首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 46 毫秒
1.
The methods of C. W. Sheppard and A. S. Householder (Jour. App. Physcis,22, 510–20, 1951), H. D. Landahl (Bull. Math. Biophysics,16, 151–54, 1954) and H. E. Hart (Bull. Math. Biophysics,17, 87–94, 1955;ibid.,19, 61–72, 1957;ibid.,20, 281–87, 1958) are employed in studying the kinetics of generalN compartment systems. It is shown that the nature of the transfer processes occurring in fluid flow systems and the chemical processes occurring in quadratic systems and in catalyzed quadratic systems can in principle be completely determined for all polynomial dependencies. Systems involving three-body and higher-order interactions can be completely solved, however, only if supplementary information is available. Research supported by the Atomic Energy Commission, Contract AT (30-1)-1551.  相似文献   

2.
《Plant Ecology & Diversity》2013,6(2-3):167-178
Background: The Wachau region along the river Danube in eastern Austria represents one of central Europe's hotspots of plant and animal species diversity. One of the typical landscape elements is vineyards, mostly established as linear elements on terraces along the slopes, with a characteristic and species-rich flora and fauna on terrace slopes lying between the cultivated terraces.

Aims: We addressed the question of how the genetic variation of four plant species of open grassland vegetation types is distributed. We asked if levels and distribution of genetic diversity of the plant species Aster amellus, Gentianella aspera, Pulsatilla grandis, and Stachys recta were correlated with geographic distances along the terrace slopes.

Methods: The dominant inherited molecular marker system random amplified polymorphic DNA (RAPD ) was used to estimate and compare the distribution of genetic diversity of the four selected species.

Results: We found only low levels of correlation of the distribution of genetic variation with linear geographic patterns and obtained indirect evidence for high levels of gene flow between adjacent terrace slopes.

Conclusions: We found that genetic diversity parameters of the four target species did not mirror the pattern of linear landscape elements, indicating that gene flow acts efficiently against the linear distribution of genetic variation.  相似文献   

3.
【目的】探讨Ⅵ型分泌系统(typeⅥsecretion system,T6SS)效应蛋白Clpv在鼠伤寒沙门菌(Salmonella enterica serovar Typhimurium)致病过程中的功能。【方法】以鼠伤寒沙门菌SL1344基因组为模板克隆clpv基因,并比较与其他革兰氏阴性菌台湾假单胞菌(Pseudomonas taiwanensis)、植生拉乌尔菌(Raoultella planticola)、鳗利斯顿氏菌(Listonella anguillarum)、菠萝多源菌(Pantoea ananatis)、粘放线菌(Actinomyces viscosus)和大肠埃希菌(Escherichia coli)的同源性;将clpv基因克隆至pEGFP-N1载体构建重组质粒pEGFP-Clpv,利用Western blotting、实时荧光定量聚合酶链式反应(real-time quantitative polymerase chain reaction,q-PCR)、荧光显微镜以及流式细胞术检测蛋白表达、定位及诱导小鼠巨噬细胞M1型和M2型极化水平。【结果】clpv基因全长为2637 bp,与台湾假单胞菌的同源性最高;Western blotting、qPCR和免疫荧光检测表明重组蛋白大小约120 kDa,在细胞中有明显绿色荧光并且主要定位于细胞膜;q-PCR和流式细胞术结果发现Clpv转染组巨噬细胞M1型极化显著增加(P<0.01),M2型巨噬细胞极化显著减少(P<0.01)。【结论】成功克隆表达鼠伤寒沙门菌T6SS效应蛋白Clpv,并明确其胞内表达定位以及对巨噬细胞极化的影响。  相似文献   

4.
Previous papers by F. M. Snell (Jour. Theor. Biol.,8, 469–479, 1965) and M. A. Fox and H. D. Landahl (Bull. Math. Biophysics,27, Spec. Issue, 183–190, 1965) have found that the formulation by previous authors for the oxygen flow rates through hemoglobin solution as a function of pressure determined by E. Hemmingsen and P. F. Scholander (Science,132, 1379–1381, 1960) did not give a satisfactory quantitative fit of the curve for constant pressure difference. The suggestion of Fox and Landahl that the Bohr effect involving the shift in acidity accompanying the oxidation of Hb should give rise to voltage and pH differences in oxyhemoglobin transport is examined in more detail. In this paper, the previous expressions for the total oxygen flow rate in terms of the end point concentrations are extended to include the effects of the electrical field. Estimates of the potential difference shows it to be negligible. A derivation of a voltage-pH relation shows that the Nernst relation does not apply and a negligible voltage difference does not preclude a pH shift which is the more probable explanation of the discrepancies observed. Several other predictions suitable for experimental testing are made.  相似文献   

