检索结果-南通市图书馆

MECHANICAL PERTURBATION INDUCED MOLECULAR ALIGNMENTS IN A SIDE-CHAIN LIQUID CRYSTALLINE POLYACETYLENE, POLY{10-[4-(4'-METHOXYPHENOXY-CARBOML)PHENOXYCARBONYL]-1-DECYNE}

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 1999年第3期17卷 289-294页

作者： Ben-zhong Tang Xiang-xing Kong Xin-de Feng department of Chemistry, Hong Kong university of Science & Technology, Clear Water Bay, Kowloon, Hong Kong, china department of Polymer Science & Engineering, College of Chemistry, Peking university, Beijing 100871, china department of Chemistry Hong Kong University of Science and Technology Clear Water Bay Kowloon Hong Kong department of Polymer Science and Engineering College of Chemistry Peking University Beijing 100871 China

A new liquid crystalline polyacetylene containing a phenyl benzoate mesogen (5) is synthesized,whose mesomorphic properties are found to be easily 'tunab1e' by simple mechanical perturbation. Thepolymerization of 10- [ 4 - (4' -methoxyphenoxycarbonyl )phenoxycarbonyl] - 1 -decyne (4 ) in itiated by theWCl_6-Ph_4Sn/dioxane complex yields polymer 5 with a M_w of 28400. The molecular structure of 5 ischaracterized by NMR, IR, and UV spectroscopy and its liquid crystalline behavior is investigated by DSC,POM, and XRD analysis. Upon mechanical perturbation, 5 exhibits unusual agitation-induced high-strengthdisclinations, shear-induced inversion walls, and solidification-induced banded textures. Such phenomenahave been observed in the main-chain liquid crystalline polymers with rigid backbones, but have seldom beenreported for the side-chain liquid crystalline polymers with flexible backbones, suggesting that the rigidpolyacetylene backbone of 5 plays a constructive role in inducing the novel molecular alignments.

关键词： Liquid crystals Side-chain liquid crystalline polymers Polyacetylenes High-strength disclinations Inversion walls Banded textures Molecular alignments

PEM:a lightweight program memory encryption mechanism for embedded processor

在线全文

学校读者我要写书评

暂无评论

The Journal of china Universities of Posts and Telecommunications 2010年第1期17卷 77-84页

作者： HUO Wen-jie,LIU Zheng-lin,ZOU Xue-cheng department of Electronics of Science and Technology,Huazhong university of Science and Technology,Wuhan 43.074,china department of Electronics of Science and Technology Huazhong University of Science and Technology Wuhan 430074 China

Application of embedded systems is faced with multiple threats against security. To solve this problem, this article proposes a new program memory encryption mechanism （PEM） to enhance the security of embedded processor. The new mechanism encrypts all the programs via a secure cache structure. It not only caches the instructions read from the off-chip memory, but also stores the pad values used to encrypt the plaintext. It effectively accelerates encryption and reduces the performance overhead. Besides the encryption, PEM also monitors the program modifications and reset behaviors to reduce the risk of vicious tamper. The experiment indicates that PEM has an average of 2.3.% performance improvement and results in a 25.71% power reduction in the write-back stage. The new scheme offers a good balance between performance and security. It is fully practicable for embedded processor.

关键词： embedded processor memory encryption advanced encryption standard (AES) secure cache hardware protection

Antitumor Effect of Antisense Ornithine Decarboxylase Adenovirus on Human Lung Cancer Cells

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 410-416页

作者： Hui TIAN~(1*),Lin LI~1,Xian-Xi LIU~2,and Yan ZHANG~2 ~1 department of Thoracic Surgery,Shandong university Qi Lu Hospital,Jinan 250012,china ~2 Experimental Center of Medical Molecular Biology,School of Medicine,Shandong university,Jinan 250012,china department of Thoracic Surgery Shandong University Qi Lu HospitalJinan 250012 China Experimental Center of Medical Molecular Biology School of Medicine Shandong UniversityJinan 250012 China

