检索结果-南通市图书馆

Randomization of protein encoding gene during species evolution

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 1998年第4期43卷 299-303页

作者： GE Weiwen 1 and HE Fuchu 2.1. Institute of Hygiene and Environment Medicine, Tianjin 3.0050, china 2. Institute of {2. Medicine, Beijing 100850, china Institute of Hygiene and Environment Medicine Tianjin China Institute of radiation Medicine Beijing China

Employing chi_square test, the authors observed the bias of 4 kinds of bases’ locating in 3.codon positions in gene sequence, and proved that there is a positive correlation between higher chi_square value and protein coding structure. By this, the observation that genes undergo progressive reduction in chi_values along evolution direction will reflect the progressive randomization of gene structures and the loss of the characteristics of protein coding sequences. The result proposed that during the evolution of life, genes are unexpectedly degenerating.

关键词： chi_square test gene sequence randomization evolution.

Human hepatopoietin augmenter of liver regeneration──A hepatotrophic factor for liver regeneration, and its potential antihepatitis effect in vivo

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 1998年第12期43卷 1026-1031页

作者： YANG Xiaoming 1, WANG Aimin 2. ZHOU Ping 3. XIE Ling 1, WANG Qingming 1, WU Zuze 1 and HE Fuchu 1 1. Institute of radiation Medicine, Beijing 100850, {2. 2. No. 2.2.Hospital of PLA, Baoding 071000, {2. 3. General Hospital of the Air Institute of radiation Medicine Beijing China No. 2.2.Hospital of PLA Baoding China General Hospital of the Air Force of PLA Beijing China

The effect of human hapatopoietin i.e. augmenter of liver regeneration (hALR) was determined on hepatocyte DNA synthesis, and on CCl 4-induced hepatitis in animal in vitro and in vivo. It is found that ALR could directly stimulate DNA synthesis of hepatocytes in primary culture in a dose-dependent manner. In 3.% hepatectomied rats, significant DNA synthesis occurred in control rats ; even so, exogenous hALR gene encoding protein increased DNA synthesis of regeneration liver by 2.3.fold compared with control rats. A lower dose of CCl 4 was administrated in rats and the effect of ALR on DNA synthesis of regenerating liver 48 h after CCl 4 administration was analyzed. Few Budr-labeled hepatocytes were visible in control rats. However, exogenous hALR markedly increased the number of labeled cells in a dose-dependent manner. Statistical analysis showed that 10 or 40 μg·kg -1 ALR protein stimulated DNA synthesis by 1.7 and 4.8 fold respectively. In addition to enhancing cell growth, adiministration of hALR achieved a significant improvement in reversing the lethality of rat hepatic failure when compared with that of control group; the elevation of cytosolic enzymes was dramatically suppressed by exogenous hALR in CCl 4-treated mice in vivo and in vitro; histologically, hepatocytes around the central vein were necrotic, and the degree of hepatocyte necrosis in control mice was more prominent than that in the mice given 40 μg·kg-1 hALR 48 h after CCl 4 administration. We also noted that hALR had a strong antihepatitis effect in vitro which was determined with primary cultured rat hepatocytes. These findings suggest that hALR protects the integrity of hepatocytes against severe hepatitis, and indicate that ALR may be an important regulator of liver regeneration and play a major role in liver injury repair. It proves ALR adminstration to be a useful treatment to accelerate liver regeneration and to prevent the onset of hepatitis or intrahepatic cholestasis induced by toxin.

关键词： liver regeneration hepatopoietin DNA synthesis hepatitis.

Compression behavior of Zr_(41)Ti_(14)Cu_(12.5)Ni_(10)Be_(2..5) bulk metallic glass up to 2. GPa

在线全文

学校读者我要写书评

暂无评论

Science china(Physics,Mechanics & Astronomy) 2005年第3期48卷 319-324页

作者： LI Gong 1, 2., ZHAN Zaiji 2., LIU Jing 3., YUN Jinku 1 , SUN Liling 2., LIU Riping 1 , ZHANG Jun 2.& WANG Wenkui 1, 2.1. Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, china 2. {2. for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080, china 3. BSRF, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 10003., china Key Laboratory of Metastable Materials Science and Technology Yanshan University Qinhuangdao China center for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Beijing China BSRF Institute of High Energy Physics Chinese Academy of Sciences Beijing China

The compression of a Zr41Ti14Cu12.5Ni10Be2..5 bulk metallic glass (BMG) is investigated at room temperature up to 2. GPa using in-situ high pressure energy dispersive X-ray diffraction with a synchrotron radiation source. The pressure-induced structural relaxation is exhibited. It is found that below about 8 GPa, the existence of excess free volume contributes to the rapid structural relaxation, which gives rise to the rapid volumetric change, and the structural relaxation results in the structural stiffness under higher pressure.

关键词： bulk metallic glass, high pressure, structural relaxation, synchrotron radiation.

