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   6810篇
  免费   516篇
  国内免费   5篇
电工技术   66篇
综合类   1篇
化学工业   1796篇
金属工艺   178篇
机械仪表   173篇
建筑科学   263篇
矿业工程   22篇
能源动力   267篇
轻工业   945篇
水利工程   41篇
石油天然气   42篇
无线电   496篇
一般工业技术   1513篇
冶金工业   251篇
原子能技术   56篇
自动化技术   1221篇
  2024年   31篇
  2023年   70篇
  2022年   120篇
  2021年   219篇
  2020年   207篇
  2019年   176篇
  2018年   299篇
  2017年   329篇
  2016年   382篇
  2015年   226篇
  2014年   330篇
  2013年   664篇
  2012年   383篇
  2011年   507篇
  2010年   386篇
  2009年   406篇
  2008年   361篇
  2007年   328篇
  2006年   265篇
  2005年   192篇
  2004年   175篇
  2003年   149篇
  2002年   148篇
  2001年   80篇
  2000年   86篇
  1999年   77篇
  1998年   84篇
  1997年   74篇
  1996年   68篇
  1995年   49篇
  1994年   47篇
  1993年   39篇
  1992年   32篇
  1991年   31篇
  1990年   16篇
  1989年   21篇
  1988年   19篇
  1987年   15篇
  1986年   14篇
  1985年   26篇
  1984年   12篇
  1983年   12篇
  1982年   19篇
  1981年   18篇
  1980年   12篇
  1979年   14篇
  1978年   13篇
  1977年   15篇
  1976年   13篇
  1974年   11篇
排序方式: 共有7331条查询结果,搜索用时 15 毫秒
11.
Metal Science and Heat Treatment - The effect of solid boronizing at 950°C for 2 and 4 h on the phase composition, microstructure, hardness and abrasive wear of steel AISI 304L is studied...  相似文献   
12.
13.
14.
In submerged cultures performed in chemically defined fermentation medium containing glucose and glutamate, the growth and production of water‐soluble red pigments and citrinin by the filamentous fungus Monascus ruber were studied under various carbon/nitrogen (C/N) ratios. The specific production of the red pigments was optimal at a glucose/glutamate ratio of about 10 and then steadily decreased at higher C/N ratio. In contrast, the production of the mycotoxin increased with increased C/N with an optimum in the range of 30–45. In a fed‐batch mode, it was also found that the production of pigments was not favoured in fed‐batch mode by feeding the medium with glucose while keeping the C/N ratio lower than 10. This low production likely resulted from concurrent high accumulation of L‐malic acid that was reported to inhibit this production. In contrast, this mode of cultivation was rather favourable for the production of the mycotoxin.  相似文献   
15.
Progesterone is a natural hormone steroid used in humans for several treatments and in livestock for artificial insemination, which exhibits two polymorphic forms at ambient conditions: form 1 and form 2. Form 2 is metastable and more soluble than form 1; however, it is not suitable to use as powder raw material because it transforms into form 1 by the effects of grinding. A polymorphic screening of progesterone based on polymer-induced heteronucleation method was performed as an alternative to prepare the metastable form. Polyvinyl alcohol, hydroxypropyl methylcellulose (HPMC), dextran, gelatin, polyisoprene (PI) and acrylonitrile-butadiene (NBR) copolymer were used. Crystals were prepared from 0.5, 10 and 40?mg/mL solutions in acetone at room temperature by solvent evaporation. The samples were characterized by X-ray powder diffraction, differential scanning calorimetry (DSC), scanning electron microcopy and attenuated total reflectance infrared Fourier transform spectroscopy. Form 1 was nucleated from 40?mg/mL solutions on the six polymers and from 10?mg/mL solutions on PI and NBR. The mixture of form 1 and form 2 was obtained from 10?mg/mL solution on HPMC, dextran and gelatin and from 0.5?mg/mL solution crystallizations. Therefore, the polymeric devices, which crystallized the metastable and more soluble polymorph (2) of progesterone, would be a promissory alternative for the pharmaceutical applications.  相似文献   
16.
17.
18.
Class I hydrophobin Vmh2, a peculiar surface active and versatile fungal protein, is known to self‐assemble into chemically stable amphiphilic films, to be able to change wettability of surfaces, and to strongly adsorb other proteins. Herein, a fast, highly homogeneous and efficient glass functionalization by spontaneous self‐assembling of Vmh2 at liquid–solid interfaces is achieved (in 2 min). The Vmh2‐coated glass slides are proven to immobilize not only proteins but also nanomaterials such as graphene oxide (GO) and quantum dots (QDs). As models, bovine serum albumin labeled with Alexa 555 fluorophore, anti‐immunoglobulin G antibodies, and cadmium telluride QDs are patterned in a microarray fashion in order to demonstrate functionality, reproducibility, and versatility of the proposed substrate. Additionally, a GO layer is effectively and homogeneously self‐assembled onto the studied functionalized surface. This approach offers a quick and simple alternative to immobilize nanomaterials and proteins, which is appealing for new bioanalytical and nanobioenabled applications.  相似文献   
19.
20.
The Journal of Supercomputing - Deep learning algorithms have yielded remarkable results in medical diagnosis and image analysis, besides their contribution to improvements in a number of fields...  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