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1.
FBP和FCNN网络是模式识别中应用最为广泛的两种神经网络,本文将这两种网络应用于车型识别,分别建立了车型识别模型。利用混沌对初值的极端敏感依赖提出了FCNN网络算法,通过对车型图像数据库进行仿真实验,对比分析它们各自的识别率和泛化能力等性能指标,证明了FCNN网络算法的有效性。  相似文献   

2.
Summary Five topics concerning medical population genetics have been selected for discussion: in the field of population cytogenetics, the frequency of chromosomal aberrations and the roles of mutation and selection in the maintenance of balanced rearrangements are studied; the long term genetic effects of treatment and prevention of genetic diseases are reviewed; the relationships between malaria and the sickle-cell trait are discussed; some recent works concerning human DNA polymorphisms in the field of population, genetics are presented, and finally, some methods of genetic epidemiology are described.  相似文献   

3.
This paper is concerned primarily with the evaluation and comparison of objective and subjective weather forecasts. Operational forecasts of three weather elements are considered: (1) probability forecasts of precipitation occurrence, (2) categorical (i.e. non-probabilistic) forecasts of maximum and minimum temperatures and (3) categorical forecasts of cloud amount. The objective forecasts are prepared by numerical-statistical procedures, whereas the subjective forecasts are based on the judgements of individual forecasters. In formulating the latter, the forecasters consult information from a variety of sources, including the objective forecasts themselves. The precipitation probability forecasts are found to be both reliable and skilful, and evaluation of the temperature/cloud amount forecasts reveals that they are quite accurate/skilful. Comparison of the objective and subjective forecasts of precipitation occurrence indicates that the latter are generally more skilful than the former for shorter lead times (e.g. 12–24 hours), whereas the two types of forecasts are of approximately equal skill for longer lead times (e.g. 36–48 hours). Similar results are obtained for the maximum and minimum temperature forecasts. Objective cloud amount forecasts are more skilful than subjective cloud amount forecasts for all lead times. Examination of trends in performance over the last decade reveals that both types of forecasts for all three elements increased in skill (or accuracy) over the period, with improvements in objective forecasts equalling or exceeding improvements in subjective forecasts. The role and impact of the objective forecasts in the subjective weather forecasting process are discussed in some detail. The need to conduct controlled experiments and other studies of this process, with particular reference to the assimilation of information from different sources, is emphasized. Important characteristics of the forecasting system in meteorology are identified, and they are used to describe similarities and differences between weather forecasting and forecasting in other fields. Acquisition of some of these characteristics may be beneficial to other forecasting systems.  相似文献   

4.
In immuno-induced exocrine pancreatic carcinomas, which keep their exocrine secretory specificity through their different evolution stages [(1), (2)], normal B, A and D endocrine cells are still found, demonstrated by immunochemical techniques. They are localized in the islets of Langerhans. B and A cells are scattered in adenomatous pancreatic remains, and in the anaplasic carcinoma; D cells are found in the ductular and adenomatous remains. The three types of endocrine secretion granules are analyzed by electron microscopy at the early and late stages of carcinogenesis. The origin of the persisting endocrine cells and the nature of undifferentiated cells proliferating from the ductular epithelium are discussed.  相似文献   

5.
The structure and function of tRNA genes of higher eukaryotes   总被引:1,自引:0,他引:1  
E Kubli 《Experientia》1981,37(1):1-9
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6.
Summary In smooth endoplasmic membranes of rat splenic cells, glycosyl-transferase activities are located in various structures. These structures are separated by sucrose density gradient centrifugation. At the bottom are mannosyl- and N-acetyl-glucosaminyl-transferases; in the medium are mannosyl-and galactosyl-transferases; at the top are also mannosyl- and galactosyl-transferases, but no N-acetyl-glucosaminyl-transferase.  相似文献   

7.
The features and intensities of electric and magnetic fields in the environment are described. Natural as well as technical constant and variable fields are considered in the light of their possible biological effects. The upper limits of the various fields are discussed. Results of laboratory measurements and also of epidemiological investigations are presented. The question is raised whether atmospheric small ions can cause a biological effect.  相似文献   

