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Chinese Journal of polymer science 2000年第4期18卷 343-349页

作者： Lun-han Ding Yue Li Yan Jiang Zhe Cao Jia-xian Huang department of polymer science and {3., university of science and Technology of China, Hefei 23.026, China department of chemistry, Nankai university, Tianjin 3.0071, China Univ Sci & Technol China Dept Polymer Sci & Engn Hefei 230026 Peoples R China Nankai Univ Dept Chem Tianjin 300071 Peoples R China

Methacrylic acid first was neutralized with an aqueous solution of NaOH to pH = 6.0 similar to 7.0, vinylene carbonate (VCA) was added to the solution, then monomers were copolymerized in paraffin oil by means of reverse-phase suspension polymerization and hydrophilic copolymeric supports were prepared. The properties of the supports were determined using trypsin and results show that the amount of enzymes coupled to the supports and the specific activity of immobilized trypsin are related to the content of VCA structure units, reaction time and concentration of enzyme solution, etc.

关键词： vinylene carbonate methacrylic acid fixed enzyme support trypsin

Contributions of different land cover types in Otindag Sandy Land and Bashang area of Hebei Province to the material source of sand stormy weather in beijing

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Chinese science Bulletin 2003年第17期48卷 1853-1856页

作者： LIU Hongyan, TIAN Yuhong & DING Deng department of Ecology, college of Environmental sciences,{3., beijing 100871, China department of Ecology College of Environmental Sciences Peking University Beijing 100871 China

Different land cover types in Otindag Sandy Land and Bashang area of Hebei Province are linked to a material source of sand stormy weather in beijing based on results of field vegetation and soil survey and laboratory works. Results of grain size analysis show that dust release potential in per unit area of moving sandy land is small, while lowland meadow and meadow steppe in stony hills have high potential of releasing dusts in per unit area during sand stormy weather occurrence. Further considering the effects of vegetation, it is inferred that the moving sandy land served as a material source of past dust storm and the possi-bility of dust release in per unit area is low in current time. Typical steppe in stony hills is undergoing desertification and its dust release possibility in per unit area is high. Farmland has strong potential of release dusts when they are ploughed in spring, but a large amount of therophytes grow and thus prevent dusts from release when cultivation was terminated. Potentials of dust release in per unit area in fixed sand dunes, stony mountain meadow steppe and lowland meadow are low due to high cover of perennials. Sand dune reactivation and desiccation of lakes and lowlands under estimated future climatic change will make them serve as a future material source of sand stormy weather.

关键词：河北北京沙暴土地覆盖砂地坝上地区材料源

Effects of Al(i-Bu)_3.on Propylene polymerization and Copolymerization by rac-Me_2Si(Ind)_2ZrCl_2/MAO

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Chinese Chemical Letters 1998年第1期9卷 83-85页

作者： Zhi qiang FAN Yong Hui ZHANG qi WANG Lin Xian feng ({3. of polymer science and engineering, Zhejiang university, HangZhou 3.0027) Zhejiang Univ Dept Polymer Sci & Engn Hangzhou 310027 Peoples R China

The effects of adding Al(i-C_4H_9)_3.(TBA) to rac-Me2Si(Ind)2ZrCl2/ MAO catalyzed propylene-1-octene copolymerization were studied. At TBA /MAO (Al/AI mole ratio) of about 0.6, the polymerization activity was found to be much higher than the system without TBA. Increases of polymer molecular weight and 1-octene content from addition of TBA were also observed.

关键词： propylene-1-octene polymerization metallocene catalyst

NEW OPTICALLY ACTIVE AROMATIC POLYIMIDES Ⅱ: SYNTHESIS AND PROPERTIES OF OPTICALLY ACTIVE AROMATIC POLYIMIDE BASED ON (R)-(+)-2, 2′-BIS (2-TRIFLUORO-4-AMINOPHENOXY)-1, 1′-BINAPHTHYL

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Chinese Journal of polymer science 1999年第1期17卷 87-90页

作者： qi-ding Mi Yu Ma Lian-xun Gao Meng-xian Ding Changchun Institute of Applied chemistry, Chinese Academy of sciences Changchun {3.022, China department of chemistry, peking university, beijing 100871 中科院长春应用化学所吉林长春 130022 中科院长春应用化学所吉林长春

Optically active (R)-(+)-2, 2' -bis(2 -trifluoro-4 -aminophenoxy)- 1, 1' -binaphthyl was prepared from1, 1'-bi-2-naphthol. The optically active aromatic polyimide was also successfully synthesized. This newpolymer has good solubility, thermal stability etc. Its specific rotation was found to be +174°, and itschiroptical property was also studied.

