检索结果-南通市图书馆

Relationship between Hydrogen Diffusion and Blistering Nucleation and Growth

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2016年第11期23卷 1188-1194页

作者： Jin-xu li Hang YIN Xi-na yanG Qian li Ping ZHANG Chun-qian XIE yan-jing SU li-jie QIAO Corrosion and Protection Center Environment Sensitive Fracture Laboratory(MOE)University of Science and Technology Beijing

The formation condition of hydrogen blister in 18Ni maraging steel without any inner or external stress was investigated. The results show that the critical diffusible hydrogen concentration of a blister forming is about 1.4×10^-5 , which is corresponding to the current density of 30 mA/cm^2 during cathodic charging in a sodium hydroxide solution. For a 0.1 cm thick sample, no matter the current density is equal to or much larger than the critical value, it spends at least about 132 h to form a hydrogen blister when hydrogen charging in single direction. It is approxi- mately equal to the time for hydrogen atom to diffuse throughout the sample, which exactly depends on the hydrogen diffusion coefficient and the penetration depth. The very first clear suggestion was reported that the incubation period for hydrogen blister nucleation was necessary. According to the Fick＇s laws, calculations show that the normalized hydrogen concentration in the escaping surface almost reaches 0.96 times of the charging surface, which means that the diffusion almost reaches a dynamic balance. A model was illustrated to describe the competitive relationship between hydrogen diffusion and blister formation.

关键词： hydrogen blister trap maraging steel hydrogen diffusion incubation time

Remote Sensing Monitoring of Gullies on a Regional Scale: A Case Study of Kebai Region in Heilongjiang Province, China

在线全文

学校读者我要写书评

暂无评论

Chinese Geographical Science 2015年第5期25卷 602-611页

作者： ZHANG Shuwen li Fei li Tianqi yanG Jiuchun BU Kun CHANG liping WANG Wenjuan yan Yechao Northeast Institute of Geography and Agroecology Chinese Academy of Sciences College of Earth Science Jilin University Henan University

Gully erosion is one of the major causes of land degradation in most areas and attracts increasing attention from researchers. We monitored gullies in the Kebai region in Heilongjiang Province of China by using remote sensing data and found that gully density increased with the increase in slope when the slope was less than 3°. Gully density in sunny slopes or windward slopes was greater than in shady slopes or leeward slopes because of the impacts of freezing and thawing, wind and solar radiation. Specifically, the gully density in northeast slope was the greatest and in southwest was the smallest. Gully density was reduced with increasing slope length and the longer the slope length, the less the gully density changed between 1965 and 2005. Affected by runoff, gullies most easily to occur in concave slopes and the critical elevation for gully erosion was 250–275 m. Moreover, hilly regions had the greatest gully density, followed by tableland regions, whereas the gully density in flatlands was the lowest. However, the gully density of these three types of landforms all increased between 1945 and 2000, and the portion of increase was 57.45%(hill), 52.91%(mesa) and 25.32%(plain), respectively.

关键词： gully density gully erosion monitoring remote sensing Kebai region, China

Proteomic analysis of salt and osmotic-drought stress in alfalfa seedlings

在线全文

学校读者我要写书评

暂无评论

Journal of Integrative Agriculture 2016年第10期15卷 2266-2278页

作者： MA Qiao-li KANG Jun-mei LONG Rui-cai CUI yan-jun ZHANG Tie-jun XIONG Jun-bo yanG Qing-chuan SUN yan College of Animal Science and Technology China Agricultural University Beijing 100193 P.R. China Institute of Animal Science Chinese Academy of Agricultural Sciences Beijing 100193 P.R.China School of Chemistry & Chemical Engineering Ningxia University Yinchuan 750021 P.R. China Institute of Animal Science Hubei Academy of Agricultural Sciences Wuhan 430064 P.R.China

Alfalfa is widely grown and is one of the most important forage crops in the world, but its growth and biomass production are markedly reduced under salt and drought stress, particularly during the early seedling stage. To identify the mechanisms behind salt and drought responsiveness at the alfalfa seedling stage, the proteins expressed were analyzed under no-treatment, 200 mol L–1 Na Cl and 180 g L–1 PEG treatment conditions during the seedling stage. Out of more than 800 protein spots detected on two-dimensional electrophoresis（2-DE） g els, 35 proteins showed statistically significant responses（P〈0.05） to Na Cl and PEG stress, which were selected for tandem mass spectrometric identification, owing to their good resolution and abundance levels, and 32 proteins were positively identified. The identified proteins were divided into seven functional categories： photosynthetic metabolism, protein biosynthesis, folding and assembly, carbohydrate metabolism-associated proteins, stress defense related protein, metabolism of nucleic acid, other function categories and unknown proteins. Our results suggested that these proteins may play roles in alfalfa adaptation to salt and drought stress. Further study of these proteins will provide insights into the molecular mechanisms of abiotic stress and the discovery of new candidate markers in alfalfa.