8.
首先介绍了农田渍害的表现特征;其次根据监测原理,将国内外农田溃害遥感监测的主要方法分为地表指示标志法、地下水位反演法和与非遥感方法相结合的综合分析法,并分别对各类方法的原理、技术、适用范围及优缺点进行分析,发现各种方法均能解决特定的农田渍害监测问题,同时也存在着缺陷和局限性;最后,进行了总结并指出了两种潜在的遥感监测方...  相似文献   

9.
The espins are novel actin-bundling proteins that are produced in multiple isoforms from a single gene. They are present at high concentration in the parallel actin bundle of hair cell stereocilia and are the target of deafness mutations in mice and humans. Espins are also enriched in the microvilli of taste receptor cells, solitary chemoreceptor cells, vomeronasal sensory neurons and Merkel cells, suggesting that espins play important roles in the microvillar projections of vertebrate sensory cells. Espins are potent actin-bundling proteins that are not inhibited by Ca2+. In cells, they efficiently elongate parallel actin bundles and, thereby, help determine the steadystate length of microvilli and stereocilia. Espins bind actin monomer via their WH2 domain and can assemble actin bundles in cells. Certain espin isoforms can also bind phosphatidylinositol 4,5-bisphosphate, profilins or SH3 proteins. These biological activities distinguish espins from other actin-bundling proteins and may make them well-suited to sensory cells.  相似文献   

10.
Summary Temporal and regional variations in psychological processes have been associated with three geological factors. They are geochemical profiles, geomagnetic variations, and tectonic stresses. In the geochemical domain, copper, aluminum, zinc, and lithium may influence the incidence of thought disorders such as schizophrenia and senile dementia. These common elements are found in many soils and ground water. Geomagnetic variations have been correlated with enhanced anxiety, sleep disturbances, altered moods, and greater incidences of psychiatric admissions. The effects are usually brief but pervasive. Transient and very local epidemics of bizarre and unusual behaviors are sociological phenomena that sometimes precede increases in earthquake activity within a region; they have been hypothesized to be associated with tectonic strain. Many of the contemporary correlations between geological factors and human behavior are also apparent within historical data. The effects of geophysical and geochemical factors upon human behavior are not artifactual, but they are complex and often not detected by the limited scope of most studies.  相似文献   

11.
The contents of Scala Graduum Caloris are described, supplemented by unpublished material. Both temperature measurements by his linseed oil thermometer and those based upon his law of cooling are shown to be reasonably accurate to 300°C, but above that value they are much too low. The apparent agreement and the deviation are explained by the differences between the assumptions that Newton made in deriving his law of cooling and the conditions in which he used it. Newton's attempts to link terrestrial and celestial science in applications in the Principia are shown to fail from his confounding the concepts of temperature, heat and radiant intensity and his ignorance of most factors affecting the temperature rise of irradiated materials. Other comments on varied aspects of heat, mainly published in the Queries, are set out and analysed. His originality is assessed.  相似文献   

12.
13.
14.
Life without oxygen: what can and what cannot?   总被引:1,自引:0,他引:1  
A J Zehnder  B H Svensson 《Experientia》1986,42(11-12):1197-1205
The basic principles involved in the biotransformation of organic carbon compounds in the absence of molecular oxygen (dioxygen) are presented in this paper. The role of various electron acceptors during the breakdown of organic compounds is discussed and the metabolic end-products expected are summarized. The different biochemical possibilities and strategies for the anaerobic degradation of organic matter and the metabolic response of some organisms to anaerobiosis are elucidated. Positive and negative effects of anaerobiosis on environmentally relevant processes and their influence on man and on animals are reviewed. Finally, some examples of the biotechnological application of anaerobic processes are presented.  相似文献   

