检索结果-南通市图书馆

Biotic communities of the marine ecosystem in Meizhou Bay

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental sciences 1996年第1期8卷 48-56页

作者： Ren Jiuchang Cai Xiaoming (Center of Environmental sciences,peking university, beijing 100871,china)Chen Bin(college of life sciences, peking university, beijing 100871, china )li Peng(college of Chemistry and Molecular Engineering, peking university, Bei china

The current situation of biotic communities in Meizhou Bay is presented in this *** species composition,seasonal variation,and distribution of phytoplankton,zooplankton, red tide organisms,fishes,and benthos in Meizhou Bay were investigated,and the content of chlorophyll a and primary production and their seasonal variation were also *** water quality of Meizhou Bay was monitored by measuring the density of Escherichia coli. Results reveal that there is a great variety of species in Meizhou Bay and the water in Meizhou Bay is *** the individual numbers of various organisms are very low, especially those of ***,there are more than 40 species of red tide organisms and there exist opportunities of red tides between May and *** these demand cautious be taken in the future development of this area although it has great environment capacity.

关键词： biotic community marine ecosystem Meizhou Bay.

Anti-nociceptive role of neuropeptide Y in the nucleus accumbens in rats with inflammation, an effect modulated by mu- and kappa-opioid receptors

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2期16卷 133-141页

作者： li Jinju and YU Longchuan (Laboratory of Neurobiology, college of life sciences, and National Laboratory of Biomembrane and Membrane Biotechnology, peking university, beijing 100871, china) [a]Laboratory of Neurabiology College of life Sciences and National Laboratory of Biomembrane and Membrane Biotechnology Peking University Beijing China

Recent study in our laboratory showed that neuropeptide Y (NPY) plays an antinociceptive role in the nucleus accum-bens (NAc) in intact rats. The present study was performed to further investigate the effect of NPY in nociceptive modulation in the NAc of rats with inflammation, and the possible interaction between NPY and the opioid systems. Experimental inflammation was induced by subcutaneous injection of carrageenan into the left hindpaw of rats. Intra-NAc administration of NPY induced a dose-dependent increase of hindpaw withdrawal latencies (HWLs) to thermal and mechanical stimulations in rats with inflammation. The anti-nociceptive effect of NPY was significantly blocked by subsequent intra-NAc injection of the Y1 receptor antagonist NPY28-36, suggesting an involvement of Y1 receptor in the NPY-induced anti-nociception. Furthermore, intra-NAc administration of the opioid antagonist naloxone significantly antagonized the increased HWLs induced by preceding intra-NAc injection of NPY, suggesting an involvement of the endogenous opioid system in the NPY-induced anti-nociception in the NAc during inflammation. Moreover, the NPY-induced anti-nociception was attenuated by following intra-NAc injection of the μ-opioid antagonist β-funaltrexamine (β-FNA), and κ-opioid antagonist nor-binaltorphimine (nor-BNI), but not by S-opioid antagonist naltrindole, indicating that μ- and K-opioid receptors, not S-opioid receptor, are involved in the NPY-induced anti-nociception in the NAc in rats with inflammation.

关键词： nucleus accumbens, neuropeptide Y, Y1 receptor, carrageenan anti-nociception, μ- and κ-opioid receptors.

Induction of apoptosis in purified animal and plant nuclei by Xenopus egg extracts

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Cell Research 1999年第2期9卷 79-90页

作者： JIANG ZHENG FAN SHAN ZHU YING li SUN ZHONG HE ZHAI (college of life sciences, peking university, beijing 100871, china) 1college of life sciences Peking University Beijing 100871 China 1college of life sciences Peking University Beijing 100871 China 1college of life sciences Peking University Beijing 100871 China 1college of life sciences Peking University Beijing 100871 China

We have developed a cell-free system that can trigger the nuclei purified from mouse liver and suspensioncultured carrot cells to undergo apoptosis as defined by the formation of apoptotic bodies and nucleosomal DNA fragments. The effects of different divalent cations and cycloheximide on DNA cleavage in this system were *** fact that nuclei of plant cells can be induced to undergo apoptosis in a cell-free animal system suggests that animals and plants share a common signal transduction pathway triggering in the initiation stage of apoptosis.

