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Science china Chemistry 2010年第8期53卷 1634-1640页

作者： GAO HaiYang1,2,HU Hao1 & WU Qing1,2 1Institute of Polymer Science,school of Chemistry and Chemical Engineering,sun yat-sen (zhongshan) university,guangzhou 510275,china 2Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education sun yat-sen (zhongshan) university,guangzhou 510275,china Institute of Polymer Science School of Chemistry and Chemical Engineering Sun Yat-Sen (Zhongshan) University Guangzhou China Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education Sun Yat-Sen (Zhongshan) University Guangzhou China

A novel bis(α-alkyloxoimine) titanium(IV) complex was synthesized and used as a catalyst precursor to catalyze homo-and copolymerization of ethylene and *** titanium complex activated with methylalumoxane exhibits good activities for the homopolymerizations of ethylene and norbornene under high temperature to produce high-molecular-weight linear polyethylene and vinyl-type polynorbornene,***-norbornene copolymers with high molecular weight can also be produced by this *** incorporation of norbornene from 0 to 76 mol% in the copolymers can be controlled by varying the charged norbornene.13C NMR analyses show that the microstructures of the ethylene-norbornene copolymers with low norbornene incorporation are predominantly alternated and isolated norbornene units,while those with high norbornene incorporation are random polymers containing long norbornene sequences.

关键词： catalyst ethylene norbornene polymerization copolymerization

A provable secure fuzzy identity based signature scheme

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Science china(Information Sciences) 2012年第9期55卷 2139-2148页

作者： WANG ChangJi 1,2 1 school of Information Science and Technology,sun yat-sen university,guangzhou 510275,china 2 Guangdong Province Information Security Key Laboratory,sun yat-sen university,guangzhou 510275,china school of Information Science and Technology Sun Yat-sen University Guangzhou China Guangdong Province Information Security Key Laboratory Sun Yat-sen University Guangzhou China

To use biometrics identities in an identity based encryption system,Sahai and Waters first introduced the notion of fuzzy identity based encryption(FIBE) in *** et *** it to digital signature and introduced the concept of fuzzy identity based signature(FIBS) in 2008,and constructed an FIBS scheme based on Sahai and Waters's FIBE *** this paper,we further formalize the notion and security model of FIBS scheme and propose a new construction of FIBS scheme based on bilinear *** proposed scheme not only provides shorter public parameters,private key and signature,but also have useful structures which result in more efficient verification than that of Yang et al.'s FIBS *** proposed FIBS scheme is proved to be existentially unforgeable under a chosen message attack and selective fuzzy identity attack in the random oracle model under the discrete logarithm assumption.

关键词： identity based cryptosystem fuzzy identity based encryption fuzzy identity based signature

Spontaneous chiral-symmetry breaking of lattice QCD with massless dynamical quarks

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Science china(Physics,Mechanics & Astronomy) 2007年第1期50卷 6-14页

作者： LUO XiangQian Department of Physics,school of Physics and Engineering,sun yat-sen university,guangzhou 510275,china Department of Physics School of Physics and Engineering Sun Yat-Sen University Guangzhou China

One of the most challenging issues in QCD is the investigation of spontaneous chiral-symmetry breaking, which is characterized by the non-vanishing chiral condensate when the bare fermion mass is zero. In standard methods of the lattice gauge theory, one has to perform expensive simulations at multiple bare quark masses, and employ some modeled functions to extrapolate the data to the chiral limit. This paper applies the probability distribution function method to computing the chiral condensate in lattice QCD with massless dynamical quarks, without any ambiguous mass extrapolation. The results for staggered quarks indicate that this might be a promising and efficient method for investigating the spontaneous chiral-symmetry breaking in lattice QCD, which deserves further investigation.

关键词： lattice QCD spontaneous chiral-symmetry breaking dynamical quarks

Chemical weathering and chemical runoffs in the seashore granite hills in South china

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Science china Earth Sciences 2010年第8期53卷 1195-1204页

作者： GAO QuanZhou & TAO Zhen school of Geography and Planning, sun yat-sen university, guangzhou 510275, china school of Geography and Planning Sun Yat-sen University Guangzhou China

