检索结果-南通市图书馆

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

在线全文

学校读者我要写书评

暂无评论

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,{2. (Now known as beijing univer-sity of Technology), beijing 100022, china 2. center of Environmental Sciences, Peking univer.ity, beijing 100871, china 1. center of Chemistry and Bioengineering of Cancer Research Beijing Polytechnic University Beijing 100022 China 2. center of Environmental Sciences Peking University Beijing 100871 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.

Electric-stimulus rate encoding algorithm of Mandarin tonal information in cochlear implant

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2006年第12期16卷 1315-1321页

作者： GUAN Tian~1, GONG Qin~1 and YE Datian~2.*(1. Department of biomedical engineering, Tsinghua {2., beijing 100084, china 2. Research center of biomedical engineering, Graduate School at Shenzhen, Tsinghua {2., Shenzhen 518055, china) [a]Department of biomedical engineering Tsinghua University Beijing China [b]Research center of biomedical {2. Graduate School at Shenzhen Tsinghua University Shenzhen China

The modern multi-channel cochlear implants usually extract and encode the temporal envelope cues. This kind of algorithms can hardly satisfy the users who speak tonal languages, such as Mandarin. Many studies have tried to enhance the recognition ability of Mandarin through encoding tonal information and made suggestions to frequency-modulate the fixed pulse-rate carrier with the extracted tonal information based on the rate-pitch theory in electric hearing. However, how to encode and deliver the tonal information such as F_0by changing electric-stimulus rate has not got further study in clinical electric-stimulus mode. The present paper focuses on this matter by piecewise calculating the appreciable electric-stimulus rates. Then an electric-stimulus encoding algorithm of Mandarin tone is brought forward and testified through acoustic simulations. Such conclusion can be drawn that this algorithm of electric-stimulus rate could convey tonal information well and help to enhance the Mandarin speech recognition ability.

关键词： cochlear implant tone fundamental frequency electric-stimulus rate.

MNDO research on alkylation of DNA bases by the non-α-position metabolite of 3, 5-dimethyl-N-nitrosopeperazine

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 Science Bulletin 1997年第8期42卷 698-700页

作者： ZHONG Rugang and DAI Qianhuancenter for Cancer Chemistry and Bioengineering,{2., beijing 100022. china center for Cancer Chemistry and Bioengineering Beijing Polytechnic IJniversity Beijing China

IT is a commonly accepted concept that having formed alkyldiazonium ions after α-hydroxyla-tion,the metabolites of N-nitroso compounds(NNCs)combine with DNA and initiate *** the complex relationship between carcinoge... 详细信息

关键词： nitrosopeperazine di-region theory alkylation of DNA MNDO.

Large field of view computed laminography with the asymmetric rotational scanning geometry

在线全文

学校读者我要写书评

暂无评论

Science china(Technological Sciences) 2010年第8期53卷 2261-2271页

作者： FU Jian 1,2.,JIANG BaiHong&LI Bin 1 School of Mechanical engineering and Automation,Beihang univer.ity,{2. 100191,china 2.Research center of Digital Radiation Imaging and biomedical Imaging,Beihang univer.ity,{2. 100191,china 1. School of Mechanical engineering and Automation Beihang University Beijing 100191 China2. Research Center of Digital Radiation Imaging and Biomedical Imaging Beihang University Beijing 100191 China

X-ray computed laminography(CL)is used in the fields of industrial inspection and medical *** can provide the internal structure three-dimensional(3D)information of a region of the objects *** is important to the clinical diagnosis and the quality control of flat objects like printed circuit boards,aircraft wings and satellite solar *** the restriction that the imaging region must be within the X-ray beam formed by the X-ray source and the detector,the imaging field of view of CL is limited by the size of detector.A new CL method with an asymmetric rotational cone-beam scanning geometry,called large field of view CL,is presented to overcome the existing *** can extend the imaging region when the imaging spatial resolution keeps the same as that of the conventional *** can also improve the imaging spatial resolution when the imaging region keeps the same as that of the conventional *** asymmetric configuration can be achieved by offsetting the detector from the conventional symmetric *** does not,however,require new detectors and X-ray source nor alter the scanning mechanical *** filtered back-projection(FBP)reconstruction algorithm and the data truncation smoothing functions have been deduced to reconstruct the images directly from the data acquired with this asymmetric *** performed numerical studies and experiments to demonstrate and validate the proposed approach. Results in these studies and experiments confirm that the proposed method can enlarge the imaging region and improve the spatial *** proposed approach may find applications in the CL system with the rotational scanning geometry.

