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排序方式: 共有817条查询结果,搜索用时 15 毫秒
811.
812.
Lin-ding WANG 《Virologica Sinica》2007,(3)
Kaposi's sarcoma-associated herpesvirus(KSHV)is the primary etiological agent of Kaposi's sarcoma,primary effusion lymphoma and muticentric Castleman's disease.In common with the other herpesviruses,KSHV exhibits both latent and lytic life cycles,both of which are characterized by distinct gene expression profiles and programs.KSHV encodes proteins which play essential roles in the inhibition of host adaptive and innate immunity,the inhibition of apoptosis,and the regulation of the cell cycle.KSHV also encodes several proteins which have transforming and intrcellular signalling activity. 相似文献
813.
814.
A NEW PRIMITIVE CHALICOTHERE (PERISSODACTYLA,MAMMALIA) FROM THE EARLY EOCENE OF HUBEI, CHINA 总被引:1,自引:1,他引:0
'I.DESCR1PTIoNorderPerissodactylaOwen,l848SuperfamilyCbalicotherioideacall,l872'Family?EomoropidaeVret,l958GehusDanjiangiagen.nov.TypespeciesDaniiangiapingigen.etsp-nov.DiagnoaisSma1lprimitivecha1icothere(lengthofM/l=8.3mm),skullshallowwithcranialrostrumrelatively1ong,mandibularhorizontalramusandmandibularsymphysisfairlylongandsha1low,teeth1ow-crowned,dentitionformula:3.l.4.3/3.1.4.3.Premolarnonmolariform,P2/2tIenchant,P4/withincipientmesostyle.M/widerthan1engthwithW-shapedectoIoph,… 相似文献
815.
INTanDUCTIONFungalhyphaeextendbytipgrowthandhaveahigherconceotration0fCa2 intheiraPicesthantheirbases,afactwhichispr0bablyrelatedt0theimp0rtentroleplayedbycalcinminestablishingandmaintainingapical0rganizati0n,mor-ph0g9nesis,and,grtiWth[1-6].Tounderstandthethefullcti0nofCa2 inhyphaltipgrbwth,'Ca' -bindingproteinsmustbeidentifiedandtheirflincti0nsdetermined.CaM,a,ubiquitousilltracellularCa' -bindingpr0teinwhichfuncti0nst0mediatemanyCa' -regulatedpr0cessesincells,naturallyhasbeenreceivedal… 相似文献
816.
Weng Peixuan 《生物数学学报》1995,(1)
61.IntroductionIn〔2〕and〔5〕,MackeyandGlasshaveproposedamodelforresplratorydynamlcswhichIsbasedonthelevelofconcentrationofCOzInthe.arterialbloodofamammal.Let一(t)b6th68ft6fls!COflC6lltfstlottofCOZ,th6flH[sgOV6tfl6dbyth66qU8tlofiwherer,p,0,narepositiveparameters,rlsanonnegatlvedelayandvmdenotesthemaxi-—uffi‘V6tttllst1Ofl’rateOfCOZ.Iflsf6Celltpsp6f〔3),GOpslS8ffiy6tslObtslllEdSUfflCIElltconditionsforallpositivesolutionsof(1.1)tooscillateaboutthePositiveequl… 相似文献
817.
László ORL 《生物学前沿》2009,4(4):557-568
Ecological practice is telling us that to identify Nature's rules, we should look for regularities in the resulting effects. Hidden rules are involved and the effects are manifested by compositional, functional, and structural transitions. This paper's focus is on two conjectures regarding the governance of specific transition compo-nents, the first supposedly under global co-ordination, and the second under superimposed site specific instability oscillations. The reality of any apparent regularity in these is the sole condition for the regularity's acceptance as a rule. Reality is testable but in retrospect only, based on time series analyses. Since long pollen spectra supply the evidence, the time period involved is measured in thousands of years. For maximal usefulness, a spectrum should have a long period length, dated horizons intensely sampled at short time steps, and precisely identified taxa. Period length and time step width matter because both may have a masking effect on the regularities. There is, of course, a natural limit for period length, which is set by the age of the pollen bearing sediments. We completed the analysis of 23 spectra using techniques deemed suitable for testing the conjectures. The spectra originated from sites in the Americas where we found suitable spectra in sufficient numbers and in geographic contiguity from the Arctic region to the Antarctic. The presented results have clear indications that the two conjectures identify real rules. The main body of the paper narrates the analyses and provides explanations. Informative materials, too voluminous for inclusion in the paper, are made available on the Internet at URL: www.vegetationdynamics.com linking to "Appen-dices Ta". 相似文献