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排序方式: 共有670条查询结果,搜索用时 12 毫秒
1.
R Legouis M Cohen-Salmon I del Castillo J Levilliers L Capy JP Mornow C Petit 《Canadian Metallurgical Quarterly》1993,17(2):516-518
The human KAL gene, responsible for the X-linked Kallmann syndrome, was isolated previously. Southern blot analysis using human cDNA probes detected cross-hybridization with DNA from several organisms, including chicken and quail. The entire coding sequences of chicken and quail KAL cDNAs were determined. A comparison of these cDNAs with the human KAL cDNA reveals an overall identity of 73 and 72%, respectively. This results in 76 and 75% identity at the protein level. The highest conservation was found in the WAP four-disulfide core motif and in two of the four fibronectin type III repeats reported in the human protein. These results further support the hypothesis that the KAL protein is an extracellular matrix component with anti-protease and adhesion functions. 相似文献
2.
3.
J de Seze JC Hache P Vermersch CF Arndt CA Maurage F Pasquier JL Laplanche MM Ruchoux D Leys A Destée H Petit 《Canadian Metallurgical Quarterly》1998,51(4):962-967
OBJECTIVE: The predictive value of electrophysiologic visual testing in Creutzfeldt-Jakob disease (CJD) was investigated, and the retinal pathologic findings in three cases are reported. BACKGROUND: The fatal prognosis of CJD, its transmissibility, and the lack of treatment make early diagnosis essential in averting human-to-human transmission. Electroretinogram and visual evoked potentials have been studied in few cases of CJD. METHODS: A visual electrophysiologic examination was performed in 41 consecutive patients referred with suspected CJD. The disease had been diagnosed in 24 patients (CJD group; 15 were confirmed neuropathologically and 9 by clinicolaboratory methods in accordance with diagnostic criteria). The remaining 17 patients were diagnosed with other neurologic disorders, and served as a control group. RESULTS: Flash electroretinogram revealed a significant decrease in the amplitude of the B1 wave (<60 microV) and the B/A ratio (<2) in the CJD group compared with those in the control group. Flash visual evoked potentials revealed no significant difference in latency, but amplitude was increased (>10 microV) in the CJD group, especially in patients with myoclonus. CONCLUSIONS: The visual electrophysiologic abnormalities provide an interesting noninvasive diagnostic tool in idiopathic CJD. The B1-wave decrease is closely correlated with the outer plexiform layer abnormalities observed on neuropathologic examination. 相似文献
4.
Phillip H. Henna Dejan D. Andjelkovic Petit P. Kundu Richard C. Larock 《应用聚合物科学杂志》2007,104(2):979-985
New polymeric thermosets were prepared through the bulk free‐radical copolymerization of 100% conjugated linseed oil, acrylonitrile, and divinylbenzene. Under the appropriate reaction conditions and with the appropriate curing sequence, 61–96 wt % of the oil was incorporated into the crosslinked thermosets. The resulting yellow, transparent thermosets varied from being soft and flexible to being hard and brittle. Dynamic mechanical analysis and thermogravimetric analysis showed that these thermosets had good mechanical properties and thermal stability. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 979–985, 2007 相似文献
5.
NOx sorption and reduction capacities of 12-tungstophosphoric acid hexahydrate (H3PW12O40·6H2O, HPW) were measured under representative alternating conditions of lean and rich exhaust-type gas mixture. Under lean conditions, the sorption of NOx is large and is equivalent to 37 mg of NOx/gHPW. Although a part of these NOx remains unreduced, HPW is able to reduce some of the NOx to produce N2 by a reaction between the sorbed NO2 and hydrocarbon (HC), but this process is slow. The addition of 1% Pt affects strongly the chemical behaviour occurring during the course of a rich operation. The NO desorption observed at the beginning of the rich phase is strongly accelerated. The direct correlation between NO2 consumption and CO2 production shows that the principal pathway is the reaction CO+NO2→CO2+NO. In a mixture of reducing gas (CO, HC, H2), the competition is strongly in favour of CO though in its absence the reaction observed was the hydrogenation of propene to propane. 相似文献
6.
Maud Cansell Noredine Moussaoui Alain Pierre Petit Alain Denizot Nicole Combe 《European Journal of Lipid Science and Technology》2006,108(6):459-467
Two n‐3 polyunsaturated fatty acid (PUFA)‐rich diets differing in their chemical and physical forms were given to rats during 2 wk. Liposomes [phospholipids (PL) organized in bilayer structures] made from a natural marine lipid extract or a mixture of fats containing fish oil [similar fatty acids esterified in triacylglycerols (TAG)] were used. The influence of n‐3 PUFA dietary sources on plasma parameters, i.e. TAG, cholesterol and PL concentrations, was investigated. A similar hypotriglyceridemic effect of n‐3 PUFA from liposomes or fish oil was observed. In contrast, feeding rats with liposomes led to different PL and cholesterol patterns. In the plasma of rats fed liposomes, total cholesterol amounts were positively correlated with PL levels. Liposome and fish oil feedings caused a marked increase in the amounts of n‐3 PUFA, which occurred mainly at the expense of n‐6 PUFA. However, the enrichment in n‐3 PUFA in the different plasma lipid classes differed substantially when ingested in the form of fish oil or liposomes. These results were interpreted in terms of different lipid bioavailability and metabolic fate during the digestive steps and in the liver, with the dietary source. 相似文献
7.
