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   86篇
  免费   2篇
化学   75篇
数学   5篇
物理学   8篇
  2022年   2篇
  2021年   6篇
  2019年   2篇
  2018年   2篇
  2017年   4篇
  2016年   1篇
  2015年   1篇
  2014年   5篇
  2013年   1篇
  2012年   3篇
  2011年   6篇
  2010年   4篇
  2009年   3篇
  2008年   11篇
  2007年   7篇
  2006年   4篇
  2005年   4篇
  2004年   6篇
  2003年   1篇
  2002年   7篇
  2001年   2篇
  2000年   1篇
  1998年   1篇
  1997年   1篇
  1994年   1篇
  1988年   1篇
  1970年   1篇
排序方式: 共有88条查询结果,搜索用时 15 毫秒
71.
Momordica charantia is a popular vegetable associated with effective complementary and alternative diabetes management in some parts of the world. However, the molecular mechanism is less commonly investigated. In this study, we investigated the association between a major cucurbitane triterpenoid isolated from M. charantia, 3β,7β,25-trihydroxycucurbita-5,23(E)-dien-19-al (THCB) and peroxisome proliferator activated receptor gamma (PPARγ) activation and its related activities using cell culture and molecular biology techniques. In this study, we report on both M. charantia fruit crude extract and THCB in driving the luciferase activity of Peroxisome Proliferator Response Element, associated with PPARγ activation. Other than that, THCB also induced adipocyte differentiation at far less intensity as compared to the full agonist rosiglitazone. In conjunction, THCB treatment on adipocytes also resulted in upregulation of PPAR gamma target genes expression; AP2, adiponectin, LPL and CD34 at a lower magnitude compared to rosiglitazone’s induction. THCB also induced glucose uptake into muscle cells and the mechanism is via Glut4 translocation to the cell membrane. In conclusion, THCB acts as one of the many components in M. charantia to induce hypoglycaemic effect by acting as PPARγ ligand and inducing glucose uptake activity in the muscles by means of Glut4 translocation.  相似文献   
72.
Hydrophilic cotton textiles, used in hospitals and sportswear, are prone to the growth of microorganisms (bacteria, fungi) resulting in hygiene and health risks. Thus, healthcare concerns have motivated the interest for the development of multifunctional antimicrobial cotton fabrics. Moreover, cotton textiles are also used in medical applications such as wound dressings. Their functionalization with anti-inflammatory agents is desirable in order to accelerate cicatrisation in the treatment of chronic wounds. This review summarizes recent advances (from January 2016 to January 2021) on the modification and coating of cotton fabrics with nanostructures (mainly metal and metal oxide nanoparticles, functionalized silica nanoparticles) to provide them antimicrobial (antibacterial and antifungal) and anti-inflammatory properties.  相似文献   
73.
The immobilization of phosphine-free perfluoro-tagged palladium nanoparticles Pd-1 on fluorous silica gel (FSG) and their utilization in the Heck reaction have been investigated. High yields of vinylic substitution products have been obtained. Recycling studies have shown that the solid-supported palladium catalyst can be readily recovered and reused several times without significant loss of activity. Reactions and recovery of the solid-supported palladium catalyst system can be carried out in the presence of air, without any particular precaution.  相似文献   
74.
Two bismuth ferrite potential precursors systems, namely Fe(NO3)3·9H2O-Bi(NO3)3·9H2O-glycine/urea with different metal nitrate/organic compound molar ratios have been investigated in order to evaluate their suitability as BiFeO3 precursors. The presence into the precursor of both reducing (glycine and urea) and oxidizing (NO3) components, modifies dramatically their thermal behaviour comparative with the raw materials, both from the decomposition stoichiometries and temperature occurrence intervals points of view. Also, the thermal behaviour is dependent on the fuel nature but practically independent with the fuel content. The fuel nature influences also some characteristics of the resulted oxides (phase composition, morphologies). In the case of the oxides prepared using urea as fuel, a faster evolution toward a single phase composition with the temperature rise is evidenced, the formation of the BiFeO3 perovskite phase being completed in the temperature range of 500–550°C.  相似文献   
75.
76.
