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排序方式: 共有123条查询结果,搜索用时 31 毫秒
111.
层次码BOM与指针码BOM转换模型及算法 总被引:1,自引:0,他引:1
提出了两种结构BOM的转换模型,并给出了基于SQL的算法,该算法已在实际系统中得到应用. 相似文献
112.
Vincent JL Patel GH Fox MD Snyder AZ Baker JT Van Essen DC Zempel JM Snyder LH Corbetta M Raichle ME 《Nature》2007,447(7140):83-86
The traditional approach to studying brain function is to measure physiological responses to controlled sensory, motor and cognitive paradigms. However, most of the brain's energy consumption is devoted to ongoing metabolic activity not clearly associated with any particular stimulus or behaviour. Functional magnetic resonance imaging studies in humans aimed at understanding this ongoing activity have shown that spontaneous fluctuations of the blood-oxygen-level-dependent signal occur continuously in the resting state. In humans, these fluctuations are temporally coherent within widely distributed cortical systems that recapitulate the functional architecture of responses evoked by experimentally administered tasks. Here, we show that the same phenomenon is present in anaesthetized monkeys even at anaesthetic levels known to induce profound loss of consciousness. We specifically demonstrate coherent spontaneous fluctuations within three well known systems (oculomotor, somatomotor and visual) and the 'default' system, a set of brain regions thought by some to support uniquely human capabilities. Our results indicate that coherent system fluctuations probably reflect an evolutionarily conserved aspect of brain functional organization that transcends levels of consciousness. 相似文献
113.
Gros-Louis F Dupré N Dion P Fox MA Laurent S Verreault S Sanes JR Bouchard JP Rouleau GA 《Nature genetics》2007,39(1):80-85
The past decade has seen great advances in unraveling the biological basis of hereditary ataxias. Molecular studies of spinocerebellar ataxias (SCA) have extended our understanding of dominant ataxias. Causative genes have been identified for a few autosomal recessive ataxias: Friedreich's ataxia, ataxia with vitamin E deficiency, ataxia telangiectasia, recessive spastic ataxia of Charlevoix-Saguenay and ataxia with oculomotor apraxia type 1 (refs. 6,7) and type 2 (ref. 8). Nonetheless, genes remain unidentified for most recessive ataxias. Additionally, pure cerebellar ataxias, which represent up to 20% of all ataxias, remain poorly studied with only two causative dominant genes being described: CACNA1A (ref. 9) and SPTBN2 (ref. 10). Here, we report a newly discovered form of recessive ataxia in a French-Canadian cohort and show that SYNE1 mutations are causative in all of our kindreds, making SYNE1 the first identified gene responsible for a recessively inherited pure cerebellar ataxia. 相似文献
114.
科技项目的评标决策模型研究 总被引:2,自引:0,他引:2
研究了科技项目招标投标过程中的标书评价问题,给出了一种基于灰色趋势关联分析的评标决策模型,并且以某新产品计划科技招标项目的评标工作为例,基于评标决策模型用实际数据对新产品计划科技招标项目进行了评标研究. 相似文献
115.
提出一种基于分布式神经网络的事例相似度评估的体系结构及实现方法 ,即通过输入新旧事例中特征之间的两两相似度 ,利用神经网络来确定新旧事例之间的综合相似度 ,以此来改善不良结构决策领域中基于事例推理系统的事例检索性能 相似文献
116.
你是否知道,是谁创制了第一台电视机?是谁发明了立体声装置?又是谁创造了不少关键性的新技术而使雷达付诸实用?不是别人,正是那个使立体声录制于胶片声带成为现实的同一个人,他所设计的基本电子线路至今还为许多现代电子设备所采用。他就是不列颠人阿兰·布仑雷恩(Alan Blum-lein)。他在1942年6月7日去世时才38岁。 相似文献
117.
基于GA算法的科技项目联合投标伙伴选择模型 总被引:1,自引:0,他引:1
根据联合投标伙伴选择决策特征,针对联合投标伙伴选择过程中决策因素多、信息量大、候选投标伙伴数量多等问题,运用遗传算法基本思想,构造灰色效果测度适应度函数,设计搜索调整机制,结合算例,给出使用基于GA算法的科技项目联合投标伙伴选择模型的一般过程.该模型具有快速收敛、鲁棒性和全局最优搜索能力. 相似文献
118.
以我国某大型施工企业的施工索赔管理为背景,在分析施工索赔特点、工作模式、超文本的构成方式及特点的基础上,提出了施工索赔决策的主题结构,并分析主题结构的作用;提出了基于超文本问题描述的施工索赔模型,描述了基于该模型的索赔智能信息网络的构造;最后提出了辅助施工索赔决策系统的结构以及实现技术. 相似文献
119.
Upwelling-driven nearshore hypoxia signals ecosystem and oceanographic changes in the northeast Pacific 总被引:2,自引:0,他引:2
Grantham BA Chan F Nielsen KJ Fox DS Barth JA Huyer A Lubchenco J Menge BA 《Nature》2004,429(6993):749-754
Seasonal development of dissolved-oxygen deficits (hypoxia) represents an acute system-level perturbation to ecological dynamics and fishery sustainability in coastal ecosystems around the globe. Whereas anthropogenic nutrient loading has increased the frequency and severity of hypoxia in estuaries and semi-enclosed seas, the occurrence of hypoxia in open-coast upwelling systems reflects ocean conditions that control the delivery of oxygen-poor and nutrient-rich deep water onto continental shelves. Upwelling systems support a large proportion of the world's fisheries, therefore understanding the links between changes in ocean climate, upwelling-driven hypoxia and ecological perturbations is critical. Here we report on the unprecedented development of severe inner-shelf (<70 m) hypoxia and resultant mass die-offs of fish and invertebrates within the California Current System. In 2002, cross-shelf transects revealed the development of abnormally low dissolved-oxygen levels as a response to anomalously strong flow of subarctic water into the California Current System. Our findings highlight the sensitivity of inner-shelf ecosystems to variation in ocean conditions, and the potential impacts of climate change on marine communities. 相似文献
120.
Ali K Bilancio A Thomas M Pearce W Gilfillan AM Tkaczyk C Kuehn N Gray A Giddings J Peskett E Fox R Bruce I Walker C Sawyer C Okkenhaug K Finan P Vanhaesebroeck B 《Nature》2004,431(7011):1007-1011
Inflammatory substances released by mast cells induce and maintain the allergic response. Mast cell differentiation and activation are regulated, respectively, by stem cell factor (SCF; also known as Kit ligand) and by allergen in complex with allergen-specific immunoglobulin E (IgE). Activated SCF receptors and high-affinity receptors for IgE (FcvarepsilonRI) engage phosphoinositide 3-kinases (PI(3)Ks) to generate intracellular lipid second messenger signals. Here, we report that genetic or pharmacological inactivation of the p110delta isoform of PI(3)K in mast cells leads to defective SCF-mediated in vitro proliferation, adhesion and migration, and to impaired allergen-IgE-induced degranulation and cytokine release. Inactivation of p110delta protects mice against anaphylactic allergic responses. These results identify p110delta as a new target for therapeutic intervention in allergy and mast-cell-related pathologies. 相似文献