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Communications in Nonlinear Science and Numerical Simulation 1999年第3期4卷 186-190页

作者： Guoqian CHEN and J. H. W. LEE(Centre for environmental sciences, peking university, beijing 100871, china) (Department of Civil Engineering, university of Hong Kong, Hong Kong, china) Centre for environmental sciences Peking University Beijing 100871 China Department of Civil Engineering University of Hong Kong Hong Kong China

IntroductionThethermal,abodyofbuoyalfluidinafluidwithwhichitcanmixandgivennamebygliderpilotstothosemassesofwarmairrisingfromhotgroundwarmedbysunshineinwhichtheycansoar,***],duetoi... 详细信息

IntroductionThethermal,abodyofbuoyalfluidinafluidwithwhichitcanmixandgivennamebygliderpilotstothosemassesofwarmairrisingfromhotgroundwarmedbysunshineinwhichtheycansoar,***],duetoi...

关键词： environmental fluid mechanics thermal turbulence modeling

Probability parametric imaging with DCE-MRI data to identify prostate cancer in the peripheral zone

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Progress in Natural Science:Materials International 2006年第9期16卷 948-953页

作者： HUANG Xinrui, WANG Qiang, XU Yufeng, WANG Xiaoying and BAO Shanglian ( The Key Laboratory of Medical Physics and Engineering, peking university, beijing 100871, china The Medical school of peking university, beijing 100083, china 3. The First Hospital of peking university, beijing 100034, china) The Key Laboratory of Medical Physics and Engineering Peking University Beijing 100871 China The Medical school of peking university Beijing 100083 China The First Hospital of peking university Beijing 100034 China

To quantitatively analyze prostate dynamic contrast-enhanced magnetic resonance images (DCE-MRI), a retrospective study was carried out to construct a mathematical model to predict whether a lesion is cancerous or not. With known diagnosis of 52 re-gions-of-interest (10 malignant, 26 benign and 16 normal) in peripheral zone (PZ) of prostate from 18 patients undergoing needle biopsy and 8 normal volunteers, we combined feature parameters (k1, k2 and tp) from the linear-slope model with logistic regression to determine the statistical probability model. Prostate cancerous probability maps were derived using the model on each subject to examine the correlation between the model-based prediction and the known diagnosis. Compared the model prediction results of 52 regions-of-interest with the histopathologic results, the total agreement rate was 90.4 % ; the agreement rate was 60 % for the malignant and 97. 6 % for the nonmalignant. The diagnostic results only referencing the probability maps by two radiologists showed a high agreement in tissue characteristics and lesion location with the combining results from other diagnostic techniques such as PSA (prostate specific antigen) level and MRS (magnetic resonance spectroscopy) .

关键词： time-intensity curve prostate DCE-MRI logistic regression probability parametric image.

Application　of　face－graph　in　heavy　metal　pollution　assessment　in　river　sediment

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Journal of environmental sciences 1994年第2期6卷 206-214页

作者： Jia Zhenbang Zhao Zhijie(Geography Department, peking university,beijing 100871, china)Zhang Hui(Chinese Research Academy of environmental sciences,beijing, china)Zhang Baoquan Zhao Lihua(environmental Protection Survey Station, Benxi, china)

On the basis of sedimentation principles and environmental chemical characteristics of heavymetal, combine international new methods-face graph on heavy metal pollution assessment withmulti-variable graph expression, the article made a synthetical assessment study on state of heavymetal pollution and potential ecological risk of Taizi River sediment in Benxi City reach. The re-sults of the study indicated that the state of heavy metal pollution of Taizi River in Benxi Cityreach is very serious, appropriate counter measures should be taken.

关键词： face graph heavy metal pollution sediment potential ecological risk index.

