigated in this paper. Test results on the IEEE 118-bus test bed are provided  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