检索结果-南通市图书馆

Frontiers of Chemical Science and Engineering 2008年第1期2卷 80-84页

作者： Shihao GAO Changquan GAO Chenghui SUN Xinqi ZHAO school of Material Science and Technology Beijing Institute of TechnologyBeijing 100081China pingdingshan no.55 middle school Pingdingshan 467091China

2-(5-Amino-1,2,4-thiadiazol-3-yl)-2-(Z)-meth-oxyiminoacetic acid 2-benzothiazolyl thioester(III),an important intermediate of the fourth generation cephalos-porins,was efficiently synthesized by reacting 2-(5-amino-1,2,4-thiadiazol-3-yl)-2-(Z)-methoxyiminoacetic acid(I)with 2,29-dibenzothiazole disulfide(II)in the presence of *** of reaction time,temperature,solvents,catalysts and feeding molar ratio on the yield and quality of products were investigated,and an im-proved procedure suitable for industrial production was *** 1,2-dichloroethane as solvent,triphe-nylphosphine as reducer,and triethylamine as catalyst,n(I):n(II):n(triphenylphosphine)51.0:1.0:1.0,the product was obtained at room temperature in 98.1%*** purity of the product without further purification is 98.7%determined by HPLC *** procedure could be a suitable alternative to the traditional processes because of its easy handling,high yield and low cost.

关键词： pharmaceutical engineering 2-(5-amino-1 2 4-thiadiazol-3-yl)-2-(Z)-methoxyiminoacetic acid 2-benzothiazolyl thioester cephalosporin thioesterification

The rotation of polarization of a terahertz wave through subwavelength metallic structures

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 China(Physics,Mechanics & Astronomy) 2013年第3期Mechanics & Astronomy) .卷 514-518页

作者： LIU JianFeng ZHOU QingLi SHI YuLei ZHANG CunLin Beijing Key Laboratory for Terahertz Spectroscopy and Imaging Key Laboratory of Terahertz OptoelectronicsMinistry of EducationDepartment of PhysicsCapital Normal University Beijing no.55 middle school

Structures consisting of a planar array of subwavelength metallic bars fabricated on a dielectric substrate are theoretically investigated in order to rotate the polarization of a normally incident terahertz wave in the resonance frequency *** attribute this phenomenon to one component of the terahertz electric field parallel to inclined metallic bars which is reflected strongly due to the terahertz re-radiation from accelerated electrons in the metallic bars,while the other component perpendicular to the bars transmits almost entirely through the *** theoretical analysis,we obtain the transmitted-terahertz components polarized in the x-and y-directions,*** studies indicate polarization of a terahertz wave can be rotated within two specific frequency bands when the terahertz impinges on the double-bar sample.

关键词： terahertz metamaterial polarization

Cross sections for 14 MeV neutron interaction with lutetium isotopes and their theoretical excitation functions

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics C 2024年第5期48卷 244-256页

作者：宋月丽周丰群李勇张晓朋姬鹏飞孙小军 school of Electrical and Mechanical Engineering Pingdingshan UniversityPingdingshan 467000China school of Information Engineering Pingdingshan UniversityPingdingshan 467000China

The cross-sections for the 175Lu(n,p)175Yb,175Lu(n,α)172Tm,176Lu(n,α)173Tm,175Lu(n,2n)174mLu,and 175Lu(n,2n)174gLu reactions at 13.57,14.0314.62,and 14.86 MeV neutron energies were measured using an activation *** theoretical excitation functions of these reactions were calculated using the Talys-1.95 *** reaction cross-section data experimentally obtained were analyzed and compared with experimental data reported in the literature,data from five major evaluated nuclear data libraries of IAEA,and theoretical values based on *** data obtained at some neutron energies agree with some of the data reported in the literature and theoretical values based on *** consistency of the theoretical curves of excitation functions based on Talys-1.95 with the data obtained in this study and those reported in the literature is higher than that of the evaluation curves of excitation functions for the 175Lu(n,p)175Yb,175Lu(n,α)172 Tm,and 176Lu(n,α)173Tm *** study is helpful because it provides new evaluated reaction cross-section data on lutetium(which is a fusion reactor material),improves the quality of neutron-induced reaction cross section data libraries,and advances the research on related applications.

关键词： nuclear reaction cross sections of lutetium isotopes activation technique D-T neutron theoretical calculations Talys-1.95

New cross section measurements on tungsten isotopes around 14 MeV neutrons and their excitation functions

在线全文

学校读者我要写书评

暂无评论

Chinese Physics C 2022年第5期46卷 95-107页

作者： Yong Li Fengqun Zhou Yajuan Hao Xiaoqiang Ma Pengfei Ji Xiaopeng Zhang Shuqing Yuan school of Electrical and Mechanical Engineering Pingdingshan UniversityPingdingshan 467000China school of Information Engineering Pingdingshan UniversityPingdingshan 467000China

