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   436274篇
  免费   7337篇
  国内免费   1382篇
电工技术   7792篇
综合类   343篇
化学工业   65602篇
金属工艺   16998篇
机械仪表   14119篇
建筑科学   9432篇
矿业工程   2217篇
能源动力   12189篇
轻工业   32989篇
水利工程   4559篇
石油天然气   8041篇
武器工业   21篇
无线电   51185篇
一般工业技术   88900篇
冶金工业   83325篇
原子能技术   9325篇
自动化技术   37956篇
  2022年   2579篇
  2021年   4594篇
  2020年   3539篇
  2019年   4372篇
  2018年   7767篇
  2017年   7736篇
  2016年   8255篇
  2015年   5240篇
  2014年   8314篇
  2013年   22334篇
  2012年   13375篇
  2011年   17068篇
  2010年   13618篇
  2009年   14981篇
  2008年   15561篇
  2007年   15107篇
  2006年   13409篇
  2005年   11942篇
  2004年   11273篇
  2003年   11108篇
  2002年   10417篇
  2001年   10116篇
  2000年   9526篇
  1999年   9991篇
  1998年   26926篇
  1997年   18282篇
  1996年   13825篇
  1995年   10139篇
  1994年   8900篇
  1993年   8901篇
  1992年   6225篇
  1991年   5881篇
  1990年   5867篇
  1989年   5505篇
  1988年   5204篇
  1987年   4561篇
  1986年   4460篇
  1985年   4999篇
  1984年   4583篇
  1983年   4116篇
  1982年   3799篇
  1981年   3885篇
  1980年   3567篇
  1979年   3443篇
  1978年   3432篇
  1977年   3919篇
  1976年   5225篇
  1975年   2926篇
  1974年   2727篇
  1973年   2800篇
排序方式: 共有10000条查询结果,搜索用时 218 毫秒
51.
Herein, we report the photosensing property of CdS thin films. CdS thin films were coated onto glass substrates via a spray pyrolysis method using different spray pressures. Prepared films were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and optical and photoluminescence spectroscopy. XRD analysis demonstrated the growth of crystalline CdS films with crystallite sizes varying from 26 to 29 nm depending on the pressure. The SEM and EDAX analyses revealed nearly-stoichiometric CdS films with smooth surfaces and slight variation in grain morphology due to pressure changes. Optical measurements showed a direct bandgap varying from 2.37 eV to 2.42 eV due to pressure changes. A photodetector was also fabricated using the grown CdS films; the fabricated photodetector exhibited good performance depending on the spray pressure. A spray pressure of 1.5 GPa resulted in high photoresponsivity and external quantum efficiency.  相似文献   
52.
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   
53.
The germline carrier of the BRCA1 pathogenic mutation has been well proven to confer an increased risk of breast and ovarian cancer. Despite BRCA1 biallelic pathogenic mutations being extremely rare, they have been reported to be embryonically lethal or to cause Fanconi anemia (FA). Here we describe a patient who was a 48-year-old female identified with biallelic pathogenic mutations of the BRCA1 gene, with no or very subtle FA-features. She was diagnosed with ovarian cancer and breast cancer at the ages of 43 and 44 and had a strong family history of breast and gynecological cancers.  相似文献   
54.
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   
55.
56.
57.
58.
Topics in Catalysis - In this work, a simple thermal-catalytic system was used to valorize peanut shells (Arachis hypogaea), the residual biomass from the peanut industry. To accomplish this...  相似文献   
59.
Polymer Bulletin - In this study, we synthesized a new ion-imprinted polymer (IIP) based on introduction of amidoxime groups in acrylonitrile, complexation with Cd2+ ions and polymerization with...  相似文献   
60.
Debittered trub (brewing waste) is an important source of protein source (70.26%). Trub and whey protein were used for 5% protein enrichment of ice cream frozen by liquid nitrogen. Three formulations were elaborated: ice cream standard (ICS), ice cream with whey protein (ICW) and ice cream with trub (ICT). Chemical composition, rheological properties, texture, overrun, melting rate, scanning electron microscopy and a sensorial test were performed. Results showed that ICT presented a higher viscosity, obtained on the upward curve up to 6.76 Pa s−1, consistency index (22.96 (Pa s−1)n), hysteresis area (140.40 mPa s−1) and hardness (31113.33 g) but a lower melting rate (0.38 g min−1), overrun (13.92%) and sensorial acceptability than the other formulations. The addition of trub debittered for protein enrichment improved ice cream properties and demonstrated that it could be used as a food ingredient.  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