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Inrecentyears,adversehealtheffectsofinhal ableparticles(PM10)havedrawnmoreattention.Moreover,epidemiologicalstudieshavehighlighteda possiblelinkbetweentheincreasesinPM10concentra tionandtheadultmorbidityandmortality[1,2].How ever,thebiologicalmechanismoftheadverseeffects isstillunclear.Therearemanyhypothesesonthe mechanismscausingpulmonarydamagebyparticulate matters,ofwhichawidelyacceptedhypothesisis thatthebioavailabletransitionmetalsonparticlesur facemayproducefreeradicals,whichplayanimpor… 相似文献
434.
Based on the sticking point of the low intelligence of the existing management decision system, this paper puts forward the idea of enriching and refining the knowledge of the system and endowing it with the ability to learn by means of adopting three types of heterogeneous knowledge representation and knowledge management measures. At length, this paper outlines the basic framework of an intelligence system for the sake of management decision problem. 相似文献
435.
The evidence of human activities around Erhai Lake catchment was revealed by pollen records from a sediment core in the lake, northwest Yunnan Province. The chronologic sequence based on AMS ^14C data made it possible for pollen results to compare with archaeological records and historical documents. The preliminary deforestation started from the selective clearance at about 5500 ^14C a BP, marked by the loss of vertically distributed montane forest and the expansion of second pine woodland across the catchment. The deforestation resulted in the increase of surface runoff and the enhanced erosion in the catchment. The increased herbs of pasture and crop suggested the primitive agriculture and stockbreeding in study region. With the limited human activity, as well as the suitable climatic condition, second pine forest expanded quickly, resulting in the weakened soil erosion around the basin. The strong forest clearance inferred from pollen occurred since 2160 ^14C a BP, paralleling to the first dense immigration of population, when Yeyu County was first set up around west coast of Erhai Lake, documented in historic record. The development of agriculture led to the steady enhancement of soil erosion from farming land, increasing the input of fine materials and nutrients to the lake. Moreover, the serious deforestation by human activity stressed the vulnerability in ecosystem of the landscape. The time of primary anthropologic impact recorded from pollen is earlier than that of the oldest archaeological record by 1500 a (^14C year). 相似文献
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Partial leptin deficiency and human adiposity. 总被引:11,自引:0,他引:11
I S Farooqi J M Keogh S Kamath S Jones W T Gibson R Trussell S A Jebb G Y Lip S O'Rahilly 《Nature》2001,414(6859):34-35
The adipocyte-derived hormone leptin is crucial for energy homeostasis in mammals; mice and humans without it suffer from a voracious appetite and extreme obesity. The effect on energy balance of variations in plasma leptin above a minimal threshold is uncertain, however, particularly in humans. Here we examine a group of individuals who are genetically partially deficient in leptin, and show that differences in circulating leptin levels within the range found in normal human populations can directly influence the laying down of fat tissue (adiposity). 相似文献
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Jinghui Li Rui Kang Ali Mosleh Xing Pan .School of Reliability Systems Engineering Beihang University Beijing P.R.China .Center for Risk Reliability University of Maryl College Park MD USA 《系统工程与电子技术(英文版)》2011,(6):1015-1022
This paper presents a methodology for automatically generating risk scenarios for dynamic reliability applications in which some dynamic characteristics(e.g.,the order,timing and magnitude of events,the value of relevant process parameters and initial conditions) have a significant influence on the evolution of the system.The main idea of the methodology is:(i) making the system model "express itself" through simulation by having the model driven by an elaborated simulation engine;(ii) exploiting uniform design to pick out a small subset of representative design points from the space of relevant dynamic characteristics;(iii) for each selected design point,employing a depth-first systematic exploration strategy to cover all possible scenario branches at each branch point.A highly dynamic example adapted from the literature(a chemical batch reactor) is studied to test the effectiveness of the proposed methodology. 相似文献
440.
Stephens P Edkins S Davies H Greenman C Cox C Hunter C Bignell G Teague J Smith R Stevens C O'Meara S Parker A Tarpey P Avis T Barthorpe A Brackenbury L Buck G Butler A Clements J Cole J Dicks E Edwards K Forbes S Gorton M Gray K Halliday K Harrison R Hills K Hinton J Jones D Kosmidou V Laman R Lugg R Menzies A Perry J Petty R Raine K Shepherd R Small A Solomon H Stephens Y Tofts C Varian J Webb A West S Widaa S Yates A Brasseur F Cooper CS Flanagan AM Green A Knowles M Leung SY Looijenga LH 《Nature genetics》2005,37(6):590-592
We examined the coding sequence of 518 protein kinases, approximately 1.3 Mb of DNA per sample, in 25 breast cancers. In many tumors, we detected no somatic mutations. But a few had numerous somatic mutations with distinctive patterns indicative of either a mutator phenotype or a past exposure. 相似文献