Interannual variability of Antarctic Oscillation and its influence on East Asian climate during boreal winter and spring

在线全文

学校读者我要写书评

暂无评论

Science china Earth Sciences 2006年第5期49卷 554-560页

作者： FAN Ke1,2.3.& WANG Huijun2.1. Nansen-Zhu International Research center, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 10002., {2. 2. Department of Atmospheric Science, Yunnan University, Kunming 650091, {2. 3. Graduate University of the Chinese Academy of Sciences, Beijing 100049, {2. Nansen-Zhu International Research center Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China Department of Atmospheric Science Yunnan University Kunming China Graduate University of the Chinese Academy of Sciences Beijing China

The interannual variability of Antarctic Oscillation (AAO) and its influence on East Asian climate during both boreal winter and spring are addressed. The results show that the positive AAO anomaly decreases the cold activity over East Asia during both boreal winter and spring. AAO-related barotropic meridional teleconnection from Antarctic to Arctic is found through analysis of mean me- ridional circulations. This meridional teleconnection is remarkable over Eurasia during boreal winter and over the Pacific Ocean during boreal spring. The results also show that zonal mean zonal wind at high latitudes in Southern Hemisphere has well positive correlation with that of Eurasia during boreal winter and has negative correlation with Pacific North American teleconnection (PNA) during boreal spring, which again display the meridional teleconnection. Thus, local meridional teleconnection is a possible linkage for interaction of circulations at mid-high latitudes between both hemispheres.

关键词： Antarctic Oscillation, Eurasian west wind, meridional teleconnection, mean meridional circulation.

Comprehensive evaluation of mechanism of "chimney effect" using principles of magnetism, geochemistry and mineralogy

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 1998年第9期43卷 743-748页

作者： LIU Qingsheng 1, CHENG Tongjin 2.and LIU Shugen 3.1. Department of Applied Geophysics, china University of Geosciences, Wuhan 43.074, china 2. center of Petroleum Geochemistry, china National Star Petroleum Corporation, Hefei 2.0}02., china 3. The St Department of Applied Geophysics China University of Geosciences Wuhan China center of Petroleum Geochemistry China National Star Petroleum Corporation Hefei China The State Key Laboratory of Oil/Gas Reservoir Geology and Exploitation of china Chengdu Institute of Technology Chengdu China

Study of forming mechanism of "chimney-effect" (CE) has important significance for basic theory and applications of non-seismic geophysical and geochemical methods locating oil/gas reservoirs. The theoretical basis of comprehensive evaluation of mechanism of CE using principles of magnetism, geochemistry and mineralogy has been reviewed, with the problems to be solved: (ⅰ) study for the relationship between process of oil/gas migration and geochemical field; (ⅱ) analysis of genesis of magnetic, geochemical and mineralogical anomaly; (ⅲ) interpretation of surface soil magnetism and geochemical anomaly combined with seismic data.

关键词： chimney effect (CE) hydrocarbon microseepage oil/gas accumulation.

Study on lithogeochemistry of Middle Jurassic basalts from southern china represented by the Fankeng basalts from Yongding of Fujian Province

在线全文

学校读者我要写书评

暂无评论

Science china Earth Sciences 2006年第10期49卷 1020-1031页

作者： ZHOU Jincheng1,2. JIANG Shaoyong1,2. WANG Xiaolei1,2. YANG Jinghong 1,2.& ZHANG Mengqun 3.1. State Key Laboratory of Mineral Deposit Research, Nanjing University, Nanjing 2.0093. {2. 2. Department of Earth Sciences, Nanjing University, Nanjing 2.0093. {2. 3. Modern Analysis center, Nanjing University, Nanjing 2.0093. {2. State Key Laboratory of Mineral Deposit Research Nanjing University Nanjing China Department of Earth Sciences Nanjing University Nanjing China Modern Analysis center Nanjing University Nanjing China

There exists an E-W trending Middle Jurassic volcanic zone in southern china. The Fankeng basalts in the Yongding basin of Fujian Province are considered to be a typical example. The Fankeng basalts have TiO2.contents in the range of 1.92.-3.2.%. They are classified as high-Ti basalts. They also have higher total Fe (averaging FeO* = 11.09%). The Middle Jurassic Fankeng basalts from southwestern Fujian have obvious distinctive lithogeochemical features from early Cre- taceous basalts from southeastern coast of china. They have higher HFSE, such as Th, Nb, Ta, Zr and Ti. Their element ratios related with HFSE, such as Zr/Ba, La/Nb, La/Ta ,Zr/Y, Ti/Y, Ba/Nb, K/Ti and Rb/Zr are similar to those of OIB. The most samples have ε Nd(T) of-0.70-0.2., which are near chondrite. Some samples have higher ε Nd(T) of ***, these basaltic magmas might be derived from depleted asthenospheric mantle. The lithogeochemical characteristics of the Fankeng basalts may be caused by interaction between asthenosphere and lithosphere at the time. The (Early-) Middle Jurassic basalts and gabbros from southeastern Hunan, southern Jiangxi and northern Guangdong provinces show similar geochemical features to those of the Fankeng basalts from the Yongding of Fujian. Occurrence of these OIB-type basalts in the area may be regarded as the petrological mark of upwelling of asthenosphere at the time. Upwelling of asthenosphere has led to tectonic extension and the formation of rifted basin in the area.

