检索结果-南通市图书馆

Local environment regulation of transition metal dichalcogenide-based single-atom catalysts

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2024年第9期43卷 4019-4037页

作者： Ming-Hui Li Jing Li xiao-yu zheng Yao Zhou Advanced Research Institute of Multidisciplinary Science and School of Chemistry and Chemical Engineering Beijing Institute of TechnologyBeijing 100081China Laser Micro/Nano Fabrication Laboratory School of Mechanical EngineeringBeijing Institute of TechnologyBeijing 100081China

Single-atom catalysts have risen significant attention in the realm of green electrocatalytic energy conversion to address energy and environmental sustainability *** metal dichalcogenide(TMD)-based single-atom catalysts are considered highly effective in electrocatalysis due to the TMDs'notable specific surface area,tunable elemental species and efficient utilization of single *** order to enhance electrocatalytic performance,it is imperative to elaborately engineer the local environment surrounding the active sites of single atoms within *** this review,we initially explore the effects of synthesis methods on single-atom active sites and the influence of loading of single atoms on catalytic performance for *** modulation strategies of the local environment surrounding single-atom sites in TMDs are elaborated,including substitution engineering,surface adsorption,vacancies,spatial confinement and dual-atom site *** each modulation strategy,the effects of diverse local environments on various electrocatalytic applications are presented,such as the oxygen evolution reaction,oxygen reduction reaction,nitrogen reduction reaction,CO_(2)reduction reaction and CO ***,this study presents a comprehensive overview of the challenges encountered and the potential directions for the advancement of single-atom catalysts based on TMDs in the realm of electrocatalysis.

关键词： Single-atom catalysts Transition metal dichalcogenide Local environment Electrocatalysis

L‑Tyrosine Metabolic Pathway in Microorganisms and Its Application in the Biosynthesis of Plant‑Derived Natural Products

在线全文

学校读者我要写书评

暂无评论

World Journal of Traditional Chinese Medicine 2022年第3期8卷 386-394页

作者： Yi‑Wen Zhang Feng Nie xiao‑yu zheng Shu‑Juan Zhao The SATCM Key Laboratory for New Resources and Quality Evaluation of Chinese Medicine The MOE Key Laboratory for Standardization of Chinese Medicines and Shanghai Key Laboratory of Compound Chinese MedicinesInstitute of Chinese Materia MedicaShanghai University of Traditional Chinese MedicineShanghaiChina Experiment Center for Teaching and Learning Shanghai University of Traditional Chinese MedicineShanghaiChina

L-tyrosine,an aromatic amino acid,is an important upstream precursor for the synthesis of a series of valuable natural products such as flavonoids and phenolic *** recent years,regulation of the L‑tyrosine metabolic pathway has been devoted to enhancing the production of L-tyrosine and the derived bioactive compounds in microorganisms,usually by increasing the supply of precursors,blocking competitive routes,and modulating the transport ***,we reviewed the strategies to promote L-tyrosine production in microbial hosts and the common strategies to produce bioactive compounds in engineered Escherichia coli and Saccharomyces cerevisiae to better understand and utilize the L-tyrosine metabolic pathway for microbial overproduction of diverse valuable aromatic compounds in the future.

关键词： Biosynthesis Escherichia coli L-tyrosine Saccharomyces cerevisiae

Research Progress on the Pharmacological Mechanisms of Chinese Medicines that Tonify Qi and Activate Blood Against Cerebral Ischemia/Reperfusion Injury

在线全文

学校读者我要写书评

暂无评论

World Journal of Traditional Chinese Medicine 2022年第2期8卷 225-235页

作者： xiao-yu zheng Ye-Hao Zhang Wen-Ting Song Dennis Chang Jian-Xun Liu Beijing University of Chinese Medicine Graduate SchoolBeijing 100029 Institute of Basic Medical Sciences of Xiyuan Hospital China Academy of Chinese Medical SciencesBeijing Key Laboratory of Pharmacology of Chinese MateriaBeijing 100091China NICM Health Research Institute Western Sydney UniversityWestmeadNSW 2751Australia

Cerebral ischemia-reperfusion injury(CIRI) refers to a pathological phenomenon that aggravates the injury after the restoration of blood perfusion and oxygen supply to the cerebral ischemia-induced tissues and organs, with a relatively high incidence. The traditional Chinese medicine(TCM) believes that Qi deficiency and blood stasis are the cause of CIRI. Therefore, Chinese medicine for tonifying Qi and activating blood is regarded as an important choice for the treatment of CIRI. In recent years, it has been found that many Chinese herbal medical ingredients and compound Chinese medicine(CCM) have significant anti-CIRI effects, and their mechanisms of action mainly include improving brain blood supply, neuroprotection, regulating signal pathways such as TLR4/HO-1/Bcl-2, protecting mitochondrial function, regulating related protein levels, and regulating oxidative molecule levels. This article summarizes and introduces the pharmacological mechanisms of Tonifying-Qi and activating-blood Chinese medicine and CCM which have the function of anti-CIRI. Our goal is to provide effective reference for further researches on the cerebral protection of related TCMs or compounds and their clinical application.

