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   7635篇
  免费   639篇
  国内免费   232篇
电工技术   343篇
综合类   338篇
化学工业   1470篇
金属工艺   430篇
机械仪表   419篇
建筑科学   371篇
矿业工程   149篇
能源动力   268篇
轻工业   732篇
水利工程   114篇
石油天然气   170篇
武器工业   22篇
无线电   903篇
一般工业技术   1148篇
冶金工业   542篇
原子能技术   83篇
自动化技术   1004篇
  2024年   30篇
  2023年   127篇
  2022年   271篇
  2021年   324篇
  2020年   240篇
  2019年   185篇
  2018年   247篇
  2017年   237篇
  2016年   251篇
  2015年   282篇
  2014年   396篇
  2013年   577篇
  2012年   495篇
  2011年   535篇
  2010年   399篇
  2009年   420篇
  2008年   405篇
  2007年   368篇
  2006年   339篇
  2005年   272篇
  2004年   182篇
  2003年   220篇
  2002年   213篇
  2001年   169篇
  2000年   125篇
  1999年   110篇
  1998年   165篇
  1997年   107篇
  1996年   91篇
  1995年   92篇
  1994年   63篇
  1993年   71篇
  1992年   50篇
  1991年   53篇
  1990年   52篇
  1989年   30篇
  1988年   27篇
  1987年   28篇
  1986年   21篇
  1985年   19篇
  1984年   23篇
  1983年   21篇
  1982年   15篇
  1981年   27篇
  1980年   24篇
  1979年   16篇
  1978年   11篇
  1977年   15篇
  1976年   17篇
  1973年   8篇
排序方式: 共有8506条查询结果,搜索用时 15 毫秒
1.
余满春  张立红 《辽宁化工》2003,32(8):354-356
介绍了书籍装订热熔胶生产工艺及产品的技术指标,对1000t/a生产装置的投资与产品成本进行了核算。分析结果表明,总投资110万元,年利润达266万元。  相似文献   
2.
3.
In 1995 a national drug policy was finalized in Nepal. The authors outline the measures that were recommended for its implementation and the activities that have so far been undertaken. Much remains to be done, most notably in assisting, coordinating and supervising these activities.  相似文献   
4.
PES News     
This paper presents a new method for the generation of a reference voltage for a dynamic voltage restorer (DVR). These voltages, when injected in series with a distribution feeder by a voltage source inverter, can tightly regulate the voltage at the load terminal against imbalance or harmonics in the source side. It is stipulated that the DVR does not supply any real power in the steady state. The reference voltage generation scheme is validated through digital computer simulation studies.  相似文献   
5.
This paper gives a first comparison of specific absorption rate (SAR) induced in a child-sized (CS) head and an adult head using a dual-band mobile phone. In the second study, the visible human head is considered and comparison of SAR induced in a CS or child-like (CL) head and an adult head using a dual-band mobile phone is given. All the peaks of average SAR over a mass of 10 and 1 g in the head and the power budget are determined in the two comparisons using the finite-difference time-domain method. The differences between the results for adult and CS or CL heads are given at 900 and 1800 MHz. No important differences are noted for the peak SAR averaged over 10 g (SAR10 g), between the two adult head models, as well as between the two child head models. The peak SAR10 g in the brain of the CS or CL head is slightly more significant than that for the adult one.  相似文献   
6.
Methods are proposed for designing interpolation models for the preliminary determination and subsequent forecasting of general and fractional breakthrough coefficients for dust used with granular filters, as employed in energy-saving and high-performance dust trapping from technological gases and ventilation discharges in refractory production. The models are supplied with nomograms, which makes them widely suitable for experts working in environmental protection at refractory-producing organizations. The main factors are identified that influence the performance. The results are of interest to experts in related areas of industry such as building materials and engineering ceramics and so on. Translated from Novye Ogneupory, No. 4, pp. 64–67, April, 2008.  相似文献   
7.
Carbon nanotubes (CNTs) have been synthesized using the arc discharge method with a rotating graphite disc as the cathode. Arcing was carried out in open air and without the use of catalysts. The current density was maintained constant through out the experiment, while, the rate of rotation of the cathode and atmosphere under which arcing was carried out were changed during experimentation. Characterization of the samples produced indicates that rotation of the cathode has a significant impact on the quality and yield of the process. It is proposed that rotation of the cathode drags plasma formed between two electrodes away from high temperature region. This results in a sudden quenching of the reactive plasma. The time available for nucleation and growth phenomena is significantly reduced and thus leads to the formation of highly graphitic multi walled CNTs (yield 60%) and traces of double walled CNTs.  相似文献   
8.
9.
10.
提出一种金属圆锥弹簧与橡胶圆锥弹簧复合而成的弹簧.分析表明:它可以应用于弹性耦合激励振动筛和座式直线振动筛。  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