Ornithine decarboxylase (ODC),the first enzyme of polyamine biosynthesis,was found toincrease in cancer cells,especially lung cancer *** chemotherapeutic agents aimed at decreasingODC gene expression showed inhibitory effects on cancer cells,ha this study,we examined the effects ofadenoviral transduced antisense ODC on lung cancer *** adenovirus carrying antisense ODC(rAd-ODC/Ex3.s) was used to infect lung cancer cell line *** 3.(4,5-methylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide assay was used to analyze the effect on cell *** of ODC and concentrationof polyamines in cells were determined by Western blot analysis and high performance liquid *** deoxynucleotidyl transferase-mediated biotin-dUTP nick-end labeling was used to analyze *** expression of ODC in A-549 cells was reduced to 54%,and that of three polyamines wasalso decreased through the rAd-ODC/Ex3.s ***,cell growth was substantially inhibitedand terminal deoxynucleotidyl transferase-mediated biotin-dUTP nick-end labeling showed that rAd-ODC/Ex3.scould lead to cell apoptosis,with apoptosis index of 46%.This study suggests that rAd-ODC/Ex3.s has anantitumor effect on the human lung cancer cells.

关键词： polyamine putrescine biosynthesis antisense technology gene therapy A-549 lung cancer cell line

Recent progress and future directions of chinaFLUX

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science china earth sciences 2006年第S2期49卷 1-23页

作者： YU Guirui , FU Yuling, SUN Xiaomin, WEN Xuefa & ZHANG Leiming Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic sciences and Natural Resources Research, Chinese Academy of sciences, Beijing 100101, china School of {3. sciences, Graduate university of the Chinese Academy of sciences, Beijing 100049, china

The eddy covariance technique has emerged as an important tool to directly measure carbon dioxide, water vapor and heat fluxes between the terrestrial ecosystem and the atmosphere after a long history of fundamental research and technological developments. With the realization of regional networks of flux measurements in North American, European, Asia, Brazil, Australia and Africa, a global-scale network of micrometeorological flux measurement (FLUXNET) was established in 1998. FLUXNET has made great progresses in investigating the environmental mechanisms controlling carbon and water cycles, quantifying spatial-temporal patterns of carbon budget and seeking the "missing carbon sink" in global terrestrial ecosystems in the past ten years. The global-scale flux measurement also built a platform for international communication in the fields of resource, ecology and environment sciences. With the continuous development of flux research, FLUXNET will introduce and explore new techniques to extend the application fields of flux measurement and to answer questions in the fields of bio-geography, eco-hydrology, meteorology, climate change, remote sensing and modeling with eddy covariance flux data. As an important part of FLUXNET, chinaFLUX has made significant progresses in the past three years on the methodology and technique of eddy covariance flux measurement, on the responses of CO2 and H2O exchange between the terrestrial ecosystem and the atmosphere to environmental change, and on flux modeling development. Results showed that the major forests on the North-South Transect of Eastern china (NSTEC) were all carbon sinks during 2003.to 2005, and the alpine meadows on the Tibet Plateau were also small carbon sinks. However, the reserved natural grassland, Leymus chinensis steppe in Inner Mongolia, was a carbon source. On a regional scale, temperature and precipitation are the primary climatic factors that determined the carbon balance in major terrestrial ecosystems in

关键词： eddy covariance flux measurement carbon budget terrestrial ecosystem FLUXNET chinaFLUX.

低剂量硝酸镧对小鼠肾脏自由基防御机能的影响

在线全文

学校读者我要写书评

暂无评论

中国稀土学报 2002年第Z2期20卷 190-192页

作者：黄可欣李冬梅聂毓秀吉林大学基础医学院组胚教研室吉林长春130025 长春大学特教部吉林长春130021

通过采用肾组织匀浆生化测定法,观察不同剂量硝酸镧灌胃一个月后,小鼠肾组织中超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、脂质过氧化物(LPO)、谷胱甘肽过氧化物酶(GSH PX)含量的变化,探讨了低剂量硝酸镧的抗氧化作用;结果表明:雌性、雄性... 详细信息

通过采用肾组织匀浆生化测定法,观察不同剂量硝酸镧灌胃一个月后,小鼠肾组织中超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、脂质过氧化物(LPO)、谷胱甘肽过氧化物酶(GSH PX)含量的变化,探讨了低剂量硝酸镧的抗氧化作用;结果表明:雌性、雄性小鼠20.0,10.0mg·kg-1Cu ZnSOD和CAT的含量均较对照组明显降低;而GSH Px和LPO的含量均较对照组显著升高。雌性、雄性小鼠0.1,0.2,2.0mg·kg-1组Cu ZnSOD,CAT,GSH Px和LPO的含量与对照组无显著性差异。较高剂量(20.0,10.0mg·kg-1)的硝酸镧的直接损伤可使小鼠肾脏脂质过氧化反应增强,清除自由基的能力下降。较低剂量(0.1,0.2,2.0mg·kg-1)的硝酸镧对小鼠肾脏自由基的生成和清除无影响。

