检索结果-南通市图书馆

Composition Operators with Universal Translates on S^(2)(D)

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2023年第12期39卷 2452-2464页

作者： Kai Kai HAN yan yan tang School of Mathematics and Statistics Hebei University of Economics and BusinessShijiazhuang 050061P.R.China School of Mathematics and Statistics He'nan UniversityKaifeng 475004P.R.China

It is known that the Invariant Subspace Problem for Hilbert spaces is equivalent to the statement that all minimal non-trivial invariant subspaces for a universal operator are one *** this paper,we characterize all linear fractional composition operators and their adjoints that have universal translates on the space S^(2)(D).Moreover,we characterize all adjoints of linear fractional composition operators that have universal translates on the Hardy space H^(2)(D).In addition,we consider the minimal invariant subspaces of the composition operator Cφa on S^(2)(D),where φa(z)=az+1-a,a ∈(O,1).Finally,some relationships between complex symmetry and universality for bounded linear operators and commuting pairs of operators on a complex separable,infinite dimensional Hilbert space are explored.

关键词： Universal operator composition operator invariant subspace complex symmetry

Thermodynamic analysis on the formation mechanism of MgO·Al_2O_3 spinel type inclusions in casing steel

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2010年第1期17卷 32-38页

作者： Hai-yan tang Jing-she Li School of Metallurgical and Ecological Engineering University of Science and Technology Beijing Beijing 100083 China

MgO·Al2O3 spinel type inclusions in casing steel were analyzed by scanning electron microscope （SEM） and energy dispersive spectrometer （EDS）. The results show that there are three forms. One is pure MgO·Al2O3 spinel, another is the composite oxide of the Mg-Al-Ca-Si-O system, and the third is the complex with oxide as a core covered by sulfide. The formation mechanisms were studied. The influences of slag basicity and vacuum degree on the magnesium content during the vacuum treatment of molten steel and furnace lining in molten steel were calculated with the coexistence theory of slag structure. The results show that the magnesium content increases with the increase in slag basicity and aluminum content in molten steel, and decreases with the increase in CO partial pressure.

关键词： magnesium-aluminum spinel basicity theoretical model formation mechanism

New mechanistic pathways for CO oxidation catalyzed by single-atom catalysts： Supported and doped Au1/ThO2

在线全文

学校读者我要写书评

暂无评论

Nano Research 2016年第12期9卷 3868-3880页

作者： Bo Long yan tang Jun Li Department of Chemistry and Laboratory of Organic Optoelectronics & Molecular Engineering of the Ministry of Education Tsinghua University Beijing 100084 China College of Information Engineering Guizhou Minzu University Guiyang 550025 China

Single-atom catalysts are of great interest and importance for designing new high-performance low-cost catalysts. We investigated CO oxidation catalyzed by single gold atoms supported on thoria （Au/ThO2） and doped ThO2 using density functional theory with Hubbard-type on-site Coulomb interaction （DFT ＋ U）. The calculation results show that the Au-doped THO2（111） catalyst exhibits remarkable catalytic activity for CO oxidation via the Eley-Rideal mechanism in three steps, where the rate-determining step is decomposition of the OCOO＋ intermediate with an energy barrier of 0.58 eV. Moreover, our results also reveal a new mechanism of CO oxidation on a gold adatom supported by THO2（111）, where O2 is adsorbed only at the Th site on the surface, and the gas-phase CO then reacts directly with the activated O2＋ to form CO2, which is the rate-limiting step, with a barrier of 0.46 eV. It is found that CO oxidation can occur without CO and O2 coadsorption on Au, which was previously considered a key intermediate. Therefore, these results provide new insights into CO oxidation on isolated gold atoms supported by the 5f-element compound THO2（111）. This mechanism can help clarify the catalytic cycle of CO oxidation, support the design of high- performance low-cost catalysts, and elucidate the redox properties of actinide oxides.

