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Content-based medical image retrieval (CBMIR) is a powerful resource to improve differential computer-aided diagnosis. The major problem with CBMIR applications is the semantic gap, a situation in which the system does not follow the users’ sense of similarity. This gap can be bridged by the adequate modeling of similarity queries, which ultimately depends on the combination of feature extractor methods and distance functions. In this study, such combinations are referred to as perceptual parameters, as they impact on how images are compared. In a CBMIR, the perceptual parameters must be manually set by the users, which imposes a heavy burden on the specialists; otherwise, the system will follow a predefined sense of similarity. This paper presents a novel approach to endow a CBMIR with a proper sense of similarity, in which the system defines the perceptual parameter depending on the query element. The method employs ensemble strategy, where an extreme learning machine acts as a meta-learner and identifies the most suitable perceptual parameter according to a given query image. This parameter defines the search space for the similarity query that retrieves the most similar images. An instance-based learning classifier labels the query image following the query result set. As the concept implementation, we integrated the approach into a mammogram CBMIR. For each query image, the resulting tool provided a complete second opinion, including lesion class, system certainty degree, and set of most similar images. Extensive experiments on a large mammogram dataset showed that our proposal achieved a hit ratio up to 10% higher than the traditional CBMIR approach without requiring external parameters from the users. Our database-driven solution was also up to 25% faster than content retrieval traditional approaches.  相似文献   
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From a scientific point of view, heat transfer is different in solar furnaces compared with classical ones and the influence of direct concentrated solar radiation on sintered parts needs to be studied in detail to determine the feasibility of solar furnaces in manufacturing small workpieces. This study was performed on cylindrical samples with controlled morphology obtained by a powder metallurgy 3D printing technique. All samples were heated with a heating rate of 120 ± 10 °C/minute, with 0, 1, 2, 3, 4 and 5 min holding times at 900 °C and 930 °C. The morphology of the samples was analyzed microscopically, the microhardness was determined before and after sintering, and the results were correlated with the sintering parameters (temperature, heating rate and holding time). The best results were obtained at 930 °C with 5 min holding time from the microhardness value and microstructure point of view.  相似文献   
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Bedo  D. G. 《Chromosome research》1994,2(3):191-199
The distribution and replication of heterochromatin in polytene trichogen chromosomes of the Old World screw-worm fly,Chrysomya bezziana, were studied using fluorescent staining techniques. Quinacrine and distamycin-DAPI, which selectively stain AT-rich DNA, and chromomycin, specific for GC-rich sequences, were used. Bright quinacrine and DA-DAPI fluorescence was found in the sex chromosome body and in all autosomal centromere regions. Chromomycin (CMA) staining results in very little bright fluorescence of the sex chromosome body and autosomal centromeric regions, but many bright bands of varying morphology are distributed in autosomal arms. The expected negative CMA staining of quinacrine and DA-DAPI bright regions was not found. The lack of reciprocal staining patterns may result from changes in the higher order chromatin structure of polytene chromosomes, or intercalation of divergent heterochromatic sequences. Comparison of the different staining techniques in mitotic and polytene cells shows that heterochromatin is differentially under-replicated, so that the proportions of the distinct fluorescent-specific chromatin changes during polytenization. CMA staining within autosomal arms suggests that repeated sequences intercalated in euchromatin are co-replicated during polytenization. The numerous fluorescent markers described also provide further morphological features for use in comparative cytological analysis ofC. bezziana.  相似文献   
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Butyrate produced a biphasic modulation of the thyroid hormone receptor in neuroblastoma N2A cells increasing receptor number by 20-35% at concentrations 0.25-0.75 mM and decreasing receptor levels by 30-55% at 2-4 mM. The half-life of the receptor, as assessed by its disappearance after incubation with 18 microM cycloheximide was 8.4 hr in control cells and 10.3 hr and 5.0 hr in cells incubated with 0.25 and 4 mM butyrate, respectively. This compound increased the abundance of multyacetylated forms of histone H4 from 30% in control cells to almost 70% with butyrate 4 mM. In glioma C6 cells, the fatty acid produced a dose-dependent increase of receptor levels (up to 3-4-fold with 2-5 mM butyrate) and had little effect in increasing multiacetylation (from 30% in controls to 42-46% with 2-5 mM butyrate). Recent studies have shown that the c-erbA proto-oncogen codes for the thyroid hormone receptor. In N2A and C6 cells, 2 c-erbA-related mRNAs, one measuring 2.6 kb and the other 6 kb, were detected. Both forms were differently regulated by butyrate. This compound decreased the abundance of the 2.6 kb forms in both cell types, even at the concentrations at which there was an elevation of receptor levels. Only the largest mRNA correlated with receptor concentration increasing by 2-3-fold after treatment of C6 cells with butyrate, and undergoing a smaller but biphasic change in N2A cells. Our data suggest that modification of chromatin structure probably secondary to acetylation induces changes in thyroid hormone receptor levels in neuroblastoma and glioma cells by affecting both receptor stability and receptor mRNA levels.  相似文献   
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Human Leucocyte Antigen (HLA) testing is useful in the clinical work-up of coeliac disease (CD) with high negative but low positive predictive value. We construct a genomic risk score (GRS) using HLA risk genotypes to improve CD prediction and guide exclusion criteria. Imputed HLA genotypes for five European CD case-control GWAS (n > 15,000) were used to construct and validate an interpretable HLA-based risk model (HDQ15), which shows statistically significant improvements in predictive performance upon all previous HLA-based risk models. Conditioning on this model, we find two novel associations, HLA-DQ6.2 and HLA-DQ7.3, that interact significantly with HLA-DQ2.5 (p = 2.51 × 10−9, 1.99 × 10−7, respectively). Integrating these novel alleles into a new risk model (HDQ17) leads to predictive performance equivalent or better than the strongest reported GRS (GRS228) using 228 single nucleotide polymorphisms (SNPs). We also demonstrate that our proposed HLA-based models can be implemented using only six HLA tagging SNPs with statistically equivalent predictive performance. Using insights from our model to guide exclusionary criteria, we find the positive predictive value of CD testing in high-risk populations can be increased by 55%, from 17.5 to 27.1%, while maintaining a negative predictive value above 99%. Our results suggest that HLA typing is currently undervalued in CD assessment.Subject terms: Medical genetics, Coeliac disease, Genetic interaction, Genome-wide association studies, Genetic testing  相似文献   
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