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排序方式: 共有379条查询结果,搜索用时 250 毫秒
21.
HU Tao YANG Weiwei WANG Cheng BU Yali JIN Feng ZHANG Dongwen GU Min LIU Wenhui LIANG Qinghua LIU Ruiqing FENG Xiaomiao MA Yanwen 《高等学校化学研究》2021,37(2):286-292
Sodiumion batteries(SIBs)have attracted intensive attention as promising alternative to lithium-ionbatteries(LIBs)for large scale energy storage systems because of low cost of sodium,similar energy storage mechanism and the reasonable performance.However,it is still a great challenge to search and design a robust structure of anode materials with excellent cycling stability and high rate capability for SIBs.Herein,multilayer porous vanadium nitride(VN)microsheets are synthesized through a facile and scalable hydrothermal synthesis-nitrogenization strategy as an effective anode material for SIBs.The multilayer porous VN microsheets not only offer more active sites for fast Na+insertion/extraction process and short diffusion pathway,but also effectively buffer the volume change of anode due to more space in the multilayer porous structure.The large proportions of capacitive behavior imply that the Na+charge storage depends on the intercalation pseudocapacitive mechanism.The multilayer porous VN microsheets electrodes manifest excellent cycling stability and rate capability,delivering a discharge capacity of 156.1 mA·h/g at 200 mA/g after 100 cycles,and a discharge capacity of 111.9 mA·h/g at 1.0 A/g even after 2300 cycles with the Coulombic efficiency of nearly 100%. 相似文献
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基于叶绿素荧光光谱分析的稻瘟病害预测模型 总被引:3,自引:0,他引:3
为了实现稻瘟病的快速、准确和无损检测,力求构建稻瘟病害预测模型。根据水稻叶片相对病害面积将稻瘟病划分为3个等级,通过激光诱导法采集不同病害等级的活体水稻叶片叶绿素荧光光谱。选取502~830 nm波段激光诱导叶绿素荧光光谱(LICF)作为研究对象,利用Savitzky-Golay平滑法(SG)和一阶导数变换(FDT)对光谱信息进行预处理,通过主成分分析(PCA)方法获取经SG-FDT预处理后光谱的特征向量,根据累积贡献率和方差选取前3个主成分进行分析。将试验样本分为建模样本和检验样本,以稻瘟病害等级为预测指标,利用建模样本的133片叶片的光谱和病害信息分别结合判别分析(DA)、多类逻辑回归分析(MLRA)和多层感知器(MLP)建立稻瘟病的预测模型,利用检验样本的89片叶片的光谱和病害信息对所建模型进行预测检验,完成对PCA-DA、PCA-MLRA和PCA-MLP的对比寻优。结果表明,PCA-DA,PCA-MLRA和PCA-MLP模型均能完成对稻瘟病害的预测,但PCA-MLP模型的平均预测准确率能够达到91.7%,相比PCA-DA和PCA-MLRA模型,在稻瘟病害3个等级上均具有较好的分类和预测能力。 相似文献
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Dimitrios A. Lamprou Thomas G. Nevell Colin R. Willis 《Applied Surface Science》2010,256(6):1961-5087
Measurements of surface-liquid interactions (contact-angle goniometry) and tip-surface adhesion forces (atomic force microscopy) combined with infrared spectroscopic studies have been used to investigate surface-preparation and solution-deposition conditions for the reproducible formation of self-assembled molecular structures on gold-coated tips and substrates for atomic force microscopy. Preliminary data show that surface-saturated self-assembled monolayers form reproducibly on prolonged (>20 h) exposure of gold-coated glass substrates to ethanolic solutions of ω-functionalised alkanethiols in the concentration range 80-160 mmol dm−3. The data also show that exposure for 16 h to alkanethiol concentrations in the range 160-240 mmol dm−3 promote bilayer formation whereas concentrations of 240-320 mmol dm−3 result in the deposition of multilayers, the average orientation of which is parallel to that of the first molecular layer; the use of parent 1-undecanethiol solutions at concentrations of 1-80 mmol dm−3 results in incomplete monolayer coverage. 相似文献
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A laser-plasma EUV source is described, which is going to be utilized for characterization of EUV optical components and sensoric devices in the wavelength region from 11 to 13 nm. EUV radiation is generated by focusing a Nd:YAG laser into a double stream gas puff target. By the use of different target gases, broadband as well as narrow-band EUV radiation can be obtained. The emission characteristics of the radiation is monitored by the help of different diagnostic tools including a pinhole camera, an EUV spectrometer, and various EUV photodiodes, either directly or after reflection from multilayer mirrors. Theoretical calculations of collision-induced energy transfer are given in order to explain the observed high degree of electronic excitation in the utilized target gases. 相似文献
28.
Kai Jiang Andriy Zakutayev Jason Stowers Michael D. Anderson Janet Tate David H. McIntyre David C. Johnson Douglas A. Keszler 《Solid State Sciences》2009,11(9):1692-1699
High-quality TiO2 thin films have been deposited from aqueous titanium-peroxo solutions via spin coating. The effects of precursor solution pH on the crystallization behavior, morphology, density, and refractive index of the films are reported. From X-ray diffraction measurements, the amorphous as-deposited films are found to crystallize in the anatase phase at 250 °C. Surface and cross-section SEM images reveal that films deposited from an acidic precursor are more uniform and denser than those deposited from a basic precursor. X-ray reflectivity measurements show that films with smooth surfaces and high densities (up to 87% of single-crystal anatase) can be produced at temperatures as low as 300 °C. Measured densities are consistent with high refractive indices at 633 nm of 2.24 and 2.11 for films derived from acidic and basic precursors, respectively. The uniformity and dense nature of the films have allowed fabrication of multilayer dielectric optical elements with thermal processing at only 300 °C. The distributed Bragg reflector with four bilayers exhibits a reflectance of 92% and a stop band width of 150 nm. The optical microcavity has a quality factor of 20. The optical properties of all elements agree well with theoretical models, indicating good optical quality. Use of the precursor chemistry for direct photopatterning of TiO2 films without a polymer resist is also demonstrated. 相似文献
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The present review summarizes recent, and important previous, findings on properties of mucin layers and multilayers and ways to tailor their properties. Specifically, progress has been made in understanding the effects of mucin type, preparations, ambient conditions and surface properties on adsorption and on mixed layer assembly including multilayers. Apart from structural features the stability, lubrication and biological functions of such layers are addressed. 相似文献
30.
Lei Liu Bin Wang Xuewei Cao Xiaoxuan Xu Yufang Wang 《Journal of Quantitative Spectroscopy & Radiative Transfer》2011,112(17):2733-2740
Using T-matrix method, plasmon resonance properties of metal core–shell nanoparticles are systematically investigated. It is shown that dielectric/metal core–shell structure may be excited stronger at resonance than metal/dielectric and hetero-metal ones, but the resonance states are extremely sensible to the layers thickness. For three-layer nanospheres, resonance properties will be dominated by a sub-10 nm silver outermost shell, while only weakened by a silica one. Finally, tiny eccentric distance between the centers of core and shell in eccentric two-layer nanoparticles may fundamentally change the resonance mode of nanoparticles, and results in higher local electrical field enhancement than concentric nanospheres. 相似文献