关键词： Optical activity 1, 1′-Bi-2-naphthol, Polyimide

Distinguishing malignant from normal stomach tissues and its in vivo, in situ measurement in operating process using FTIR Fiber-Optic techniques

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science China chemistry 2005年第2期48卷 167-175页

作者： XU Yizhuang1, YANG Limin1, XU Zhi3. ZHAO Ying2, LING Xiaofeng3. LI qingbo1, WANG Jiansheng4, ZHANG Nengwei3. ZHANG Yuanfu1 & WU Jinguang1 1. The State Key Laboratory of Rare Earth Materials and Applications, college of chemistry and Molecular {3., peking university, beijing 100871, China 2. Institute of chemistry, Chinese Academy of sciences, beijing 100080, China 3. department of Surgery, Third Hospital, peking university, beijing 100083. China 4. department of Oncology Surgery, the First Hospital of Xi’an Jiaotong {13., Xi’an 710061, China Correspondence should be addressed to Wu Jinguang (email: wujg@***) 1. The State Key Laboratory of Rare Earth Materials and Applications College of Chemistry and Molecular Engineering Peking University 100871 Beijing China 2. department of Surgery Third Hospital Peking University 100083 Beijing China 3. Institute of chemistry Chinese Academy of Sciences 100080 Beijing China 4. department of Oncology Surgery the First Hospital of Xi’an Jiaotong University 710061 Xi’an China

Gastric tissue samples were studied using mid-IR fiber-optic attenuated total reflectance (ATR) spectroscopy. FTIR spectra of 90 tissue samples from 48 patients, including 3. normal and 58 malignant tissue samples, were chosen as examples. Malignancy was usually characterized by the absence of CH and C=O bands, a weak amide II band near 1545 cm-1, a shift of the amide I band to lower wave number, a decrease in the ～1450 cm-1 peak to less than the～1400 cm-1 peak. Subtraction spectra indicate that the amide I and amide II bands of normal and malignant tissues have larger differences in peak positions and relative intensities. The statistical analysis results confirm this conclusion. The results indicate that FTIR fiber optic techniques provide important information about cancerous tissue of the stomach, which can be used to differentiate the malignant tissue from the normal tissue. Based on the above results we successfully realize the detection of the tumor tissues of digestive tract in vivo and in situ. And the results of detection cancer near operating room and in vivo and in situ in the operating room are consistent with the conclusions for the samples stored in liquid N2, which is the basis for the clinical application.

关键词： FTIR, Fiber-Optics, stomach tissues, cancer, diagnosis.

User-experience-based availability analysis model and its application in P2P storage systems

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science China(Information sciences) 2011年第8期54卷 1585-1595页

作者： WU Yu, YANG Zhi,QU Zhi, XIAO Zhen & DAI YaFei department of Computer science,peking {3.,beijing 100871,China 1. department of Computer science Peking University Beijing 100871 China

Data availability is one of the most important properties of peer-to-peer (P2P) storage *** analysis model and data placement are two key design *** in P2P storage system are both providers and *** characteristic determines that the availability analysis must be user-centric,and thereby enhance the quality of service and decrease the system *** popular approach in recent studies is simple random placement with steady-state model,which has the following drawbacks:1) It ignores the up/down patterns of nodes,whose availability is over-estimated or under-estimated at different periods of time.2) It ignores the access patterns of users,so the availability perceived by users is hard to evaluate precisely.3. It ignores the huge difference of nodes’ availability, thus leading to the absence of incentive. This paper proposes a novel user-experience-based availability model, which evaluates the availability of P2P storage system in terms of user experience,which can degenerate to traditional availability analysis model. Based on the new model,this paper proposes decentralized data placement algorithms for two typical P2P storage applications:"data sharing"and"personal backup".By the trace-driven simulation, we prove that our methods can enhance the availability perceived by users greatly,reduce the variance of the availability dramatically and eliminate the nodes with low availability in data-sharing applications;meanwhile,it can provide different-level service to encourage users according to their contributions.

关键词： P2P storage user experience availability data replacement

A　SIMPLE　ESTIMATOR　FOR　AN　EXPONENTIAL　TAIL　COEFFICIENT

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Systems science and Mathematical sciences 1996年第2期9卷 151-156页

作者： qi Yongcheng(department of Probability and Statistics, peking university,{3., China) 北京大学概率统计系北京

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ＡＳＩＭＰＬＥＥＳＴＩＭＡＴＯＲＦＯＲＡＮＥＸＰＯＮＥＮＴＩＡＬＴＡＩＬＣＯＥＦＦＩＣＩＥＮＴＱＩＹｏｎｇｃｈｅｎｇ（ＤｅｐａｒｔｍｅｎｔｏｆＰｒｏｂａｂｉｌｉｔｙａｎｄＳｔａｔｉｓｔｉｃｓ，ＰｅｋｉｎｇＵｎｉｖｅｒｓｉｔｙ，Ｂｅｉｊｉｎｇ１００８７...