5.
【目的】耐药基因细菌水平基因转移导致的耐药菌数量增加引发的公共安全问题日益引起人们关注,监测环境中耐药菌变得极为重要。【方法】采集湛江3处滨海浴场的水体、沙滩土样,通过平板稀释涂布和琼脂扩散法进行浴场微生物数量、多样性和抗生素耐药性分析。【结果】3处浴场水体无机氮含量偏高,浴场微生物数量随着客流量逐渐增加,沙滩中微生物数量显著高于水体。浴场细菌分布于3门12科18属,水体中变形菌门(Proteobacteria,49.64%)占优势,沙滩则是厚壁菌门(Firmicutes,54.74%)占优势。浴场细菌对β-内酰胺类耐药率较高,青霉素、万古霉素和头孢曲松耐药率分别达到23.25%、20.53%和17.42%,耐药菌株主要分布于芽孢杆菌属(Bacillus)、弧菌属(Vibrio)、假单胞菌属(Pseudomonas)、链霉菌属(Streptomyces)和肠杆菌属(Enterobacter),水体中多重耐药细菌数量显著高于沙滩,集中于人流量多的浴场。【结论】滨海浴场环境中细菌耐药菌种类多,需持续监测以评估对当前地区公共卫生的潜在影响。  相似文献   

6.
Equations are derived for the flow of an anisotropic fluid in a tube. It is argued that these provide a model for arterial blood flow. Particular attention is paid to the effect of radial differences in hematocrit. Sequels to this paper (Bull. Math. Biophysics,29, 565–574; forthcoming, 1967) will respectively demonstrate possible wall-directed forces on the erythrocyte and enlarge on the physiological consequence of hematocrit variations. The present article develops the basic equations and explores the possible role of anisotropic effects in blood flow.  相似文献   

7.
Taxonomic changes are made to reflect a reassessment of morphology based on the results of molecular phylogenetic studies. A new genus, Davilanthus, is described to include six species that collectively form the sister group to Simsia, and includes the following species transferred from Viguiera: Davilanthus davilae, Davilanthus hidalgoanus, Davilanthus hypargyreus, Davilanthus huajuapanus, Davilanthus purpusii, and Davilanthus sericeus. Three species formerly placed in Viguiera ser. Grammatoglossae are transferred to Simsia: Simsia benziorum, Simsia ovata, and Simsia rhombifolia.  相似文献   

8.
Paulo H. Labiak 《Brittonia》2011,63(1):139-149
Stenogrammitis , a new genus of grammitid ferns, is segregated from Lellingeria based on morphological and molecular evidence. It differs from Lellingeria by linear leaves usually less than 5 mm wide, clathrate iridescent rhizome scales that are glabrous except for a single apical cilium, veins unbranched and only one per segment, fertile veins usually with the dark sclerenchyma visible beneath the sporangia, and x = 33. In contrast, Lellingeria has broader laminae, veins pinnate within the segments, and fertile veins not visible beneath the sporangia. Melpomene, which is sister to Stenogrammitis and Lellingeria, differs from those two genera by reddish setae on the leaves and rhizome scales papillate at the apex. Some species of Stenogrammitis are also distinctive by hemidimorphic laminae that have the fertile portion less dissected than the sterile. Stenogrammitis is pantropical and currently comprises 24 species, 12 of which occur in the Neotropics, six in Africa, four in Madagascar, and two on Pacific Islands. New combinations are made for Stenogrammitis aethiopica, S. anamorphosa, S. ascensionensis, S. boivinii, S. delitescens, S. jamesonii, S. hartii, S. hellwigii, S. hildebrandtii, S. limula, S. luetzelburgii, S. myosuroides, S. nutata, S. oosora, S. paucipinnata, S. prionodes, S. pumila, S. ruglessii, S. rupestris, S. saffordii, S. strangeana, S. tomensis, S. subcoriacea, and S. wittigiana. Lectotypifications are made for Grammitis muscosa, Polypodium itatiayense, P. oosorum var. micropecten, P. serrulatum forma major, P. serrulatum forma minor, S. luetzelburgii, S. myosuroides, and S. wittigiana. Illustrations are presented for the diagnostic characters of the genus, as well as a map with the geographical distribution.  相似文献   

