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   417篇
  免费   28篇
电工技术   10篇
化学工业   72篇
金属工艺   4篇
机械仪表   8篇
建筑科学   11篇
矿业工程   3篇
能源动力   31篇
轻工业   76篇
水利工程   6篇
无线电   111篇
一般工业技术   44篇
冶金工业   28篇
原子能技术   6篇
自动化技术   35篇
  2024年   1篇
  2023年   2篇
  2022年   4篇
  2021年   16篇
  2020年   10篇
  2019年   15篇
  2018年   16篇
  2017年   19篇
  2016年   21篇
  2015年   9篇
  2014年   26篇
  2013年   41篇
  2012年   30篇
  2011年   22篇
  2010年   15篇
  2009年   12篇
  2008年   12篇
  2007年   17篇
  2006年   16篇
  2005年   13篇
  2004年   7篇
  2003年   8篇
  2002年   11篇
  2001年   12篇
  2000年   6篇
  1999年   8篇
  1998年   22篇
  1997年   4篇
  1996年   5篇
  1995年   7篇
  1994年   6篇
  1993年   7篇
  1992年   4篇
  1991年   2篇
  1990年   6篇
  1989年   5篇
  1988年   1篇
  1987年   2篇
  1984年   2篇
  1979年   1篇
  1976年   1篇
  1972年   1篇
排序方式: 共有445条查询结果,搜索用时 15 毫秒
1.
2.
Novel phospholipid (PL)-cyclosporine conjugates were prepared and studied as potential prodrugs for inflammatory bowel disease (IBD). Our approach relies on phospholipase A2 (PLA2), which is overexpressed in the inflamed intestinal tissues, as the prodrug activator to potentially release cyclosporine at the site of inflammation. PL-cyclosporine prodrug conjugates with methylene linkers of various lengths between the sn-2 position of the PL and cyclosporine were synthesized and evaluated for in vitro activation. Surprisingly, despite previous work indicating that conjugates with six methylene linkers between the lipid and drug would suffer rapid enzymatic hydrolysis, with cyclosporine this was not observed. However, compounds with longer linkers (n=10, 12 methylene units) display complete release of the drug by PLA2-catalyzed hydrolysis, thus demonstrating the importance and profound impact of structural fine-tuning. This study represents a proof-of-concept for our hypothesis and a first step towards a truly targeted IBD treatment with cyclosporine that could be administered throughout the GI tract.  相似文献   
3.
In order to produce fermented sausages with prebiotic fibre and improved fatty acid composition, 16% of pork back fat was replaced with inulin gelled suspension (I) and inulin linseed oil gelled emulsion (IO). Physico-chemical analysis, fatty acid profiles, lipid oxidation, microbiological, textural, colour and sensory analysis were carried out. The fat content was lower in I (31.38%) and IO (35.36%) modified sausages compared to control (44.37%) (< 0.05). IO sausages had lower SFA and MUFA and higher PUFA content with an improved n-6/n-3 ratio (2.23) (< 0.05) and α-linolenic acid increment (5.74 g per 100 g). Reformulation led to decrease in springiness, chewiness and hardness and increase in adhesiveness of the sausages. Modified sausages had lower L* and higher a* values, while b* values of I sausages did not differ compared to control sausages. Modified sausages were acceptable regarding all sensory attributes. Lipid oxidation parameters showed higher susceptibility to oxidation and lipolysis in IO sausages.  相似文献   
4.
