检索结果-南通市图书馆

生物化学与生物物理进展 2001年第4期28卷 467-469页

作者：郭淑贞童坦君张宗玉北京大学医学部生物化学与分子生物学系北京100083

细胞衰老与个体衰老、机体自我保护及细胞癌变等多种重要生理、病理现象密切相关 ,其机制研究可望应用于癌症治疗 .

关键词：细胞衰老衰老相关基因基因克隆

A preliminary study on vegetation-erosion dynamics and its applications

在线全文

学校读者我要写书评

暂无评论

science china Earth sciences 2005年第5期48卷 689-700页

作者： WANG Zhaoyin 1,2 , WANG Guangqian 1 , LI Changzhi 1 & WANG Feixin 1 1. department of Hydraulic Engineering, Tsinghua univer.ity, Beijing 100084, china 2. International Research and Training center on Erosion and Sedimentation, Beijing 100084, china 1. department of Hydraulic Engineering Tsinghua University 100084 Beijing China 2. International Research and Training center on Erosion and Sedimentation 100084 Beijing China

Vegetation-erosion dynamics is a new interdisciplinary science, studying the laws of evolution of watershed vegetation under the action of various ecological stresses. Introducing a qualitative expression of ecological stresses in this paper, the present authors establish the cou- pled differential equations for the vegetation-erosion process and derive a theoretical solution. The model is applied to the Anjiagou watershed on the Loess Pateau and the Xiaojiang water- shed and its sub-watersheds on the Yunnan Plateau. The calculated results agree well with the vegetation development processes. Abstracted from the differential equations the so-called vegetation-erosion chart is worked out, with which we can predict the development trend of vegetation under no human stresses. It is demonstrated that the erosion control is important for vegetation development and reforestation must be a long-term strategy. On the Yunnan Plateau with relatively high precipitation and temperature, vegetation can be greatly improved if erosion is controlled. On the dry and cold Loess Pateau suffering from high rate of soil erosion, however, vegetation can effectively control erosion but erosion reduction exhibits low effectiveness on vegetation development. Vegetation in the area is not stable and management is always needed to maintain the vegetation.

关键词： vegetation-erosion dynamics, human activities, coupled differential equations, erosion control, vigor ofvegetation.

Effects of epoxyeicosatrienoic acids on levels of eNOS phosphorylation and relevant signaling transduction pathways involved

在线全文

学校读者我要写书评

暂无评论

science china(Life sciences) 2005年第5期48卷 495-505页

作者： CHEN Ruijuan1, JIANG Jiangang1, XIAO Xiao2 & WANG Daowen1 1. The institute of Hypertension and department of Internal Medicine, Tongji Hospital, Tongji Medical College, Huazhong univer.ity of science & Technology, Wuhan 430030, china 2. departments of molecular Genetics and Biochemistry & Gene Therapy center, univer.ity of Pittsburgh, Pittsburgh, PA, USA 1. The institute of Hypertension and department of Internal Medicine Tongji Hospital Tongji Medical College Huazhong University of Science & Technology 430030 Wuhan China 2. departments of molecular Genetics and Biochemistry & Gene Therapy center University of Pittsburgh Pittsburgh PA USA

Endothelial nitric oxide synthase (eNOS) is a key enzyme responsible for the regu-lation of vascular homeostasis. Many humor factors and mechanical forces can affect eNOS ac-tivity via phosphorylation modification but the mechanisms involved vary with stimuli applied. We have demonstrated that cytochrome P450 (CYP) epoxygenase-dependent metabolites of ara-chidonic acid, epoxyeicosatrienoic acids (EETs), can robustly up-regulate eNOS expression and its activity, however the relevant signaling pathways responsible for activity regulation are not well known. In this study, we explored the role of PI3 kinase (PI3K)/protein kinase B (Akt) sig-naling pathway in eNOS expression and its phosphorylation in response to EETs via direct addi-tion of EETs into cultured bovine aorta endothelial cells (BAECs) and recombinant adeno- asso-ciated virus-mediated transfection of CYP epoxygenase genes CYPF87V and CYP2C11 to pro-duce endogenous EETs followed by co-treatment with PI3K or Akt inhibitor. Results show that both exogenous and endogenous EETs could remarkably enhance eNOS expression and its phosphorylation at Ser1179 and Thr497 residues; PI3K inhibitor LY294002 could inhibit EETs-induced increase in eNOS-Ser(P)1179 but had no effect on the change of eNOS-Thr(P)497, while Akt inhibitor could attenuate the increase in phosphor-eNOS at both residues; both of the two inhibitors could block EETs-enhanced eNOS expression. These results lead to conclusions: (i) EETs-mediated regulation of eNOS activity may be related with the changes of phosphoryla-tion level at eNOS-Ser1179 via PI3K/Akt and eNOS-Thr497 via Akt; (ii) PI3K/Akt signaling pathway is involved in the up-regulation of eNOS expression by EETs.

关键词： epoxyeicosatrienoic acids, endothelial nitric oxide synthase (eNOS), PI3 kinase, Protein kinase B (Akt), phosphorylation.