关键词： Exponential tail regular variation estimator.

Density-functional formula for strongly correlated systems

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Progress in Natural science:Materials International 2005年第5期15卷 395-401页

作者： WANG Huaiyu1*, HAN Rushan2 and CHEN Nanxian1(1. department of Physics, Tsinghua university, beijing 100084, China 2. department of Physics, peking university, beijing 100871, China) department of Physics Tsinghua University Beijing 100084 China department of Physics Peking University Beijing 100871 China

Density functional method is applied for strongly correlated systems. Based on the assumption that the systems are composed of electrons in singly-occupied orbitals and those in doubly-occupied orbitals, a set of self-consistent equations are obtained by standard variation procedure. The equations consist of two parts. One part is to solve the wave functions of the electrons in singly-occupied orbitals and the other is to solve the wave functions of the electrons in doubly-occupied orbitals. The physical meanings of the terms appearing in the equations are discussed.

关键词： density-functional theory strongly correlated systems doubly-occupied orbital two-particle wave function self-consistent equations.

A malware detection model based on a negative selection algorithm with penalty factor

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science China(Information sciences) 2010年第12期53卷 2461-2471页

作者： ZHANG PengTao 1,2 , WANG Wei 1,2 & TAN Ying 1,2 1 department of Machine Intelligence, School of Electronics engineering and Computer science,{3., beijing 100871, China 2 Key Laboratory of Machine Perception, Ministry of Education,{3., beijing 100871, China 1. department of Machine Intelligence School of Electronics Engineering and Computer Science Peking University Beijing 100871 China2. Key Laboratory of Machine Perception Ministry of Education Peking University Beijing 100871 China

A malware detection model based on a negative selection algorithm with penalty factor (NSAPF) is proposed in this paper. This model extracts a malware instruction library (MIL), containing instructions that tend to appear in malware, through deep instruction analysis with respect to instruction frequency and file frequency. From the MIL, the proposed model creates a malware candidate signature library (MCSL) and a benign program malware-like signature library (BPMSL) by splitting programs orderly into various short bit strings. Depending on whether a signature matches "self", the NSAPF further divides the MCSL into two malware detection signature libraries (MDSL1 and MDSL2), and uses these as a two-dimensional reference for detecting suspicious programs. The model classifies suspicious programs as malware and benign programs by matching values of the suspicious programs with MDSL1 and MDSL2. Introduction of a penalty factor C in the negative selection algorithm enables this model to overcome the drawback of traditional negative selection algorithms in defining the harmfulness of "self" and "nonself", and focus on the harmfulness of the code, thus greatly improving the effectiveness of the model and also enabling the model to satisfy the different requirements of users in terms of true positive and false positive rates. Experimental results confirm that the proposed model achieves a better true positive rate on completely unknown malware and a better generalization ability while keeping a low false positive rate. The model can balance and adjust the true positive and false positive rates by adjusting the penalty factor C to achieve better performance.

关键词： penalty factor negative selection algorithm signature extraction artificial immune system mal- ware detection

On the boundary value problem for harmonic maps of the Poincaré disc

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Chinese science Bulletin 1997年第24期42卷 2025-2045页

作者： LI Zhongdepartment of Mathematics, peking university, beijing 100871, China department of Mathematics Peking University Beijing China

The boundary value problem for harmonic maps of the Poincare disc is discussed. The emphasis is on the non-smoothness of the given boundary values in the problem. Let T . be a subspace of the universal Teichmüller space, defined as a set of normalized quasisymmetric homeomorphisms h of the unit circle S onto itself where h admits a quasiconformal extension to the unit disc D with a complex dilatation μ satisfyingwhere ρ(z)|dz|2 is the Poincare metric of D. Let B . be a Banach space consisting of holomorphic quadratic differentials φ in D with normsIt is shown that for any given quasisymmetric homeomorphism h : S1→S1∈ T . , there is a unique quasiconformal harmonic map of D with respect to the Poincare metric whose boundary corresponding is h and the Hopf differential of such a harmonic map belongs to B .

关键词： Harmonic maps quasiconfomial mappings universal Teichmüller spaces.