New cross sections of the^(183)W(n,α)^(180m)Hf,^(186)W(n,d*)^(185)Ta,^(182)W(n,p)^(182)Ta,^(184)W(n,p)^(184)Ta,^(182)W(n,2n)^(181)W,^(184)W(n,α)^(181)Hf,and^(186)W(n,α)^(183)Hf reactions were measured in the neutron energy range of 13.5-14.8 MeV via the activation technique to improve the database and resolve *** neutrons in this energy range were produced via the T(d,n)^(4)He reaction on a solid Ti-T *** activities of the irradiated monitor foils and samples were measured using a well-calibrated high-resolution HPGe *** calculations of the excitation functions of the seven nuclear reactions mentioned above in the neutron energies from the threshold to 20 MeV were performed using the nuclear theoretical model program TALYS-1.9 to aid new evaluations of cross sections on tungsten *** experimental data obtained were analyzed and compared with that of previous experiments conducted by other researchers,and with the evaluated data available in the five major evaluated nuclear data libraries of IAEA(namely ENDF/B-VIII.0 or ENDF/B-VII.0,JEFF-3.3,JENDL-4.0u+,CENDL-3.2,and BROND-3.1 or ROSFOND-2010),and the theoretical values acquired using TALYS-1.9 nuclear-reaction modeling *** new cross section measurements agree with those of some recent experiments and theoretical excitation curves at the corresponding *** consistency of the theoretical excitation curves based on TALYS-1.9 with these experimental data is better than that of the evaluated curves available in the five major nuclear data libraries of IAEA.

关键词： cross sections tungsten activation technique off-line gamma-ray spectrometry theoretical calculations TALYS-1.9

Cryptanalysis of Public Key Cryptosystems Based on Non-Abelian Factorization Problems

在线全文

学校读者我要写书评

暂无评论

Tsinghua Science and Technology 2016年第3期21卷 344-351页

作者： Jinhui Liu Aiwan Fan Jianwei Jia Huanguo Zhang Houzhen Wang Shaowu Mao Computer school of Wuhan University Wuhan 430072China Computer school of pingdingshan University Pingdingshan 467001China

Advances in quantum computers threaten to break public-key cryptosystems （e.g., RSA, ECC, and EIGamal）, based on the hardness of factoring or taking a discrete logarithm. However, no quantum algorithms have yet been found for solving certain mathematical problems in non-commutative algebraic structures. Recently, two novel public-key encryption schemes, BKT-B cryptosystem and BKT-FO cryptosystem, based on factorization problems have been proposed at Security and Communication Networks in 2013. In this paper we show that these two schemes are vulnerable to structural attacks and linearization equations attacks, and that they only require polynomial time complexity to obtain messages from associated public keys. We conduct a detailed analysis of the two attack methods and show corresponding algorithmic descriptions and efficiency analyses. In addition, we provide some improvement suggestions for the two public-key encryption schemes.

关键词： cryptography post-quantum cryptography public key encryption cryptanalysis linear equations

Measurements of the Cross-sections of Produced Short-Lived Nuclei Induced by Neutrons around 14 MeV on Isotopes of Tungsten

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2019年第11期36卷 10-13页

作者： Xiao-Jun Sun Feng-Qun Zhou Yue-Li Song Yong Li Peng-Fei Ji Xin-Yi Chang Henan Key Laboratory of Research for Central Plains Ancient Ceramics Pingdingshan UniversityPingdingshan 467000 school of Electrical and Mechanical Engineering Pingdingshan UniversityPingdingshan 467000

New experimental cross-section data for the^180 W(n,2 n)^179 mW,^186 W(n,2 n)185 mW and186 W(n,p)186 Ta reactions at the neutron energies of 13.5 and 14.4 MeV are obtained by the activation technique. The neutron beams are produced by means of the3 H(d,n)4 He reaction. The gamma activities of the product nuclei are measured by a high-resolution gamma-ray spectrometer with a coaxial high-purity germanium detector. The neutron fluence is determined using the monitor reaction^93 Nb(n,2 n)^92 mNb. The results in the current work are discussed and compared with the measurement results found in the literature. It is shown that these higher accuracy experimental cross-section data around the neutron energy of 14 MeV agree with some previous experimental values from the literature within experimental uncertainties.

关键词： technique. reaction. purity

Activation cross sections for reactions induced by 14 MeV neutrons on natural copper

在线全文

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2018年第10期29卷 254-260页

作者： Jing-Jie Ma Feng-Qun Zhou Xiao-Jun Sun Xiao-Peng Zhang Shu-Qing Yuan school of Electrical and Mechanical Engineering Pingdingshan UniversityPingdingshan 467000China Henan Quality Polytechnic Pingdingshan 467000China

The cross sections for the^(63)Cu(n,a)^(60(m+g))Co,^(65)Cu(n,2 n)^(64)Cu, and ^(65)Cu(n,p)^(65)Ni reactions have been studied in the neutron energy range of 13.5–14.8 MeV using the activation technique. The neutron beams were produced via the^3 H(d,n)~4 He reaction. The neutron energies of different directions in the measurements were determined beforehand by the method of cross section ratios for the^(90)Zr(n,2 n)^(89 m+g)Zr and ^(93)Nb(n,2 n)^(92 m)Nb reactions. The results in the present work were discussed and compared with measurement results found in the literatures.

