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   669320篇
  免费   9760篇
  国内免费   1736篇
电工技术   11783篇
综合类   1220篇
化学工业   99033篇
金属工艺   26830篇
机械仪表   20047篇
建筑科学   15580篇
矿业工程   4081篇
能源动力   16616篇
轻工业   53724篇
水利工程   7611篇
石油天然气   14991篇
武器工业   47篇
无线电   70808篇
一般工业技术   130627篇
冶金工业   136232篇
原子能技术   15044篇
自动化技术   56542篇
  2021年   5879篇
  2020年   4276篇
  2019年   5559篇
  2018年   10334篇
  2017年   10352篇
  2016年   11085篇
  2015年   7402篇
  2014年   11499篇
  2013年   28637篇
  2012年   19075篇
  2011年   25668篇
  2010年   19174篇
  2009年   21514篇
  2008年   21737篇
  2007年   21396篇
  2006年   18649篇
  2005年   20286篇
  2004年   18771篇
  2003年   17828篇
  2002年   15756篇
  2001年   15838篇
  2000年   14381篇
  1999年   15078篇
  1998年   41050篇
  1997年   28511篇
  1996年   21543篇
  1995年   15934篇
  1994年   13754篇
  1993年   13554篇
  1992年   9561篇
  1991年   9157篇
  1990年   9090篇
  1989年   8765篇
  1988年   8253篇
  1987年   7412篇
  1986年   7307篇
  1985年   7934篇
  1984年   7428篇
  1983年   6683篇
  1982年   6369篇
  1981年   6591篇
  1980年   6291篇
  1979年   6190篇
  1978年   6177篇
  1977年   7421篇
  1976年   10128篇
  1975年   5420篇
  1974年   5134篇
  1973年   5286篇
  1972年   4489篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
61.
Golubev  N. V.  Ignat’eva  E. S.  Maurus  A. A.  Ziyatdinova  M. Z.  Lopatina  E. V.  Lorenzi  R.  Paleari  A.  Sigaev  V. N. 《Glass and Ceramics》2021,77(11-12):415-418
Glass and Ceramics - The influence of Al2O3 as an additive and the heat-treatment regime on the luminescence spectra of gallate glass-ceramics was investigated. It is shown that its luminescence...  相似文献   
62.
Russian Engineering Research - Models based on regression analysis for predicting the operational efficiency of high-pressure roller crushers are considered. A systematized and structured...  相似文献   
63.
In this paper, we present a novel memory access reduction scheme (MARS) for two-dimension fast cosine transform (2-D FCT). It targets programmable DSPs with high memory-access latency. It reduces the number of memory accesses by: 1) reducing the number of weighting factors and 2) combining butterflies in vector-radix 2-D FCT pruning diagram from two stages to one stage with an efficient structure. Hardware platform based on general purpose processor is used to verify the effectiveness of the proposed method for vector-radix 2-D FCT pruning implementation. Experimental results validate the benefits of the proposed method with reduced memory access, less clock cycle and fewer memory space compared with the conventional implementation.  相似文献   
64.
65.
This study aimed to evaluate the physicochemical characteristics and sensory attributes of beef burgers with the addition of pea fibre as a partial substitute of meat or fat. Three formulations were prepared: control (CON) – similar to the commercial formulation; fibre/less meat (FLM)—5% meat reduction and addition of 1% pea fibre; fibre/less fat (FLF)—7% fat reduction and addition of 1% pea fibre. Non-significant differences were obtained for pH, colour parameters (L* and b*), texture profile, cooking loss and size reduction among formulations. Moreover, sensory analysis with consumers of beef burgers did not indicate differences among the formulations for all the analysed attributes. Therefore, pea fibre is a promising partial replacer for meat and fat in beef burgers due to the preservation of technological parameters and sensory acceptance.  相似文献   
66.
The role of the following factors in the selection of technological bases for manufacturing is considered: the accessibility of the machined surfaces; their parameters and dimensional relationships; their position relative to the forces acting; and the uniformity of the margin distribution.  相似文献   
67.
Theoretical Foundations of Chemical Engineering - New research results, as well as those published earlier by the authors, on the synthesis of azo compounds based on nitroanilines obtained by the...  相似文献   
68.
The price of cobalt has increased by some 450% in the past two years, mainly due to increasing demand for lithium–ion batteries. With an official 2017 production of 64 kt, the Democratic Republic of Congo produces more than half of the world’s cobalt. African Copperbelt operations have traditionally focused on copper production; however, it has now become imperative to also consider cobalt recovery from these ores. A plethora of processing routes is possible. Most hydrometallurgical flowsheets recover cobalt from the raffinate of the low-grade copper solvent-extraction circuit. Downstream purification processes include sequential precipitation with a variety of reagents, solvent extraction, and ion exchange. Product choices include hydroxide, carbonate, sulfate, and metal cathode. This study assesses technical and economic advantages and limitations of various approaches to the hydrometallurgical processing of cobalt in an African context.  相似文献   
69.
Theoretical Foundations of Chemical Engineering - The extraction of nitric and oxalic acids by neutral compounds TBP, DBBP, and TBPO have been studied. The optimal conditions of their separation...  相似文献   
70.
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