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   44篇
  免费   4篇
化学   29篇
晶体学   1篇
力学   1篇
数学   3篇
物理学   14篇
  2023年   2篇
  2021年   1篇
  2020年   3篇
  2019年   3篇
  2018年   2篇
  2017年   2篇
  2016年   6篇
  2015年   5篇
  2014年   3篇
  2013年   2篇
  2012年   3篇
  2011年   5篇
  2010年   2篇
  2009年   2篇
  2008年   3篇
  2007年   1篇
  2006年   1篇
  1999年   1篇
  1978年   1篇
排序方式: 共有48条查询结果,搜索用时 750 毫秒
41.
Scutellaria oblonga Benth., a hitherto phytochemically unexplored Indian medicinal folklore plant was extracted with acetone and subjected to chromatography to yield nine flavonoids, for the first time from this plant. Antimicrobial assays were performed against 11 foodborne pathogens, and three molecules (Techtochrysin, Negletein and Quercitin-3-glucoside) depicted significant activity. These molecules were assessed for their rate of antibacterial action using time–kill curves which depicted complete inhibition of most of the bacteria within 12–16 h. The significant biofilm-reducing capability exhibited by these three molecules formed a significant finding of the current study. In most of the experiments, a 90–95% reduction in biofilms was observed. Thus, flavonoids as natural molecules from S. oblonga could be further researched to be used as potent antimicrobial and antibiofilm agents.  相似文献   
42.
The commercial mass production of perovskite solar cells requires full compatibility with roll‐to‐roll processing with enhanced device stability. In line with this, the present work addresses following issues simultaneously from multiple fronts: (i) low temperature processed (140 °C) ZnO is used as electron transport layer (ETL) for fabricating the mixed organic cation based perovskite solar cells, (ii) the expensive hole transporting layer (HTL) spiro‐OMeTAD is replaced with F4TCNQ doped P3HT and (iii) the fabrication method does not incorporate the dopant TBP which is known to induce degradation processes in perovskite layer. All the devices under study were fabricated in ambient conditions. The F4TCNQ doped P3HT (HTL) based devices exhibits 14 times higher device stability compared to the conventional Li‐TFSI/TBP doped P3HT devices. The underlying mechanism behind the enhanced device lifetime in F4TCNQ doped P3HT (HTL) based devices was investigated via in‐depth electronic, ionic and polaronic characterization. The enhanced polaronic property in F4TCNQ doped P3HT HTL device ascertains its superior hole extraction and electron blocking capability; and consequently higher stability retained even after a month of ageing.

  相似文献   

43.
The effect of film thickness and substrate orientation on ferromagnetism in Mn doped ZnO thin films have been studied. The Mn doped ZnO films of different thickness (15, 35 and 105 nm) have been grown on both Si (100) and Si (111) substrates. The structural, electrical, optical, elemental and magnetic properties of the films have been investigated by X‐ray diffraction (XRD), Hall Effect measurements, photoluminescence (PL), energy dispersive spectroscopy (EDS) and vibrating sample magnetometer (VSM), respectively. It is found that all the properties are strongly influenced by the film thickness and substrate orientation. The XRD analysis confirmed that the formation of high quality monophasic hexagonal wurtzite structure for all the grown films. The room temperature VSM measurements showed that the films of lower thickness have better ferromagnetism than that of the thicker films grown on both the substrates. Among the lower thickness films, the film grown on Si (111) substrate has higher saturation magnetization (291×10‐5 emu cm‐3) due to high density of the defects. The observed ferromagnetism has been well justified by XRD, Hall measurements and PL. The presence of Mn atoms in the film has been confirmed by EDS. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   
44.
A sensitive imidazole based fluorescent sensor like 4, 5-diphenyl-2(E)-styryl-1H-imidazole, for ZnO has been designed and synthesized via simple steps. The absorption, fluorescence, SEM, EDX and IR studies indicate that imidazole derivative is bound on the surface of ZnO semiconductor. Based on photo-induced electron transfer (PET) mechanism, fluorescent enhancement has been explained and apparent binding constant has been calculated. Ligand adsorption on ZnO nanoparticle lowers of the HOMO and LUMO energy levels of imidazole derivative and the chemical affinity between the nitrogen atom of the imidazole and zinc ion on the surface of the nano oxide may be a reason for strong adsorption of the ligand on nanoparticle. The electron injection from photo excited imidazole derivative to the ZnO conduction band (S(*)→S(+) + e (CB) (-) ) accounts for the enhanced fluorescence.  相似文献   
45.
The stability of convective motion of a fluid driven by volumetric heat sources and applied pressure gradient is investigated. The viscosity of the fluid is assumed to depend linearly on temperature. The sufficient conditions for the existence of such a flow are obtained based on the energy inequalities. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   
46.
The recently reported sensing characteristics of the mixed-potential-type yttria-stabilized zirconia (YSZ)-based hydrocarbon (HC) sensor attached with ZnCr2O4-sensing electrode (SE) were found to be changed after the 10-day operation at 550 °C under the wet condition (5 vol.% water vapor). To improve the stability of the present sensor, the several modifications of the SE material by adding YSZ powder were examined. As a result, the sensor using the laminated (ZnCr2O4/YSZ)-SE gave the stable electromotive force (emf) response against 100 ppm C3H6 at 550 °C for about one month examined. Based on the scanning electron microscopy (SEM) observation and the AC complex-impedance measurements, it was concluded that the stable behavior of the sensor using the laminated (ZnCr2O4/YSZ)-SE was provided by the stabilization of the interface between ZnCr2O4 grains and YSZ particles. The fabricated sensor exhibited the linear dependence of sensitivity on the logarithm of either C3H6 concentration (in the range of 20-800 ppm) or mixtures of various hydrocarbons (HCs) (in the range of 90-2600 ppmC). In addition, the emf response was not altered by the change of O2 (2-20 vol.%), H2O (0-10.8 vol.%) and CO2 (0-20 vol.%) concentrations, and no interference of other gases (CO, NO, NO2, H2, and CH4) was observed.  相似文献   
47.
To increase the sensitivity in surface‐enhanced Raman scattering (SERS) measurement, a three‐dimensional (3D) SERS substrate was prepared by the decoration of silver nanoparticles (AgNPs) on the side walls of ZnO nanowires. The prepared 3D SERS substrates provide the advantages of highly loaded density of AgNPs, with a large specific surface area to interact with analytes, and the ease for the analytes to access the surfaces of AgNPs. To prepare the substrates, ZnO nanowires were first grown on a glass plate by wet chemical method. By treating SnCl2 on the surfaces of ZnO nanowires, Ag seeds could be formed on the side wall of the ZnO nanowires, which were further grown to a suitable size for SERS measurements via photochemical reduction. To optimize and understand the influences of the parameters used in preparation of the substrates, the reaction conditions were systematically adjusted and examined. Results indicated that AgNPs could be successfully decorated on the side wall of the ZnO nanowires only by the assistances of SnCl2. The size and density of AgNPs were affected by both the concentration of silver nitrate and the irradiation time. With optimized condition, the prepared 3D substrates provided an enhancement factor approaching 7 orders of magnitude compared with conventional Raman intensity. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   
48.
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