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1.
Changes in the population structure of influenza B virus in the Ukraine since 1980 has been studied. New strains of the virus have been identified and the epidemic potentials of different strains have been compared. The data on the drift mechanism of the origin of the intermediate strains of influenza B virus have been observed. A suggestion on the etiological prognostication of the epidemic process has been made.  相似文献   

2.
The extent of rotting of commercially stored Cox's Orange Pippin apples by Gloeosporium species has been severe in recent years. G. perennans has been found to be mainly responsible.
Tree infections of this fungus have usually been found to be prevalent in the orchards on farms where storage losses of fruit have occurred, and conidia of G. perennans have been found on cankers at all seasons during the year. Winter as well as summer pruning cuts have been found to become infected. Detached leaves of Cox's Orange Pippin have been successfully inoculated with G. perennans in the laboratory and the fungus has also been found on dead detached leaves in the orchard after picking time. Considerable variations have been found in the susceptibility to rotting of samples of different varieties of apple and samples of Cox's Orange Pippin apples from different orchards. Periodic loading of fruit with spores after picking has shown that resistance declines with length of storage. Wide variation in the time at which rotting commences in commercially stored samples has been observed. A series of inoculations on picked and unpicked immature fruit has shown that the apple loses its resistance to attack on picking. Lenticels which are impermeable to gaseous exchange have been shown to be resistant to penetration by the fungus. Temperature affects the development of lenticel rotting by G. perennans , infection being most rapid at temperatures of about 20°. Rotting can occur at 0° C.  相似文献   

3.
Since its invention in the mid 1980s atomic force microscopy has revolutionised the way in which surfaces can be imaged. Close to atomic resolution has been achieved for some materials and numerous images of molecules on surfaces have been recorded. Atomic force microscopy has also been of benefit to biology where protein molecules on surfaces have been studied and even whole cells have been investigated. Here we report a study of red blood cells which have been imaged in a physiological medium. At high resolution, the underlying cytoskeleton of the blood cell has been resolved and flaws in the cytoskeleton structure may be observed. Comparison of the normal 'doughnut' shaped cells with swollen cells has been undertaken. Differences in both the global properties of the cells and in the local features in cytoskeleton structure have been observed.  相似文献   

4.
New perspectives on photophosphorylation have been offered from the standpoint of the torsional mechanism of energy transduction and ATP synthesis. New experimental data on the involvement of malate anions in ATP synthesis in an acid-base malate bath procedure has been reported on spinach chloroplast thylakoids as the model system. The data cannot be reconciled with the chemiosmotic theory but has been shown to be naturally explained by the torsional mechanism. The path of malic acid in the acid and base stages of the experiment has been traced, offering further strong support to the new paradigm. Classical observations in the field have been re-interpreted in the light of these findings. A new concept of ion translocation, energy transduction and coupling at the overall physiological level in photophosphorylation has been presented and a large number of novel experimentally testable predictions have been made and shown to arise as logical consequences of the new perspectives.  相似文献   

5.
A method has been developed for immobilisation of antisera on fresh plastic tubes through an immunochemical bridge. This type of immobilisation has been shown to be more consistent than direct adsorption on plastic. Such immunochemically coated antisera on plastic tube has been used in the development of a noncentrifugation radioimmunoassay. This assay system has been found to be technically as sound as the conventional method.  相似文献   

6.
An experimental program has been carried out in order to investigate the mechanical behavior of porcine corneas. We report the results of inflation tests on the whole cornea and uniaxial tests on excised corneal strips, performed on 51 fresh porcine eyes. Uniaxial tests have been performed on specimens cut from previously inflated corneas. The cornea behavior is characterized by means of elastic stiffness, measured on both average pressure-apex displacement and average uniaxial stress-strain curves; and by means of transversal contraction coefficient, peak stress, and failure stress measured on uniaxial stress-strain curves. Uniaxial tests performed on excised strips allowed to measure the anisotropy in the corneal stiffness and to compare the stiffness of the cornea with the one of the sclera. Viscous properties of the cornea have been obtained through uniaxial relaxation curves on excised corneal strips. The relevant geometrical parameters have been measured and, with the aid of the elastic thin shell theory, a stress-strain curve has been derived from the average inflation test data and compared with similar data available in the literature. The experimental system has been developed in view of future applications to the mechanical testing of both porcine and human corneas.  相似文献   

