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91.
防止沥青质沉积造成的储层损害是疏松砂岩稠油油藏开发生产中遇到的技术难题之一。采用岩心流动实验装置,建立了可定量评价原油沥青质沉积所引起储层损害的新方法,并对沉积过程中影响损害程度的几种因素进行了系统的评价。另外,建立了沥青质沉积抑制剂和清除剂作用效果的评价方法,并筛选出适用于疏松砂岩稠油油藏的沥青质沉积抑制剂YZ-06和DA-80以及沥青质沉积清除剂L-01和L-02,从而形成了从室内评价沥青质沉积引起储层损害到化学方法控制该损害的储层保护新技术。  相似文献   
92.
海洋深水钻井过程中如钻遇浅层含气砂岩,气体进入钻井液,在海底低温和高压作用下易形成气体水合物,并堵塞井筒、环空或防喷器, 严重影响钻井工程。利用自制四氢呋喃旋转试管测试平台,实验研究了海洋钻井常用的钻井液处理剂(无机盐、有机盐、高分子聚合物)对气体水合物形成的影响。结果表明:无机盐、有机盐能很好地抑制水合物的形成,而聚合物在高浓度时才会有较好的抑制效果,低浓度时则会促进水合物形成。  相似文献   
93.
在套管射孔压裂井中,存在影响井生产动态的裂缝伤害:瓶颈裂缝和压裂液滤失形成的滤失带伤害。运用分析方法研究了上述伤害对井产能的影响。分析结果表明两种类型的裂缝伤害都会降低压裂井产能,与滤失带伤害相比,瓶颈裂缝大幅度地降低了井产能,最大降幅达7倍。虽然压裂液滤失对井产能的影响没有瓶颈裂缝那么大,但也降低多一半。在实际施工中,应采用各种措施消除瓶颈裂缝和减小压裂液滤失。  相似文献   
94.
黑墩目标区是新疆三塘湖盆地的一个三级构造单元,在燕山晚期—喜山期遭受强烈挤压作用,地层变形强烈,构造复杂。搞清楚目标区的构造特征成为寻找油气的首要任务。通过运用断层相关褶皱理论及可视化计算机技术对目标区三维地震数据体的解释,客观地认识到断层转折褶皱、生长断层转折褶皱及复合型三角构造楔是黑墩目标区的主要构造样式。  相似文献   
95.
Extremes of the electrocardiographic QT interval, a measure of cardiac repolarization, are associated with increased cardiovascular mortality. We identified a common genetic variant influencing this quantitative trait through a genome-wide association study on 200 subjects at the extremes of a population-based QT interval distribution of 3,966 subjects from the KORA cohort in Germany, with follow-up screening of selected markers in the remainder of the cohort. We validated statistically significant findings in two independent samples of 2,646 subjects from Germany and 1,805 subjects from the US Framingham Heart Study. This genome-wide study identified NOS1AP (CAPON), a regulator of neuronal nitric oxide synthase, as a new target that modulates cardiac repolarization. Approximately 60% of subjects of European ancestry carry at least one minor allele of the NOS1AP genetic variant, which explains up to 1.5% of QT interval variation.  相似文献   
96.
Analysis of a RanGTP-regulated gradient in mitotic somatic cells   总被引:1,自引:0,他引:1  
Kaláb P  Pralle A  Isacoff EY  Heald R  Weis K 《Nature》2006,440(7084):697-701
The RanGTPase cycle provides directionality to nucleocytoplasmic transport, regulating interactions between cargoes and nuclear transport receptors of the importin-beta family. The Ran-importin-beta system also functions in mitotic spindle assembly and nuclear pore and nuclear envelope formation. The common principle underlying these diverse functions throughout the cell cycle is thought to be anisotropy of the distribution of RanGTP (the RanGTP gradient), driven by the chromatin-associated guanine nucleotide exchange factor RCC1 (refs 1, 4, 5). However, the existence and function of a RanGTP gradient during mitosis in cells is unclear. Here we examine the Ran-importin-beta system in cells by conventional and fluorescence lifetime microscopy using a biosensor, termed Rango, that increases its fluorescence resonance energy transfer signal when released from importin-beta by RanGTP. Rango is predominantly free in mitotic cells, but is further liberated around mitotic chromatin. In vitro experiments and modelling show that this localized increase of free cargoes corresponds to changes in RanGTP concentration sufficient to stabilize microtubules in extracts. In cells, the Ran-importin-beta-cargo gradient kinetically promotes spindle formation but is largely dispensable once the spindle has been established. Consistent with previous reports, we observe that the Ran system also affects spindle pole formation and chromosome congression in vivo. Our results demonstrate that conserved Ran-regulated pathways are involved in multiple, parallel processes required for spindle function, but that their relative contribution differs in chromatin- versus centrosome/kinetochore-driven spindle assembly systems.  相似文献   
97.