9.
This paper describes Ascogrammitis, a new genus of grammitid ferns formerly combined under Terpsichore. Seventeen species are recognized, including five new ones: A. clavigera, A. colombiensis, A. loxensis, A. oxapampensis, and A. tungurahuae. New combinations are made for A. alan-smithii, A. anfractuosa, A. angustipes, A. athyrioides, A. clathrata, A. cuencana, A. david-smithii, A. dilatata, A. nana, A. pichinchae, A. pichinchensis, A. stuebelii, and a lectotype is chosen for Polypodium induens. A key is provided to distinguish the species, and illustrations are provided for 12 species. The genus occurs primarily in neotropical cloud forests, with the greatest diversity in the Andes. Ascogrammitis is one of two monophyletic groups of grammitid ferns that are consistently associated with Acrospermum, an epibiotic bitunicate ascomycete that produces black clavate fruiting bodies.  相似文献   

10.
【目的】为探明锡林河流域潜在不产氧光合细菌(anoxygenic photosynthetic bacteria,AnPB)的陆向分异特征及影响因素。【方法】本研究沿着陆向梯度依次采集水生湍流带、缓流带、滞流带、水偏湿生样带、湿偏旱生样带、旱生样带土壤样品。基于文献建立AnPB在科水平的数据库,运用16S rRNA基因高通量测序筛选科水平潜在AnPB类群及其组成丰度的陆向分异,运用皮尔逊相关性及冗余分析等研究土壤理化因子对潜在AnPB陆向分异的影响。【结果】紫色硫细菌(外硫红螺菌科)和紫色非硫细菌(红杆菌科、红环菌科、醋酸杆菌科、丛毛单胞菌科、全噬菌科)主要分布在水生及水偏湿生生境,其相对丰度与湿度呈显著(P<0.05)或极显著(P<0.01)正相关关系;紫色非硫细菌(红螺菌科、慢生根瘤菌科、生丝微菌科、红菌科)、芽单胞菌科、酸杆菌科、绿色非硫细菌(蔷薇菌科)等主要分布在湿偏旱生和旱生环境中,其相对丰度与盐度和全氮含量呈显著(P<0.05)或极显著(P<0.01)正相关关系;多元回归树分析显示,盐度、湿度、全氮对潜在AnPB陆向分异的总解释度分别为62.39%、...  相似文献   

11.
Job Kuijt 《Brittonia》2009,61(2):144-162
Twelve new South American species of Loranthaceae (Aetanthus, Cladocolea, Oryctanthus, and Struthanthus) and Viscaceae (Dendrophthora and Phoradendron) are described and illustrated: Aetanthus trifolius, Cladocolea rostrifolia, Dendrophthora lanceolata, Dendrophthora rotundata, Dendrophthora tenuis, Dendrophthora werffii, Oryctanthus minor, Phoradendron pascoi, Phoradendron vasquezianum, Struthanthus apiculatus, Struthanthus schultesii, and Struthanthus sessiliflorus. Additionally, Cladocolea alternifolia, previously thought to be probably extinct, is reported to occur on Ilha Grande, just west of Rio de Janeiro, Brazil.  相似文献   

