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   2883篇
  免费   126篇
  国内免费   10篇
电工技术   41篇
综合类   10篇
化学工业   610篇
金属工艺   133篇
机械仪表   95篇
建筑科学   45篇
矿业工程   10篇
能源动力   196篇
轻工业   308篇
水利工程   19篇
石油天然气   4篇
无线电   244篇
一般工业技术   642篇
冶金工业   261篇
原子能技术   18篇
自动化技术   383篇
  2023年   41篇
  2022年   101篇
  2021年   127篇
  2020年   92篇
  2019年   104篇
  2018年   118篇
  2017年   134篇
  2016年   127篇
  2015年   64篇
  2014年   121篇
  2013年   222篇
  2012年   141篇
  2011年   189篇
  2010年   141篇
  2009年   117篇
  2008年   131篇
  2007年   115篇
  2006年   77篇
  2005年   69篇
  2004年   48篇
  2003年   56篇
  2002年   53篇
  2001年   31篇
  2000年   35篇
  1999年   31篇
  1998年   54篇
  1997年   55篇
  1996年   36篇
  1995年   26篇
  1994年   23篇
  1993年   28篇
  1992年   19篇
  1991年   21篇
  1990年   21篇
  1989年   23篇
  1988年   19篇
  1987年   21篇
  1986年   14篇
  1985年   22篇
  1984年   10篇
  1983年   11篇
  1981年   14篇
  1980年   11篇
  1979年   17篇
  1978年   7篇
  1977年   7篇
  1976年   21篇
  1975年   8篇
  1974年   9篇
  1973年   10篇
排序方式: 共有3019条查询结果,搜索用时 15 毫秒
1.
2.
Multimedia Tools and Applications - A secret sharing scheme partitions a secret into a set of shares and distributes them among the eligible participants, with each participant receiving one share...  相似文献   
3.
Wireless Personal Communications - In this paper, cooperative communication (CC) assisted cognitive wireless sensor network (CWSN) is presented for monitoring health and activity of an end-user in...  相似文献   
4.
5.
This paper presents the design criteria, procedure, and implementation of a soft-switched power-factor-correction (PFC) circuit based on the extended-period quasi-resonant (EPQR) principles. All power electronic devices including switches and diodes in the circuit are fully soft switched. The design method is demonstrated in a prototype circuit. The operating principles are confirmed with computer simulation and experimental results. A comparison of the EP-QR operation and zero-voltage-transition (ZVT) pulse-width modulation (PWM) method  相似文献   
6.
High purity gallium oxide nanopowders have been synthesized by using a simple precipitation technique with calcination at elevated temperature. From the X-ray pattern, the phase purity of the synthesized powders was confirmed as β-Ga2O3. Elemental quantification (stoichiometry) of Ga2O3 was also examined from the X-ray energy dispersive analysis (EDAX). Based on the recorded Fourier Transform Infrared (FTIR) spectrum of Ga2O3, the IR bands due to Ga–O bond and crystal lattice vibrations have been identified in the wavenumber range 400–4,000 cm−1. From the measured SEM images, it is obvious to notice that the pH value has been playing a dominant role in obtaining morphologically different gallium oxide nanopowders. Thermogravimetric analysis reveals 8.3% of weight loss when the sample was heated to the temperature of 1,100 °C from the room temperature, which also shows a crystalline phase transformation. It is very interesting to report that a broad blue emission at 455 nm has been measured from the synthesized gallium oxide nanopowders.  相似文献   
7.
8.
In the absence of adequate autogenous vein for tibial artery bypass in limb salvage surgery, the use of prosthetic grafts with a distal anastomotic vein cuff or patch has shown promising results. Here, we describe how the Florester Internal Vessel Occluder (Meadox UK, Bedfordshire, UK) can facilitate the construction of a distal anastomotic vein cuff.  相似文献   
9.
The effects of composition and thermal treatment on the water sorption and diffusional properties of idealized protein gels arranged in bilayer configurations were determined; these water binding/migration properties were related to the mechanical characteristics of the gels. Samples were prepared from whey protein concentrate (WPC), they consisted of water:WPC ratios of 1.5 to 5.67, and were thermally set for 20–60 min. Moisture migration rates from samples interfaced with filters were determined, as were moisture sorption capacities of samples immersed in water. The physical properties of the gels were assessed by uniaxial compression and microscopy. Results showed that gel strength and consequent extent of protein interaction—as affected by thermal treatment—controlled the ability of the gel structure to absorb water. Sorption was exponentially correlated with gel modulus and linearly correlated with a function of protein content, heating time, and immersion time. Rates of diffusion from interfaced gels were dependent solely on water content. It was concluded that the degree of protein interaction, whether influenced by concentration or thermal treatment, affected network extensibility and thus the capacity of the gels to act as receptors of moisture. Results have implications for the functionality of shelf-stable sandwiches and other multicomponent foods.  相似文献   
10.
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