检索结果-南通市图书馆

Chemical characteristics and source apportionment of PM_(2.5) in a petrochemical city: Implications for primary and secondary carbonaceous component

引用

Journal of Environmental Sciences 2021年第5期33卷 322-335页

作者： Guangxuan Yan Puzhen Zhang jie Yang jingwen Zhang Guifen Zhu Zhiguo cao jing Fan Zirui Liu Yuesi Wang School of Environment Henan Normal UniversityKey Laboratory for Yellow River and Huai River Water Environment and Pollution ControlMinistry of EducationHenan Key Laboratory for Environmental Pollution ControlXinxiang 453007China State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry Institute of Atmospheric PhysicsChinese Academy of ScienceBeijing 100029China Center for Excellence in Regional Atmospheric Environment Institute of Urban EnvironmentChinese Academy of ScienceXiamen 361021China University of Chinese Academy of Science Beijing 100049China

To study the pollution features and underlying mechanism of PM_(2.5) in Luoyang, a typical developing urban site in the central plain of China, 303 PM_(2.5) samples were collected from April 16 to December 29, 2015 to analyze the elements, water soluble inorganic ions, organic carbon and elemental carbon. The annual mean concentration of PM_(2.5) was 142.3 μg/m^(3), and 75% of the daily PM_(2.5) concentrations exceeded the 75 μg/m^(3). The secondary inorganic ions, organic matter and mineral dust were the most abundant species, accounting for 39.6%, 19.2% and 9.3% of the total mass concentration, respectively. But the major chemical components showed clear seasonal dependence. SO_(4)^(2-) was most abundant specie in spring and summer, which related to intensive photochemical reaction under high O_3 concentration. In contrast, the secondary organic carbon and ammonium while primary organic carbon and ammonium significantly contributed to haze formation in autumn and winter, respectively. This indicated that the collaboration effect of secondary inorganic aerosols and carbonaceous matters result in heavy haze in autumn and winter. Six main sources were identified by positive matrix factorization model: industrial emission, combustion sources, traffic emission, mineral dust, oil combustion and secondary sulfate, with the annual contribution of 24%, 20%, 24%, 4%, 5% and 23%, respectively. The potential source contribution function analysis pointed that the contribution of the local and short-range regional transportation had significant impact. This result highlighted that local primary carbonaceous and precursor of secondary carbonaceous mitigation would be key to reduce PM_(2.5) and O_3 during heavy haze episodes in winter and autumn.

关键词： PM_(2.5) Seasonal variations Positive matrix factorization Emission sources

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Myoglobin/Gold Nanoparticles/Carbon Spheres 3-D Architecture for the Fabrication of a Novel Biosensor

引用

Nano Research 2009年第3期2卷 210-219页

作者： Xiao Chen jing jing Zhang jie Xuan Jun jie Zhu Key Laboratory of Analytical Chemistry for Life Science Ministry of EducationSchool of Chemistry and Chemical EngineeringNanjing UniversityNanjing 210093China

A novel biosensor based on a myoglobin/gold nanoparticles/carbon spheres(Mb AuNPs CNs)3-D architecture bioconjunction has been fabricated for the determination of hydrogen peroxide(H2O2).Cyclic voltammetry(CV),Fourier transform infrared(FT-IR)spectroscopy and scanning electron microscopy(SEM)were used to characterize the bioconjunction of the AuNPs CNs with *** results demonstrate that the AuNPsCNs hybrid material is more effective in facilitating electron transfer of the immobilized enzyme than CNs alone,which can be attributed to the unique nanostructure and larger surface area of the *** biosensor displayed good performance for the detection of H_(2)O_(2)with a wide linear range from 0.28μmol/L to 116.5μmol/L and a detection limit of 0.12μmol/*** Michaelis-Menten constant KMapp value was estimated to be 0.3 mmol/*** resulting biosensor exhibited fast amperometric response,and good stability,reproducibility,and selectivity to H_(2)O_(2).

关键词： Biosensor myoglobin gold nanoparticles carbon spheres hydrogen peroxide direct electron transfer

来源：

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

EELS study on BST thin film under electron beam irradiation

引用

Science China(Technological Sciences) 2004年第6期47卷 659-666页

作者： RAO jie ZHU jing Electron Microscopy Laboratory Department of Materials Science and EngineeringTsinghua Univer-sityBeijing 100084China

It was found that BST thin film was damaged by the irradiation of high density electron beam (the current density was about 2 nA/cm2). In-situ and real time EELS showed that the intensity ratio of Ti to O edge and the distance between Ti and O edge changed. It indicated that the film lost oxygen and thus the oxidation states of positive ions lowered. EELS study with high spatial resolution proved that compared with the inner of columnar grains, the grain boundaries with special structure and chemical environment were the main passageway of oxygen loss.