Explanation of the mechanism of carcinogenesis and syntheses of anticancer agents with high selectivity

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Science china Chemistry 2006年第1期49卷 44-62页

作者： DAI Qianhuan1,2 1. Center of Chemistry and Bioengineering of Cancer Research, beijing Polytechnic university (Now known as beijing Univer-sity of Technology), beijing 100022, china 2. Center of environmental sciences, peking university, beijing 100871, china Center of Chemistry and Bioengineering of Cancer Research Beijing Polytechnic University Beijing China Center of environmental sciences Peking University Beijing China

In 1979, the mechanism of chemical carcinogenesis, a challenging anddifficult scientific problem pending for a number of years, was explained by Dai Qianhuan. Themechanism named di-region theory predicted that a carcinogen always metabolizes to form a specialbi-functional alky-lating agent. This agent induces cross-linkages between the complementary basepairs in DMA and switches on initial mutageneses in genomes including point and frameshiftmutations. This, in turn, induces further deep mutageneses including the production of variouschimeric chromosomes, deletions and other aberrations found in genomes. In the end this initiatescarcinogenesis of the whole cell through the reverse transcription mechanism after a lengthyincubation period. Recently, this laboratory has verified that physical carcinogenesis, includingthe oncogenesis induced by radiation and asbestos as well as the carcinogenesis induced byendogenous factors such as estrogen or diethyl-stilbestrol switch on carcinogenesis by inducing theformation of cross-linkages between the complementary base pairs in DNA. Di-region theory has nowbeen supported by many experimental observations such as mutational spectra of various *** potential for carcinogenesis, teratogenesis, sterility and mutagenesis lumped together asgenetic toxicity appears to originate almost uniformly from the cross-linking between complementarybases, i.e. malignant cross-linking, which is in accordance with di-region theory. Other forms ofcross-linking between non-complementary bases, benign cross-linkings, show bi-functional alkylationanticancer activity but lack genetic toxicity. The predictable design and synthesis of a highselectivity anticancer agent with high efficacy and low genetic toxicity, a goal long pursued incancer chemotherapy, have been realized for the first time in this laboratory by inhibitingmalignant and heightening benign cross-linking using the principles of di-region theory. A series ofpatented new anticanc

关键词： mechanism of carcinogenesis, di-region theory, minoplatin, selectivity of anticancer agent, cross-linking between DNA bases, anticancer platinum complexes, predictive design of anticancer agent, second generation anticancer agent.

Balanced multiple description subband coding based on multifilter banks

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Science china(Information sciences) 2011年第11期54卷 2359-2372页

作者： WANG Ning 1,LI BaoBin 2 & PENG LiZhong 1 1 LMAM,school of Mathematical sciences,peking university,beijing 100871,china 2 school of Information Science and Engineering,Graduate university of Chinese Academy of sciences,beijing 100190,china LMAM School of Mathematical Sciences Peking University Beijing China school of Information Science and Engineering Graduate University of Chinese Academy of Sciences Beijing China

Multiple description coding is one of the source coding techniques to alleviate the problems of packet loss in *** encoder generates several different descriptions of the source and the decoder can produce a useful reconstruction with any received subset of these *** of the earlier works concentrated on redundancy and the average distortion of the single-description reconstructions,which is insufficient to describe the *** this paper,a metric of the coding system,balance eccentric modulus,is defined to evaluate the difference in quality between the individual *** the discrete wavelet transform becomes trivial polyphase transform when setting the balance eccentric modulus at zero,we introduce a multiwavelet based scheme ***,a sufficient condition for balanced multiwavelet based multiple description coding is presented.

关键词： multiple description coding rate-distortion theory balance eccentric modulus balanced multiwavelet multifilter bank

Mapping the Antigenic Peptides of Sm26/2 in Glutathione S-Transferases of Schistosoma Mansoni

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Chinese Chemical Letters 1998年第4期9卷 377-379页

作者： Jia Xi XU Meng Shen CAI(College of Chemistry and Molecular Engineering, peking university, beijing 100871 (school of Pharmaceutical sciences, beijing Medical university, beijing 100083) Coll. of Chem./Molec. Engineering Peking University Beijing 100871 China school of Pharmaceutical sciences Beijing Medical University Beijing 100083 China

Six antigenic peptides of Sm26/2 glutathione S-transferase of schistosoma mansoni have been predicted according to their hydrophilicity, flexibility, accessibility, charge distribution and beta-turn in the secondary structure by the determination of its primary structure, and synthesized by solid phase method. Two of them showed good antigenicity by Dot-ELISA. They would be candidate peptides of synthetic anti-schistosomal vaccine.

