Transcription. Oxygen sensing gets a second wind     

Bruick RK  McKnight SL 《Science (New York, N.Y.)》2002,295(5556):807-808

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Biodiversity loss in the ocean: how bad is it?     

Murawski S  Methot R  Tromble G 《Science (New York, N.Y.)》2007,316(5829):1281-4; author reply 1281-4

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Preschool program improves cognitive control     

Diamond A  Barnett WS  Thomas J  Munro S 《Science (New York, N.Y.)》2007,318(5855):1387-1388

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T cell activation by lipopeptide antigens   总被引：2，自引：0，他引：2  

Moody DB  Young DC  Cheng TY  Rosat JP  Roura-Mir C  O'Connor PB  Zajonc DM  Walz A  Miller MJ  Levery SB  Wilson IA  Costello CE  Brenner MB 《Science (New York, N.Y.)》2004,303(5657):527-531

Unlike major histocompatibility proteins, which bind peptides, CD1 proteins display lipid antigens to T cells. Here, we report that CD1a presents a family of previously unknown lipopeptides from Mycobacterium tuberculosis, named didehydroxymycobactins because of their structural relation to mycobactin siderophores. T cell activation was mediated by the alphabeta T cell receptors and was specific for structure of the acyl and peptidic components of these antigens. These studies identify a means of intracellular pathogen detection and identify lipopeptides as a biochemical class of antigens for T cells, which, like conventional peptides, have a potential for marked structural diversity.  相似文献   

Pattern-oriented modeling of agent-based complex systems: lessons from ecology   总被引：6，自引：0，他引：6  

Grimm V  Revilla E  Berger U  Jeltsch F  Mooij WM  Railsback SF  Thulke HH  Weiner J  Wiegand T  DeAngelis DL 《Science (New York, N.Y.)》2005,310(5750):987-991

Agent-based complex systems are dynamic networks of many interacting agents; examples include ecosystems, financial markets, and cities. The search for general principles underlying the internal organization of such systems often uses bottom-up simulation models such as cellular automata and agent-based models. No general framework for designing, testing, and analyzing bottom-up models has yet been established, but recent advances in ecological modeling have come together in a general strategy we call pattern-oriented modeling. This strategy provides a unifying framework for decoding the internal organization of agent-based complex systems and may lead toward unifying algorithmic theories of the relation between adaptive behavior and system complexity.  相似文献   

Quantitative analysis of culture using millions of digitized books   总被引：1，自引：0，他引：1  

Michel JB  Shen YK  Aiden AP  Veres A  Gray MK;Google Books Team  Pickett JP  Hoiberg D  Clancy D  Norvig P  Orwant J  Pinker S  Nowak MA  Aiden EL 《Science (New York, N.Y.)》2011,331(6014):176-182

We constructed a corpus of digitized texts containing about 4% of all books ever printed. Analysis of this corpus enables us to investigate cultural trends quantitatively. We survey the vast terrain of 'culturomics,' focusing on linguistic and cultural phenomena that were reflected in the English language between 1800 and 2000. We show how this approach can provide insights about fields as diverse as lexicography, the evolution of grammar, collective memory, the adoption of technology, the pursuit of fame, censorship, and historical epidemiology. Culturomics extends the boundaries of rigorous quantitative inquiry to a wide array of new phenomena spanning the social sciences and the humanities.  相似文献   

不同年代大豆品种(系)根系生长动态的比较研究   总被引：1，自引：0，他引：1  

王智权  谢甫绨  王海英  丁雪丽  谢志涛  张惠君 《辽宁农业科学》2006,(4):9-12

不同年代大豆品种根干重积累动态可以用Logistic曲线方程进行模拟。在不同施肥水平下,根干重最大增长速率及出现的时间和平均增长速率有所不同。根干重最大增长速率出现的时间,中国当代品种、美国当代品种及中国20世纪20年代的品种间差异不显著,各品种间差异及施肥处理间差异也不显著。根干重最大增长速率,中国当代、美国当代及中国20世纪20年代的品种间差异不显著,各品种间差异也不显著,施肥处理间差异显著。平均增长速率,中国当代、美国当代及中国20年代的品种间差异显著,各品种间及施肥处理间差异也显著。不同施肥水平、不同生育时期,中国当代品种与美国当代品种根干重都比中国20年代品种大。  相似文献   

Nanominerals, mineral nanoparticles, and Earth systems   总被引：4，自引：0，他引：4  

Hochella MF  Lower SK  Maurice PA  Penn RL  Sahai N  Sparks DL  Twining BS 《Science (New York, N.Y.)》2008,319(5870):1631-1635

Minerals are more complex than previously thought because of the discovery that their chemical properties vary as a function of particle size when smaller, in at least one dimension, than a few nanometers, to perhaps as much as several tens of nanometers. These variations are most likely due, at least in part, to differences in surface and near-surface atomic structure, as well as crystal shape and surface topography as a function of size in this smallest of size regimes. It has now been established that these variations may make a difference in important geochemical and biogeochemical reactions and kinetics. This recognition is broadening and enriching our view of how minerals influence the hydrosphere, pedosphere, biosphere, and atmosphere.  相似文献   

One-way control of FWA imprinting in Arabidopsis endosperm by DNA methylation   总被引：1，自引：0，他引：1  

Kinoshita T  Miura A  Choi Y  Kinoshita Y  Cao X  Jacobsen SE  Fischer RL  Kakutani T 《Science (New York, N.Y.)》2004,303(5657):521-523

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Restriction of DNA replication to the reductive phase of the metabolic cycle protects genome integrity     

Chen Z  Odstrcil EA  Tu BP  McKnight SL 《Science (New York, N.Y.)》2007,316(5833):1916-1919

When prototrophic yeast cells are cultured under nutrient-limited conditions that mimic growth in the wild, rather than in the high-glucose solutions used in most laboratory studies, they exhibit a robustly periodic metabolic cycle. Over a cycle of 4 to 5 hours, yeast cells rhythmically alternate between glycolysis and respiration. The cell division cycle is tightly constrained to the reductive phase of this yeast metabolic cycle, with DNA replication taking place only during the glycolytic phase. We show that cell cycle mutants impeded in metabolic cycle-directed restriction of cell division exhibit substantial increases in spontaneous mutation rate. In addition, disruption of the gene encoding a DNA checkpoint kinase that couples the cell division cycle to the circadian cycle abolishes synchrony of the metabolic and cell cycles. Thus, circadian, metabolic, and cell division cycles may be coordinated similarly as an evolutionarily conserved means of preserving genome integrity.  相似文献