Additives to MgB2 can improve the superconducting functional characteristics, such as critical current density (J c) and irreversibility field (H irr). Recently, we have shown that repagermanium (C6H10Ge2O7) is an effective additive, enhancing both J c and H irr. To look into details of the processes taking place during the reactive sintering, a thermal analysis study (0.167 K s?1, in Ar) is reported. We used differential scanning calorimetry between 298 and 863 K and simultaneous thermogravimetric—differential thermal analysis between 298 and 1233 K. Samples were mixtures of powders with composition 97 mol% MgB2 and 3 mol% C6H10Ge2O7. Up to 863 K, repagermanium decomposes by multiple steps and forms amorphous phases. A reaction with MgB2 is not observed. Above this temperature, partial decomposition of MgB2 occurs. Crystalline Ge and MgO are detected before formation of Mg2Ge and MgB4, when temperature approaches the melting point of Ge (1211 K). Carbon substitution for boron in the crystal lattice of MgB2 is observed for samples heated above 863 K. The amount of substitutional C does not significantly change with temperature.  相似文献   
77.
Recyclable and readily prepared Ni and Pd nanocomposite carbon aerogels have been successfully used in the Suzuki–Miyaura reaction in water medium and aerobic conditions. In these ligand-free and environmentally-friendly conditions the Ni–carbon aerogel shows better recyclability than the corresponding palladium material. No appreciable leaching of Nickel could be detected after six reaction cycles. Interestingly enough, we have demonstrated for the first time that metal embedded carbon aerogels can be also used in water medium.  相似文献   
78.
Silica-gel supported binam-derived prolinamides are efficient organocatalysts for the direct intramolecular and intermolecular aldol reaction under solvent-free conditions using conventional magnetic stirring. These organocatalysts in combination with benzoic acid showed similar results to those obtained under similar homogeneous reaction conditions using an organocatalyst of related structure. For the intermolecular process, the aldol products were obtained at room temperature and using only 2 equiv of the ketone with high yields, regio-, diastereo- and enantioselectivities. Under these reaction conditions, also the cross aldol reaction between aldehydes is possible. The recovered catalyst can be reused up to nine times providing similar results. More interestingly, these heterogeneous organocatalysts can be used in the intramolecular aldol reaction allowing the synthesis of the Wieland–Miescher and ketone analogues with up to 92% ee, with its reused being possible up to five times without detrimental on the obtained results.  相似文献   
79.
The relationship of in-silico predicted physical/chemical properties and human toxicity is analyzed for a statistically significant sample size of chemical compounds. Results for compounds with known toxicity endpoints, as designated by EPA's Toxic Release Inventory (TRI), are compared to a series of commercial chemicals that are not regulated under TRI. Physical properties for all compounds are predicted using Schrodinger's QikProp, an established tool for predicting adsorption, distribution, metabolism, and excretion (ADME) characteristics. The results of this analysis indicate that the physical/chemical property distributions of TRI chemicals are statistically significantly different from those of bulk commercial chemicals, particularly related to properties associated with bioavailability. Using a partitioning analysis, several key physical/chemical properties and ranges are identified that can be used to readily differentiate TRI chemical characteristics from those of bulk commercial chemicals.  相似文献   
80.
Determination of carbamate pesticides such as carbaryl, carbofuran, propoxur and bendiocarb was demonstrated on a microchip with newly designed microchannels developed for efficient solvent extraction. The pesticides were hydrolyzed to corresponding naphthols, coupled with p-nitrobenzenediazonium fluoroborate reagent, and then extracted into 1-butanol as colored azo derivatives and detected with a thermal lens microscope. Optimum flow rates for the aqueous and organic phases were evaluated in the continuous-flow chemical process established in the microchip. The calibration lines showed good linearity in the range of concentrations of 0.03 - 3 ppm (10(-7) - 10(-5) M) and a mass detection limit down to a nanogram level was achieved that is at least two orders of magnitude lower than the LODs for conventional spectrophotometric methods. Azo derivatives of the pesticides were successfully separated and identified by micellar electrokinetic chromatography (MEKC) using a sample prepared on a bulk scale.  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