A Kääb  E Berthier  C Nuth  J Gardelle  Y Arnaud 《Nature》2012,488(7412):495-498
Glaciers are among the best indicators of terrestrial climate variability, contribute importantly to water resources in many mountainous regions and are a major contributor to global sea level rise. In the Hindu Kush-Karakoram-Himalaya region (HKKH), a paucity of appropriate glacier data has prevented a comprehensive assessment of current regional mass balance. There is, however, indirect evidence of a complex pattern of glacial responses in reaction to heterogeneous climate change signals. Here we use satellite laser altimetry and a global elevation model to show widespread glacier wastage in the eastern, central and south-western parts of the HKKH during 2003-08. Maximal regional thinning rates were 0.66?±?0.09 metres per year in the Jammu-Kashmir region. Conversely, in the Karakoram, glaciers thinned only slightly by a few centimetres per year. Contrary to expectations, regionally averaged thinning rates under debris-mantled ice were similar to those of clean ice despite insulation by debris covers. The 2003-08 specific mass balance for our entire HKKH study region was -0.21?±?0.05?m?yr(-1) water equivalent, significantly less negative than the estimated global average for glaciers and ice caps. This difference is mainly an effect of the balanced glacier mass budget in the Karakoram. The HKKH sea level contribution amounts to one per cent of the present-day sea level rise. Our 2003-08 mass budget of -12.8?±?3.5 gigatonnes (Gt) per year is more negative than recent satellite-gravimetry-based estimates of -5?±?3?Gt?yr(-1) over 2003-10 (ref. 12). For the mountain catchments of the Indus and Ganges basins, the glacier imbalance contributed about 3.5% and about 2.0%, respectively, to the annual average river discharge, and up to 10% for the Upper Indus basin.  相似文献   
98.
以光纤传像束为基础搭建激光焊金属蒸气的多角度同步成像平台,从平台的3个方向获取金属蒸气的二维投影图像,并以二维投影图像为基础,采用基于中心投影模型的代数迭代法进行金属蒸气图像的三维重建,以获得金属蒸气图像辐射亮度的三维分布.结果表明:对于高功率激光焊接而言,金属蒸气图像的辐射亮度呈现出由内到外而逐渐降低的变化趋势,其中心部分的辐射亮度分布并不连续,且存在相对孤立的离散区域;当匙孔的开口与激光入射点重合时,金属蒸气的尺寸较小且贴近于工件表面;当熔池波动而造成匙孔失稳时,金属蒸气图像出现了形态异常和较为显著的尺寸变化.  相似文献   
99.
针对典型交通场景下智能车多车协作的实时性、可靠性及分布式协作的要求,提出了基于可靠预约ALOHA的介质访问层信道接入协议,通过使用动态时分复用信道而提高车间通信的实时性,用预约时隙和广播机制而提高通信的可靠性与分布式特性,并设计了针对车队和超车的多车协作算法.同时,通过实验验证了通信协议及系统的可行性与可靠性.  相似文献   
100.
1 IntroductionIn the Bayesian game modeIs[1t2], the uncertainty of objectives is described with probability. But sometbe the uncertainty in practice i8 gben by some fuzzy parnders, and theobjectives of players mny not be to mallmize the expected payOffs[3'4'5j. [6,7l discussed themodeIs for endogenous Stackelberg and price leadership under complete infOmation. In [8,9],we studied the Cournot and Stackelberg models with fuzzy parameters. In this paPer, we givea new subjective equllibrinm fo…  相似文献   
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