7.
It has been systematized modern data on the myocardial regeneration and the regulation of cardiac cell proliferation in mammals and man. It has been performed an analysis published works which indicate that cardiomyocyte division and DNA synthesis in myocardial cells increase in many times during different pathological conditions. It has been generalized and analyzed results of experimental and clinical researches on the participation of stem cells in the regeneration of the heart. It has been present literature data on the telomeres and telomerase in cardiomyocytes.  相似文献   

8.
The influence of both insertion and strength/elasticity of each extensor in patellofemoral disorders was fully investigated through a two-dimensional mathematical model analysis in a horizontal plane, in combination with experimental design theory for analyzing mutually correlated influences. In the model, patellofemoral joint profiles projected on a horizontal plane have been expressed as spline functions. Each muscle of the quadriceps has been represented as a string pulled by the respective force; fascias and tendons have been represented by springs. Nonlinear equations have been constructed to represent the forces involved, and then solved by numerical iteration. An analysis of variance was performed on the data derived from a series of simulations, obtaining the following results. The strength of most extensors has been shown to have an influence on the increase in lateral contact force but not patellar translation. The tibial tubercle position has significant influence on both patellar translation and lateral contact force. The quadriceps' insertion on the femur has no influence on patellar translation. The insertion of each extensor on the patella has been shown to have a strong effect on patellar translation but not on contact force.  相似文献   

9.
孢粉-植被-气候关系研究进展   总被引:20,自引:0,他引:20       下载免费PDF全文
随着全球变化研究的不断深入 ,第四纪孢粉学研究已取得了长足的进步 ,特别是近些年来 ,孢粉 植被 气候关系研究已成为世界孢粉学界的热点之一。空气孢粉学的研究在大气环境污染监测、花粉过敏症、农业收成预报和第四纪植被与环境重建等方面得到了广泛应用 ,并不断发展 ;近年来 ,为开展全球范围的古环境研究 ,各大洲相继建立了孢粉数据库 ,大量开展表土孢粉研究。中国第四纪孢粉数据库的建立 ,汇集了我国近半个世纪积累的孢粉资料 ,并利用中国第四纪孢粉数据 ,系统开展了中国现代表土孢粉、6kaBP(中全新世 )及 1 8kaBP(末次盛冰期 )的生物群区模拟及重建 ,建立了花粉 气候转换函数和响应面模型 ,并取得了良好的结果 ;冲积物孢粉学和环境考古孢粉学研究 ,也取得了一定成果 ,但研究还有待于深入 ;特征指示种花粉雨研究 ,对古生态环境重建也具有重要的意义。  相似文献   

10.
Effect of some organic phosphorous compounds on the carp Cyprinus carpio L. in consecutive stages of its development has been studied. The least and most vulnerable stages in carp's development under the action of these compounds have been identified. The gravity of disorders in fish organism on early stages and the degree of pathological changes induced by organic phosphorous compounds have been shown. Embryotoxic and gonadotoxic effect of these compounds has been found.  相似文献   

11.
The inborn seizure response of Papio papio to intermittent light stimulation has been reviewed as a model of human epilepsy. The electrographic and clinical features have been described and useful methodology has been outlined. A diurnal cyclicity in seizure responsiveness has been described with greatest seizure severity at 8 AM in parallel with a rise in urinary output of cortisol. Hormonal influences on the seizure response have been described for ethinyl estradiol, thyroxin, and triiodothyronine. Evidence regarding neurotransmitter involvement has been reviewed. Data regarding use of the animal for anticonvulsant testing in single and chronic doses has been discussed. Particular advantages of the model for study of age-related drug effects and the assessment of the effects of chronically administered anticonvulsant agents on learning and memory have been described.  相似文献   

12.
近年来在拟南芥、水稻等模式植物中对赤霉素信号转导途径进行了广泛的研究,主要是通过对赤霉素相关突变体的生理及分子生物学研究,鉴定出一些介入赤霉素信号转导途径的重要基因,并根据相应蛋白的特征结构域,推导了它们的功能.利用双突变体分析相关基因,提出了赤霉素信号转导途径的基本机理,但植物激素的网状交互调控机制仍需进一步研究.  相似文献   

