检索结果-南通市图书馆

Fluorescence dynamics of interactions between polyamide PyPyPyβDp and DNA

science china Chemistry 2006年第1期49卷 75-80页

作者： ZHANG Huijuan1,2, WANG Jin3. WU Yishi1, YUAN Gu3. AI Xicheng1, WANG Li4 & ZHANG Jianping1 1. State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of sciences, beijing 100080, china 2. School of Life science and technology, beijing Institute of technology, beijing 100081, china 3. college of Chemistry and Molecular Engineering, Peking University, beijing 100080, china 4. Center for Condensed Matter Physics, Institute of Physics, Chinese Academy of sciences, beijing 100080, china Correspondence should be addressed to Ai Xicheng and Zhang Jianping 1. State Key Laboratory for Structural Chemistry of Unstable and Stable Species Institute of Chemistry Chinese Academy of Sciences Beijing 100080 China 2. School of Life science and technology Beijing Institute of Technology Beijing 100081 China 3. college of Chemistry and Molecular Engineering Peking University Beijing 100080 China 4. Center for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Beijing 100080 China

The photophysical properties of the polyamide PyPyPyβDp (PPP) were investigated by means of steady-state absorption and fluorescence spectroscopies, as well as time-resolved fluo-rescence spectroscopy. It was found that the excited-state properties of PPP are very sensitive to solvents. In TKMC buffer PPP exhibited weak fluorescence with a decay time constant of 16 ps, while with the decrease of the solvent polarity PPP showed the blue-shifted peak position, increased inten-sity and lengthened life-time for its fluorescence behavior. In the presence of calf thymus DNA, it was observed that the fluorescence intensity was enhanced and the fluorescence lifetime increased from 16 to 3. ps for PPP, which verified that PPP bound into the minor groove of DNA duplex.

关键词： polyamide (PPP), calf thymus DNA (ctDNA), time-resolved fluorescence spectroscopy, recognition dynamics.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Surface Nanocrystallization of Magnesium Alloy AZ91D by High-Energy Shot Peening

引用

Journal of Wuhan University of technology(Materials science) 2009年第4期24卷 515-519页

作者：张津 School of Materials science & Engineering University of Science and Technology Beijing college of Materials science & Engineering Chongqing University of Technology

High-energy shot peening （HESP）, a method to produce severe plastic deformation by high velocity flying balls, was applied on die cast magnesium alloy AZ91D. Effects of surface nanocrystallization by HESP and heat treatment at different temperatures were investigated. The mi- crostructure evolution was conducted using X-ray diffraction （XRD） and field emission scanning electronic microscopy （FESEM）. The hardness was measured by microhardness tester. The experimental results show that surface nanocrystrallization of AZ91D obtained by HESP would lead to the increase of microhardness. Low temperature heated at 100℃ for 1 h do not change the property obviously. However, both the microstructure and microhardness vary greatly after heat treatment at 400℃ for 1 h.

关键词： AZ91 D surface nanocrystallization HESP microhardnss corrosion resistance

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

A class of discounted models for singular diffusion control

引用

Chinese science Bulletin 2000年第5期45卷 405-408页

作者： LIU Kunhui, QIN Mingda & LU Chuanlai1. college of sciences, Northern Jiaotong University, beijing 100044,{3. 2. Department of Mathematics and Mechanics, beijing University of science and technology, beijing 100083..china 3. Department of Information Engineering, beijing University of Posts and Telecommunications, beijing 100876,{3. Correspondence should be addressed to Lu Chuanlai college of sciences Northern Jiaotong University Beijing China Department of Mathematics and Mechanics Beijing University of Science and Technology Beijing China Department of Information Engineering Beijing University of Posts and Telecommunications Beijing China

A kind of discounted problems for singular diffusion control have been studied. The drift and diffusion coefficients of state process are nonlinear. The class of models has been basically extended from a corresponding one established by Karatzes et al. before. By applying some analysis methods different from earlier works, the sufficient and necessary conditions of the existence of optimal control have been obtained. If an optimal control exists, it is a 'transient reflection' of state process for two lines.