关键词： Apoptosis Xenopus laevis cell-free carrot mouse dATP

Recombinant scorpion insectotoxin AaIT kills specifically insect cells but not human cellss

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Cell Research 2002年第2期12卷 143-150页

作者： SHENG JIAN JI, FENG liU, ER Qiu li, Yu XIAN ZHUThe National Laboratory of Protein Engineering and Plant Genetic Engineering, college of life sciences, peking university, beijing 100871, china 1The National Laboratory of Protein Engineering and Plant Genetic Engineering College of Life Sciences Peking University Beijing 100871 China 1The National Laboratory of Protein Engineering and Plant Genetic Engineering College of Life Sciences Peking University Beijing 100871 China 1The National Laboratory of Protein Engineering and Plant Genetic Engineering College of Life Sciences Peking University Beijing 100871 China 1The National Laboratory of Protein Engineering and Plant Genetic Engineering College of Life Sciences Peking University Beijing 100871 China

The nucleotide sequence deduced from the amino acid sequence of the scorpion insectotoxin AaIT was chemically synthesized and was expressed in Escherichia coli. The authenticity of this in vitro expressed peptide was confirmed by N-terminal peptide sequencing. Two groups of bioassays, artificial diet incorporation assay and contact insecticidal effect assay, were carried out separately to verify the toxicity of this recombinant toxin. At the end of a 24 h experimental period, more than 60% of the testing diamondback moth （Plutella xylostella） larvae were killed in both groups with LC50 value of 18.4 μM and 0.70 μM respectively. Cytotoxicity assay using cultured Sf9 insect cells and MCF-7 human cells demonstrated that the toxin AaIT had specific toxicity against insect cells but not human cells. Only 0.13 μM recombinant toxin was needed to kill 50% of cultured insect cells while as much as 1.3 μM toxin had absolutely no effect on human cells. Insect cells produced obvious intrusions from their plasma

关键词： Scorpion toxin AaIT prokaryotic expression cytotoxicity.

Universal hierarchical symmetry for turbulence and general multi-scale fluctuation systems

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2009年第3期25卷 279-294页

作者： Zhen-Su She Zhi-xiong Zhang State Key Laboratory for Turbulence and Complex Systems, college of Engineering, peking university, 100871 beijing, china State Key Laboratory for Turbulence and Complex Systems College of Engineering Peking University 100871 Beijing China

Scaling is an important measure of multi-scale fluctuation systems. Turbulence as the most remarkable multi-scale system possesses scaling over a wide range of scales. She-Leveque （SL） hierarchical symmetry, since its publication in 1994, has received wide attention. A number of experimental, numerical and theoretical work have been devoted to its verification, extension, and modification. Application to the understanding of magnetohydrodynamic turbulence, motions of cosmic baryon fluids, cosmological supersonic turbulence, natural image, spiral turbulent patterns, DNA anomalous composition, human heart variability are just a few among the most successful examples. A number of modified scaling laws have been derived in the framework of the hierarchical symmetry, and the SL model parameters are found to reveal both the organizational order of the whole system and the properties of the most significant fluctuation structures. A partial set of work related to these studies are reviewed. Particular emphasis is placed on the nature of the hierarchical symmetry. It is suggested that the SL hierarchical symmetry is a new form of the self-organization principle for multi-scale fluctuation systems, and can be employed as a standard analysis tool in the general multi-scale methodology. It is further suggested that the SL hierarchical symmetry implies the existence of a turbulence ensemble. It is speculated that the search for defining the turbulence ensemble might open a new way for deriving statistical closure equations for turbulence and other multi-scale fluctuation systems.

关键词： Turbulence. Scaling law. She-Leveque modelHierarchical symmetry Self-organization - Turbulenceensemble

Lattice Boltzmann Method used for the aircraft characteristics computation at high angle of attack

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 2068-2073页

作者： DU TeZhuan,li XiangQun,ZHANG Xialing&WANG YiWei college of Engineering,peking university,beijing 100871,china 1. college of Engineering Peking University Beijing 100871 China

Traditional Finite Volume Method(FVM)and Lattice Boltzmann Method(LBM)are both used to compute the high angle attack aerodynamic characteristics of the benchmark aircraft model named *** though the software requires flow on the order of Ma<0.4,simulation at Ma=0.5 is run in PowerFLOW after theoretical *** consistency with the wind tunnel testing is satisfied,especially for the LBM which can produce perfect results at high angle *** can accurately capture the detail of flows because it is inherently time-dependent and parallel and suits large-scale computation very well.

