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   841626篇
  免费   11798篇
  国内免费   2434篇
电工技术   15602篇
综合类   804篇
化学工业   124740篇
金属工艺   34952篇
机械仪表   27283篇
建筑科学   19498篇
矿业工程   4344篇
能源动力   22634篇
轻工业   65466篇
水利工程   8842篇
石油天然气   14957篇
武器工业   48篇
无线电   96769篇
一般工业技术   167848篇
冶金工业   159171篇
原子能技术   16733篇
自动化技术   76167篇
  2022年   4811篇
  2021年   7398篇
  2020年   5543篇
  2019年   7009篇
  2018年   16290篇
  2017年   16408篇
  2016年   15053篇
  2015年   8666篇
  2014年   13889篇
  2013年   38061篇
  2012年   23296篇
  2011年   34587篇
  2010年   28250篇
  2009年   30651篇
  2008年   31063篇
  2007年   31976篇
  2006年   23837篇
  2005年   23512篇
  2004年   21717篇
  2003年   21411篇
  2002年   19724篇
  2001年   19319篇
  2000年   18084篇
  1999年   19057篇
  1998年   48985篇
  1997年   34315篇
  1996年   26345篇
  1995年   19705篇
  1994年   17157篇
  1993年   16980篇
  1992年   12236篇
  1991年   11418篇
  1990年   11320篇
  1989年   10880篇
  1988年   10074篇
  1987年   9033篇
  1986年   8832篇
  1985年   9833篇
  1984年   9089篇
  1983年   8137篇
  1982年   7574篇
  1981年   7689篇
  1980年   7231篇
  1979年   7074篇
  1978年   6877篇
  1977年   8155篇
  1976年   10692篇
  1975年   5935篇
  1974年   5553篇
  1973年   5718篇
排序方式: 共有10000条查询结果,搜索用时 78 毫秒
81.
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   
82.
83.
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   
84.
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   
85.
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   
86.
87.
88.
89.
90.
This study aimed to evaluate the physicochemical characteristics and sensory attributes of beef burgers with the addition of pea fibre as a partial substitute of meat or fat. Three formulations were prepared: control (CON) – similar to the commercial formulation; fibre/less meat (FLM)—5% meat reduction and addition of 1% pea fibre; fibre/less fat (FLF)—7% fat reduction and addition of 1% pea fibre. Non-significant differences were obtained for pH, colour parameters (L* and b*), texture profile, cooking loss and size reduction among formulations. Moreover, sensory analysis with consumers of beef burgers did not indicate differences among the formulations for all the analysed attributes. Therefore, pea fibre is a promising partial replacer for meat and fat in beef burgers due to the preservation of technological parameters and sensory acceptance.  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