关键词： BST thin film irradiation damage EELS

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Organocatalytic Oxidative Amidation of Aldehydes with Tetrazoles to Construct 2,5-Diaryl 1,3,4-Oxadiazoles

引用

Chinese Journal of Chemistry 2015年第11期33卷 1239-1243页

作者： jing cao Liang Wang School of Petrochemical Engineering Changzhou University Changzhou Jiangsu 213164 China

A practical and metal-flee oxidative amidation of aldehydes with tetrazoles into 1,3,4-oxadiazoles has been de- veloped by employing tetrabutylammonium iodide （TBAI） as catalyst and tert-butyl hydroperoxide （TBHP） as oxidant. A wide range of 2,5-disubstituted 1,3,4-oxadiazoles can be conveniently generated in moderate to good yields. Gram-scale reaction was also realized in this catalytic system.

关键词： 1,3,4-oxadiazoles oxidative amidation tetrazoles aldehydes organocatalysis

来源：

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

Lensless Ghost Diffraction with Partially Coherent Sources: Effects of the Source Size, Transverse Coherence, Detector Size and Defocusing Length

引用

Chinese Physics Letters 2011年第9期28卷 132-135页

作者： LIN jie CHENG jing School of Electronics and Information Engineering South China University of TechnologyGuangzhou 510641 School of Physics and Optoelectronic Engineering Guangdong University of TechnologyGuangzhou 510006 Department of Physics South China University of TechnologyGuangzhou 510641

Lensless ghost diffraction with partially coherent sources is investigated theoretically and *** on the classical optical coherent theory and the Gauss–Shell model of the partially coherent sources,we derive an analytical imaging formula of lensless ghost diffraction(LGD).Using this formula,we can see the effects of the transverse size and coherence of the sources,the detector size and defocusing length on the quality of *** results are presented to show that for different detector sizes and defocusing lengths,high quality LGD can be realized by using sources with appropriate transverse sizes and coherent *** findings can be used to choose the optimal parameters in the design of a realistic LGD system.

关键词： ghost Ghost coherent

来源：

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

Ensemble relation network with multi-level measure

引用

The Journal of China Universities of Posts and Telecommunications 2022年第3期29卷 15-24,33页

作者： Li Xiaoxu Qu Xue cao jie College of Computer and Communication Lanzhou University of TechnologyLanzhou 730050China College of Electrical and Information Engineering Lanzhou University of TechnologyLanzhou 730050China Engineering Research Center of Urban Railway Transportation of Gansu Province Lanzhou 730050China

Fine-grained few-shot learning is a difficult task in image classification. The reason is that the discriminative features of fine-grained images are often located in local areas of the image, while most of the existing few-shot learning image classification methods only use top-level features and adopt a single measure. In that way, the local features of the sample cannot be learned well. In response to this problem, ensemble relation network with multi-level measure(ERN-MM) is proposed in this paper. It adds the relation modules in the shallow feature space to compare the similarity between the samples in the local features, and finally integrates the similarity scores from the feature spaces to assign the label of the query samples. So the proposed method ERN-MM can use local details and global information of different grains. Experimental results on different fine-grained datasets show that the proposed method achieves good classification performance and also proves its rationality.

关键词： fine-grained image classification few-shot learning local feature learning metric learning

来源：

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

Characterization of polyoxometalates by electrospray ionization mass spectrometry

引用

Science China Chemistry 2015年第7期58卷 1206-1210页

作者： Qiaodi Jia Yan Zhang jie cao Key Laboratory of Cluster Science Ministry of Education of China Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials School of Chemistry Beijing Institute of Technology

The electrospray behaviors of saturated, substituted, and lacunary polyoxometalates （POMs） with classic Keggin and Dawson structures were investigated systematically by electrospray mass spectrometry （ESI-MS）. The anions included Keggin [SiW12O40]4-, [SiW11O39]8-, [SiW10O36]8 , [SiW9O34]10-, Dawson [P2W18O62]6-, [P2W17O61]10-, and metal-substituted Keggin derivatives such as [PW11MnO40]7-, [SiW10V2O40]6-, and [GeWgCu3O37]10-. Common species observed in the mass spectra arose from the protonation or cationization of either intact or dehydrated precursor ions. Compared to saturated and substituted POMs, lacunary POMs exhibited distinguished MS behaviors such as a much higher degree of cationization and dehydration of the bare polyoxoanions present in the mass spectra. In addition, some of these lacunary POMs were found to undergo subtle speciation change in solution. Freshly prepared solutions are suggested for synthetics for which lacunary POMs are starting materials. The advantages of the cation-exchange process which are prior to MS analysis are illustrated by an example.