关键词： LBM CFD high AOA

Size-dependent hydroxyl radicals generation induced by SiO_2 ultra-fine particles: The role of surface iron

在线全文

学校读者我要写书评

暂无评论

Science china Chemistry 2009年第7期52卷 1033-1041页

作者： SHANG Yu1, ZHU Tong1, li Yi1,2 & ZHAO JinCai3 1 college of Environmental sciences and Engineering, peking university, beijing 100871, china 2 Chinese Academy of Meteorological sciences, beijing 100871, china 3 Institute of Chemistry, Chinese Academy of sciences, beijing 100871, china 1. college of Environmental sciences and Engineering Peking University Beijing 100871 China 2. Chinese Academy of Meteorological sciences Beijing 100871 China 3. Institute of Chemistry Chinese Academy of Sciences Beijing 100871 China

Oxidative stress and hydroxyl radicals (·OH) play important roles in adverse health effects caused by inhalable ambient air particles (PM10). The ultra-fine fraction of PM10 has been hypothesized as one of the critical contributors to ·OH generation. Both in vivo and in vitro studies have shown that ultra-fine particles (UFPs) or nano-particles generate more ·OH than larger particles with identical mass and composition. Both the surface area and surface-adsorbed redox-active metals have been suggested as factors to determine the oxidative capacity of UFPs. In this study, the ·OH-generating capability of dif-ferent sizes of SiO2 particles was investigated in order to determine which factor influences particle-induced ·OH generation. The amount of ·OH generated in both acellular and cellular systems was quantified using a capillary electrophoresis method following exposure to SiO2 particles with diameters of 14, 100, and 500 nm. The amount of ·OH was strongly dependent on particle size, and a significant enhancement was observed only with 14 nm particles. Further studies indicated a close association between ·OH and iron ion concentration (R2 = 0.812, p<0.01). Washed particles, with their surface iron being removed, did not generate ·OH. The iron-containing leachate from these washings was able to enhance ·OH production as untreated particles did. Therefore, the presence of adsorbed iron on the surface of the SiO2 particles is presented as a possible mechanism of UPFs-induced ·OH generation. The SiO2 acted as an inert substrate, and the surface of ultra-fine SiO2 particles acted as a carrier for iron.

关键词： ultra-fine particles nano-particles ·OH oxidative stress size-effect

Heterogeneous reaction of SO_2 on TiO_2 particles

在线全文

学校读者我要写书评

暂无评论

Science china Chemistry 2010年第12期53卷 2637-2643页

作者： SHANG Jing,li Jia & ZHU Tong State Key Joint Laboratory of Environmental Simulation and Pollution Control college of Environmental sciences and Engineering,peking university,beijing 100871,china 1. State Key Joint Laboratory of Environmental Simulation and Pollution Control college of Environmental sciences and Engineering Peking University Beijing 100871 China

The heterogeneous reaction of SO2 on TiO2 particles was studied using in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS).The influences of the oxygen concentration,relative humidity (RH),and ultraviolet (UV) light illumination (λ=365 nm) intensity on the reaction were *** main product of the heterogeneous reaction of SO2 on TiO2 particles was sulfate with UV illumination and sulfite without *** production of sulfate was promoted significantly with UV illumination or water,and there was a synergistic effect when both were *** the dry system without UV,the heterogeneous reaction of SO2 on TiO2 particles was found to be second-order for SO2 and the initial uptake coefficient,BET,was determined to be 1.94 × *** UV and RH=40%,the reaction order was first-order and the initial uptake coefficient was 1.35 × 10-5.

关键词： SO2 TiO2 DRIFTS heterogeneous oxidation

Antiviral compounds and one new iridoid glycoside from Cornus officinalis

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2期16卷 142-146页

作者： WANG Yue, li Zhengquan, CHEN lirong and XU Xiaojie (college of Chemistry and Molecular Engineering, peking university, beijing 100871, china) [a]college of Chemistry and Molecular Engineering Piking University Beijing China

From Cornus officinalis Sieb. et Zucc., bioassay-guided fractionation led to the isolation of four active tannin compounds with high effectiveness of inhibiting Hepatitis C virus NS3 serine protease in vitro. The compounds are: 1,2,3, 6-tetragalloyl-β-D-glucopyranose (1), 1,2,3,4,6- pentagalloyl-β-D-glucopyranose (2), Tellimagrandin I (3) and Tellimagrandin II(4). The four compounds could inhibit HCV NS3 protease in vitro with IC50 values of 6.98, 5.11, 7.0 and 4.8μmol/L respectively. In addition, a new iridoid glycoside (5) was also isolated from Cornus officinalis Sieb. et Zucc., which was assigned to be 7-O-butyl morroniside by spec-troscopic analysis.

关键词： inhibitor HCV NS3 protease iridoid glycoside Cornus officinalis Sieb. et Zucc.