关键词： interaction between asthenosphere and lithosphere, lithogeochemistry, basalts, Middle Jurassic, southern china.

An integrated decision method for prediction of tropical cyclone movement by using genetic algorithm

在线全文

学校读者我要写书评

暂无评论

Science china Earth Sciences 2005年第3期48卷 429-440页

作者： YANG Yuanqin1 & WANG Jizhi2.1. National Meteorological center, Beijing 100081,china 2. Chinese Academy of Meteorological Sciences, Beijing 100081, china National Meteorological center Beijing China Chinese Academy of Meteorological Sciences Beijing China

In this study an integrated decision method for the multi-prediction results of tropical cyclone movements by using genetic algorithm (GA) has been adopted. A genetic learning artifi- cial neural network (GLANN) as a learning mechanism for track prediction was developed through training with the huge samples of typhoon tracks from 1884 to 2.02. The prediction of typhoon motion is to consider how to suit the dynamic change of environment, where typhoon passed through. The neural network structure is described by GA. A fitness function for choice of GA is given to approach the maximum of fitness (the minimum of the errors). Parallel comparing analyses for prediction abilities of unusual typhoon tracks in recent years by GLANN with multi-forecast methods were conducted. More types of cases were employed in the comparing analyses, which consist of the typhoon, Winnie, No.11, in 1997, characterized by a long life over the ocean and in the mainland with severe effect on china, the 10 unusual typhoon tracks in the 1990s, the tracks with landfall and affected action in 1998 and the typhoons born in the Northwestern Pacific and the South china Sea in 2.00, including the 2.—48 h forecast, etc. The results indicated that for prediction ability of typhoon tracks, specially for unusual typhoons, GA decision-making developed in this study is superior to the others.

关键词： genetic algorithm, integrated decision, prediction of tropical cyclone.

A new family of windows——convolution windows and their applications

在线全文

学校读者我要写书评

暂无评论

Science china(Technological Sciences) 2005年第4期48卷 468-480页

作者： ZHANG Jieqiu1,2. LIANG Changhong1 & CHEN Yanpu3.1. Department of Applied Math. & Phys., College of Science, Airforce Engineering University, Xi’an 710051, china 2. National Key Laboratory of Antennas and Microwave Technology, Xidian University, Xi’an 710071, china 3. Computer center, Xi’an Communication College, Xi’an 710106, china Department of Applied Math. & Phys. College of Science Airforce Engineering University National Key Laboratory of Antennas and Microwave Technology Xidian University Computer center Xi"an Communication College

A new family of windows is constructed by convolutions via a few rectangular windows with same time width and is thus referred to as convolution windows. The expressions of the second-order up to the eighth-order convolution windows in both the time and frequency domains are derived. Their applications in high accuracy harmonic analysis of periodic signals are investigated. Comparisons between the proposed windows and some known windows with the same width shows that, when the synchronous deviation of data sampling is slight, the proposed ones have the least effect of spectral leakage. Therefore, the new windows are well suited for high accuracy harmonic analysis and parameter estimation for periodic signals. The error analysis and computer simulations show that the estimation errors, corresponding to frequency, amplitude and phase of every harmonic component of a signal, are proportional to the pth power of the relative frequency deviation in case of the pth-order convolution window is applied to windowing signal of approximately p cycles. By introducing real time adjustment in sampling interval, the proposed algorithm can adaptively trace signal frequency and lead to less sampling synchronous deviation. The proposed approach has the advantages of easy implementation and high measure precision and can be used in harmonic analysis of quasi-periodic signals whose fundamental frequency drifts slowly with time.

关键词： signal processing harmonic analysis window function convolution window synchronous error spoctral leakage

Scale correlation between vegetation and soil in larch forest, NE china

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2001年第1期13卷 51-57页

作者： MA Ke ming 1, ZU Yuan gang 2. Michel Godron 3.(1. Reserch center for Eco Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, {2.. E mail: mkm@*** 2. Open Research Laboratory of Forest Plant Ecology, Northeast Fo Research center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 Chin

After the analysis on the linages of species, the fractal dimensions of vegetation and soil in a managed larch(Larix gmelini) forest in Daxingan Mountains, NE china were estimated separately, and their scale correlation was discussed. (1) The dominant species of the larch forest, larch and the important accompany species, birch (Betula platyphylla) were homogeneously distributed along the transect. The other species were heterogeneous, and can be divided into three groups located on the right, left and central parts of the transect respectively. The transect can be separated into two parts at the position for the 2.th quadrat(580m). (2. The fractal dimension in the large scale range from 2.0 to 400m was lower than that in the small scale range from 0 to 2.0m in the forest, indicating the different variation regularities of spatial heterogeneity in different scale ranges. The inflection point at 2.0m was one of the key scales of spatial hierarchy of the larch forest. (3. The scale variation of the forest was correlated with that of soil pH on large scales, which reflected the indirect control of the dominant species to the spatial pattern and species distribution of understorey by changing soil acidity in the forest and the indirect effects of forest management.

关键词： fractal dimension larch forest scale variation soil spatial heterogeneity species linkX