Surface runoffs and the contents of major ions and dissolved silicon were surveyed and analyzed based on weekly sampling for one year in a granite watershed of Zhuhai City, Guangdong Province. The results demonstrated that the slope runoff played an essential role in feeding the rivulet during precipitation, whereas the groundwater was more important for the rivulet in the non-raining stages. Dissolved silicon, Na+, HCO3-, and Clions constituted the major chemical components of the rivulet water. Atmospheric CO2 and H2SO4 sourced from the oxidation of pyrite were the main erosive mediums in the natural chemical weathering. Natural chemical weathering, the wet and dry deposition of sea-salt, and acids precipitation contributed approximately equal shares of anions to the rivulet water. The ratio of NO3- to SO42- was more than 1.0 in the runoff of the studied seashore watershed, whereas it is less than 1.0 in the Xijiang River that is adjacent to the study area. This implied that the chemical composition of runoff is controlled mainly by the differences in atmospheric acid precipitation caused by human activities and lithology within the catchments under the same bio-climate zone. The CO2 flux consumed by the rock chemical weathering processes within the seashore granite watershed in South china was (0.35-1.37)×105 mol km-2 a-1.

关键词： chemical weathering granite ion sea-salt acid deposition CO2

On the diophantine equation X^2-(1+a^2)Y^4 =-2a

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Science china Mathematics 2010年第8期53卷 2143-2158页

作者： YUAN PingZhi 1 & ZHANG ZhongFeng 2 1 school of Mathematics,South china Normal university,guangzhou 510631,china 2 school of Mathematics & Computational Science,sun yat-sen university,guangzhou 510275,china school of Mathematics South China Normal University Guangzhou China school of Mathematics & Computational Science Sun Yat-Sen University Guangzhou China

Let a≥1 be an *** this paper,we will prove the equation in the title has at most three positive integer solutions.

关键词： algebraic approximations continued fractions elliptic curves quartic equations

A distribution space for Hilbert transform and its applications

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Science china Mathematics 2008年第12期51卷 2217-2230页

作者： YANG LiHua school of Mathematics and Computing Science, sun yat-sen university, guangzhou 510275, china school of Mathematics and Computing Science Sun Yat-Sen University Guangzhou China

In this paper, a new distribution space is constructed and the definition of the classical Hilbert transform is extended to it. It is shown that is the biggest subspace of on which the extended Hilbert transform is a homeomorphism and both the classical Hilbert transform for L p functions and the circular Hilbert transform for periodic functions are special cases of the extension. Some characterizations of the space are given and a class of useful nonlinear phase signals is shown to be in . Finally, the applications of the extended Hilbert transform are discussed.

关键词： Hilbert transform distribution time-frequency analysis 44A15 46F12

FG020326-loaded nanoparticle with PEG and PDLLA improved pharmacodynamics of reversing multidrug resistance in vitro and in vivo

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Acta Pharmacologica Sinica 2007年第6期28卷 913-920页

作者： Wen-jing DENG~2,Xiao-qiang YANG~2,Yong-ju LIANG~2,Li-ming CHEN~2,Yan-yan YAN~2,Xin-tao SHUAI~3,Li-wu FU~(2,4)~2 State Key Laboratory of Oncology in Southern china Cancer Center,sun yat-sen university,guangzhou 510060,china ~3 school ofChemistry and Chemical Engineering of sun yat-sen university,guangzhou 510275,china State Key Laboratory of Oncology in Southern china Cancer Center Sun Yat-Sen University Guangzhou China school of Chemistry and Chemical Engineering of sun yat-sen university Guangzhou China

Aim:FG020326,a novel imidazole derivative,is a potent multidrug-resistance(MDR) modulator in vitro and in ***,FG020326 is ***-FG020326 is a FG020326-1oaded nanoparticle formed with diblock copolymers ofpoly (ethylene glycol)-block-poly (D,L-lactic acid) (PEG:PDLLA,PEDLLA) thatcan solubilize *** work was intended to evaluate the pharmacody-namics of PEDLLA-FG020326 on reversing MDR in vitro and in ***:Cytotoxicity was determined by tetrazolium *** intracellular accumulationand efflux of doxorubicin (Dox) were detected by fluorescence *** function of P-glycoprotein was examined by Rhodamine 123 (Rh123) accumu-lation detected by flow *** KBv200 cell xenograft model was estab-lished to investigate the effect of PEDLLA-FG020326 on reversing MDR in ***:PEDLLA-FG020326 and FG020326 exhibited 56.4-and 35.9-fold activityin reversing KBv200 cells to vincristine (VCR) resistance,respectively and 14.98-and 7.64-fold to Dox resistance,***-FG020326 was much stron-ger than FG020326,resulting in the increase of Dox and Rh 123 accumulation andthe decrease of intracellular Dox extrusion in KBv200 ***,PEDLLA-FG020326 exhibited more powerful activity than FG020326 in enhancing the effectof VCR against KBv200 cell xenografts in nude mice,but did not appear more ***:The pharmacodynamics of FG020326 was improved by incorporatingit into a micellar nanoparticle formed with PEG-block-PDLLA copolymers.