关键词： CO oxidation single gold catalysis catalytic mechanism actinide oxides

News Topic Detection Based on Capsule Semantic Graph

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

Big Data Mining and Analytics 2022年第2期5卷 98-109页

作者： Shuang yang yan tang the College of Computer and Information Science Southwest UniversityChongqing 400000China

Most news topic detection methods use word-based methods,which easily ignore the relationship among words and have semantic sparsity,resulting in low topic detection *** addition,the current mainstream probability methods and graph analysis methods for topic detection have high time *** these reasons,we present a news topic detection model on the basis of capsule semantic graph(CSG).The keywords that appear in each text at the same time are modeled as a keyword graph,which is divided into multiple subgraphs through community *** subgraph contains a group of closely related *** graph is used as the vertex of *** semantic relationship among the vertices is obtained by calculating the similarity of the average word vector of each *** the same time,the news text is clustered using the incremental clustering method,where each text uses CSG;that is,the similarity among texts is calculated by the graph *** relationship between vertices and edges is also considered when calculating the *** results on three standard datasets show that CSG can obtain higher precision,recall,and F1 values than several latest *** results on large-scale news datasets reveal that the time complexity of CSG is lower than that of probabilistic methods and other graph analysis methods.

关键词： news topic detection capsule semantic graph graph kernel

Symmetry Analysis and Similarity Solutions of a Resonant Davey-Stewartson System

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2009年第10期52卷 581-587页

作者： GAO Yuan tang Xiao-yan Department of Physics Shanghai Jiao Tong University Shanghai 200030 China

Lie point symmetry analysis is performed to a recently proposed(2+1)-dimensional nonlinear system,theresonant Davey-Stewartson *** similarity solutions of the RDS equation are thus obtained.

关键词： resonant Davey-Stewartson system symmetry similarity solution

Histological and ultrastructural changes induced by selenium in early experimental gastric carcinogenesis

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2005年第29期11卷 4457-4460页

作者： yan-Ping Su Jun-Min tang yan tang Hui-Ying Gao Department of Histology and Embryology Taishan Medical College Taian 271000 Shandong Province China Department of Histology and Embryology Peking University Health Science Center Beijing 100083 China

AIM： To investigate the effect and significance of selenium in early experimental gastric carcinogenesis. METHODS： Weaning male Wistar rats were divided randomly into normal control group, experiment control group, low selenium （2 mg/L） group and high selenium （4 mg/L） group. Wistar rat gastric carcinogenesis was induced by N-methyl-N-nitro-N-nitroso guanidine （MNNG）（20 mg/kg） gavage dally for 10 d. Na2SeO3 was given by piped drinking 1 wk prior to MNNG gavage. The rats were killed at the 43^rd wk. The surface characteristics of gastric mucosa were observed with naked eyes. Histopathologic changes of rat gastric mucosa were observed by HE staining and AB-PAS methods. The changes of cellular ultrastructure were observed under transmission electron microscope. Statistical analysis was carried out by SPSS. RESULTS： The incidence rate of gastric mucosa erosion, hemorrhage and intestinal metaplasia was 0, 45.5%, 66.7%, and 92.9%, respectively （92.9% vs 45.5%, P〈0.05） in the normal control group, experiment control group, low selenium group, and high selenium group. Leiomyoma formed in the process of inducement of rat gastric carcinoma. Dietary Na2SeO3 （2 and 4 mg/L） slightly increased the incidence rate of leiomyoma （0.23%, 46.6%, and 46.6%）. gastric mucosa did not change in the course of rat gastric carcinogenesis. Dietary Na2SeO3 by pipe drinking could expand the intracellular secretory canaliculus of parietal cells and increase the number of endocrine cells and lysosomes. CONCLUSION： Dietary Na2SeO3 by pipe drinking aggravates gastric erosion, hemorrhage and promotes intestinal metaplasia of gastric mucosa. The mechanism may be related with the function of parietal cells.