12.
Lithospermum (Boraginaceae) comprises approximately 40 species in both the Old and New Worlds, with a center of diversity in the southwestern United States and Mexico. Using ten cpDNA regions, a phylogeny of Lithospermum and related taxa was reconstructed. Lithospermum (including New World and Old World species) and related New World members of Lithospermeae form a monophyletic group, with Macromeria, Onosmodium, Nomosa, Lasiarrhenum, and Psilolaemus nested among species of Lithospermum. New World Lithospermeae also is a monophyletic group, with Eurasian species of Lithospermum sister to this group. Because Lithospermum is not monophyletic without the inclusion of the other New World genera, species from these genera are transferred to Lithospermum, and appropriate nomenclatural changes are made. New combinations are Lithospermum album, Lithospermum barbigerum, Lithospermum dodrantale, Lithospermum exsertum, Lithospermum helleri, Lithospemum leonotis, Lithospermum notatum, Lithospermum oaxacanum, Lithospermum pinetorum, Lithospermum rosei, Lithospermum trinverium, and Lithospermum unicum; new names are Lithospermum chiapense, Lithospermum johnstonii, Lithospermum macromeria, Lithospermum onosmodium, Lithospermum rzedowskii, and Lithospermum turneri.  相似文献   

13.
As part of our study of the Acanthaceae of Costa Rica and from a phylogenetic study of Ruellia as a whole, we place R. barbillana and R. metallica in synonymy with R. terminalis. We discuss species limits of R. terminalis and provide a key that distinguishes it from close relatives including R. grantii, R. oaxacana, and R. phyllocalyx. Ruellia puri is put into synonymy with R. jussieuoides, and R. standleyi is synonymized with R. ochroleuca. Disjunct distributions characterize R. terminalis, R. jussieuoides, and R. ochroleuca, although this pattern is most extreme in R. ochroleuca. Phylogenetic analysis of DNA sequence data lends support to our synonymy decisions. New lectotypifications are provided for Arrhostoxylum achimeniflorum, Dipteracanthus puri, Dipteracanthus puri β angustifolius, Dipteracanthus puri γ gymnocladus, Lychniothyrsus ochroleucus, and Otacanthus pearcei .  相似文献   

14.
【目的】D-泛酸(D-pantothenic acid,DPA)是一种重要的功能化合物,被广泛应用于医疗保健、化妆品、动物食品和饲料等领域,具有良好的市场前景及应用。本研究以实验室保藏的大肠杆菌菌株DPAP10为底盘菌株,利用CRISPR干扰(clustered regularly interspaced palindromic repeats interference,CRISPRi)技术,筛选影响工程菌株DPA生物合成的内源性基因靶点。【方法】构建了p Target和pd Cas9的双质粒CRISPRi系统,可以实现对基因单个或组合表达抑制,摇瓶发酵检测基因抑制对DPA合成的影响;通过实时荧光定量聚合酶链式反应(real-time fluorescence quantitative polymerase chain reaction,RT-q PCR)检测了基因抑制后的转录水平;通过高效液相色谱(high performance liquid chromatography,HPLC)检测了中间代谢物分析代谢通路变化。【结果】成功从126个靶基因中筛选得到5个显著影响DPA合成的关键...  相似文献   

15.
The principle of biotopological mapping (Rashevsky, 1954,Bull. Math. Biophysics,16, 317–48) is given a generalized formulation, as the principle of relational epimorphism in biology. The connection between this principle and Robert Rosen’s representation of organisms by means of categories (1958,Bull. Math. Biophysics,20, 317–41) is studied. Rosen’s theory of (M,R)-systems, (1958,Bull. Math. Biophysics,20, 245–60) is generalized by dropping the assumption that only terminalM i components are sending inputs into theR i components. It is shown that, if the primordial organism is an (M,R)-system, then the higher organisms, obtained by a construction well discussed previously (1958,Bull. Math. Biophysics,20, 71–93), are also (M,R)-systems. Several theorems about such derived (M,R)-systems are demonstrated. It is shown that Rosen’s concept of an organism as a set of mappings throws light on phenomena of synesthesia and also leads to the conclusion that Gestalt phenomena must occur not only in the fields of visual and auditory perception but in perceptions of any modality.  相似文献   

16.
In a previous paper (Bull. Math. Biophysics,29, 549–563, 1967) the author derived equations to represent the flow of blood in an artery. It was pointed out that these did not completely characterize the system and that an additional hypothesis was required. The hypothesis of minimal energy dissipation had been thought to imply a central tendency on the part of suspended particles (erythrocytes). It is here shown that if the fluid is non-Newtonian this may not be so.  相似文献   