关键词： alfalfa salinity stress osmotic stress seedling growth proteomics

Recent advances in remote C(sp^(3))-H functionalization via chelating group-assisted metal-catalyzed chain-walking reaction

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2024年第11期35卷 99-110页

作者： Jian Han li-li Zeng Qin-Yu Fei yan-Xiang Ge Rong-Hui Huang Fen-Er Chen School of Pharmacy Changzhou UniversityChangzhou 213164China Engineering Center of Catalysis and Synthesis for Chiral Molecules Department of ChemistryFudan UniversityShanghai 200433China Shenzhen Research Institute of Nanjing University Shenzhen 518057China

Aliphatic C(sp^(3))-H moieties are ubiquitous in numerous organic *** functionalization of inert C(sp^(3))-H bonds is a powerful and straightforward approach for the efficient construction of diverse carbon-carbon or carbon-heteroatom *** group directed metal-catalyzed remote functionalization of readily available alkenes has emerged as an appealing strategy for rapidly accessing various value-added aliphatic *** the aid of directing groups,variousα-,β-andγ-functionalized alkanes could be synthesized smoothly with excellent *** preferred formation of a stable five-or six-membered metallacycle intermediate terminates the chain-walking at a specific methylene site,which serves as the driving force for excellent site-selective migratory *** review herein is aimed at summarizing the recent progress on the metal-catalyzed regiodivergent functionalization of unactivated alkenes by merging alkene isomerization and cross-coupling with the assistance of directing *** but not least,the current situations and future directions in this field are highlighted and discussed.

关键词： Chelating group Chain-walking Regiodivergent Unactivated alkenes C(sp^(3))-H functionalization Transition-metal catalysis

Assessment tools of nursing work environment in magnet hospitals: A review

在线全文

学校读者我要写书评

暂无评论

International Journal of Nursing Sciences 2014年第4期1卷 437-440页

作者： li-yan Gu ling-Juan Zhang Nursing Department Changhai Hospital Affiliated to Second Military Medical UniversityShanghaiChina

In the 1990s,the American Nurses Association established a certification program called the Magnet Recognition Program through the American Nurses Credentialing Centre(ANCC)to complement the quality care provided to patients by *** the program was recognised,hospitals were identified as magnet hospitals[1].Some studies show that magnet hospitals provide a healthier working environment for nurses,accompanied by higher nurse satisfaction and better patient prognosis than non-magnet hospitals[2e5].The nursing work environment is the sum of various elements that directly or indirectly affect the patient care system[6].Improving the nursing work environment is a focal point and challenge for nursing ***,administrators in magnet hospitals usually apply a variety of assessment tools for effective evaluation of the nursing work environment to maintain and improve the health of the environment.

关键词： Evaluation studies Magnet hospitals Nursing work environment literature review

Role of Heavy Metal Ions in the Formation of Oxyfluoride Glasses and Glass Ceramics

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

Journal of Materials Science & Technology 2014年第12期30卷 1213-1216页

作者： Min liu lijuan Zhao yan liu Zijian Lan lifen Chang Yiming li Hua Yu The MOE Key Laboratory of Weak light Nonlinear Photonics and School of Physics Nankai University TEDA Applied Physics Institute Nankai University

In order to investigate the influence of different heavy metal ions on the formation of the oxyfluoride glasses and glass ceramics, samples with different Pb F2/Cd F2 ratios have been prepared by the melting quenching and thermal treatment method. The different effects of Pb2 tand Cd2ton the glass network structure are investigated by FTIR and Raman spectra. During the formation of glass network structure, Pb2 tprefers to break the Sie Oe Si bond and subsequently bond to F for charge compensation, and Cd2 tprefers to break the SieO eA l bond and is surrounded by O2. Pb2 tand F gather together and form the fluoride nanocrystals,while Cd2 tremains in oxide matrix after thermal treatment. Introduction of proper Cd F2 is important to adjust and control the glass network structure and crystallization process in the fabrication of the transparent glass ceramics.

