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排序方式: 共有128条查询结果,搜索用时 15 毫秒
61.
Celera公司对人类和其他几种复杂生物体的基因组测序的商业冒险,震动了国际人类基因组计划界;但是它能够赚钱吗?在美国华盛顿北郊的一栋不起眼的办公楼里,一家10个月前刚搬来的DeleraGenowics公司,准备成为世界上最大的基因组数据生产商。今年,它计划开始以一种真正的工业化规模生产出原初生物学数据并向世界销售。尽管Celera公司试图将他们得到的基本生物学知识转化为一种商业,公司总裁克雷格·文特尔(1.CndgVenter)承诺他将‘“公开”这项3亿美元以上的投资的第一项也是最重要的一项产品——人类基因组的DNA序列。非盈利性… 相似文献
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New inhibitor of reagin-mediated anaphylaxis 总被引:4,自引:0,他引:4
B J Broughton P Chaplen P Knowles E Lunt D L Pain K R Wooldridge R Ford S Marshall J L Walker D R Maxwell 《Nature》1974,251(5476):650-652
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A 30-min treatment with neuromuscular blocking doses of either physostigmine or d-tubocurarine was associated with a 44% or 36% (respectively) reduction in rat skeletal muscle carnosine levels in vivo. 相似文献
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Nicastro F Mathur S Elvis M Drake J Fang T Fruscione A Krongold Y Marshall H Williams R Zezas A 《Nature》2005,433(7025):495-498
Recent cosmological measurements indicate that baryons comprise about four per cent of the total mass-energy density of the Universe, which is in accord with the predictions arising from studies of the production of the lightest elements. It is also in agreement with the actual number of baryons detected at early times (redshifts z > 2). Close to our own epoch (z < 2), however, the number of baryons detected add up to just over half (approximately 55 per cent) of the number seen at z > 2 (refs 6-11), meaning that about approximately 45 per cent are 'missing'. Here we report a determination of the mass-density of a previously undetected population of baryons, in the warm-hot phase of the intergalactic medium. We show that this mass density is consistent, within the uncertainties, with the mass density of the missing baryons. 相似文献
68.
Stromatolite reef from the Early Archaean era of Australia 总被引:3,自引:0,他引:3
The 3,430-million-year-old Strelley Pool Chert (SPC) (Pilbara Craton, Australia) is a sedimentary rock formation containing laminated structures of probable biological origin (stromatolites). Determining the biogenicity of such ancient fossils is the subject of ongoing debate. However, many obstacles to interpretation of the fossils are overcome in the SPC because of the broad extent, excellent preservation and morphological variety of its stromatolitic outcrops--which provide comprehensive palaeontological information on a scale exceeding other rocks of such age. Here we present a multi-kilometre-scale palaeontological and palaeoenvironmental study of the SPC, in which we identify seven stromatolite morphotypes--many previously undiscovered--in different parts of a peritidal carbonate platform. We undertake the first morphotype-specific analysis of the structures within their palaeoenvironment and refute contemporary abiogenic hypotheses for their formation. Finally, we argue that the diversity, complexity and environmental associations of the stromatolites describe patterns that--in similar settings throughout Earth's history--reflect the presence of organisms. 相似文献
69.
Living Life as Inquiry 总被引:2,自引:0,他引:2
In this paper I explain what I mean by living life as inquiry, showing how I apply notions of inquiry as method to many areas of my professional and personal activities and how research ideas are generated and tested throughout my life space. The paper has twin tracks which reflect the interwoven processes I am describing and advocating. One is more practice based; in it I outline some of my inquiry practices and dilemmas, and give two examples from my work situation. The second track is more focused on theory, highlighting ideas about systemic analysis, influencing change, relational work, and gender. Writing the paper became an example of my topic. I therefore note features of the text which illustrate processes and practices of inquiry. 相似文献
70.
Processing of mutant cystic fibrosis transmembrane conductance regulator is temperature-sensitive. 总被引:65,自引:0,他引:65
Cystic fibrosis transmembrane conductance regulator (CFTR) is a plasma membrane Cl- channel regulated by cyclic AMP-dependent phosphorylation and by intracellular ATP. Mutations in CFTR cause cystic fibrosis partly through loss of cAMP-regulated Cl- permeability from the plasma membrane of affected epithelia. The most common mutation in cystic fibrosis is deletion of phenylalanine at residue 508 (CFTR delta F508) (ref. 10). Studies on the biosynthesis and localization of CFTR delta F508 indicate that the mutant protein is not processed correctly and, as a result, is not delivered to the plasma membrane. These conclusions are consistent with earlier functional studies which failed to detect cAMP-stimulated Cl- channels in cells expressing CFTR delta F508 (refs 16, 17). Chloride channel activity was detected, however, when CFTR delta F508 was expressed in Xenopus oocytes, Vero cells and Sf9 insect cells. Because oocytes and Sf9 cells are typically maintained at lower temperatures than mammalian cells, and because processing of nascent proteins can be sensitive to temperature, we tested the effect of temperature on the processing of CFTR delta F508. Here we show that the processing of CFTR delta F508 reverts towards that of wild-type as the incubation temperature is reduced. When the processing defect is corrected, cAMP-regulated Cl- channels appear in the plasma membrane. These results reconcile previous contradictory observations and suggest that the mutant most commonly associated with cystic fibrosis is temperature-sensitive. 相似文献