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   703篇
  免费   43篇
电工技术   8篇
综合类   3篇
化学工业   146篇
金属工艺   18篇
机械仪表   9篇
建筑科学   58篇
矿业工程   4篇
能源动力   26篇
轻工业   152篇
水利工程   2篇
无线电   39篇
一般工业技术   91篇
冶金工业   117篇
原子能技术   1篇
自动化技术   72篇
  2023年   7篇
  2022年   15篇
  2021年   23篇
  2020年   19篇
  2019年   22篇
  2018年   29篇
  2017年   23篇
  2016年   18篇
  2015年   27篇
  2014年   27篇
  2013年   53篇
  2012年   43篇
  2011年   48篇
  2010年   35篇
  2009年   27篇
  2008年   33篇
  2007年   30篇
  2006年   28篇
  2005年   17篇
  2004年   15篇
  2003年   11篇
  2002年   13篇
  2001年   6篇
  2000年   6篇
  1999年   5篇
  1998年   13篇
  1997年   9篇
  1996年   7篇
  1995年   10篇
  1994年   8篇
  1993年   6篇
  1992年   7篇
  1991年   7篇
  1990年   8篇
  1989年   8篇
  1988年   13篇
  1987年   8篇
  1986年   12篇
  1985年   3篇
  1983年   4篇
  1981年   4篇
  1980年   3篇
  1978年   4篇
  1975年   5篇
  1973年   2篇
  1964年   2篇
  1962年   2篇
  1959年   3篇
  1956年   2篇
  1955年   2篇
排序方式: 共有746条查询结果,搜索用时 31 毫秒
11.
12.
13.
14.
15.
到家之后,利用家里的大屏幕电视无疑更能发挥视频的震撼效果。我们需要什么设备?是最近炒得火热的电视盒子?还是利用手头不用的笔记本电脑?或者DIY一台小巧精致的HTPC?要不就干脆直接购买智能电视?电视的视频最佳搭档,究竟是谁?  相似文献   
16.
17.
The very early stages of the oxidation of an Fe20Cr2Al alloy, unmodified and ion-implanted by aluminium, yttrium and a combination of both elements, Al and Y, were studied at 1100 °C in oxygen using two-stage-oxidation exposures with 18O2 as a tracer and subsequent characterisation of the scales using SIMS analyses of distribution of oxygen isotopes and oxide-related negative ion clusters, SEM observations of the surface morphology and photoluminescence spectroscopy analysis of the phase composition. The scales formed in all cases, except for the Al-implanted alloy, exhibited layered structures, with the outer part comprising Fe- and Cr-rich oxide, and the inner part being Al2O3, which grew due to a mixed outward–inward mechanism . The alumina sub-layers contained the transient oxides and α-Al2O3. Implanted Al significantly affected the mechanism of the scale growth, providing that the scale consisted essentially of α-Al2O3, and grew via a mixed inward-outward mechanism typical for scales on alumina formers.  相似文献   
18.
A sequence S is nonrepetitive if no two adjacent blocks of S are the same. In 1906 Thue proved that there exist arbitrarily long nonrepetitive sequences over 3 symbols. We consider the online variant of this result in which a nonrepetitive sequence is constructed during a play between two players: Bob is choosing a position in a sequence and Alice is inserting a symbol on that position taken from a fixed set A. The goal of Bob is to force Alice to create a repetition, and if he succeeds, then the game stops. The goal of Alice is naturally to avoid that and thereby to construct a nonrepetitive sequence of any given length.We prove that Alice has a strategy to play arbitrarily long provided the size of the set A is at least 12. This is the online version of the theorem of Thue. The proof is based on nonrepetitive colorings of outerplanar graphs. On the other hand, one can prove that even over 4 symbols Alice has no chance to play for too long. The minimum size of the set of symbols needed for the online version of Thue?s theorem remains unknown.  相似文献   
19.
This review presents the state‐of‐the‐art concerning the application of natural and artificial high‐intensity sweeteners, fructans and bulking agents such as polyols as sugar replacers in sweet‐baked goods and their effects on product characteristics. The recent much publicised attention given to weight gain of the population and its consequences on the occurrence of diet‐related diseases in developed countries has influenced the food manufacturers attempts to provide the consumer with reduced energy products. The replacement of sucrose in sweet bakery products by alternative natural or artificial sweeteners can be a challenging issue. Sucrose as a main ingredient in sweet bakery products contributes, aside from providing sweetness, to numerous processing and product characteristics. Intense sweeteners have a high sweetness compared with sucrose but lack in their contribution to the body of the product, whereas the replacement of sucrose with bulking sweeteners may result in products with a similar body but a lack in taste and flavour.  相似文献   
20.
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