关键词： computed laminography image reconstruction reconstruction algorithm imaging field of view imaging spatial resolution

Studies on repairing of hemisected thoracic spinal cord of adult rats by using a chitosan tube filled with alginate fibers

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2006年第10期16卷 1051-1055页

作者： LI Xiaoguang, YANG Zhaoyang and YANG Yi ( beijing center for Neural Regeneration and Repairing, Capital {2. of Medical Sciences, beijing 100054, china Department of Bioengineering, beijing {2. of Aeronautics and Astronautics, beijing 100083, china National center of biomedical Analysis, beijing 100850, china) [a]beijing center for Neural Regeneration and Repairing Capital University of Medical Sciences Beijing China [b]Department of Bioengineering Beijing University of Aeronautics and Astronautics Beijing China [c]National center of biomedical Analysis Beijing China

A chitosan tube filled with alginate fibers was implanted into the injured spinal cord of a rat for repairing the damaged tissue. Twelve months after the operation, the morphological observation demonstrated that this chitosan tube could induce regeneration of myelinated and non-myelinated axons and blood vessels. The Basso-Beattie-Bresnahan (BBB) behavioral evaluation confirmed that the implants played a key role in the long-term restoration of rats motor functions. It is a promising start in the treatment of the patients with the injury of the spinal cord.

关键词： spinal cord injury regeneration function recovery chitosan alginate behavioral evaluation.

Quick image-processing method of UAV without control points data in earthquake disaster area

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

中国有色金属学会会刊：英文版 2011年第S3期21卷 523-528页

作者： LI Chang-chun1, ZHANG Guang-sheng1, LEI Tian-jie2. 3, GONG A-du2. 3 1. School of Surveying & Land Information engineering, Henan polytechnic {2., Jiaozuo 454000, china 2. Key Laboratory of Environmental Change and Natural Disaster, Ministry of Education, beijing Normal {2., beijing 100875, china 3. Ministry of Civil Affairs/Ministry of Education of china Academy of Disaster Reduction and Emergency Management, beijing Normal {2., beijing 100875, china [a] School of Surveying & Land Information engineering Henan Polytechnic University Jiaozuo 454000 China [b] Key Laboratory of Environmental Change and Natural Disaster Ministry of Education Beijing Normal University Beijing 100875 China [c] Ministry of Civil Affairs/Ministry of Education of china Academy of Disaster Reduction and Emergency Management Beijing Normal University Beijing 100875 China

The methods of unmanned aerial vehicles images splicing rapidly and rectifying without control points data, only using auxiliary data recorded by unmanned aerial vehicle (UAV) system, were researched. Two algorithms were proposed, including UAV images auto- splicing rapidly after image blocking and UAV images rectifying based on pseudo center points of auxiliary data. When SIFT algorithm for UAV images splicing is applied, the accuracy is very high, but the efficiency is very low. The splicing efficiency is improved greatly based on SIFT algorithm after image blocking. The results show that rectifying accuracy is very high and has no visual dislocation when pseudo center points of auxiliary data is applied.

关键词： unmanned aerial vehicles SIFT algorithm blocking quickly splicing rectification

Experimental verifications on chemical carcinogenesis, a bifunctional alkvlation between DNA interstrands

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2000年第12期45卷 1075-1079页

作者： DAI Qianhuan, ZHANG Qingrong, WANG Lihui, PEI Shu, WANG Qing &QUBocenter for Chemistry and Bioengineering of Cancer,{2., beijing 100022, china center for Chemistry and Bioengineering of Cancer Beijing Polytechnic University Beijing China

It is evidenced by the filter elution method that two carcinogenic aromatic hydrocarbons, benzo[a]pyrene and dibenzo[a,h]anthracene, two carcinogenic metal salts, beryllium chloride and cadmium chloride, four carcinogenic aromatic amines, 2.aminofluorene, p-naphthylamine, 4-aminobiphenyl and benzidine, can all induce DNA interstrand and DNA-protein cross-link in L12.o culture. However, under the same condition, the corresponding non-carcinogenic compounds, including benzo[k]fluorancene, anthracene, magnesium chloride, zinc chloride, a-naphthylamine, 2.aminobiphenyl and m-toluidine, cannot produce any cross-link adducts. All these results are consistent with the di-region theory that carcinogens are bio-bifunctional alkylation agents. This method can also be used to discriminate carcinogens and non-carcinogens.