Comparisons of Graph-structure Clustering Methods for Gene Expression Data

在线全文

学校读者我要写书评

暂无评论

Acta Biochimica et Biophysica Sinica 2006年第6期38卷 379-384页

作者： Zhuo FANG~1,Lei LIU~(2,4),Jiong YANG~3,Qing-Ming LUO~(1*),and Yi-Xue LI~(2*) ~1 Hubei Bioinformatics and molecular Imaging Key Laboratory,College of Life science and Technology, Huazhong univer.ity of science and Technology,Wuhan 430074,china ~2 Shanghai center for Bioinformatics Technology,Shanghai 200235,china ~3 department of EECS,Case Western Reserve univer.ity,Cleveland 44106,USA ~4 W.M.Keck center for Comparative and Functional Genomics,univer.ity of Illinois at Urbana-Champaign,Urbana 61801,USA HubeiBioinformaticsandmolecularImagingKeyLaboratory CollegeofLifeScienceandTechnologyHuazhongUniversityofScienceandTechnologyWuhan430074China ShanghaicenterforBioinformaticsTechnology Shanghai200235China W.M

Although many numerical clustering algorithms have been applied to gene expression dataanalysis,the essential step is still biological interpretation by manual *** correlation betweengenetic co-regulation and affiliation to a common biological process is what biologists ***,weintroduce some clustering algorithms that are based on graph structure constituted by biological *** applying a widely used dataset,we compared the result clusters of two of these algorithms in terms ofthe homogeneity of clusters and coherence of annotation and matching *** results show that theclusters of knowledge-guided analysis are the kernel parts of the clusters of Gene Ontology (GO)-Clustersoftware,which contains the genes that are most expression correlative and most consistent with ***,knowledge-guided analysis seems much more applicable than GO-Cluster in a largerdataset.

关键词： clustering expression pattern biological function

氢分子分立区和连续区(11.0—19.0 eV)的光学振子强度研究

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

物理学报 1999年第5期48卷 816-824页

作者：钟志萍张卫华徐克尊凤任飞李家明清华大学现代应用物理系单原子分子测控科学与技术研究中心中国科学技术大学近代物理系中国科学院物理研究所

利用通道规律，并考虑了转动分布对跃迁峰型的影响，对测量得到的绝对氢分子光吸收谱进行了分析．文中逐个确定了１１０—１５０ｅＶ各振动态的振子强度，并得到了Ｂ′１Σ＋ｕ的解离强度．同时，利用多重散射Ｘα自洽场方法计算了... 详细信息

利用通道规律，并考虑了转动分布对跃迁峰型的影响，对测量得到的绝对氢分子光吸收谱进行了分析．文中逐个确定了１１０—１５０ｅＶ各振动态的振子强度，并得到了Ｂ′１Σ＋ｕ的解离强度．同时，利用多重散射Ｘα自洽场方法计算了氢分子分立区和连续区（１１０—１９０ｅＶ）的光吸收谱．通过计算值和实验绝对测量值的比较可以说明，在自洽层次。

关键词：氢分子振动光谱连续区分立区光学振子强度

用类氧原子波函数计算H_7^-团簇正八体中心结构的能量曲线

在线全文

学校读者我要写书评

暂无评论

原子与分子物理学报 1999年第1期16卷 69-72页

作者：朱俊卿勇四川联合大学应用物理系四川联合大学原子分子物理研究所

选用类氧原子波函数，在单中心球模型近似下，利用变分法计算了Ｈ－７团簇正八面体中心结构的能量曲线。结果表明，当中心Ｈ原子核到顶角Ｈ原子核之间的距离Ｒ＝１．５８ａ０时，体系能量有一极小值－４．０８９４５３ｈ．ａ．ｕ．。这... 详细信息

选用类氧原子波函数，在单中心球模型近似下，利用变分法计算了Ｈ－７团簇正八面体中心结构的能量曲线。结果表明，当中心Ｈ原子核到顶角Ｈ原子核之间的距离Ｒ＝１．５８ａ０时，体系能量有一极小值－４．０８９４５３ｈ．ａ．ｕ．。这表明Ｈ－７的正八面体中心结构是可能稳定存在的。计算结果与用ＭＡＣＱＭ法计算的结果基本相符，表明提出的物理模型及其计算方法是合理的。

关键词： H7^-团簇能量单中心球模型类氧原子波函数

SEMI-CRYSTALLINE PROPERTIES AND PHOTOPOLYMERIZATION KINETICS OF MODIFIED DENDRITIC POLY（ETHER-AMIDE）

在线全文

学校读者我要写书评

暂无评论

SEMI-CRYSTALLINE PROPERTIES AND PHOTOPOLYMERIZATION KINETICS...

