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251.
O. B. Sheynin 《Archive for History of Exact Sciences》1989,39(4):337-377
Communicated by
H. Freudenthal 相似文献
252.
Agent-oriented Aid-modeling for the Distributed Activity Network 总被引:6,自引:0,他引:6
DENG Gui|shi LI Wen|lei O. Moeschlin .Institute of Systems Engineering Dalian University of Technology Dalian China .Department of Mathematics Fern University in Hagen D Germany 《系统科学与系统工程学报(英文版)》2000,(1)
1 IntroductionModern system characters distributed problem solving from the view of new generation ofDSS.Thus,traditional DSS(P.Sage,1 992 ) will separate the system into4 main parts atdifferent allocation,so that it needs an environment of information technologies (R.Blanning,1 995) and the supportoforganizational connectivity(M.Jeusfeld,1 997) .Atthesame time,distributed decision processing requires coalescent problem modeling andcollaborated decision.The distributed problem solves in… 相似文献
253.
通信电子战信号反演处理——I:概论 总被引:2,自引:0,他引:2
通信电子战信号处理迫切需要一个具有宏观指导意义的方法论。反演方法既是地球物理学中的基本处理方法,又是人类两大基本推理方法的一个子方法。讨论了反演方法及其理论的一般定义。指出在电子学与通信及其信号处理领域,将问题统一到信号反演的框架下,不仅有利于对处理方法的理论研究,而且有利于吸收那些在非电子学领域已经建立的反演方法及其理论。给出了关于通信电子战信号反演处理的定义,并提出其概念模型和目标参数。 相似文献
254.
255.
Systemic Practice and Action Research - This paper explores the usefulness of rich pictures as a method in Systemic Lean Intervention (SLI) process. It combines Lean and Systems Thinking analytical... 相似文献
256.
Cloning and expression of a rat D2 dopamine receptor cDNA 总被引:24,自引:0,他引:24
J R Bunzow H H Van Tol D K Grandy P Albert J Salon M Christie C A Machida K A Neve O Civelli 《Nature》1988,336(6201):783-787
Dopamine receptors are classified into D1 and D2 subtypes on the basis of their pharmacological and biochemical characteristics. The D2 dopamine receptor has been implicated in the pathophysiology and treatment of movement disorders, schizophrenia and drug addiction. The D2 dopamine receptor interacts with guanine nucleotide-binding proteins to induce second messenger systems. Other members of the family of receptors that are coupled to G proteins share a significant similarity in primary amino-acid sequence and exhibit an archetypical topology predicted to consist of seven putative transmembrane domains. We have taken advantage of the expected nucleotide sequence similarities among members of this gene family to isolate genes coding for new receptors. Using the hamster beta 2-adrenergic receptor gene as a hybridization probe we have isolated related genes including a cDNA encoding the rat D2 dopamine receptor. This receptor has been characterized on the basis of three criteria: the deduced amino-acid sequence which reveals that it is a member of the family of G-protein-coupled receptors; the tissue distribution of the mRNA which parallels that of the D2 dopamine receptor; and the pharmacological profile of mouse fibroblast cells transfected with the cDNA. 相似文献
257.
Recognition of haemagglutinins on virus-infected cells by NKp46 activates lysis by human NK cells 总被引:41,自引:0,他引:41
Mandelboim O Lieberman N Lev M Paul L Arnon TI Bushkin Y Davis DM Strominger JL Yewdell JW Porgador A 《Nature》2001,409(6823):1055-1060
Natural killer (NK) cells destroy virus-infected and tumour cells, apparently without the need for previous antigen stimulation. In part, target cells are recognized by their diminished expression of major histocompatibility complex (MHC) class I molecules, which normally interact with inhibitory receptors on the NK cell surface. NK cells also express triggering receptors that are specific for non-MHC ligands; but the nature of the ligands recognized on target cells is undefined. NKp46 is thought to be the main activating receptor for human NK cells. Here we show that a soluble NKp46-immunoglobulin fusion protein binds to both the haemagglutinin of influenza virus and the haemagglutinin-neuraminidase of parainfluenza virus. In a substantial subset of NK cells, recognition by NKp46 is required to lyse cells expressing the corresponding viral glycoproteins. The binding requires the sialylation of NKp46 oligosaccharides, which is consistent with the known sialic binding capacity of the viral glycoproteins. These findings indicate how NKp46-expressing NK cells may recognize target cells infected by influenza or parainfluenza without the decreased expression of target-cell MHC class I protein. 相似文献
258.
Alafara A. Baba Kuranga I. Ayinla Folahan A. Adekola Rafiu B. Bale Malay K. Ghosh Abdul G. F. Alabi Abdul R. Sheik Ismael O. Folorunso 《矿物冶金与材料学报》2013,20(11):1021-1028
The dissolution kinetics of a Nigerian chalcopyrite ore in hydrochloric acid was studied in this article. Acid concentration, reaction temperature, and ore particle size were chosen as experimental parameters. The chemical and morphological studies of the ore before and after leaching at optimal conditions were carried out by X-ray diffraction (XRD) and scanning electron microscopy (SEM). It is revealed that increasing the acid concentration and system temperature and decreasing the ore particle size greatly enhances the dissolution rate. The dissolution kinetics was found to follow the shrinking core model for the diffusion control mechanism where the activation energy (Ea) of 32.92 kJ·mol?1 was obtained for the process and supported by morphological changes at a higher dissolution of 91.33%. 相似文献
259.
Triiodothyronine injected daily to pregnant rats for the last week of gestation (50 microgram/100 g b.wt) increased the specific activities of 5 acid glycosidases in the fetal forebrain and cerebellum. Cortisone (50 mg/100 g b.wt) administered in the same period had no effect on cerebellum acid hydrolases, but decreased their activity in the forebrain. 相似文献
260.
Poulet F Bibring JP Mustard JF Gendrin A Mangold N Langevin Y Arvidson RE Gondet B Gomez C Berthé M Erard S Forni O Manaud N Poulleau G Soufflot A Combes M Drossart P Encrenaz T Fouchet T Melchiorri R Bellucci G Altieri F Formisano V Fonti S Capaccioni F Cerroni P Coradini A Korablev O Kottsov V Ignatiev N Titov D Zasova L Pinet P Schmitt B Sotin C Hauber E Hoffmann H Jaumann R Keller U Forget F;Omega Team 《Nature》2005,438(7068):623-627
The recent identification of large deposits of sulphates by remote sensing and in situ observations has been considered evidence of the past presence of liquid water on Mars. Here we report the unambiguous detection of diverse phyllosilicates, a family of aqueous alteration products, on the basis of observations by the OMEGA imaging spectrometer on board the Mars Express spacecraft. These minerals are mainly associated with Noachian outcrops, which is consistent with an early active hydrological system, sustaining the long-term contact of igneous minerals with liquid water. We infer that the two main families of hydrated alteration products detected-phyllosilicates and sulphates--result from different formation processes. These occurred during two distinct climatic episodes: an early Noachian Mars, resulting in the formation of hydrated silicates, followed by a more acidic environment, in which sulphates formed. 相似文献