关键词： schistosoma mansoni glutathione S-transferase antigenic peptide peptide vaccine

Application of cathodoluminescence to zircon in FEG-ESEM

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Progress in Natural Science:Materials International 2006年第9期16卷 919-924页

作者： CHEN Li , XU Jun and SU Li (Electron Microscopy Laboratory, school of Physics, peking university, beijing 100871, china Geology Experimental Center, china university of Geoscience, beijing 100083, china) Electron Microscopy Laboratory School of Physics Peking University Beijing 100871 China Geology Experimental Center China University of Geoscience Beijing 100083 China

Cathodoluminescence (CL) image analysis of zircon is a key step of mineral micro-area compositional investigation and U-(Th)-Pb dating. We introduce a system consisting of field emission ESEM and high performance cathodoluminescence. This system has obvious advantages in imaging resolution and CL spectrum. We acquired some zircon CL images and spectra to demonstrate the ability of this system. Our results show that this system has a great potential application to characterize and identify the genesis of zircon.

关键词： zircon cathodoluminescence ESEM.

On the local wellposedness of 3-D water wave problem with vorticity

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Science china Mathematics 2007年第8期50卷 1065-1077页

作者： Ping ZHANG~1 Zhi-fei ZHANG~2 1 Academy of Mathematics and Systems Science,Chinese Academy of sciences,beijing 100080,china 2 school of Mathematical sciences,peking university,beijing 100871,china Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing China school of Mathematical sciences Peking University Beijing China

In this article, we first present an equivalent formulation of the free boundary problem to 3-D incompressible Euler equations, then we announce our local wellposedness result concerning the free boundary problem in Sobolev space provided that there is no self-intersection point on the initial surface and under the stability assumption that $\frac{{\partial p}}{{\partial n}}(\xi )\left| {_{t = 0} } \right. \leqslant - 2c_0 < 0$ being restricted to the initial surface.

关键词： water-waves free boundary incompressible Euler equations primary 35Q35 76B03 secondary 35J67 35L80

Frontal genesis of moisture atmosphere during the early 2008 persistent freezing-rain event in southern china

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Science china Earth sciences 2010年第3期53卷 454-464页

作者： QIAN WeiHong1 & FU JiaoLan1,2 1 Department of Atmospheric sciences, school of Physics, peking university, beijing 100871, china 2 National Meteorological Center of CMA, beijing, 100081, china Department of Atmospheric sciences School of Physics Peking University Beijing China National Meteorological Center of CMA Beijing China

From January 10 to February 2, 2008, a severe and persistent freezing-rain event occurred in southern and southwestern china. Here we use an observational analysis to compare the persistent freezing-rain event in the early 2008 with the winter precipita- tion in the late 2007 over south of the Yangtze River (Jiangnan). The persistent freezing-rain event was directly linked to the activity of quasi-stationary front. The gradient of equivalent temperature (ET) can well indicate the frontal genesis of moist atmosphere (moisture front) and its activity as well as its relationship with precipitation belt. The precipitation types (snow and freezing rains) are related to the vertical structure of moisture front. The inversion profile of ET vertical distribution is a typical synoptic condition that caused the freezing-rain event. The horizontal gradient of ET with a criterion of 10℃ / 100 km, which reflects the accumulation and release of atmospheric energy, can be applied to predict the precipitation 5-10 days in advance.

关键词： freezing-rain event frontal genesis extended-range weather forecast winter Jiangnan