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排序方式: 共有85条查询结果,搜索用时 15 毫秒
1.
JF Delaloye S Leyvraz E Outcha Adjahoto J Bauer P De Grandi 《Canadian Metallurgical Quarterly》1996,19(2):204-206
We report two cases of metastatic non-functioning pancreatic endocrine tumour with very elevated plasma levels of alpha-fetoprotein. In these two cases, serial plasma levels of alpha-fetoprotein, initially normal, correlated well with hepatic tumour progression and were associated with fatal outcome. These results suggest that elevated plasma concentration of alpha-fetoprotein may be caused by metastatic pancreatic endocrine tumour and than alpha-fetoprotein serial measurement may be useful in prognostic evaluation. 相似文献
2.
Grandi F. Scalas M.R. 《IEEE transactions on pattern analysis and machine intelligence》1993,19(7):641-660
Data access cost evaluation is fundamental in the design and management of database systems. When some data items have duplicates, a clustering effect that can heavily influence access costs is observed. The availability of a finite amount of buffer memory in real systems has an even more dramatic impact. A comprehensive cost model for clustered data retrieval by an index using a finite buffer is presented. The approach combines and extends previous models based either on finite buffer or on uniform data clustering assumptions. The computational costs of the formulas proposed are independent of the data size or of the query cardinality and need only a single statistics per search key, the clustering factor, to be maintained by the system. The predictive power and the accuracy of the model are shown in comparison with actual costs resulting from simulations 相似文献
3.
L. Durieux J. Kropáček G. D. de Grandi F. Achard 《International journal of remote sensing》2013,34(18):4175-4182
Boreal forests and wetlands play an important role in the climate system, in particular through biosphere–atmosphere flux exchanges. They are an important pool of carbon and their role as sink or source of greenhouse gases is not fully understood. Accurate mapping of the vegetation of Siberia can therefore contribute to a better understanding of these processes at regional scale and of their effects on the climate through regional biosphere modeling. The potential of the combination of radar data with medium‐resolution optical data to obtain regional‐scale land cover mapping is investigated using multi‐spectral imagery from the MERIS sensor at 300 m resolution and a high resolution radar mosaic (pixel spacing of 100 m) covering Western and Eastern Siberia compiled in the framework of the Global Boreal Forest Mapping project. For this purpose, capabilities of oriented‐object image analysis associated to wavelet multi‐resolution techniques are investigated. Results show that wavelet multi‐resolution textures bring relevant additional information for land cover classification. Suggestions are made for the implementation of an object‐based wavelet multi‐resolution texture estimator. 相似文献
4.
Toma S.; Campagnoli S.; Gregoriis E.De; Gianna R.; Margarit I.; Zamai M.; Grandi G. 《Protein engineering, design & selection : PEDS》1989,2(5):359-364
On the basis of the homology with the Bacillus thermoproteolyticuszinc endopeptidase thermotysin, we hypothesized that Glu-143and His-231 are the key residues for the catalytic activityof the Bacillus subtilis neutral protease. To test this possibilityby site-directed mutagenesis, we substituted these two residueswith Ala, Ser, Trp and Arg, and Leu, Val and Cys respectively.All these substitutions dramatically affected the amount ofsecreted mutant proteins, as determined by immunological methods,and their catalytic activities. No appreciable secretion wasobserved with the three Glu mutants Trp, Ser and Arg, whereasthe GluAla mutant enzyme was secreted at a level of afew hundred micrograms per litre of culture. The His mutantswere all secreted at higher levels (in the order of a few milligramsper litre) and their residual catalytic activity could be determinedusing Z-Ala-Leu-Ala as substrate. Our results confirm the keyrole played by Glu-143 and His-231 in catalysis and moreoversuggest the existence of a relationship between the catalyticactivity of the enzyme and the extent of its secretion. In thiscontext, we present data suggesting an autoproteolytic mechanismof cleavage of the precursor form of the enzyme, analogous tothe one previously reported for the B.subtilis subtilisin. 相似文献
5.