15.
M A Persinger 《Experientia》1987,43(1):92-104
Temporal and regional variations in psychological processes have been associated with three geological factors. They are geochemical profiles, geomagnetic variations, and tectonic stresses. In the geochemical domain, copper, aluminum, zinc, and lithium may influence the incidence of thought disorders such as schizophrenia and senile dementia. These common elements are found in many soils and ground water. Geomagnetic variations have been correlated with enhanced anxiety, sleep disturbances, altered moods, and greater incidences of psychiatric admissions. The effects are usually brief but pervasive. Transient and very local epidemics of bizarre and unusual behaviors are sociological phenomena that sometimes precede increases in earthquake activity within a region; they have been hypothesized to be associated with tectonic strain. Many of the contemporary correlations between geological factors and human behavior are also apparent within historical data. The effects of geophysical and geochemical factors upon human behavior are not artifactual, but they are complex and often not detected by the limited scope of most studies.  相似文献   

16.
Macroeconomic indicators are typically appraised in seasonally adjusted form, and forecasts are often presented in a similar way (as annual changes, for example). Moreover, the quarterly macroeconomic models used in forecasting are commonly estimated from seasonally adjusted data. Nevertheless, these models can generate forecasts with seasonal patterns, and this paper assesses the cause and cure of this phenomenon. It is found that forecast seasonality is induced by seasonality in the various inputs: exogenous variables, residual adjustments, the dynamic specification of certain equations, and annual changes in policy variables. Series changing annually but observed quarterly are termed ‘intercalated series’, and are simple examples of periodic processes. Forecast seasonality can be removed by appropriate adjustment of all these inputs. Models containing explicit future expectations variables solved in a model-consistent manner are also considered: numerical sensitivity to the terminal quarter may result from terminal conditions that require adjustment when seasonality is present.  相似文献   

17.
It is becoming increasingly clear that lipids are key regulators of cellular function and that these effects are quite diverse. First, the lipid environment in the cellular membrane bilayer is important in maintaining the normal function of receptors, enzymes, transporters and so on that are localized in the membrane. Phosphoinositides are important regulators of signalling molecules. Lipid metabolites formed by a number of enzymes including the cyclooxygenases, lipoxygenases and P450s also mediate important cellular functions. Fatty acids and lipid metabolites can also activate the nuclear peroxisome proliferator-activated receptors. Finally, a wide variety of lipid molecules are generated nonenzymatically by free-radical mechanisms that also exert potent biological effects in a wide variety of organs. Presented are a series of eight reviews that broadly cover all of these topics in some detail.  相似文献   

18.
归纳总结了近些年来国内外在镁硼酸盐动力学研究进展,内容主要包括氯柱硼镁石、天然矿物中不舍氯的硼镁石(如:章氏硼镁石,三方硼镁石,库水硼镁石,多水硼镁石等)的平衡结晶固相和动力学方程,提出了未来镁硼酸盐动力学研究的发展趋势。  相似文献   

19.
20.
Hydroxyproline-rich glycoproteins (HRGPs) are ubiquitous architectural components of the growing plant cell wall, accounting for as much as 10-20% of the dry weight. HRGPs are implicated in all aspects of plant growth and development, including responses to stress. The HRGP superfamily contains three major groups which represent a continuum of peptide periodicity and hydroxyproline-O-glycosylation. These groups range from the highly periodic and lightly arabinosylated repetitive proline-rich proteins (PRPs), through the crosslinked extensins which are periodic and highly arabinosylated, to the arabinogalactan-proteins (AGPs) which are the most highly glycosylated and least periodic. The repetitive units are small, often only four- to six-residue-glycosylated modules viewed hypothetically as functional motifs, or glycomodules. The Hyp contiguity hypothesis predicts that Hyp arabinosylation increases with Hyp contiguity and that clustered noncontiguous Hyp residues are sites of arabinogalactan polysaccharide addition in the AGPs and gums. Recent results involving glycosylation site mapping of endogenous HRGPs and HRGP design using synthetic genes have corroborated the hypothesis. The uses of synthetic genes in HRGP glycosylation site mapping and structural/functional analysis are also discussed.  相似文献   

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