17.
Summary. The Adoretini of the Malagasy endemic genus Adorodocia Brenske 1893 is revised. Fourteen new species and one new subspecies are described and compared with their most closely related species: A. constricta n. sp., A. cuccodoroi n. sp., A. flava n. sp., A. liliae n. sp., A. marginata n. sp., A. peyrierasi n. sp., A. pseudoconstricta n. sp., A. pseudoflava n. sp., A. pseudostrigata n. sp., A. recta n. sp., A. robusta n. sp., A. sogai n. sp., A. vadoni n. sp., A. viettei n. sp. and A. vittaticollis flavipes n. ssp. The synonymy between Adoretus strigatus Waterhouse 1878, and Pseudadorodocia aenigma Arrow 1901, is confirmed. Thus, based on the results of this study, the genus Adorodocia includes 16 species, and one of them is represented by two subspecies. Diagnostic characters to separate the species in the genus deal mostly with the shape of parameres, color of body and legs, shape of pronotum and female eighth tergite, setation of pronotum and elytra. Key to species, diagnoses and distribution for each species are provided. Endophallus and female genitalia are illustrated for the first time for this genus.  相似文献   

18.
In a previous paper (Bull. Math. Biophysics,29, 565–574, 1967) the author developed equations to represent velocity and hematocrit profiles in quasi-Poiseuille flow of blood. It was assumed that energy dissipation was minimized and that the viscosity depended on hematocrit and shear rate according to the Casson formula. These equations are simplified considerably, placed in a form more suitable for numerical solution and shown to depend on a single dimensionless parameter. Typicalin vivo values for this parameter are calculated.  相似文献   

19.
Abstract

Marion Endicott, Emily Carr: The Story of an Artist, Women's Educational Press: Toronto, Canada, 1981, 64 pages, n.p.i. (paperback)

Jean Lipman with Margaret Aspin-wall, Alexander Calder and his Magic Mobiles, Hudson Hills Press: New York, 1981, 96 pages, $15.00

M. B. Goffstein, Lives of the Artists, Farrar, Straus & Giroux: New York, 1982, unpaged, $8.95

Trina Schart Hyman, Self-Portrait, Addison-Wesley: Reading, Massachusetts, 1981, unpaged, $8.95

Andrew Glass, Jackson Makes his Move, Warne: New York, 1982, unpaged, $9.95

Tom Seidmann-Freud, The Magic Boat, Greenwillow: New York, 1981, unpaged, $5.95

Ernest Nister, Magic Windows, Philomel Books: New York, 1980, unpaged, $6.95

Lothar Meggendorfer, The City Park, Viking: New York, 1981, unpaged, $10.95

J. F. Schreiber (verses by Anthea Bell), The Great Menagerie, Viking: New York, 1980, unpaged, $7.95

Lothar Meggendorfer, International Circus, Viking: New York, 1980, unpaged, $7.95

Eric Hill, Spot's First Walk, G. P. Putnam's Sons: New York, 1981, unpaged, $7.95

Robert Crowther and lames R. Diaz (paper engineer), The Most Amazing Hide-and-Seek Counting Book, Viking: New, York, 1981, 14 pages, $8.95

Demi, Where is Willie Worm? Random House: New York, 1981, unpaged, $3.50

John Goodall and Tor Lokvig (paper engineer), PADDY FINDS A JOB, Atheneum: New York, 1981, unpaged, $6.95

Eric Carle, The Honeybee and the Robber, Philomel: New York, 1981, 15 pages, $10.95  相似文献   

20.
The genus Xenocylapus Bergroth, 1922 is revised. Nine new species, Xenocylapus aculeatus sp. nov., X. aquilonius sp. nov., X. bicolor sp. nov., X. globulus sp. nov., X. heissi sp. nov., X. panamaensis sp. nov., X. serrulatus sp. nov., X. tenuis sp. nov., and X. waorani sp. nov., are described from Brazil, Honduras, Mexico, and Panama. New genus and species Henryfulvius gracilis gen. nov., sp. nov. is described from Ecuador. Illustrations of the male genitalia, color photographs of dorsal and lateral views of the adult of most species, scanning electron micrographs of selected structures of X. tenuis, and keys to species of the genus Xenocylapus are provided.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号