关键词：稀土金属肾脏小鼠

Chemical components and microtopography of (100) surface for orthopyroxene

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2003年第9期48卷 931-934页

作者： XUE Jiyue, PAN Yuguan, LUO Gufeng & LU Haipingdepartment of earth sciences, Nanjing {3., Nanjing 210093.chinaCorrespondence should be addressed to Xue Jiyue (e-mail: xuezhou@***) department of earth sciences Nanjing University Nanjing 210093 China

XPS and AES depth composition profile studies were carried on to understand chemical components of (100) surfaces for Chengde hypersthene from Hebei Province, china, and Bamble enstatite from Norway. Also, to understand the microtopography of them the AFM observation was carried on. There are obvious differences between chemical components of (100) surface and those of mineral inner. Compared with inner mineral Si4+ proportion in total cations has no distinguished variation, whereas Ca2+ and Al3. proportions increase respectively, and Mg2+ proportion decreases. AES depth composition profile of 2000s shows that at a depth of 70 nm the atomic concentrations (%) for each element (except Si in Chengde hypersthene) slightly go up and down, but the average values have no obvious change. On the profile, the atomic concentrations (%) of Al and Si for Chengde hypersthene present a compensated relationship. Obviously, the Si and Al must have the relationship of isomorphic replacement on the (100) surface. The image of AFM shows that there is hillock growth on the (100) surface in the layered form of the polygon with 0 to several hundreds nm in thickness. The growth is a sort of secondary phyllosilicate minerals. The observation of the above-mentioned phenomenon and the recognition on the above regularities are benefit for understanding of the mechanism for weathering and water-rock reactions.

关键词：化学成分微地貌正辉石 XPS AES深度合成剖面图

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2002年第3期18卷 489-498页

作者： Guo Xing JI Hong Ke DU department of Mathematics, Shaanxi Normal university. Xian 710062. P. R. china department of Mathematics Shaanxi Normal University Xian P. R. China

In this paper, the similarity-invariant subspaces of B(H), which is tile Banach algebra of all bounded linear operators on a separable infinite-dimensional Hilbert space H, are completely characterized and the represe... 详细信息

关键词： Linear operator Similarity-invariant subspace Similarity-preserving linear map

Some new results about Jacobi forms

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 1997年第3期42卷 181-183页

作者： WANG Jupingdepartment of Mathematics, university of Science and Technology of china, Hefei 23.026, china department of Mathematics University of Science and Technology of China Hefei China

THE one-dimensional Jacobi forms were first systematically investigated by Eichler and Zagier, and a similar theory in a higher-dimensional case was developed by Ziegler, who gave the precise definition and some basic properties of higher-dimensional Jacobi forms. This note tries to give a satisfactory classification for a large kind of spaces of Jacobi forms. To be a little more explicit, we get a rank formula for Jacobi forms and then show that either all the

关键词： Jacobi forms rank coefficient estimation.

Phase stability in high entropy alloys:Formation of solid-solution phase or amorphous phase

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2011年第6期21卷 433-446页

作者： Sheng GUO,C.T.LIU Center of Advanced Structural Materials,MBE department, City university of Hong Kong,Kowloon,Hong Kong,china Center of Advanced Structural Materials MBE Department City University of Hong Kong Kowloon Hong Kong China

The alloy design for equiatomic multi-component alloys was rationalized by statistically analyzing the atomic size difference,mixing enthalpy,mixing entropy,electronegativity,valence electron concentration among constituent elements in solid solutions forming high entropy alloys and amorphous *** solution phases form and only form when the requirements of the atomic size difference,mixing enthalpy and mixing entropy are all *** most significant difference between the solid solution forming high entropy alloys and bulk metallic glasses lies in the atomic size *** rules provide valuable guidance for the future development of high entropy alloys and bulk metallic glasses.

关键词： high entropy alloys amorphous alloys bulk metallic glasses phase stability solid solution