关键词： saturated substituted and lacunary POMs electrospray ionization mass spectrometry cation-ion exchange process

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Is it necessary to use the entire root as a donor when transferring contralateral C7 nerve to repair median nerve？

引用

Neural Regeneration Research 2018年第1期13卷 94-99页

作者： Kai-ming Gao jie Lao Wen-jie Guan jing-jing Hu Department of Hand Surgery Huashan Hospital Fudan University Shanghai China Key Laboratory of Hand Reconstruction Ministry of Health Shanghai China Shanghai Key Laboratory of Peripheral Nerve and Microsurgery Shanghai China Nursing Department Huashan Hospital Fudan University Shanghai China

If a partial contralateral C7 nerve is transferred to a recipient injured nerve, results are not satisfactory. However, if an entire contralateral C7 nerve is used to repair two nerves, both recipient nerves show good recovery. These findings seem contradictory, as the above two methods use the same donor nerve, only the cutting method of the contralateral C7 nerve is different. To verify whether this can actually result in different repair effects, we divided rats with right total brachial plexus injury into three groups. In the entire root group, the entire contralateral C7 root was transected and transferred to the median nerve of the affected limb. In the posterior division group, only the posterior division of the contralateral C7 root was transected and transferred to the median nerve. In the entire root ＋ posterior division group, the entire contralateral C7 root was transected but only the posterior division was transferred to the median nerve. After neurectomy,the median nerve was repaired on the affected side in the three groups. At 8, 12, and 16 weeks postoperatively, electrophysiological examination showed that maximum amplitude, latency, muscle tetanic contraction force, and muscle fiber cross-sectional area of the flexor digitorum superficialis muscle were significantly better in the entire root and entire root ＋ posterior division groups than in the posterior division group. No significant difference was found between the entire root and entire root ＋ posterior division groups. Counts of myelinated axons in the median nerve were greater in the entire root group than in the entire root ＋ posterior division group, which were greater than the posterior division group. We conclude that for the same recipient nerve, harvesting of the entire contralateral C7 root achieved significantly better recovery than partial harvesting, even if only part of the entire root was used for transfer. This result indicates that the entire root should be used as a dono

关键词： nerve regeneration peripheral nerve injury brachial plexus injury avulsion injury contralateral C7 transfer nerve root entire root partial root median nerve ulnar nerve animal experiment neural regeneration

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

An oscillating multiplier on Herz type spaces

引用

Applied Mathematics(A Journal of Chinese Universities) 2011年第1期26卷 93-103页

作者： cao Wei SUN Li-jing Department of Mathematics Zhejiang University Hangzhou 310027 China Department of Mathematical Science University of Wisconsin-Milwaukee Milwaukee WI 53217 USA

In this paper, the boundedness of an oscillating multiplier mγ,β for different β on the Herz type spaces is obtained. This operator was initially studied by Wainger and FeffermanStein. Our results extend one of the main results in a paper by Xiaochun Li and Shanzhen Lu for the non-weighted case, if β is close to 1 or α is suitably large. For β ≥ 1, the results with no weights on the Herz type spaces are also new.

关键词： Oscillating multiplier Herz space atomic decomposition.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Numerical analysis of role of melting rate on electroslag remelting continuous directional solidification of a die steel

引用

Journal of Iron and Steel Research International 2021年第12期28卷 1617-1624页

作者： jie Zhang jing Li Cheng-bin Shi State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing100083China

The effect of melting rate on the temperature distribution,velocity field,macrosegregation and dendrite arm spacing during electroslag remelting continuous directional solidification process with a mould of 160 mm in diameter was *** mechanism of solute transport and dendrite growth of austenitic hot-work die steel during electroslag remelting process was *** results showed that a lower melting rate contributed to a higher temperature gradient as well as a shallower liquid metal molten *** the increase in the melting rate,the central counterclockwise vortex in the slag and clockwise vortex in the liquid metal molten pool grew,whereas the marginal clockwise vortex in the slag *** increasing melting rate,the macrosegregation of carbon became more serious,whereas the average value of secondary dendrite arm spacing first decreased and then *** secondary dendrite arm spacing reached a minimum value at melting rate of 98 kg/h,which indicated that 98 kg/h was a proper melting rate for electroslag remelting continuous directional solidification process with a mould of 160 mm in diameter.

关键词： Electroslag remelting continuous directional solidification Melting rate Numerical simulation Solidification structure Die steel

来源：

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

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：