关键词： Pb Cd Glass network Oxyfluoride glass ceramics

First Principles Study of Dopant Site Selectivity in Ordered Perovskite CaCu3Ti4O12

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2011年第3期28卷 163-166页

作者： XU li-Chun WANG Ru-Zhi DENG yang yan Hui Laboratory of Thin Film Materials College of Materials Science and EngineeringBeijing University of TechnologyBeijing 100124

We investigate the dopant site selectivity of CaCu_(3)Ti_(4)O_(12)(CCTO)using the first principles *** results show that,for four cases of possible occupancy by La atom,lattice expansions and formation enthalpies with different dopant quantities indicate that doped La cations are preferentially substituted for Ca sites in CaCu_(3)Ti_(4)O_(12),which is excellent in agreement with the experimental observation(Choi et ***.21(2009)885).Furthermore,more interesting information of doping is also explored by the analysis of density of states and it is found that La substituting for Cu may advance the electron conduction in *** supplies a potential solution for limitations of CCTO devices by exploring the effect when La substitutes for Cu sites in the CCTO crystal.

关键词： CaCu3Ti4O12 CCTO limitations

Effect of carboxylic acid groups on the supercapacitive performance of functional carbon frameworks derived from bacterial cellulose

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

Chinese Chemical Letters 2017年第12期28卷 2212-2218页

作者： Tianyun Zhang Junwei Lang li liu lingyang liu Hongxia li Yipeng Gu Xingbin yan Xin Ding College of Textiles Donghua University School of Mechanical and Electronical Engineering Lanzhou University of Technology Laboratory of Clean Energy Chemistry and Materials State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical Physics Chinese Academy of Sciences

Three-dimensional （3D） carbonaceous materials derived from bacterial cellulose （BC） has been introduced as electrode for supercapacitors in recent. Here, we report a simple strategy for the synthesis of functional carbon frameworks through 2,2,6,6-tetramethylpilperidine l-oxyl radical （TEMPO） mediated oxidation of bacterial cellulose （BC） followed by carbonization. TEMPO-mediated oxidation can efficiently convert the hydroxyls on the surface of BC to carboxylate groups to improve electrochemical activity. Because of its high porosity, good hydrophilicity, rich oxygen groups, and continuous ion transport in-between sheet-like porous network, the TEMPO-oxidized BC delivers a much higher gravimetric capacitance （137.3 Fig） at low annealing temperature of 500℃ than that of pyrolysis BC （31 F/g） at the same annealing temperature. The pyrolysis modified BC obtained at 900℃ shows specific capacitance （160.2Fig）, large current stability and long-term stability （84.2% of its initial capacitance retention after 10,000 cycles）.

关键词： Bacterial celluloseCarboxylic acid groupsTEMPO-meditated oxidationPseudocapacitanceSupercapacitorRate capability

Investigation on the interface of Cu/Al couples during isothermal heating

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2015年第3期22卷 309-318页

作者： yan-qiu Han li-hua Ben Jin-jin Yao Shu-wei Feng Chun-jing Wu School of Materials Science and Engineering University of Science and Technology Beijing

The evolutionary process and intermetallic compounds of Cu/A1 couples during isothermal heating at a constant bonding tem- perature of 550℃ were investigated in this paper. The interracial morphologies and microstructures were examined by optical microscopy, scanning electron microscopy equipped with energy dispersive X-ray spectroscopy, and X-ray diffraction. The results suggest that bonding is not achieved between Cu and A1 at 550℃ in 10 min due to undamaged oxide films. Upon increasing the bonding time from 15 to 25 min, however, metallurgical bonding is obtained in these samples, and the thickness of the reactive zone varies with holding time. In the interfacial region, the final microstructure consists of Cu9A14, CuAl, CuA12, and ct-A1 ＋ CuAl2. Furthermore, these results provide new insights into the mechanism of the imerfacial reaction between Cu and A1. Microhardness measurements show that the chemical composition exerts a signifi- cant influence on the mechanical properties of Cu/A1 couples.

关键词： copper aluminum intermetallic compounds oxide films isothermal heating