关键词： stochastic control variational equation singular stochastic control.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Edaphic factors determining variation of two ecotypes of Leymus chinensis in North china

引用

Progress in Natural science:Materials International 2006年第11期16卷 1150-1155页

作者： ZHOU Chan~1 and YANG Yunfei~2**(1. MOE Key Laboratory of Environmental Change and Natural Disasters, college of resources science and {3., beijing normal University, beijing 100875, china 2. Key Laboratory of Vegetation Ecology, Ministry of Education, Institute of Grassland science, Northeast normal University, Changchun 13.024, china) [a]MOE Key Laboratory of Environmental Change and Natural Disasters College of Resources Science and Technology Beijing Normal University Beijing China [b]Key Laboratory of Vegetation Ecology Ministry of Education Institute of Grassland Science Northeast Normal University Changchun China

To identify ecotypic variation of L. chinensis, the physiological characteristics and environmental factors were measured and assessed for grey-green and yellow-green ecotypes of L. chinensis grown in the salt-alkalized and aeolian sandy soils. Although both ecotypes presented a similar salt-alkaline tolerance under the experimental conditions, they differed in several aspects. The L. chinensis grown in the aeolian sandy soils had higher water potential and chlorophyll content and lower proline content in their leaves than those grown in the salt-alkalized habitat, and the grey-green ecotype of L. chinensis in both types of soils had higher water potential, chlorophyll and proline contents than the yellow-green ecotype. Besides, grey-green ecotypes had higher salt-alkaline tolerance than the yellow-green ecotype. The stepwise regression analysis showed that soil conductance and pH value were the main ecological factors affecting the physiology of L. chinensis. From the natural distribution of the two ecotypes, we considered that salt-alkaline in the soils is the leading factor in determining ecotypic variation of L. chinensis. The two ecotypes were first named grey-green and yellow-green ecotypes respectively.

关键词： L.chinensis ecotype adaptability variation ecological factor salt-alkaline in soil.

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Study on the changes of water cycle and its impacts in the source region of the Yellow River

引用

science china(Technological sciences) 2004年第z1期47卷 142-151页

作者： ZHANG Shifeng1, JIA Shaofeng1, LIU Changming1, CAO Wenbing2, HAO Fanghua3. LIU Jiuyu4 & YAN Huayun5 1. Institute of Geographic sciences and Natural resources Research, Chinese Academy of sciences, {3. 100101, china 2. china University of Geosciences, {3. 100083. china 3. {3. normal University, beijing 100875, china 4. Bureau of Hydrology of Yellow River Conservancy Commission, Zhengzhou 450003. china 5. Bureau of Hydrology and Water Resource Investigation of Qinghai Province, Xining 810001, china 1. Institute of Geographic sciences and Natural resources Research Chinese Academy of Sciences 100101 Beijing China2. China University of Geosciences 100083 Beijing China3. Beijing Normal University 100875 Beijing China4. Bureau of Hydrology of Yellow River Conservancy Commission 450003 Zhengzhou China5. Bureau of Hydrology and Water Resource Investigation of Qinghai Province 810001 Xining China

The water cycle in the source region of the Yellow River underwent great changes in the 1990s. The major features of the changes are as follows: the gauged runoff declined significantly while the precipitation increased slightly, and the runoff process was more concentrated on the flood season. Water balance analyses indicate that the pondage was kept in the status of negative equilibrium, causing eco-environmental problems. The runoff decrement is due to evaporation increment in this region. Studies show that the runoff process in this region is closely related to that of the other hydrological stations in the upper reaches. When the runoff declines in the source regions, the amount of water also declines in the whole upper reaches of the Yellow River, affecting the balance between water demand and supply. Meanwhile changes will take place in the water cycle of the river course system when the eco-environment deteriorates. The trend of water cycle change in the source region is that the runoff will keep declining with the increment of evaporation caused by temperature rise in the northwest of china in the 21st century. But the hydraulic engineering in the source region will help to mitigate the deterioration of local eco-environment system, though the impacts to the lower reaches of this project may not be the case.