关键词： Cerebral ischemia-reperfusion injury compound Chinese medicine ingredients of traditional Chinese medicine Qi deficiency and blood stasis Tonifying Qi and activating blood

A framework of the suggested Meta-cognitive Strategy Training model

在线全文

学校读者我要写书评

暂无评论

Sino-US English Teaching 2010年第7期7卷 31-34页

作者： ZHANG xiao-hui zheng yu-rong Foreign Languages Department Harbin Engineering University Heilongjiang 1500001 China

It is of great significance to carry out Meta-cognitive Strategy Training （MST） in current college English teaching context. After analyzing the advantages and disadvantages of some sequences and models for strategy training, the authors suggest the Meta-cognitive Strategy Training model which consists of 6 steps with Strategies-Based Instruction （SBI） employed to conduct the concrete strategy training.

关键词： meta-cognitive strategies strategy training college English teaching

PAA-capped GdF3 nanoplates as dual-mode MRI and CT contrast agents

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science Bulletin 2015年第12期60卷 1092-1100,I0002页

作者： xiao-yu zheng Ling-Dong Sun Tao zheng Hao Dong Yang Li Ye-FuWang Chun-Hua Yan Beijing National Laboratory for Molecular Sciences State Key Laboratory of Rare Earth Materials Chemistry and ApplicationsPKU-HKU Joint Laboratory in Rare Earth Materials andBioinorganic Chemistry College of Chemistry and Molecular Engineering Peking University Beijing 100871 China

Aiming at improving the sensitivity and accu- racy 9f diagnosis, the combination of magnetic resonance imaging （MRI） and X-ray computed tomography （CT） in a single probe is in urgent need. Here, we report the devel- opment of polyacrylic acid （PAA）-capped GdF3 nanoplates （NPs） as novel MRI and CT dual-mode contrast agents （CAs） with high longitudinal relaxivity （rl） and large X-ray attenuation coefficient. Uniform GdF3 rhombic NPs were fabricated by controlling reaction conditions and intro- ducing dopants. The average size of GdF3 NPs is （10.6 ：k 1.1） nm in long diagonal, （7.0 -t- 0.8） nm in short diagonal, and （4.2 -4- 1.2） nm in thickness. Ligand-exchange treat- ment was performed to render the NPs water-dispersible. The rl of PAA-capped GdF3 NPs （15.8 L/（mmol s）） is four times higher than that of clinically used Gd-DTPA. We suppose that the high r~ value originates from the con- struction of two-dimensional （2D） nanostructures, which endows nanocrystals with larger surface areas and longer rotational correlation time than those of sphere nanostruc- tures with the same volume. The CT contrast enhancement ability of PAA-capped GdF3 NPs was evaluated in com- parison with clinically used Iohexol. The above results suggest that the PAA-capped GdF3 NPs could serve as CAs for MRI and CT dual-mode imaging.

关键词： Nanoplates GdF3 Contrast agent MRI CT

在线全文

学校读者我要写书评

暂无评论

微颗粒表面磁控溅射镀金属膜

过程工程学报 2006年第Z2期6卷 173-178页

作者：俞晓正徐政沈志刚北京航空航天大学粉体技术北京市重点实验室北京100083 国家纳米技术产业化基地天津300457 北京有色金属研究总院北京100088

采用磁控溅射方法,开展了在微颗粒表面镀金属膜的实验研究.研究开发了一种在微颗粒表面真空镀金属膜的方法及设备,微颗粒包括空心微珠、不同粒度的碳化硅微粉等,所镀的金属包括铝、银、铜、钴、镍等.实验与分析结果表明,通过控制微颗粒... 详细信息

采用磁控溅射方法,开展了在微颗粒表面镀金属膜的实验研究.研究开发了一种在微颗粒表面真空镀金属膜的方法及设备,微颗粒包括空心微珠、不同粒度的碳化硅微粉等,所镀的金属包括铝、银、铜、钴、镍等.实验与分析结果表明,通过控制微颗粒的运动方式,采用磁控溅射镀金属膜,可以在微颗粒表面镀上均匀性好、附着力强和致密性好的金属膜.

