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   82825篇
  免费   17525篇
  国内免费   2022篇
电工技术   3209篇
技术理论   2篇
综合类   2506篇
化学工业   24790篇
金属工艺   3042篇
机械仪表   3808篇
建筑科学   4706篇
矿业工程   1296篇
能源动力   2175篇
轻工业   9941篇
水利工程   959篇
石油天然气   2524篇
武器工业   338篇
无线电   12123篇
一般工业技术   17194篇
冶金工业   3157篇
原子能技术   530篇
自动化技术   10072篇
  2024年   247篇
  2023年   928篇
  2022年   1580篇
  2021年   2456篇
  2020年   2982篇
  2019年   4504篇
  2018年   4540篇
  2017年   4845篇
  2016年   5268篇
  2015年   5721篇
  2014年   6089篇
  2013年   7646篇
  2012年   5550篇
  2011年   5627篇
  2010年   5181篇
  2009年   4977篇
  2008年   4565篇
  2007年   4122篇
  2006年   3970篇
  2005年   3235篇
  2004年   2673篇
  2003年   2531篇
  2002年   2403篇
  2001年   2115篇
  2000年   2026篇
  1999年   1473篇
  1998年   951篇
  1997年   779篇
  1996年   671篇
  1995年   549篇
  1994年   433篇
  1993年   295篇
  1992年   239篇
  1991年   224篇
  1990年   187篇
  1989年   165篇
  1988年   109篇
  1987年   99篇
  1986年   67篇
  1985年   59篇
  1984年   40篇
  1983年   41篇
  1982年   33篇
  1981年   25篇
  1980年   29篇
  1979年   17篇
  1978年   17篇
  1976年   19篇
  1975年   12篇
  1973年   14篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
Peer-to-Peer Networking and Applications -  相似文献   
5.
6.
7.
Lobster krill (Munida genus) represents an under‐valued crustacean frequently caught on European fishing banks. In this work, its sensory, microbiological and biochemical qualities were evaluated during chilled storage. Additionally, the effects of a prestorage antimelanosic treatment consisting of soaking in sodium metabisulphite (SMB) solutions at two different concentrations (0.25% and 0.75%) were also studied. SMB prestorage treatment provided lobster specimens that still exhibited acceptable sensory quality after 10 days of storage, while control specimens were unacceptable at that time. SMB treatment also resulted in a significant (P < 0.05) inhibition of microbial growth, mainly of Enterobacteriaceae, psychrotrophes and proteolytic bacteria. Low lipid oxidation levels were observed for all batches; however, a significantly higher (P < 0.05) retention of polyunsaturated fatty acids was found in SMB‐treated lobster, especially in the 0.75% SMB batch. The results presented here open the way to the potential commercialisation of currently under‐utilised lobster krill as a chilled product.  相似文献   
8.
A series of anionic conjugated polyelectrolytes (CPEs) is synthesized based on poly(fluorene-co-phenylene) by varying the side-chain ionic density from two to six per repeat units (MPS2-TMA, MPS4-TMA, and MPS6-TMA). The effect of MPS2, 4, 6-TMA as interlayers on top of a hole-extraction layer of poly(bis(4-phenyl)-2,4,6-trimethylphenylamine (PTAA) is investigated in inverted perovskite solar cells (PeSCs). Owing to the improved wettability of perovskites on hydrophobic PTAA with the CPEs, the PeSCs with CPE interlayers demonstrate a significantly enhanced device performance, with negligible device-to-device dependence relative to the reference PeSC without CPEs. By increasing the ionic density in the MPS-TMA interlayers, the wetting, interfacial defect passivation, and crystal growth of the perovskites are significantly improved without increasing the series resistance of the PeSCs. In particular, the open-circuit voltage increases from 1.06 V for the PeSC with MPS2-TMA to 1.11 V for the PeSC with MPS6-TMA. The trap densities of the PeSCs with MPS2,4,6-TMA are further analyzed using frequency-dependent capacitance measurements. Finally, a large-area (1 cm2) PeSC is successfully fabricated with MPS6-TMA, showing a power conversion efficiency of 18.38% with negligible hysteresis and a stable power output under light soaking for 60 s.  相似文献   
9.
10.
Pinhão seed is an unconventional source of starch and the pines grow up in native forests of southern Latin America. In this study, pinhão starch was adjusted at 15, 20 and 25% moisture content and heated to 100, 110 and 120 °C for 1 h. A decrease in λ max (starch/iodine complex) was observed as a result of increase in temperature and moisture content of HMT. The ratio of crystalline to amorphous phase in pinhão starch was determined via Fourier transform infra red by taking 1045/1022 band ratio. A decrease in crystallinity occurred as a result of HMT. Polarised light microscopy indicated a loss of birefringence of starch granules under 120 °C at 25% moisture content. Granule size distribution was further confirmed via scanning electron microscopy which showed the HMT effects. These results increased the understanding on molecular and structural properties of HMT pinhão starch and broadened its food and nonfood industrial applications.  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