Ab-initio molecular dynamics simulation on nano-system under external pressure

The 8th International Conference on Radiation Curing

作者： Wei Huanyu Kou Huiguang Shi Wenfang department of applied chemistry univer.ity of science and Technology of china Hefei Anhui 230026 P. R. china

＜正＞The dendritic poly （ether-amide）（DPEA-OH） was modified with octadecyl . isocyanate, toluene-2,4-diisocyanate and β -hydroxylethyl acrylate, producing a UV curable resin with crystalline molecular shell and amorphous interior. The ratio of these modifiers can adjust the products’ final properties to fulfil the requirements of UV curable powder coatings. The degree of crystallinity is higher with more crystallizable moieties grafted from the XRD measurements. The crystallizable resins obtained have a Tg of 41- 45℃ and a Tm of around 120℃. Their photopolymerization kinetics was also investigated.

关键词： Powder coating Dendritic poly (ether-amide) Curing kinetics Semi-crystallinity

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

science china Mathematics 2004年第z1期47卷 92-100页

作者： Jl Min, SUN Deyan & GONG XingaoSurface Physics Laboratory and department of Physics, Fudan univer.ity, Shanghai 200433, china institute of Solid State Physics, Chinese Academy of sciences, Hefei 230031, china Interdisciplary center for Theoretical studies, Chinese Academy of sciences, Beijing 100080, china Fudan Univ Surface Phys Lab Shanghai 200433 Peoples R China Fudan Univ Dept Phys Shanghai 200433 Peoples R China Chinese Acad Sci Inst Solid State Phys Hefei 230031 Peoples R China Chinese Acad Sci Interdisciplinary Ctr Theoret Studies Beijing 100080 Peoples R China

A new constant-pressure molecular dynamics (MD) method is developed to simulate the dynamic behavior and structure transition of finite system under external pressure. In this method, no artificial parameter is introduced and the computation overheads are very small. As an application, a hard-soft transition of single wall carbon nanotube (SWCNT) under external pressure is found, which is in agreement with the experiments.

关键词： phase transition, simulation, nano-particles

Back Compton Scattering in Strong Uniform Magnetic Field

在线全文

学校读者我要写书评

暂无评论

Back Compton Scattering in Strong Uniform Magnetic Field

Grouping of amino acids and recognition of protein structurally conserved regions by reduced alphabets of amino acids

6th china-Japan Joint Nuclear Physics Symposium

作者： W.Xu~(* +) Wei Huang~+ Mu-Lin Yan~+ ~*Shanghai institute of applied Physics Chinese Academy of sciences Shanghai 201800 P.R.china ~+interdisciplinary center for Theoretical Study department of Modern Physics univer.ity of science and Technology of china Hefei Anhui 230026 china

＜正＞In this paper,we show that there is a Non-Commutative Plane（NCP）in the perpendicular magnetic fields in the accelerator,and the QED with NCP（QED-NCP）has been formulated. Being similar to the theory of quantum Hall effects,an effective filling factor f（B）is introduced, which characters the possibility occupied the LLL state by the electrons living on NCE The back Compton scattering amplitudes of QED-NCP are derived,and the differential cross sections for the process with fixed initial polarizing electrons and photons are *** propose to precisely measure the polarization dependent differential cross sections of the back Compton scattenng in the perpendicular magnetic fields experimentally,which may lead to reveal the effects of QED with *** should be interesting and *** existing Spring-8’s data have been analyzed primitively,and some hints for QED-NCP effects are seen.

关键词： Compton backscattering Non-Commutative Quantum Field Theory Quantum hall effect

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

science china(Life sciences) 2007年第3期50卷 392-402页

作者： LI Jing1 & WANG Wei1,2 1 national Laboratory of Solid State Microstructure and department of Physics, Nanjing univer.ity, Nanjing 210093, china 2 interdisciplinary center of Theoretical Studies, Chinese Academy of sciences, Beijing 100080, china 1. national Laboratory of Solid State Microstructure and department of Physics Nanjing University Nanjing 210093 China 2. interdisciplinary center of Theoretical Studies Chinese Academy of Sciences Beijing 100080 China

Sequence alignment is a common method for finding protein structurally conserved/similar regions. However, sequence alignment is often not accurate if sequence identities between to-be-aligned se- quences are less than 30%. This is because that for these sequences, different residues may play similar structural roles and they are incorrectly aligned during the sequence alignment using substitu- tion matrix consisting of 20 types of residues. Based on the similarity of physicochemical features, residues can be clustered into a few groups. Using such simplified alphabets, the complexity of protein sequences is reduced and at the same time the key information encoded in the sequences remains. As a result, the accuracy of sequence alignment might be improved if the residues are properly clustered. Here, by using a database of aligned protein structures (DAPS), a new clustering method based on the substitution scores is proposed for the grouping of residues, and substitution matrices of residues at different levels of simplification are constructed. The validity of the reduced alphabets is confirmed by relative entropy analysis. The reduced alphabets are applied to recognition of protein structurally conserved/similar regions by sequence alignment. The results indicate that the accuracy or efficiency of sequence alignment can be improved with the optimal reduced alphabet with N around 9.

关键词： Grouping of amino acids and recognition of protein structurally conserved regions by reduced alphabets of amino acids