A. Rosenqvist M. Shimada B. Chapman A. Freeman G. De Grandi S. Saatchi 《International journal of remote sensing》2013,34(6-7):1375-1387
The Global Rain Forest Mapping (GRFM) project is an international endeavour led by the National Space Development Agency of Japan (NASDA), with the aim of producing spatially and temporally contiguous Synthetic Aperture Radar (SAR) data sets over the tropical belt on the Earth by use of the JERS-1 L-band SAR, through the generation of semi-continental, 100 m resolution, image mosaics. The GRFM project relies on extensive collaboration with the National Aeronautics and Space Administration (NASA), the Joint Research Centre of the European Commission (JRC) and the Japanese Ministry of International Trade and Industry (MITI) for data acquisition, processing, validation and product generation. A science programme is underway in parallel with product generation. This involves the agencies mentioned above, as well as a large number of international organizations, universities and individuals to perform field activities and data analysis at different levels. The GRFM project was initiated in 1995 and, through a dedicated data acquisition policy by NASDA, data acquisitions could be completed within a 1.5-year period, resulting in a spatially and temporally homogeneous coverage to encompass the entire Amazon Basin from the Atlantic to the Pacific; Central America up to the Yucatan Peninsular in Mexico; equatorial Africa from Madagascar and Kenya in the east to Sierra Leone in the west; and south-east Asia, including Papua New Guinea and northern Australia. Over the Amazon and Congo river basins, the project aimed to provide complete cover at two different seasons, featuring the basins at high and low water. In total, the GRFM acquisitions comprise some 13000 SAR scenes, which are currently in the course of being processed and compiled into image mosaics. In March 1999, SAR mosaics over the Amazon Basin (one out of two seasonal coverages) and equatorial Africa (both seasonal coverages) were completed; the data are available on CD-ROM and, at a coarser resolution, via the Internet. Coverage of the second-season Amazon and Central America will be completed during 1999, with the south-east Asian data sets following thereafter. All data are being provided free of charge to the international science community for research and educational purposes. 相似文献
6.
A research on the isolation of organic pollutants from water is presented. Five macroporous anionic resins: Varion AT400, Asmit 229N, Zerolite 553N, Wofatite EA60 and Amberlite IR93 were used for humic substances and other anionic organics isolation. Varion AT400 resulted to be the best anionic resin (about 90% recovery of humic substances and a lower recovery for other anionic substances). Nearly complete desorption was achieved by NaCl/NaOH 10%/2% solution, at a volume of about 3.5 times the resin bed volume. 相似文献
7.
L Solaini P Bagioni U Grandi E Angelini A Amigoni 《Canadian Metallurgical Quarterly》1996,51(12):1079-1082
The authors report their experience about 15 patients surgically treated for chronic large pericardial effusion; in 12 cases the etiology was malignant neoplasm, while in the other 3 cases was inflammatory disease. In 4 patients a simple subxiphoid pericardial drainage was carried out, while in the other cases a pericardial window was performed. These cases were managed using an anterior left thoracotomy in 8 patients and a videothoracoscopy in 3. The authors conclude that pericardial window with videothoracoscopic approach is the preferable procedure, but it cannot be used in every case because a lot of patients have seriously compromised conditions and the use of this technique can be hazardous. 相似文献
8.
In this paper, an inverter-fed ac motor drive is analyzed in order to investigate the conducted electromagnetic interferences at both the input and output sides of the inverter. HF lumped equivalent circuits for the inverter and the motor stator windings are proposed. The overall circuit model allows time- and frequency-domain analysis to be performed with standard circuit simulators. The proposed model can also predict common- and differential-mode HF current components. The equivalent circuit is verified by experimental tests carried out on a prototype of ac motor drive. 相似文献
9.
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