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101.
本文提出了智能化自完善控制策略,通过采用“知识库”存贮最佳的知识与经验,根据受控对象当前运行条件及状态,运用相应的分析逻辑及推理功能,实时地调整控制器结构及参数,以实现逐步改善控制系统性能的目的.文中将所论述的控制策略用于水轮机调速器开发研究. 相似文献
102.
M. Pavlović D. Petković M. Cvetković D. J. Macut K. Zdjelar M. Nešić O. Bosnić R. Radulović M. Mihajlović 《Cellular and molecular life sciences : CMLS》1995,51(9-10):941-944
The mechanism of the positive inotropic effect of prostacyclin (PGI2) (2.6×10?6 mol/l) on the isolated right ventricle of rat heart was studied. Our results show that the positive inotropic effect of prostacyclin is produced indirectly through beta adrenoceptors and slow Ca2+ channels, because blockade of slow Ca2+ channels with verapamil (10?6 mol/l) and beta adrenoceptors with propranolol (10?6 mol/l) abolishes this effect. Alpha adrenoceptors do not mediate the action of PGI2. 相似文献
103.
袁一方 《上海理工大学学报》1995,(1)
消失场荧光技术已被广泛应用在工业、生物和医学等领域的研究工作中.本文给出各种分层结构中消失场分布的严密电磁理论.在生物和医学上,利用受激荧光强度正比于局部电场能量的规律,可根据测得的相对荧光强度算出细胞和基板的间距.文中还给出一些消失场荧光测量的应用. 相似文献
104.
Characterization and molecular cloning of a bovine lentivirus related to human immunodeficiency virus 总被引:8,自引:0,他引:8
M A Gonda M J Braun S G Carter T A Kost J W Bess L O Arthur M J Van der Maaten 《Nature》1987,330(6146):388-391
105.
Gardner MJ Shallom SJ Carlton JM Salzberg SL Nene V Shoaibi A Ciecko A Lynn J Rizzo M Weaver B Jarrahi B Brenner M Parvizi B Tallon L Moazzez A Granger D Fujii C Hansen C Pederson J Feldblyum T Peterson J Suh B Angiuoli S Pertea M Allen J Selengut J White O Cummings LM Smith HO Adams MD Venter JC Carucci DJ Hoffman SL Fraser CM 《Nature》2002,419(6906):531-534
The mosquito-borne malaria parasite Plasmodium falciparum kills an estimated 0.7-2.7 million people every year, primarily children in sub-Saharan Africa. Without effective interventions, a variety of factors-including the spread of parasites resistant to antimalarial drugs and the increasing insecticide resistance of mosquitoes-may cause the number of malaria cases to double over the next two decades. To stimulate basic research and facilitate the development of new drugs and vaccines, the genome of Plasmodium falciparum clone 3D7 has been sequenced using a chromosome-by-chromosome shotgun strategy. We report here the nucleotide sequences of chromosomes 10, 11 and 14, and a re-analysis of the chromosome 2 sequence. These chromosomes represent about 35% of the 23-megabase P. falciparum genome. 相似文献
106.
Metallurgy: high nickel release from 1- and 2-euro coins 总被引:1,自引:0,他引:1
The amount of nickel is regulated in European products that come into direct and prolonged contact with human skin because this metal may cause contact allergy, particularly hand eczema. Here we show that 1- and 2-euro coins induce positive skin-test reactions in sensitized individuals and release 240-320-fold more nickel than is allowed under the European Union Nickel Directive. A factor contributing to this high release of nickel is corrosion due to the bimetallic structure of these coins, which generates a galvanic potential of 30-40 mV in human sweat. 相似文献
107.
The extent of linkage disequilibrium in Arabidopsis thaliana. 总被引:20,自引:0,他引:20
Magnus Nordborg Justin O Borevitz Joy Bergelson Charles C Berry Joanne Chory Jenny Hagenblad Martin Kreitman Julin N Maloof Tina Noyes Peter J Oefner Eli A Stahl Detlef Weigel 《Nature genetics》2002,30(2):190-193
Linkage disequilibrium (LD), the nonrandom occurrence of alleles in haplotypes, has long been of interest to population geneticists. Recently, the rapidly increasing availability of genomic polymorphism data has fueled interest in LD as a tool for fine-scale mapping, in particular for human disease loci. The chromosomal extent of LD is crucial in this context, because it determines how dense a map must be for associations to be detected and, conversely, limits how finely loci may be mapped. Arabidopsis thaliana is expected to harbor unusually extensive LD because of its high degree of selfing. Several polymorphism studies have found very strong LD within individual loci, but also evidence of some recombination. Here we investigate the pattern of LD on a genomic scale and show that in global samples, LD decays within approximately 1 cM, or 250 kb. We also show that LD in local populations may be much stronger than that of global populations, presumably as a result of founder events. The combination of a relatively high level of polymorphism and extensive haplotype structure bodes well for developing a genome-wide LD map in A. thaliana. 相似文献
108.
运用同时平衡原理绘制并讨论了在不同总铜浓度 T(Cu)、总锌浓度 T(Zn)以及总硫浓度 T(S)下 ,Cu- S- H2 O和Zn- S- H2 O系的 E- p H图 .确定某一固体的稳定区时必须同时考虑该物质与体系中所有其它物质的平衡反应 ,当体系中所有固态物质的稳定区确定之后 ,剩下的区域即为溶液相稳定区 .在 Cu- S- H2 O系的 E- p H图中 ,在所研究的条件下没有出现 Cu2 O(s)的稳定区 .对 Cu- S- H2 O和 Zn- S- H2 O系而言 ,在高电势区出现单质硫的稳定区 .图 6 ,参 1 相似文献
109.
Nitrogen loss from unpolluted South American forests mainly via dissolved organic compounds. 总被引:54,自引:0,他引:54
Conceptual and numerical models of nitrogen cycling in temperate forests assume that nitrogen is lost from these ecosystems predominantly by way of inorganic forms, such as nitrate and ammonium ions. Of these, nitrate is thought to be particularly mobile, being responsible for nitrogen loss to deep soil and stream waters. But human activities-such as fossil fuel combustion, fertilizer production and land-use change-have substantially altered the nitrogen cycle over large regions, making it difficult to separate natural aspects of nitrogen cycling from those induced by human perturbations. Here we report stream chemistry data from 100 unpolluted primary forests in temperate South America. Although the sites exhibit a broad range of environmental factors that influence ecosystem nutrient cycles (such as climate, parent material, time of ecosystem development, topography and biotic diversity), we observed a remarkably consistent pattern of nitrogen loss across all forests. In contrast to findings from forests in polluted regions, streamwater nitrate concentrations are exceedingly low, such that nitrate to ammonium ratios were less than unity, and dissolved organic nitrogen is responsible for the majority of nitrogen losses from these forests. We therefore suggest that organic nitrogen losses should be considered in models of forest nutrient cycling, which could help to explain observations of nutrient limitation in temperate forest ecosystems. 相似文献
110.
S. Steghaus-Kovâc U. Maschwitz A. B. Attygalle R. T. S. Frighetto N. Frighetto O. Vostrowsky H. J. Bestmann 《Cellular and molecular life sciences : CMLS》1992,48(7):690-694
Behavioral tests carried out with the four stereoisomers of 4-methyl-3-heptanol revealed thatLeptogenys diminuta ants respond specifically only to the (3R, 4S)-isomer. 相似文献