关键词：微颗粒磁控溅射金属膜表面形貌

在线全文

学校读者我要写书评

暂无评论

碳化硅颗粒表面磁控溅射镀铜膜的研究

材料工程 2008年第3期36卷 32-35页

作者：俞晓正沈志刚徐政北京航空航天大学粉体技术北京市重点实验室北京有色金属研究总院北京100088

采用直流磁控溅射方法,在SiC颗粒表面成功地沉积了金属铜膜。利用场发射扫描电子显微镜(FESEM)、能谱仪(EDS)和电感耦合等离子体发射光谱仪(ICP-AES)等测试仪器对其表面形貌和组份进行了表征。重点讨论了不同的沉积条件对薄膜结晶的影响... 详细信息

采用直流磁控溅射方法,在SiC颗粒表面成功地沉积了金属铜膜。利用场发射扫描电子显微镜(FESEM)、能谱仪(EDS)和电感耦合等离子体发射光谱仪(ICP-AES)等测试仪器对其表面形貌和组份进行了表征。重点讨论了不同的沉积条件对薄膜结晶的影响,并用X射线衍射仪(XRD)对其进行了表征。结果表明,溅射镀膜时,通过控制SiC颗粒的运动方式,可以在其表面镀上均匀、连续和致密的金属膜。溅射时间越长或溅射功率越大或温度越高,都有利于薄膜结晶。

关键词：磁控溅射金属膜碳化硅 X射线衍射仪

Experimental Study on Geometry Characteristics of Turbulent Premixed Flames for Natural Gas/Air Mixtures

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2025年第1期34卷 268-282页

作者： zheng Weilin WANG Qijiao xiao Huahua CHEN xiaoxiao XIE Fan ZENG Wen Liaoning Key Lab of Advanced Test Technology for Aerospace Propulsion System Shenyang Aerospace University State Key Laboratory of Fire Science University of science and Technology of China AVIC Shenyang Aircraft Design and Research Institute

In this study,focusing on the geometry characteristics of spherical expanding flame,the turbulent premixed flames of natural gas/air mixtures were investigated in a fan-stirred turbulent *** effects of initial temperature（T=300-400 K）,initial pressure（P=0.1-0.3 MPa）,turbulence intensity（u'=1.0-2.7 m/s）,oxygen volumetric percentage(φ（O2）=15%-21%) and carbon dioxide volumetric percentage(φ（CO2）=0-20%)were delved *** flame profile under the Cartesian coordinate system was derived from the schlieren images taken by the high-speed ***,from both macroscopic and microscopic perspectives,the influence of experimental conditions on the flame geometry characteristics was explored through flame front extraction,wavelet decomposition and network *** results demonstrate that for significant flame wrinkling,changes in species concentrations and turbulence intensity have more pronounced effects on the flame wrinkling *** wrinkling of the flame front maintains a certain degree of similarity,as evidenced by the locally concentrated distribution of the angles of the maximum fluctuation *** disturbance energy under large-scale（D6-D8） disturbances exhibits relatively high values with a similar trend,exerting a significant impact on the geometry characteristics of the flame *** peaks of correlation degree are scattered either with the decomposition scale or the development of flame radius,indicating no linear correlation between different detail ***,the probability distribution of node degrees in key wrinkled regions exhibits different trends with that of large-scale wrinkling and disturbance energy,especially with changes in initial *** occurs because the number of key wrinkles varies based on the perturbation's strength or the region's ***,an increase in the fluctuation frequency of the flame's local radius may not necessarily lead to an increase in the number of key folded regions.

关键词： fan-stirred turbulent combustor geometry characteristics large-scale wrinkling network topology wavelet decomposition

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

一种求解结构可靠度的新型计算方法

船舶力学 2007年第4期11卷 609-614页

作者：沈永春俞晓正中国船舶科学研究中心江苏无锡214082 北京航空航天大学航空科学与工程学院北京100083

提出了一种求解结构可靠度的软计算方法,该方法综合了人工神经网络的柔软性和遗传算法的全局性及并行快速性的优点。利用人工神经网络的柔软性,可以生成任意形状的函数,因而可以更加贴切地拟合功能函数;由于遗传算法具有并行处理能力,... 详细信息

提出了一种求解结构可靠度的软计算方法,该方法综合了人工神经网络的柔软性和遗传算法的全局性及并行快速性的优点。利用人工神经网络的柔软性,可以生成任意形状的函数,因而可以更加贴切地拟合功能函数;由于遗传算法具有并行处理能力,可以对多组样本同时进行处理,因此收敛速度加快。除此之外,文中的遗传算法还使用了小生境共享技术,有效地克服了陷入局部解的缺陷。并根据上述方法研制了结构可靠度分析的电算程序,算例计算表明,计算结果具有很高的精度,该算法为结构可靠度研究提供了一种新的思路和实现路径。

关键词：软计算结构可靠度功能函数人工神经网络遗传算法