关键词： source region of the Yellow River, water cycle, evaporation, negative equilibrium.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Theorems for Testing Local Activity of CNN and Application to Cardiac Purkinje Equations

引用

International Journal of Minerals,Metallurgy and Materials 2000年第2期14卷 139-146页

作者： Lequan Min(Applied science School, University of science and technology {3., {3. 100083. china) Applied science School University of Science and Technology Beijing Beijing 100083 China

The theorems for testing the local in one-port cellular neural/inear network (CNN) cells with four local state variables are presented. Using the theorems computes the bifurcation diagrams of the cardiac Purkinje fiber (CPE) equations Which describethe long-lasting action and pace-maker potentials of the Purkinje fiber of the heart. The computer simulation shows that periodic trajectories or convergent trajectories of the CPF Equations can be foun if the cormsponing cell Parameters are located in a positive domainbut nearby edge of chaos. In particular a heart with approximate normal frequency of heartbeat but non-normal electrocardiogram maysuddenly stop by slightly perturbing the parameters of the corresponding CPF Equations when the Paramders are located nearby the edge of chaos in the bifurcation diagrams. This research seems to interpret reasonbly the phenomena that patients with cardiac diseases might suddenly die without warning.

关键词： cellular neural network local activity cardiac Purkinje fiber heartbeat

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Digital close-range photogrammetric application to small-scale physical simulation experiment

引用

中国有色金属学会会刊：英文版 2011年第S3期21卷 681-685页

作者： LI Chun-yi1, CUI Xi-min2, YU Yi-ju3.1. School of Surveying and Landing Information Engineering, Henan Polytechnic University, Jiaozuo 454003. china 2. college of Geoscience and Surveying Engineering, china University of Mining and technology, beijing 100083. china 3. Surveying and Mapping Press, beijing 100045, china [a] School of Surveying and Landing Information Engineering Henan Polytechnic University Jiaozuo 454003 China [b] college of Geoscience and Surveying Engineering China University of Mining and Technology Beijing 100083 China [c] Surveying and Mapping Press Beijing 100045 China

In order to research the possibility of digital close-range photogrammetric surveying in small scale physical simulation experiment, physical model coinciding with engineering practice was constructed based on similar theory. The datum processing method and surveying precision of digital close-range photogrammetric were analyzed. And the function relationship between overburden subsidence factor qr and the ratio z/H of stratum horizon z and mining depth H was researched. The results show that surveying points position mean error along horizontal direction is ±0.13. mm and vertical direction is ±0.192 mm. Therefore, multi-taking station cross direction digital close-range photogrammetric can completely satisfy the precision need of physical simulation experiment. And the empirical formula can be utilized to represent evolution law of stratum subsidence factor.

关键词： close-range photogrammetric physical simulation light-rays adjustment surveying precision subsidence factor

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Estimating surface evapotranspiration using combined MODIS and CBERS-02 data

引用

science china(Technological sciences) 2005年第S2期48卷 145-160页

作者： XIN Xiaozhou1,2, LIU Qinhuo1, TANG Yong1,3. TIAN Guoliang1, GU Xingfa1, LI Xiaowen1,2, ZHENG Hongsheng4 & CHEN Jiayi4 1. State Key Laboratory of Remote Sensing science, Institute of Remote Sensing Applications, Chinese Academy of sciences, beijing 100101,{3. 2. Research Center for Remote Sensing and GIS, Department of Geography, beijing normal University, beijing 100875,{3. 3. Graduate University of Chinese Academy of sciences, beijing 10003.,{3. 4. Department of Atmospheric Physics, Peking University, beijing 100871,{3. 1. State Key Laboratory of Remote Sensing science Institute of Remote Sensing Applications Chinese Academy of Sciences 100101 Beijing China2. Research Center for Remote Sensing and GIS Department of Geography Beijing Normal University 100875 Beijing China3. Graduate University of Chinese Academy of Sciences 100039 Beijing China4. Department of Atmospheric Physics Peking University 100871 Beijing China