关键词： FG020326 micellar nanoparticle multidrug resistance xenografts

Calibration based universal JPEG steganalysis

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Science in china(Series F) 2009年第2期52卷 260-268页

作者： HUANG FangJun1,2 & HUANG JiWu1,2 1 school of Information Science and Technology,sun yat-sen university,guangzhou 510275,china 2 Guangdong Key Lab. of Information Security Technology,sun yat-sen university,guangzhou 510275,china school of Information Science and Technology Sun Yat-Sen University Guangzhou China Guangdong Key Lab. of Information Security Technology Sun Yat-Sen University Guangzhou China

For steganalysis of JPEG images, features derived in the embedding domain appear to achieve a preferable performance. However, with the existing JPEG steganography, the minor changes due to the hidden secret data are not easy to be explored directly from the quantized block DCT （BDCT） coefficients in that the energy of the carrier image is much larger than that of the hidden signal. In this paper, we present an improved calibration-based universal JPEG steganalysis, where the microscopic and macroscopic calibrations are combined to calibrate the local and global distribution of the quantized BDCT coefficients of the test image. All features in our method are generated from the difference signal be- tween the quantized BDCT coefficients of the test image and its corresponding microscopic calibrated image, or calculated as the difference between the signal extracted from test image and its corresponding macroscopic calibrated image. The extracted features will be more effective for our classification. Moreover, through using the Markov empirical transition matrices, both magnitude and sign dependencies along row scanning and column scanning patterns existed in intra-block and inter-block quantized BDCT coefficients are employed in our method. Experimental results demonstrate that our proposed scheme outperforms the best effective JPEG steganalyzers having been presented.

关键词： JPEG steganography steganalysis microscopic calibration macroscopic calibration

Activation of PI3-K/Akt pathway for thermal preconditioning to protect cultured cerebellar granule neurons against low potassium-induced apoptosis

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Acta Pharmacologica Sinica 2007年第2期28卷 173-179页

作者： Lin CAO~(2,3) De-xiong CAO~3 Xing-wen SU~2 Li-jun CHEN~2 Ai-lin LIU~2 Wei-jian JIAN~2 Yu-ping WU~2 Peng-xin QIU~2 Guang mei YAN~(2,4)2 Department of Pharmacology,zhongshan Medical school,sun yat-sen university,guangzhou 510080,china 3 Department of Anesthesiology The Second Affiliated Hospital,sun yat-sen university,guangzhou 510120,china Department of Pharmacology Zhongshan Medical School Sun Yat-sen University Guangzhou China Department of Anesthesiology The Second Affiliated Hospital Sun Yat-sen University Guangzhou China

Aim:This study was designed to investigate whether the activation of thephosphatidylinositol 3-kinase(PI3-K)/Akt pathway is required for thermal pre-conditioning to protect rat cerebellar granule neurons(CGN)against apoptosisinduced by low potassium,and to explore the possibility of a link between theupregulated heat shock protein(HSP)70 expression and Akt activation in theacquisition of neuroprotection induced by thermal ***:CGN cultured for 8 d in vitro were switched to 5K medium for 24 h after thermalpreconditioning(TP;43.5 ℃ for 90 min,then 37 ℃ for 1 h).To study the role of thePI3-K/Akt pathway,a PI3-K inhibitor,LY294002(20 μmol/L)was added into thecultures 1 h before TP.3-(4,5-dimethylthiazol-2-yl)2,5-diphenyltetrazolium bro-mide(MTT)assay and fluorescein diacetate staining were used to determine *** 33258 staining and agar gel electrophoresis were used to testthe morphological and biological characters of *** blot analysis wasemployed to detect the levels of phospho-Akt,phospho-glycogen synthase ki-nase 3β(GSK3β) Akt,GSK3β,and ***:TP protected CGN againstapoptosis induced by low ***294002 inhibited the neuroprotectiveeffect on CGN induced by *** induced a robust activation of Akt and theinactivation of GSK3β via ***,the activation of the PI3-K/Aktpathway by TP persisted for 24 h in the 5K ***294002(20 μmol/L)failedto inhibit the upregulated HSP70 expression induced by ***:Theactivation of the PI3-K/Akt pathway is required for TP to protect CGN againstapoptosis induced by low potassium,but the neuroprotective effect by Akt acti-vation is not mediated through the downstream induction of HSP70 expression.

关键词： thermal preconditioning heat cerebellum neurons apoptosis LY294002 phospho Akt phospho-GSK3β HSP70