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   408643篇
  免费   6008篇
  国内免费   2346篇
电工技术   8200篇
技术理论   5篇
综合类   1256篇
化学工业   65234篇
金属工艺   17309篇
机械仪表   11987篇
建筑科学   10419篇
矿业工程   2444篇
能源动力   9572篇
轻工业   38710篇
水利工程   4268篇
石油天然气   8518篇
武器工业   245篇
无线电   44287篇
一般工业技术   76522篇
冶金工业   76021篇
原子能技术   9001篇
自动化技术   32999篇
  2021年   3541篇
  2019年   3123篇
  2018年   5029篇
  2017年   4981篇
  2016年   5431篇
  2015年   4114篇
  2014年   6746篇
  2013年   17882篇
  2012年   11340篇
  2011年   15318篇
  2010年   12199篇
  2009年   13435篇
  2008年   14156篇
  2007年   14333篇
  2006年   12513篇
  2005年   11202篇
  2004年   10261篇
  2003年   9619篇
  2002年   9623篇
  2001年   9708篇
  2000年   9174篇
  1999年   9256篇
  1998年   21704篇
  1997年   15830篇
  1996年   12131篇
  1995年   9217篇
  1994年   8172篇
  1993年   8011篇
  1992年   6147篇
  1991年   5906篇
  1990年   5868篇
  1989年   5858篇
  1988年   5556篇
  1987年   4855篇
  1986年   4797篇
  1985年   5472篇
  1984年   5165篇
  1983年   4819篇
  1982年   4308篇
  1981年   4562篇
  1980年   4170篇
  1979年   4363篇
  1978年   4244篇
  1977年   4668篇
  1976年   6060篇
  1975年   3767篇
  1974年   3585篇
  1973年   3692篇
  1972年   3111篇
  1971年   2842篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Functional Properties and Food Applications of Rapeseed Protein Concentrate   总被引:1,自引:0,他引:1  
Rapeseed protein concentrate (RC), prepared with 2% hexameta-phosphate, was tested for its functionality and performance in some foods. The RC had good nitrogen solubility, fat absorption, emulsification, and whipping capacities but poor water absorption and gelling properties. It increased the emulsion stability, and protein but lowered the fat content of wieners. It also increased the cooking yield, reduced the shrinkage and tenderized meat patties. Results were similar to soybean isolate except for the poorer color and flavor. The cooking yield of RC supplemented wieners was less than the all-meat control and soybean-supplemented wieners. A 9% RC dispersion mixed with an equal volume of eggwhite produced a meringue of comparable stability and texture to that of eggwhite alone.  相似文献   
52.
No generally accepted principles and guidelines currently exist to help engineers design local interaction mechanisms that result in a desired global behavior. However, several communities have developed ways of approaching this problem in the context of niched application areas. Because the ideas underlying these approaches are often obscured or underemphasized in technical papers, the authors review the role of self-organization in their work. They provide a better picture of the status of the emerging field of self-organizing systems or autonomic computing.  相似文献   
53.
Elasticity is discussed as an aspect of viscoelasticity, which is described by the tube model. The effects of both crosslinks and entanglements contribute to this model and a discussion of how these effects can be quantified is given. At high enough concentration, entanglements ensure the existence of elastic effects even without crosslinks, and a theory is presented on how this dynamical phase change comes about.  相似文献   
54.
Pre-metal-deposition reactive ion etching (RIE) was performed on an Al0.3Ga0.7N/AlN/GaN heterostructure in order to improve the metal-to-semiconductor contact resistance. An optimum AlGaN thickness for minimizing contact resistance was determined. An initial decrease in contact resistance with etching time was explained in terms of removal of an oxide surface layer and/or by an increase in tunnelling current with the decrease of the AlGaN thickness. The presence of a dissimilar surface layer was confirmed by an initial nonuniform etch depth rate. An increase in contact resistance for deeper etches was experienced. The increase was related to depletion of the two-dimensional (2-D) electron gas (2-DEG) under the ohmics. Etch depths were measured by atomic force microscopy (AFM). The contact resistance decreased from about 0.45 Ωmm for unetched ohmics to a minimum of 0.27 Ωmm for 70 Å etched ohmics. The initial thickness of the AlGaN layer was 250 Å. The decrease in contact resistance, without excessive complications on device processing, supports RIE etching as a viable solution to improve ohmic contact resistance in AlGaN/GaN HEMTs  相似文献   
55.
56.
57.
The dynamic linewidth of 1.5 ?m ridge waveguide DFB lasers is shown to be reduced by shaping the pulse of the laser modulating waveform. Pulse shaping is performed by a second-order network designed to cancel the small-signal laser resonance. Results demonstrate a dynamic linewidth reduction from 1.4 ? to 0.55 ? FWHM for a 500 ps pulse.  相似文献   
58.
59.
It is suggested that the chord length distribution method could be useful for predicting double-bit upset rates in certain circumstances. A chord length distribution function for simultaneous path lengths in two parallelepipeds, applicable to a unidirectional flux, is derived. A proof of the system is outlined for the case under consideration  相似文献   
60.
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