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   225062篇
  免费   18058篇
  国内免费   9383篇
电工技术   13077篇
技术理论   14篇
综合类   13660篇
化学工业   37213篇
金属工艺   11873篇
机械仪表   13608篇
建筑科学   17872篇
矿业工程   5758篇
能源动力   6514篇
轻工业   14951篇
水利工程   3996篇
石油天然气   11574篇
武器工业   1748篇
无线电   27639篇
一般工业技术   28157篇
冶金工业   12207篇
原子能技术   2417篇
自动化技术   30225篇
  2024年   419篇
  2023年   3354篇
  2022年   5584篇
  2021年   8662篇
  2020年   6448篇
  2019年   5444篇
  2018年   5954篇
  2017年   6726篇
  2016年   6219篇
  2015年   8228篇
  2014年   10716篇
  2013年   13736篇
  2012年   14113篇
  2011年   15773篇
  2010年   13581篇
  2009年   13216篇
  2008年   12684篇
  2007年   12235篇
  2006年   12364篇
  2005年   10805篇
  2004年   7407篇
  2003年   6341篇
  2002年   5732篇
  2001年   5251篇
  2000年   5228篇
  1999年   5773篇
  1998年   5547篇
  1997年   4426篇
  1996年   3976篇
  1995年   3347篇
  1994年   2799篇
  1993年   2224篇
  1992年   1695篇
  1991年   1280篇
  1990年   1015篇
  1989年   888篇
  1988年   684篇
  1987年   497篇
  1986年   381篇
  1985年   322篇
  1984年   196篇
  1983年   184篇
  1982年   160篇
  1981年   143篇
  1980年   140篇
  1979年   98篇
  1978年   65篇
  1977年   81篇
  1976年   115篇
  1975年   38篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
1.
Feng  Wenran  Li  Zhen  Chen  Yingying  Chen  Jinyang  Lang  Haoze  Wan  Jianghong  Gao  Yan  Dong  Haitao 《Journal of Materials Science》2022,57(3):1881-1889
Journal of Materials Science - Although chalcogenide materials continue to generate considerable interest due to great potentials for various optoelectronic devices, annealing for a long time in...  相似文献   
2.
Multimedia Tools and Applications - With the advancement of technology and the spread of the COVID19 epidemic, learning can no longer only be done through face-to-face teaching. Numerous digital...  相似文献   
3.
Xiao  Zhu  Chen  Yanxun  Jiang  Hongbo  Hu  Zhenzhen  Lui  John C. S.  Min  Geyong  Dustdar  Schahram 《Wireless Networks》2022,28(7):3305-3322
Wireless Networks - Unmanned aerial vehicles (UAV) have been widely used in various fields because of their high mobility and portability. At the same time, due to the rapid development of...  相似文献   
4.
5.
6.
The β-Carotene (BC), an important precursor of vitamin A (VA), possesses antioxidant activity but is fat-soluble and has low bioavailability. In previous in-vitro assays evaluating antioxidant and 2,2′-azobis(2-amidinopropane) dihydrochloride (AAPH) free radical scavenging, both BC and VA showed a strong ability to scavenge radicals and protected cells from oxidative stress. Here, we used artificially simulated gastrointestinal digestion and Caco-2 cell absorption models to evaluate the bioavailability of the BC during gastrointestinal digestion and absorption using high-performance liquid chromatography (HPLC) analysis. We observed high absorptive and transfer rates of BC and detected retinol metabolites (Vitamin A). Therefore, BC can be detected in the acidic gastrointestinal environment using HPLC. Optimised method provided better separation of BC and VA in the column, improving the accuracy of the test results.  相似文献   
7.
8.
The purpose of this study was to increase the water solubility and potential bioavailability of quercetin by encapsulation in whey protein isolate (WPI) based on a green, efficient pH-driven method. According to the results, the water solubility of quercetin increased by 346.9: times after loading into WPI nanoparticles. When the initial quercetin concentration was 0.25 mg mL−1 and WPI was 2% w/v, the encapsulation efficiency reached 94.1%, the Z-average diameter was 36.63 nm, and the zeta potential was −36.4 mV at pH 7.0. The fluorescence spectroscopy assay suggested the molecular complexation of quercetin and WPI at pH 12.0. X-ray diffraction assay indicated the enclosure of amorphous quercetin in WPI. Correspondingly, the bioaccessibility increased from 2.76% to 31.23% and the Caco-2 cell monolayer uptake increased from 0% to 2.12% after nanoencapsulation. This work confirmed that the pH-driven method is an effective approach to prepare WPI–quercetin nanocapsules to improve physical and potentially biological properties of quercetin.  相似文献   
9.
Mangiferin (MGF) is a phenolic compound isolated from mango, but its poor solubility significantly limits its use. In this study, MGF was embedded into the inner aqueous phase of W1/O/W2 emulsions. Firstly, the dissolution method of MGF was determined. MGF remained stable in solution with pH 13 at 30 min, and its solubility reached 10 mg mL−1. When the pH of MGF solutions was adjusted from pH 13 to pH 6, MGF did not immediately crystallise, providing sufficient time to construct the MGF-loaded W1/O/W2 emulsions. Subsequently, the MGF-loaded W1/O/W2 emulsions were constructed using polyglycerol polyricinoleate (PGPR) and calcium caseinate (CAS). The formation and stability of the W1/O/W2 emulsions were investigated. The MGF-loaded W1/O/W2 emulsions stabilised with 1% PGPR and 1% – 3% CAS exhibited a low viscosity, limited loading capacity, and poor stability. Conversely, the MGF-loaded W1/O/W2 emulsions stabilised by 3%PGPR–3%CAS exhibited optimal loading capacity (encapsulation efficiency = 95.31% and loading efficiency = 0.91%) and stability, which was attributed to the fact that high viscosity and gel state retarded the migration of inner aqueous phase. These results indicated that the W1/O/W2 emulsions stabilised by PGPR and CAS may be a potential alternative for encapsulating mangiferin.  相似文献   
10.
《药物分析学实验》是药学专业的一门独立必修课程,是药学科学领域中的一个重要组成部分,具有较强的实践性和综合性,旨在培养学生综合运用所学知识分析药品质量的能力.综合设计性实验作为《药物分析学实验》的重要组成部分,对学生实践操作能力,发现问题、分析问题、解决问题的能力,创新能力,应用能力,团结协作能力,劳动素养等综合能力的培养具有极其重要的意义.  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