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   430400篇
  免费   7024篇
  国内免费   1386篇
电工技术   7758篇
综合类   333篇
化学工业   65557篇
金属工艺   16955篇
机械仪表   14042篇
建筑科学   9129篇
矿业工程   2217篇
能源动力   12065篇
轻工业   33016篇
水利工程   4521篇
石油天然气   8011篇
武器工业   22篇
无线电   50247篇
一般工业技术   87534篇
冶金工业   81150篇
原子能技术   9294篇
自动化技术   36959篇
  2022年   2890篇
  2021年   4602篇
  2020年   3514篇
  2019年   4465篇
  2018年   7584篇
  2017年   7514篇
  2016年   8042篇
  2015年   5150篇
  2014年   8143篇
  2013年   22144篇
  2012年   12965篇
  2011年   16744篇
  2010年   13367篇
  2009年   14811篇
  2008年   15134篇
  2007年   14772篇
  2006年   13080篇
  2005年   11684篇
  2004年   11074篇
  2003年   10905篇
  2002年   10288篇
  2001年   10060篇
  2000年   9463篇
  1999年   9875篇
  1998年   26083篇
  1997年   17954篇
  1996年   13593篇
  1995年   10004篇
  1994年   8752篇
  1993年   8843篇
  1992年   6224篇
  1991年   5868篇
  1990年   5810篇
  1989年   5452篇
  1988年   5181篇
  1987年   4540篇
  1986年   4399篇
  1985年   4930篇
  1984年   4528篇
  1983年   4080篇
  1982年   3766篇
  1981年   3861篇
  1980年   3561篇
  1979年   3394篇
  1978年   3405篇
  1977年   3999篇
  1976年   5398篇
  1975年   2894篇
  1974年   2710篇
  1973年   2789篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Theoretical Foundations of Chemical Engineering - The corona onset voltage is an important operating parameter in the electrostatic precipitation of nanoparticulate, however, its experimental...  相似文献   
52.
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   
53.
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   
54.
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   
55.
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   
56.
57.
In this study, amaranth flour was used as an ingredient to prepare gluten-free cookies. The production process and attributes of amaranth cookies were characterised, and the potential use of amaranth flour as a functional ingredient was analysed. Cookies exhibited a non-uniform reddish brown colour and a cookie factor ratio of 4.5 ± 0.6. Storage studies indicated that after 3 weeks at room temperature cookies presented slight variations in the texture. Simulated gastrointestinal digestion of this product was able to release peptides capable of exerting potential antithrombotic and antihypertensive activities, IC50 values of 0.22 ± 0.04 and 0.23 ± 0.03 mg mL−1 protein, respectively. This work demonstrates for the first time that food made with amaranth flour exerts potential antithrombotic and antihypertensive activity. In conclusion, these amaranth cookies could be an alternative way of incorporating potentially health beneficial products for people who choose a conscious diet, including coeliac or vegan consumers.  相似文献   
58.
59.
60.
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   
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