13.
Adsorption of nucleoside phosphates on the surfaces of volcanic rocks has been studied. Differences in the adsorption of some nucleoside phosphates on the surface of basalt cinder have been found. Differences in the adsorption of similarmolecules on different mineral surfaces have also been shown. Different adsorptive capacities may have served as a mechanism for the selection of organic molecules during prebiotic evolution.  相似文献   

14.
The influence of ionizing radiation (5 Gy) on the interleukin-2 inhibitor in mouse serum has been investigated. It has been shown that the concentration of IL-2 inhibitor decreases on days 3-6 and increases considerably on days 10-15 after irradiation. A correlation has been found between the number of T-helpers in spleens of exposed allogenic chimeras and low IL-2 inhibitor content of serum. An attempt has been made to use the increased IL-2 inhibitor level for improving the acceptance of allogenic cells in the sublethally exposed mice.  相似文献   

15.
Summary Tetrad and random spore analyses have been used to further develop the genetic map of Saccharomycopsis lipolytica. Mutations in 23 new nuclear genes have been isolated. Eight genes have been located on linkage fragment 1, 4 on fragment 2, 2 on fragment 5 and 3 on fragment 6. Linkage fragments 3 and 4 have been shown to be linked, and this fragment now contains 12 markers. A tentative map of the linkage fragments 1 and 3 is presented (Fig. 1). Markers exhibiting possible centromere linkage have been identified. Interference estimates suggest that there is little interference in S. lipolytica.  相似文献   

16.
Adsorption of nucleoside phosphates on the surfaces of volcanic rocks has been studied. Differences in the absorption of some nucleoside phosphates on the surface of basalt cinder have been found. Differences in the adsorption of similar molecules on different mineral surfaces have also been shown. Different adsorptive capacities may have served as a mechanism for the selection of organic molecules during prebiotic evolution.  相似文献   

17.
A 68,000 mol wt polypeptide has been identified as one of the few major proteins in the microfilament bundles of the microvilli present on intestinal epithelial cells. Antibodies against the purified protein have been used in indirect immunofluorescence microscopy on several cultured cells. The protein have been used in indirect immunofluorescence microscopy on several cultured cells. The protein is found particularly prominent in membrane ruffles, microspikes, and microvilli.  相似文献   

18.
The growth process of a living organism is studied with the help of a mathematical model where a part of the surplus power is assumed to be used for growth. In the present study, the basic mathematical framework of the growth process is based on a pioneering theory proposed by von Bertalanffy and his work is the main intellectual driving force behind the present analysis. Considering the existence of an optimum size for which the surplus power becomes maximum, it has been found that the scaling exponent for the intake rate must be smaller than the exponent for the metabolic cost. A relationship among the empirical constants in allometric scaling has also been established on the basis of the fact that an organism never ceases to generate surplus energy. The growth process is found to continue forever, although with a decreasing rate. Beyond the optimum point the percentage of shortfall in energy has been calculated and its dependence on scaling exponents has been determined. The dependence of optimum mass on the empirical constants has been shown graphically. The functional dependence of mass variation on time has been obtained by solving a differential equation based on the concept of surplus energy. The dependence of the growth process on scaling exponent and empirical constants has been shown graphically.  相似文献   

19.
Hypotheses of differences in genetic control on duration of vernalization for winter wheat have been considered. It has been shown that differences in this character are controlled by independent Vrd gene system. Monogenic dominant near-isogenic lines have been created. They differ in two non-allelic Vrd1 and Vrd2 genes with unequal expression. The response of created lines to photoperiodic changes and Vrd genes effects on various agronomic traits have been characterized. Vrd genotypes have been identified in a number of winter common wheat cultivars.  相似文献   

20.
A vast amount of psychological and physiological data has been accumulated on human responses as elementary models of human behavior. The dynamic structure of human responses in time and the characteristics of their sensory and motor components have been described in detail, and their dependence on a wide variety of factors has been revealed. Diverse aspects of the mechanism regulating human motor responses have been studied. (1)  相似文献   

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