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   403826篇
  免费   5386篇
  国内免费   1361篇
电工技术   7568篇
综合类   317篇
化学工业   60104篇
金属工艺   16473篇
机械仪表   13509篇
建筑科学   8365篇
矿业工程   2160篇
能源动力   11531篇
轻工业   28500篇
水利工程   4274篇
石油天然气   7967篇
武器工业   17篇
无线电   49265篇
一般工业技术   83107篇
冶金工业   75061篇
原子能技术   9191篇
自动化技术   33164篇
  2022年   2624篇
  2021年   3940篇
  2020年   2960篇
  2019年   3822篇
  2018年   6507篇
  2017年   6518篇
  2016年   6960篇
  2015年   4334篇
  2014年   7156篇
  2013年   20067篇
  2012年   11432篇
  2011年   15303篇
  2010年   12174篇
  2009年   13732篇
  2008年   14075篇
  2007年   13831篇
  2006年   12437篇
  2005年   11123篇
  2004年   10514篇
  2003年   10426篇
  2002年   9843篇
  2001年   9743篇
  2000年   9144篇
  1999年   9527篇
  1998年   24335篇
  1997年   16721篇
  1996年   12803篇
  1995年   9520篇
  1994年   8366篇
  1993年   8388篇
  1992年   6055篇
  1991年   5698篇
  1990年   5681篇
  1989年   5322篇
  1988年   5047篇
  1987年   4425篇
  1986年   4304篇
  1985年   4819篇
  1984年   4425篇
  1983年   3997篇
  1982年   3661篇
  1981年   3732篇
  1980年   3437篇
  1979年   3338篇
  1978年   3338篇
  1977年   3755篇
  1976年   4861篇
  1975年   2855篇
  1974年   2665篇
  1973年   2736篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
Multimedia Tools and Applications - The paper addresses the problem of human activity recognition based on the data from wearable sensors. Human activity recognition depends on a wide context of...  相似文献   
42.
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   
43.
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   
44.
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   
45.
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   
46.
47.
48.
49.
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   
50.
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   
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