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991.
The technique of neutron activation analysis (NAA) has been employed to measure the content of 29 kinds of elements in the sample of Yaozhou porcelain bodies,Then a fuzzy cluster analsis has been conducted to the NAA data and a diagram of the dynamic fuzzy cluster analysis has been achived,The results indicate that the batch of ancient Yaozhou porcelain bodies,which were of different overglaze color and were produced by different kilns during a period of over 800 years from the Tang Dynasty (618-907 A.D.) to the Yuan Dyansty(1271-1368 A.D.) ,has shared a stable and concentrated raw material source,Provenances of porcelain bodies from different times ,though having their specific independence ,enjoy a close relationship and are not far from one another,Provenances of porcelain bodies made during the Tang Dynasty and the Five Dynasties (907-960 A.D.)are found to be closer to one another,while those of the Song (960-1279A.D.) and the Jin Dynasty (1115-1234 A.D.)are comparatively concentrated in certain areas and are different from those of the Tang Dynasty .Both the tri-colored glazed pottery made in Yaozhou kilns during the Tang Dynasty and the Yaozhou porcelain bodies of the Tang period are from the same provenance.  相似文献   
992.
Ice nucleation active(INA)bacteria are the most potent heterogeneous ice nuclei in nature,which have become an important biological resource for diverse applications.Many researches have proved that INA bacteria can raise the supercooling points(SCPs)of insect pests,then reduce their cold hardiness.However,INA bacteria‘s inefficient colonization on the surface or in the guts of insects,and the high incidence of frost injury induced by their release hampered the application of INA bacteria in controlling insect pests in agricultural fields.In this study,we constructed a recombinant plasmid mob-Tn5-iceA with the ability of broad-host-range conjugal mobilization and integration of the ina gene of icaA into chromosomal DNA of many gram-negative bacteria by Tn5 transposition.In addition,Ent.cloacae strains stably carrying iceA and expressing high ice nucleation activity(INA),even in the absence of antibiotic pressure,were constructed through conjugal mobilization and Tn5 transposition.Ent,cloacae strains have benn reported to be able to efficently colonize in the guts of insects,but have weak plant epiphytic ability.Therefore,these transgenic Ent.Cloacae may be promising candidates for control of insect pests in agricultural fields.  相似文献   
993.
994.
Pre-selecting young bulls before progeny-testing with marker-assisted BLUP   总被引:1,自引:0,他引:1  
Suppose that a QTL affecting milk production trait or dairy cattle has been identified,and the relative distances between the QTL and the markers are hnown without error.The relative efficiency of pre-selection of young bulls before progeny-testing with marker-assisted BLUP(MBLUP) over conventional progeny-testing(i.e.random selection before progeny-testing)for five generations was studied using Monte Carlo simulation.Different numbers of QTL alleles(two or infinite),initial frequencies of the favorable QTL allele(0.1 and 0.5,when the QTL has two alleles),distances between the adjacent markers(5 cM or 20 cM),and ratios of the QTL variance to the genetic variance(10%,25%,and 50%)were considered in the simulation.The results showed that the relative efficiency of MBLUP was higher when the marker distance was 5 cM than that when the distance was 20 cM.The larger the QTL alleic effect,the lower the MBLUP efficiency.The relative superiority of MBLUP was higher when the QTL had two alleles and the frequency of the favorable QTL allele was low in the base population.The relative superiority of MBLUP decreased with th progress of generation in all cases and the decreasing rate was getting higher with the increase of marker density and QTL effect.  相似文献   
995.
996.
Topography of acoustic response characteristics of the midbrain inferior colliculus(IC)of the Kunming mouse was studied by using extracellular recording techniques.The characteristic frequency(CF)range represented in the different divisions of the IC differed markedly:4-15 kHz in the dorsal cortex(DC),10-70 kHz in the central nucleus(CN),and 4-35kHz in the external cortex(EC).The CF in the CN increased from dorsal and lateral to ventral and medial,higher CFs represented at its ventromedial part and lower CFs at its dorsal part.The isofrequency contours of CFs were incurvate.Minimum thresholds(MT)of the auditory neurons in DC and the central part of CN were lower(about 10dB SPL),but considerably higher in the dorsal and ventral region of EC.Results suggest that each of the divisions in the mouse IC may have different auditory functions.  相似文献   
997.
In the peralumineous granite of Yajiangqiao zircon population can be divided into two groups (i.e. Zircon Ⅰ and Zircon Ⅱ), which were formed in magmatic chamber and in emplacement place, respectively. The Hf isotope compositions of two stages of zircon show that the host magma was essentially derived from crustal material by melting. However, some higher 176Hf/177Hf ratios indicate that the granitic zircons should contain fine crystal of zircon formed in mantle-derived magma. In fact, the backscattered electron imaging and the electron microprobe analysis reveal that there is another type of zircon included within Zircon Ⅰ, which is quite different from Zircon Ⅰ and Zircon Ⅱ in morphology and chemistry. They are considered to be the product of the mantle-derived magma intruded into the granitic magma chamber at the beginning of anatexis. Thus,it is suggested that the formation of Yajiangqiao granite is related to the underplating of mantle magma.  相似文献   
998.
The idea and main theoretical results of the global analysis theory of climate system are briefly summarized in this paper. A theorem on the global behavior of climate system is given, i.e. there exists a global attractor in the dynamical equations of climate, any state of climate system will be evolved into the global attractor as time increases,indicating the nonlinear adjustment process of climate system to external forcing. The different effects of external forcing, dissipation and nonlinearity on the long-term behavior of solutions are pointed out, and some main applications of the global analysis theory are also introduced. Especially, three applications, the adjustment and evolution processes of climate, the principle of numerical model design and the optimally numerical integration, are discussed.  相似文献   
999.
Coupling and feedback between iron and sulphur in air-sea exchange   总被引:9,自引:0,他引:9  
Iron in surface seawater has been demonstrated to be the limiting nutrient factor for primary productivity in certain oceanic regions where other major nutrients are abundant[1—5]. The available Fe to the phytoplankton in seawater is related to the uptake of carbon dioxide through the ocean and, in turn, to the global greenhouse effect[6—11]. Recent reports showed that the available Fe in the seawater is closely correlative to nitrogen fixation in the ocean[12—17]. Understanding which Fe s…  相似文献   
1000.
Photoluminescence (PL) properties of porous anodic alumina (PAA) films prepared by using electrochemical anodization technique in a mixed solution of oxalic and sulfuric acid have been investigated. The PAA films have an intensive ultraviolet PL emission around 350 nm, of which a possible PL mechanism has been proposed. It was found that the incorporated oxalic ions, which could transform into PL centers and exist in the PAA films, are responsible for this ultraviolet PL emission.  相似文献   
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