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   202300篇
  免费   11494篇
  国内免费   5631篇
电工技术   7912篇
技术理论   12篇
综合类   10381篇
化学工业   31066篇
金属工艺   11194篇
机械仪表   10890篇
建筑科学   11510篇
矿业工程   4416篇
能源动力   4908篇
轻工业   11922篇
水利工程   3267篇
石油天然气   7838篇
武器工业   993篇
无线电   22307篇
一般工业技术   30484篇
冶金工业   8362篇
原子能技术   1571篇
自动化技术   40392篇
  2024年   224篇
  2023年   2081篇
  2022年   3198篇
  2021年   5003篇
  2020年   3849篇
  2019年   3319篇
  2018年   17626篇
  2017年   17049篇
  2016年   13171篇
  2015年   5410篇
  2014年   6276篇
  2013年   7484篇
  2012年   10928篇
  2011年   17552篇
  2010年   15636篇
  2009年   12550篇
  2008年   13558篇
  2007年   14031篇
  2006年   6631篇
  2005年   6775篇
  2004年   4915篇
  2003年   4513篇
  2002年   3768篇
  2001年   2942篇
  2000年   2995篇
  1999年   3131篇
  1998年   2583篇
  1997年   2097篇
  1996年   2060篇
  1995年   1676篇
  1994年   1398篇
  1993年   1023篇
  1992年   822篇
  1991年   631篇
  1990年   461篇
  1989年   374篇
  1988年   305篇
  1987年   193篇
  1986年   142篇
  1985年   116篇
  1984年   79篇
  1983年   50篇
  1982年   58篇
  1981年   40篇
  1980年   39篇
  1968年   46篇
  1966年   42篇
  1965年   45篇
  1955年   63篇
  1954年   68篇
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
1.
Journal of Materials Science: Materials in Electronics - The influences of the selenium (Se) growth condition on the electronic level structure including deep defects and further on the...  相似文献   
2.
Niu  Hao  Yang  Dan-Lei  Pu  Yuan  Wang  Dan  Wang  Jie-Xin 《Journal of Materials Science》2022,57(10):5788-5804
Journal of Materials Science - Nanocomposites have been used in various industries due to their excellent properties. For some of them, high filler content (over 50 wt%) is beneficial to improving...  相似文献   
3.
4.
5.
Hao  Shijie  Wang  Zhonghao  Sun  Fuming 《Neural Processing Letters》2022,54(4):2759-2782
Neural Processing Letters - Scale variation is one of the primary challenges in object detection. Recently, different strategies have been introduced to address this challenge, achieving promising...  相似文献   
6.
In this study, the effect of high-intensity ultrasound (HIUS) (200 and 400 W for 0, 5, 10 and 15 min respectively) on conformational changes, physicochemical, rheological and emulsifying properties of scallop (Patinopecten yessoensis) myofibrillar protein (SMP) was investigated. HIUS-treated SMP had lower α-helix content and higher β-sheet content compared with the native SMP. HIUS treatment induced the unfolding of SMP and increased the surface hydrophobicity. The particle size of SMP decreased and the absolute zeta-potential increased after ultrasonication, which in turn increased the solubility of SMP. The conformational changes and the improvement of physicochemical properties of SMP increased the ability for SMP to lower the interfacial tension at the oil–water interface and increased the percentage of adsorbed protein. As a result, the emulsifying properties, rheological properties of SMP and storage stability of emulsions were also improved. In conclusion, HIUS treatment has future potential for improving the emulsifying properties of SMP.  相似文献   
7.
The structural diversity of polyphenols and the inherent limitations of current extraction techniques pose a challenge to extract polyphenols using a simple and green method. Hence, in this study, a method was developed to simultaneously fractionate multiple classes of polyphenols by only varying ethanol-water solutions. Honeybush tea, which is rich in polyphenols, was selected as a model for this study. Solvent extraction followed by solid-phase extraction (SPE) was developed to obtain a polyphenol-rich fraction from six honeybush samples. Based on a gradient elution programme (10%, 30%, 50%, 70% and 90% (v/v) ethanol-water solution) of SPE, the Strata X cartridge showed a better recovery of most targeted polyphenols under 0.9 mL of the drying volume and 1 mL min−1 of the dispensing speed. The elution programme for fractionating most polyphenols was as follows: single elution with 50% ethanol, followed by twice elution with 70% ethanol. The antioxidant capacity was used to analyse the differences among the polyphenol-rich fractions from six honeybush samples. Principal component analysis (PCA) revealed that unfermented C. genistoides (GG) has the greatest antioxidant capacity among the honeybush species studied. Additionally, mangiferin, isomangiferin and vicenin-2 were the main contributors to the antioxidant capacity in six honeybush fractions according to the correlation study.  相似文献   
8.
The effects of cellulose microfibres (CMFs, Average size: 100 ± 5 μm) and cellulose nanofibres (CNFs, Average size: 60 ± 3 nm) on the properties of myofibrillar protein (MP) gels from duck breast meat were studied. The results demonstrated that CMFs and CNFs were mostly connected to MP by non-covalent bonds, the diffusion and cross-linking of MP molecules was promoted, and a denser and more complete gel network was formed. With the increases of CMFs and CNFs concentration (0–10%), the hardness was increased by 13.15% and 19.78% for CMFs10% and CNFs10% gels, respectively, and the elasticity was increased by 40% and 80%, respectively. At the same concentration (0–10%), the increase in gel hardness, viscoelasticity and immobilised water content was greater in the CNFs-MP group than in the CMFs-MP group. The CNFs-MP group had a tighter gel network, and CNFs had a better potential to improve the gelation performance of MP.  相似文献   
9.
10.
Corrosion and salt deposition problems severely restrict the industrialization of supercritical water oxidation. Transpiring wall reactor can effectively weaken these two problems by a protective water film. In this work, methanol was selected as organic matter, and the influences of vital structural parameters on water film properties and organic matter removal were studied via numerical simulation. The results indicate that higher than 99% of methanol conversion could be obtained and hardly affected by transpiration water layer, transpiring wall porosity and inner diameter. Increasing layer and porosity reduced reactor center temperature, but inner diameter's influence was lower relatively. Water film temperature reduced but coverage rate raised as layer, porosity, and inner diameter increased. Notably, the whole reactor was in supercritical state and coverage rate was only approximately 85% in the case of one layer. Increasing reactor length affected slightly the volume of the upper supercritical zone but enlarged the subcritical zone.  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