M. Teymouri E. Bagherzadeh C. Petit J. L. Rehspringer S. Libs A. Kiennemann 《Journal of Materials Science》1995,30(11):3005-3009
Well-defined structures like ABO3 (A = Ba, Sr, Ca; and B = Ti, Zr) perovskites were prepared by a sol-gel method which permits the formation of a crystalline structure at low-calcination temperatures (700 °C). The perovskite structures were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) methods and the carbonate present at the surface was determined by Fourier transform infra-red spectroscopy. Reactivity studies showed that the perovskite structures are stable under oxidative coupling of methane (OCM) conditions. The yield increases followed the sequence Ca < Sr < Ba and Zr < Ti, and a stable BaTiO3 gives a C2 yield of 15% at 800 °C. 相似文献
8.
Use of high-resolution satellite imagery in an integrated model to predict the distribution of shade coffee tree hybrid zones 总被引:1,自引:0,他引:1
C. Gomez M. Petit P. Hamon A. De Kochko V. Poncet 《Remote sensing of environment》2010,114(11):2731-2744
In New Caledonia (21°S, 165°E), shade-grown coffee plantations were abandoned for economic reasons in the middle of the 20th century. Coffee species (Coffea arabica, C. canephora and C. liberica) were introduced from Africa in the late 19th century, they survived in the wild and spontaneously cross-hybridized. Coffee species were originally planted in native forest in association with leguminous trees (mostly introduced species) to improve their growth. Thus the canopy cover over rustic shade coffee plantations is heterogeneous with a majority of large crowns, attributed to leguminous trees. The aim of this study was to identify suitable areas for coffee inter-specific hybridization in New Caledonia using field based environmental parameters and remotely sensed predictors. Due to the complex structure of tropical vegetation, remote sensing imagery needs to be spatially accurate and to have the appropriate bands for monitoring vegetation cover. Quickbird panchromatic (black and white) imagery at 0.6 to 0.7 m spatial resolutions and multispectral imagery at 2.4 m spatial resolution were pansharpened and used for this study. The two most suitable remotely sensed indicators, canopy heterogeneity and tree crown size, were acquired by the sequential use of tree crown detection (neural network), image processing (such as textural analysis) and classification. All models were supervised and trained on learning data determined by human expertise. The final model has two remotely sensed indicators and three physical parameters based on the Digital Elevation Model: elevation, slope and water flow accumulation. Using these five predictive variables as inputs, two modelling methods, a decision tree and a neural network, were implemented. The decision tree, which showed 96.9% accuracy on the test set, revealed the involvement of ecological parameters in the hybridization of Coffea species. We showed that hybrid zones could be characterized by combinations of modalities, underlining the complexity of the environment concerned. For instance, forest heterogeneity and large crown size, steep slopes (> 53.5%) and elevation between 194 and 429 m asl, are favourable factors for Coffea inter-specific hybridization. The application of the neural network on the whole area gave a predictive map that distinguished the most suitable areas by means of a nonlinear continuous indicator. The map provides a confidence level for each area. The most favourable areas were geographically localized, providing a clue for the detection and conservation of favourable areas for Coffea species neo-diversity. 相似文献
9.
The contribution of this paper is threefold. First, we present the paradigm of snap-stabilization. A snap- stabilizing protocol guarantees that, starting from an arbitrary system configuration, the protocol always behaves
according to its specification. So, a snap-stabilizing protocol is a time optimal self-stabilizing protocol (because it stabilizes
in 0 rounds). Second, we propose a new Propagation of Information with Feedback (PIF) cycle, called Propagation of Information with Feedback and Cleaning (). We show three different implementations of this new PIF. The first one is a basic cycle which is inherently snap-stabilizing. However, the first PIF cycle can be delayed O(h
2) rounds (where h is the height of the tree) due to some undesirable local states. The second algorithm improves the worst delay of the basic
algorithm from O(h
2) to 1 round. The state requirement for the above two algorithms is 3 states per processor, except for the root and leaf processors
that use only 2 states. Also, they work on oriented trees. We then propose a third snap-stabilizing PIF algorithm on un-oriented
tree networks. The state requirement of the third algorithm depends on the degree of the processors, and the delay is at most
h rounds. Next, we analyze the maximum waiting time before a PIF cycle can be initiated whether the PIF cycle is infinitely
and sequentially repeated or launch as an isolated PIF cycle. The analysis is made for both oriented and un-oriented trees.
We show or conjecture that the two best of the above algorithms produce optimal waiting time. Finally, we compute the minimal
number of states the processors require to implement a single PIF cycle, and show that both algorithms for oriented trees
are also (in addition to being time optimal) optimal in terms of the number of states.
WARNING: The concept of snap-stabilization was first introduced in [12]. The concept evolved over the last eight years. We
take this evolution in consideration in this paper, which includes the early results published in [10] and [12]. In particular,
infinite repetition of computation cycles is a requirement of self-stabilizing systems. This is not required in snap-stabilization because snap-stabilization ensures that the first completed computation cycle is executed according to the
specification of the problem. The correctness proofs conform to this basic property. 相似文献
10.
Antoine Petit 《Acta Informatica》1993,30(1):89-101
We introduce new finite state parallel machines, the (-)distributed automata, for trace languages. We prove that these machines give a new characterization of recognizable trace languages: a trace language is recognizable if and only if it is recognized by a (-)distributed automaton. At last, we show how the classical problem of distribution of uninterpreted tasks on several processors can be straightforward modelized by recognizable trace languages and solved using (-)distributed.This work has been partly supported by the ESPRIT Basic Research Actions No 3148 (DEMON) and by the PRC C3 and Math-Info 相似文献