PLASMODIUM VIVAX CHESSON STRAIN     

Ehrman FC  Ellis JM  Young MD 《Science (New York, N.Y.)》1945,101(2624):377-378

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PENTATHIONIC ACID,THE FUNGICIDAL FACTOR OF SULPHUR     

Young HC 《Science (New York, N.Y.)》1928,67(1723):19-20

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Evidence for ozone formation in human atherosclerotic arteries   总被引：1，自引：0，他引：1  

Wentworth P  Nieva J  Takeuchi C  Galve R  Wentworth AD  Dilley RB  DeLaria GA  Saven A  Babior BM  Janda KD  Eschenmoser A  Lerner RA 《Science (New York, N.Y.)》2003,302(5647):1053-1056

Here, we report evidence for the production of ozone in human disease. Signature products unique to cholesterol ozonolysis are present within atherosclerotic tissue at the time of carotid endarterectomy, suggesting that ozone production occurred during lesion development. Furthermore, advanced atherosclerotic plaques generate ozone when the leukocytes within the diseased arteries are activated in vitro. The steroids produced by cholesterol ozonolysis cause effects that are thought to be critical to the pathogenesis of atherosclerosis, including cytotoxicity, lipid-loading in macrophages, and deformation of the apolipoprotein B-100 secondary structure. We propose the trivial designation "atheronals" for this previously unrecognized class of steroids.  相似文献   

Bidirectional transmembrane signaling by cytoplasmic domain separation in integrins     

Kim M  Carman CV  Springer TA 《Science (New York, N.Y.)》2003,301(5640):1720-1725

Although critical for development, immunity, wound healing, and metastasis, integrins represent one of the few classes of plasma membrane receptors for which the basic signaling mechanism remains a mystery. We investigated cytoplasmic conformational changes in the integrin LFA-1 (alphaLbeta2) in living cells by measuring fluorescence resonance energy transfer between cyan fluorescent protein-fused and yellow fluorescent protein-fused alphaL and beta2 cytoplasmic domains. In the resting state these domains were close to each other, but underwent significant spatial separation upon either intracellular activation of integrin adhesiveness (inside-out signaling) or ligand binding (outside-in signaling). Thus, bidirectional integrin signaling is accomplished by coupling extracellular conformational changes to an unclasping and separation of the alpha and beta cytoplasmic domains, a distinctive mechanism for transmitting information across the plasma membrane.  相似文献   

Evidence that the reactivity of the martian soil is due to superoxide ions     

Yen AS  Kim SS  Hecht MH  Frant MS  Murray B 《Science (New York, N.Y.)》2000,289(5486):1909-1912

The Viking Landers were unable to detect evidence of life on Mars but, instead, found a chemically reactive soil capable of decomposing organic molecules. This reactivity was attributed to the presence of one or more as-yet-unidentified inorganic superoxides or peroxides in the martian soil. Using electron paramagnetic resonance spectroscopy, we show that superoxide radical ions (O2-) form directly on Mars-analog mineral surfaces exposed to ultraviolet radiation under a simulated martian atmosphere. These oxygen radicals can explain the reactive nature of the soil and the apparent absence of organic material at the martian surface.  相似文献   

Two-dimensional nanosheets produced by liquid exfoliation of layered materials   总被引：1，自引：0，他引：1  

Coleman JN  Lotya M  O'Neill A  Bergin SD  King PJ  Khan U  Young K  Gaucher A  De S  Smith RJ  Shvets IV  Arora SK  Stanton G  Kim HY  Lee K  Kim GT  Duesberg GS  Hallam T  Boland JJ  Wang JJ  Donegan JF  Grunlan JC  Moriarty G  Shmeliov A  Nicholls RJ  Perkins JM  Grieveson EM  Theuwissen K  McComb DW  Nellist PD  Nicolosi V 《Science (New York, N.Y.)》2011,331(6017):568-571

If they could be easily exfoliated, layered materials would become a diverse source of two-dimensional crystals whose properties would be useful in applications ranging from electronics to energy storage. We show that layered compounds such as MoS(2), WS(2), MoSe(2), MoTe(2), TaSe(2), NbSe(2), NiTe(2), BN, and Bi(2)Te(3) can be efficiently dispersed in common solvents and can be deposited as individual flakes or formed into films. Electron microscopy strongly suggests that the material is exfoliated into individual layers. By blending this material with suspensions of other nanomaterials or polymer solutions, we can prepare hybrid dispersions or composites, which can be cast into films. We show that WS(2) and MoS(2) effectively reinforce polymers, whereas WS(2)/carbon nanotube hybrid films have high conductivity, leading to promising thermoelectric properties.  相似文献   

Creating favorable geometries for directing organic photoreactions in alkanethiolate monolayers     

Kim M  Hohman JN  Cao Y  Houk KN  Ma H  Jen AK  Weiss PS 《Science (New York, N.Y.)》2011,331(6022):1312-1315

The products of photoreactions of conjugated organic molecules may be allowed by selection rules but not observed in solution reactions because of unfavorable reaction geometries. We have used defect sites in self-assembled alkanethiolate monolayers on gold surfaces to direct geometrically unfavorable photochemical reactions between individual organic molecules. High conductivity and stochastic switching of anthracene-terminated phenylethynylthiolates within alkanethiolate monolayers, as well as in situ photochemical transformations, have been observed and distinguished with the scanning tunneling microscope (STM). Ultraviolet light absorbed during imaging increases the apparent heights of excited molecules in STM images, a direct manifestation of probing electronically excited states.  相似文献   

木薯块根淀粉积累分子机制综述   总被引：1，自引：0，他引：1  

夏志强  邹枚伶  曾长英  陈新  吉家敏  刘晓静  王文泉 《安徽农学通报》2008,14(8):78-81

该文综述了相关的淀粉合成机理以及调控木薯淀粉合成关键酶的生化特性基因调控研究进展,认为人们对木薯淀粉的生物合成机理、关键酶的生化特性与表达调控等方面有了很大的突破。  相似文献   

基于图像处理技术的生物反应器浓度检测系统的开发     

许哲  陈洪武 《上海海洋大学学报》2007,(5):509-512

发酵过程生物参数的在线检测,是获得发酵过程生物信息的重要手段,也是进行合理最优控制的基础。但是,目前许多生物量只能离线检测,不能够为实时的控制系统利用。因此提出了基于图像处理技术的生物反应器浓度在线检测系统,系统由反应液循环与控制装置、反应液浓度光学检测装置、图像采集与处理装置、计算机以及相应的处理软件组成。通过与分光光度计的实验比较,证实了所设计的系统可以用于生物反应器浓度的在线测量,为实现发酵过程生物参数的在线检测提供了值得借鉴的设计思路和实现方法。  相似文献   

老参地短期轮作技术体系的建立Ⅰ.人参西洋参轮作体系     

田义新  王本有  盛吉明  尹春梅  金志哲  杨继祥 《吉林农业大学学报》2002,24(3):46-49

老参地问题是制约参业发展的重大难题，笔者在总结前人关于老参地研究成果和经验的基础上，采取了测土施肥，有益微生物菌剂处理，酸碱度调整等土壤处理方法，成功地实现了老参地的短期再利用，建立了周期为1－3年的人参和西洋参的短期轮作体系。在处理后的老参地上种植西洋参，其长势，产量，病虫害及烧须情况，总皂苷含量等，与对照地新林土栽参无显著差异（P＞0．05）。并开展了中试规模的推广，试验结果显示，老参地短期轮作制是改造老参地的有效措施之一，该轮作技术方法应用简便，实用，可操作性强，轮作效果好。  相似文献