关键词： Copper Activation Neutron Cross section Nuclear reaction

Cross section measurements for(n,2n),(n,α),and(n,p)reactions on rhenium isotopes around 14 MeV neutrons and their theoretical calculations of excitation functions

在线全文

学校读者我要写书评

暂无评论

Chinese Physics C 2021年第7期45卷 195-204页

作者： Fengqun Zhou Yueli Song Xinyi Chang Yong Li Shuqing Yuan Pengfei Ji Mingli Tian school of Electrical and Mechanical Engineering Pingdingshan UniversityPingdingshan 467000China Henan Key Laboratory of Research for Central Plains Ancient Ceramics Pingdingshan UniversityPingdingshan 467000China

Cross-section data of the^(185)Re(n,2n)^(184)mRe,^(185)Re(n,2n)^(184)gRe,^(185)Re(n,α)182m1+m2+gTa,^(187)Re(n,2n)^(186)g,(m)Re,^(187)Re(n,α)^(184)Ta,and^(187)Re(n,p)^(187)W reactions were measured at four neutron energies,namely 13.5,14.1,14.4,and 14.8 MeV,by means of the activation technique,relative to the reference cross-section values of the 93Nb(n,2n)92mNb *** neutrons were generated from the T(d,n)4He reaction at the K-400 Neutron Generator at China Academy of Engineering *** inducedγactivities were measured using a high-resolutionγ-ray spectrometer equipped with a coaxial high-purity germanium *** excitation functions of the six above-mentioned nuclear reactions at neutron energies from the threshold to 20 MeV were calculated by adopting the nuclear theoretical model program system Talys-1.9 with the relevant parameters properly *** measured cross sections were analyzed and compared with previous experiments conducted by other researchers,and with the evaluated data of BROND-3.1,ENDF/B-VIII.0,JEFF-3.3,and the theoretical values based on *** new measured results agree with those of previous experiments and the theoretical excitation curve at the corresponding *** theoretical excitation curves based on Talys-1.9 generally match most of experimental data well.

关键词： cross sections of(n,2n) (n,a)and(n,p)reactions rhenium isotopes activation technique off-line y-ray spectrometry theoretical calculations

Activation cross-sections of titanium isotopes at neutron energies of 13.5–14.8 MeV

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 C 2019年第9期43卷 33-45页

作者： Fengqun Zhou Yueli Song Yong Li Xiaojun Sun Shuqing Yuan Henan Key Laboratory of Research for Central Plains Ancient Ceramics Pingdingshan UniversityPingdingshan 467000China school of Electrical and Mechanical Engineering Pingdingshan UniversityPingdingshan 467000China

The cross-sections for 46Ti(n,2n)45Ti,46Ti(n,p)46m+gSc+47Ti(n,d*)46m+gSc,46Ti(n,p)46m+gSc,47Ti(n,p)47Sc+48Ti(n,d*)47Sc,47Ti(n,p)47Sc,48Ti(n,p)48Sc+49Ti(n,d*)48Sc,48Ti(n,p)48Sc,and 50Ti(n,α)47Ca reactions were investigated around neutron energies of 13.5–14.8 MeV by means of the activation *** neutrons were produced by the 3H(d,n)4He *** energies from different directions in the measurements were obtained in advance using the method of cross-section ratios for 90Zr(n,2n)89m+gZr and 93Nb(n,2n)92mNb *** results obtained are analyzed and compared with the experimental data provided by the literature and verified nuclear data in the JEFF-3.3,CENDL-3.1,ENDF/B-VIII.0 libraries,as well as results calculated by Talys-1.9 code.

关键词： titanium neutron reaction cross section D-T neutron activation technique

SUPERCONVERGENCE ANALYSIS FOR TIME-FRACTIONAL DIFFUSION EQUATIONS WITH NONCONFORMING MIXED FINITE ELEMENT METHOD

在线全文

学校读者我要写书评

暂无评论

Journal of Computational Mathematics 2019年第4期37卷 488-505页

作者： Houchao Zhang Dongyang Shi school of Mathematics and Statistics Pingdingshan University Pingdingshan 467000 China school of Mathematics and Statistics Zhengzhou University Zhengzhou 450001 China

In this paper, a fully discrete scheme based on the LI approximation in temporal direction for the fractional derivative of order in (0,1) and nonconforming mixed finite element method (MFEM) in spatial direction is established. First, we prove a novel result of the consistency error estimate with order O(h^2)of EQ1^rot element (see Lemma 2.3). Then, by using the proved character of EQ1^rot element, we present the superconvergent estimates for the original variable u in the broken H^1-norm and the flux →p =△u in the (L^2)^2-norm under a weaker regularity of the exact solution. Finally, numerical results are provided to confirm the theoretical analysis.

关键词： Nonconforming MFEM LI method Time-fractional diffusion equations Superconvergence