Spatial scale error is one of the most serious problems in the estimates of land surface heat fluxes of sensible and latent from satellite-borne data such as MODIS 1km resolution reflectance and emissive data. One of the feasible and economic ways to decrease the spatial scale error is to use high resolution land use class data together with the MODIS data. CBERS-02 data were used to produce land use class of Baiyangdian area, Hebei Province, china in the autumn of 2004. The area ratio of each class in MODIS pixel was calculated, and used to derive the heat fluxes of the mixed pixel. The results showed that the estimated heat fluxes of soil, sensible and latent have been changed remarkably after using the high resolution land class data. It could be concluded from the comparison between simulated and ground-measured fluxes as well as the theoretical analysis that high resolution land class data are useful to diminishing the scale error of heat fluxes estimated from low resolution satellite data.

关键词： surface evapotranspiration spatial scale error MODIS CBERS land class.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Influence of valence electron structures of phase and biphase interfaces of sulfides on hot brittleness in steel

引用

science china(Technological sciences) 2004年第4期47卷 488-504页

作者： LIU Yan1,3. LIU Zhilin1, ZHANG Chengwei1,2 & ZHOU Yingchun1 1. Liaoning Institute of technology, Jinzhou 121001, china 2. china National Oil and Gas Exploration and Development Corporation, {3. 100011, china 3. college of science, Northeastern University, Shengyang 110006, china 1. Liaoning Institute of technology 121001 Jinzhou China 2. college of science Northeastern University 110006 Shengyang China 3. china National Oil and Gas Exploration and Development Corporation 100011 Beijing China

This paper calculates the electron structures of phase of FeS, MnS and their biphase interface electron structures with austenite in steel. The precipitation and the transformation of FeS and MnS are investigated through studying the valence electron pair numbers on the strongest bond n A with the structure formation factor S. The continuity of electron density and its relation with stress are explored in the biphase interfaces with the electron density difference απ Using n A, S, απ we explain the reason why FeS can bring about hot brittleness in steel and the physical mechanism why MnS may eliminate or inhibit hot brittleness, based on which satisfying results are obtained by calculating several rare-earth sulfides.

关键词： valence electron structure, sulfide, hot brittleness, and rare earth.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Multiparty simultaneous quantum identity authentication with secret sharing

引用

science china(Physics,Mechanics & Astronomy) 2008年第3期51卷 321-327页

作者： YANG YuGuang1,2,WEN QiaoYan3.& ZHANG Xing4,5 1 college of Computer science and technology,{3. University of technology,{3. 100022,china 2 State Key Laboratory of Information Security (Graduate University of the Chinese Academy of sciences),{3. 100049,china 3.School of science,{3. University of Posts and Telecommunications,{3. 100876,china 4 Institute of Electronic technology,Information Engineering University,Zhengzhou 450004,china 5 Trusted Computing Laboratory,{3. University of technology,{3. 100022,china college of Computer science technology Beijing University of Technology Beijing 100022 China State Key Laboratory of Information Security [Graduate University of the Chinese Academy of sciences] Beijing 100049 China School of science Beijing University of Posts Telecommunications Beijing 100876 China Institute of Electronic technology Information Engineering University Zhengzhou 450004 China Trusted Computing Laboratory Beijing University of Technology Beijing 100022 China

Two multiparty simultaneous quantum identity authentication (MSQIA) protocols based on secret sharing are presented. All the users can be authenticated by a trusted third party (TTP) simultaneously. In the first protocol,the TTP shares a random key K with all the users using quantum secret sharing. The ith share acts as the authentication key of the ith user. When it is necessary to perform MSQIA,the TTP generates a random number R secretly and sends a sequence of single photons encoded with K and R to all the users. According to his share,each user performs the corresponding unitary operations on the single photon sequence sequentially. At last,the TTP can judge whether the impersonator exists. The sec-ond protocol is a modified version with a circular structure. The two protocols can be efficiently used for MSQIA in a network. They are feasible with current technol-ogy.

关键词： quantum identity authentication secret sharing quantum cryptography

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：