关键词： Selenium Ultrastructure Experimental gastric carcinogenesis

Genetic biosensors for small-molecule products： Design and applications in high-throughput screening

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

Frontiers of Chemical Science and Engineering 2017年第1期11卷 15-26页

作者： Qingzhuo Wang Shuang-yan tang Sheng yang Institute of Plant Physiology and Ecology Shanghai Institutes for Biological Sciences Shanghai 200025 China University of the Chinese Academy of Sciences Beijing 100049 China CAS Key Laboratory of Microbial Physiological and Metebolic Engineering Institute of Microbiology Chinese Academy of Sciences Beijing 100101 China Jiangsu National Synergetic Innovation Center for Advanced Materials Nanjing Tech University Nanjing 211816 China

Overproduction of small-molecule chemicals using engineered microbial cells has greatly reduced the production cost and promoted environmental protection. Notably, the rapid and sensitive evaluation of the in vivo concentrations of the desired products greatly facilitates the optimization process of cell factories. For this purpose, many genetic components have been adapted into in vivo biosensors of small molecules, which couple the intracel- lular concentrations of small molecules to easily detectable readouts such as fluorescence, absorbance, and cell growth. Such biosensors allow a high-throughput screen- ing of the small-molecule products, and can be roughly classified as protein-based and RNA-based biosensors. This review summarizes the recent developments in the design and applications of biosensors for small-molecule products.

关键词： biosensor small molecule product transcrip-tion factor riboswitch high-throughput screening

Calculations of dynamic multipolar polarizabilities of the Cd clock transition levels

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 Physics B 2021年第8期30卷 295-300页

作者： Mi Zhou Li-yan tang State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics Wuhan Institute of Physics and MathematicsInnovation Academy for Precision Measurement Science and TechnologyChinese Academy of SciencesWuhan 430071China University of Chinese Academy of Sciences Beijing 100049China

The pursuit of a systematic frequency uncertainty beyond 10^(-18) clock has triggered a multitude of investigations on the multipolar and higher-order lattice light *** Cd atom has been proposed as a new candidate for the development of a lattice clock because of its smaller blackbody radiation shift at room ***,we apply an improved combined method of the Dirac-Fock plus core polarization and relativistic configuration interaction methods to calculate the dynamic multipolar polarizabilities of the Cd clock *** effects of the high-order core-polarization potentials on the energies,reduced matrix elements,and multipolar polarizabilities have been evaluated *** detailed comparison with available literature demonstrates that taking into account of the high-order core-polarization potentials is a simple and effective approach to improve the results of atomic properties for heavy atoms.

关键词： Cd atomic clock multipolar polarizabilities high-order core-polarization potentials DFCP+RCI method

Penehyclidine hydrochloride attenuates cerebral vasospasm after subarachnoid hemorrhage

在线全文

学校读者我要写书评

暂无评论

Neural Regeneration Research 2011年第22期6卷 1725-1730页

作者： yan tang Xiaoyi Chen Jin Liu Laboratory of Anesthesiology and Critical Care Medicine West China Hospital Sichuan University Chengdu 610041 Sichuan Province China Department of Clinical Medicine West China Medical School Sichuan University Chengdu 610041 Sichuan Province China

A new cholinergic antagonist, penehyclidine hydrochloride （PHC）, was developed independently by Chinese scientists. Administration of PHC into muscle and the cisterna magna could relieve basilar artery vasospasm following subarachnoJd hemorrhage in animals. In addition, injecting PHC into the cisterna magna had better therapeutic effect. Moreover, PHC had the capability of reducing the expression of neuron specific enolase and S-1OOI3 protein in cerebrospinal fluid. There was no effect on the number of surviving neurons in the hippocampal CA1 region, or on the levels of superoxide dismutase and malondialdehyde.

关键词： subarachnoid hemorrhage vasospasm intracranial penehyclidine hydrochloride brain injury