In this study, the suitability of fumed silica nanoparticles (FNS) and its derivatives (amino-modified FNS (AFNS), cyanuric chloride-activated AFNS (CCAFNS) and epoxy-modified FNS (GFNS)), for covalent immobilisation of two commercial protease preparations Alcalase® and Flavourzyme® was investigated. The highest hydrolytic activities of immobilised preparations were 25 IU g−1 support (Alcalase-GFNS) and 2.95 IU g−1 support (Flavourzyme-CCAFNS). Furthermore, the immobilised preparations showed 43% and 20% of initial specific activities of commercial protease preparations, respectively. Flavourzyme-CCAFNS also exhibited the highest exopeptidase activity of 22.83 L-pNAU g−1 support. Finally, these two nanobiocatalysts were successfully applied for hydrolysis of sunflower meal protein isolate (SMPI), providing two times higher hydrolysis yields in comparison to free enzymes, justifying the applied immobilisation process. Namely, the highest hydrolysis yield (30%) was gained by the sequential hydrolysis with Alcalase-GFNS and Flavourzyme-CCAFNS, which resulted in the formation of small hydrophobic and hydrophilic peptides, ≤5 kDa, confirmed by HPLC analysis and electrophoretic separation.  相似文献   
5.
Itaconate (ITA) is an emerging powerhouse of innate immunity with therapeutic potential that is limited in its ability to be administered in a soluble form. A library of polyester materials that incorporate ITA into polymer backbones resulting in materials with inherent immunoregulatory behavior is developed. Harnessing hydrolytic degradation release from polyester backbones, ITA polymers result in the mechanism specific immunoregulatory properties on macrophage polarization in vitro. In a functional assay, the polymer-released ITA inhibits bacterial growth on acetate. Translation to an in vivo model of biomaterial associated inflammation, intraperitoneal injection of ITA polymers demonstrate a rapid resolution of inflammation in comparison to a control polymer silicone, demonstrating the value of sustained biomimetic presentation of ITA.  相似文献   
6.
Fuels production from syngas via Fischer Tropsch synthesis (FTs) is an alternative technology for clean energy production. The microkinetic model is a promising approach for gaining insight into FTs activity. In this study, a systematic microkinetic model was proposed to develop a process for cobalt-catalyzed FTs. All possible elementary reactions based on the carbide mechanism and characteristics of catalyst sites were considered in the kinetic model. The effects of the reaction rate constant, reaction pathways, and H2 to CO ratio were represented by a kinetic parameter, reaction path, and operating parameter, respectively. The model could accurately predict product distribution trends, with an R2 value and mean absolute relative residuals percentage of 0.91–0.93 and 5–43%, respectively, in comparison with experimental data. Hydrogen utilization was predicted and analyzed. High model accuracy was achieved, with a 10?10–10?3% error in the material balance.  相似文献   
7.
8.
Whey represents a significant dairy industry by-product that has recently received due attention based on the rich nutrient composition and significant transformation potential. Hereby, we investigated a possibility of whey lactose bioconversion into prebiotic compounds, galacto-oligosaccharides (GOS) using β-galactosidase transgalactosylation activity. The results showed that whey could be successfully used for GOS synthesis, since the highest GOS concentration (around 62 g L−1) was obtained batchwise using 40% (w/w) sweet whey powder solution under optimum conditions (50°C, pH 4.5). Nevertheless, an efficient immobilized preparation using methacrylic Lifetech ECR8409 immobilization carrier was developed, enabling additional process improvement and ensuring at least 4 reaction cycles with unchanged yields and 2.5- fold enhanced productivity in comparison to the soluble enzyme. Therefore, this study provides a valuable contribution to the efficient and economical valorization of whey, which can be further on utilized as functional food and feed constituent.  相似文献   
9.
10.
The transition from traditional energy sources to renewable has gained popularity and acceptance in recent years. This has been driven mainly by the current level of pollution, global warming, decommission of old nuclear power plants and the increasing cost of conventional energy sources. Nevertheless, one of the many steps to overcome is the seasonality or intermittency of renewable energy sources such as wind power. In recent years, new technologies have come up to address this problem, so the energy can be stored for future purposes. This paper analyses these energy storage alternatives for a specific case in the Columbia River Gorge for wind power. A hierarchical decision model is developed with criteria including political, social, environmental, technical and economical. The main conclusions highlight that the economical and technical criteria are among the most important ones for decision-makers.  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