关键词： mechanism of chemical carcinogenesis di-region theory DNA interstrand cross-link aromatic amines poiycyclic aromatic hydrocarbons beryllium salt cadmium salt.

A Theoretical Research on the Intermediate in the Reaction of N-Phosphorylamino-acid to form Peptide or Ribotide

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 1998年第12期9卷 0-0页

作者： Ru Gang ZHONG Zhao Long LI Yu Fen ZHAO Qian Huan DAI (Bioorganic Phosphorus Chemistry Laboratory, Tsinghua univer.ity, beijing 100084)({2. for Chem. and Bioeng. of Cancer Res., beijing polytechnic univer.ity, beijing 100022) Tsing Hua Univ Bioorgan Phosphorus Chem Lab Beijing 100084 Peoples R China beijing Polytech Univ Ctr Chem & Bioengn Canc Res Beijing 100022 Peoples R China

In order to explain the high activity of N-phosphoryl-α-amino acids, ab initio and MNDO calculations are performed to study the reaction pathway of the intermediate formation from N-dimethylphosphoryl-α-alanine (DMP... 详细信息

关键词： Phosphoryl-α-amino acid reaction pathway quantum chemistry

同方期刊数据库

Spatio-temporal pattern analysis of single-trial EEG signals recorded during visual object recognition

在线全文

学校读者我要写书评

暂无评论

Science china(Information Sciences) 2011年第12期54卷 2519-2527页

作者： WANG ChangMing 1 , HU XiaoPing 3 , YAO Li 1,2., XIONG Shi 2.& ZHANG JiaCai 2.1 National Key Laboratory of Cognitive Neuroscience and Learning, beijing Normal univer.ity, beijing 100875, china 2.College of Information Science and Technology, beijing Normal univer.ity, beijing 100875, china 3 biomedical Imaging Technology center, Emory univer.ity/Georgia Institute of Technology, Atlanta 3032., USA 1. National Key Laboratory of Cognitive Neuroscience and Learning Beijing Normal University Beijing 100875 China3. Biomedical Imaging Technology Center Emory University/Georgia Institute of Technology Atlanta 30322 USA2. College of Information Science and Technology Beijing Normal University Beijing 100875 China

Object discrimination is a fundamental cognitive function for human brains. In this study, we utilized an analysis approach for single-trial electroencephalography (EEG) to analyze the spatio-temporal activation patterns of visual objects processing in human brains, and attempted to apply it to discriminate different visual objects. The spatial patterns were respectively extracted from scalp EEG and the reconstructed cortical sources, while the experiment participants were perceiving 4 different categories of visual objects (faces, buildings, cats and cars). By classifying the patterns extracted from single-trial EEG, the presented visual objects could be discriminated by a computer, and the classification accuracies may provide a quantitative index to evaluate the spatial differences of the brain activations related to different visual objects. Our results demonstrated that the spatial patterns on both the scalp and the sources levels resulted in higher classification accuracies than chance rate. We also examined the classification results using temporally non-overlapping time intervals of different event-related potential (ERP) components. The temporal changes of classification accuracies may reflect the temporal distribution of the discriminative information in the EEG responses. The present pattern extraction and classification methods may compose a computational model for single-trial EEG data analysis in investigations of the spatio-temporal activation patterns for object recognition. These spatio-temporal patterns in EEG may be useful to identifying the discriminative spatial areas and time stages to improve the accuracies and efficiencies of object discrimination. In addition, investigating and utilizing humans'cognitive mechanisms of object recognition may improve computers' processing efficiency of visual information.

关键词： EEG spatio-temporal pattern object recognition single-trial analysis visual information processing