检索结果-南通市图书馆

Journal of Plant Ecology 2013年第6期6卷 459-467页

作者： manuel de Paz Estela Raffaele Laboratorio Ecotono INIBIOMACONICET-Universidad Nacional del ComahueQuintral 1250San Carlos de BarilocheRio Negro 8400Argentina

Aims Variations in rates and length of flowering and fruiting not only affect the reproduction of a given plant species but also the behavior and reproduction of associated *** and fruiting variations may be influenced by herbivory,especially by large *** aim of this study was to determine the effects of cattle browsing on the reproductive phenology of understory species in a subalpine post-fire Nothofagus forest in *** The effects of herbivory on plant reproductive phenology were studied in a set of experimental exclosures(fenced plots)installed since 2001 in a post-fire *** forest,located in Nahuel Huapi National Park(NHNP),*** monitored the beginning and duration of each reproductive phenological stage:floral bud,open flower,immature fruit and mature *** also counted the number of flowers,fruits,seeds and viable seeds of the dominant plants to assess whether browsing modifies temporal patterns of the flowering and fruiting *** Findings Cattle reduced the total number of species flowering and fruiting and changed the reproductive phenology of some *** found that palatable species seem to be negatively affected by browsing in terms of reduced fitness due to changes in flowering and fruiting *** contrast,cattle benefitted the reproduction of non-palatable species and could promote the invasion of shade-intolerant exotic forbs such as Cirsium *** effects of livestock reported in this study are important to understanding how browsing could alter native species establishment and possibly alter successional trajectories during recolonization after fire.

关键词： plant fitness livestock browsing flowering fruiting

Fiber Cavity Ring Down and Gain Amplification Effect

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Photonic Sensors 2016年第4期6卷 324-327页

作者： Susana SILVA Regina MAGALHAES Rosa Ana PEREZ-herrera manuel LOPEZ-AMO M. B. MARQUES O. FRAZAO IINESC TEC Rua do Campo Alegre 687 4169-007 Porto Portugal Dept. de Fisica e Astronomia da Faculdade de Ciencias da Universidade do Porto Rua do Campo Alegre 687 4169-007 Porto Portugal public University of Navarra Dept. of Electric and Electronic Engineering Campus de Arrosadla Pamplona Spain.

The effect of an erbium-doped fiber amplifier （EDFA） placed inside the fiber ring of a cavity ring down （CRD） configuration is studied. The limitations and advantages of this configuration are discussed, and the study of the ring-down time as a function of the current applied and gain to the EDFA is also presented. In this case, the power fluctuations in the output signal are strongly dependent on the cavity ring-down time with the EDFA gain.

关键词： Cavity ring down EDFA multimode laser optical fibers.

Influence of local and landscape environmental factors on alpha and beta diversity of macroinvertebrates in Andean rivers

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Mountain Science 2023年第9期20卷 2487-2501页

作者： DIAZ-ROJAS Camila A PEDROZA-RAMOS Adriana X BARRERA-herrera July A ROA-FUENTES Camilo A Ecology Unit in Aquatic Systems Research Group Pedagogical and Technological University of ColombiaUPTCAvenida Central del Norte 39-115TunjaBoyacáColombia

Research on macroinvertebrate community structure in Andean rivers has been oriented towards describing patterns of alpha and gamma diversity by taking into account environmental predictors at local spatial scales(e.g.,micro-and mesohabitats).However,the patterns of beta diversity and the importance of landscape-scale variables have been evaluated to a lesser *** objective of this study was to describe the patterns of alpha and beta diversity of benthic macroinvertebrates in the Andean rivers of the Orinoco basin and their relationship with local and landscape environmental variation.A stratified random sampling of macroinvertebrates was carried out at 40 sites(comprising an altitudinal range of between 500 and 2900 m.a.s.l.),local and landscape variables were *** results showed that the variation of alpha diversity was influenced by local and landscape variables,which are directly and indirectly related to the contribution of sediments,substrate composition and flow velocity,providing a heterogeneity of *** beta diversity was explained by the combined effect of local and landscape *** the beta diversity phenomena,turnover was predominant while nestedness presented a minor contribution and both were explained in greater proportion by local descriptors and some landscape variables,specifically those of a geomorphological *** results concur with the view of an environmental and spatial hierarchy within the river habitat and highlight the influence of multiple scales on macroinvertebrate *** above suggests that both local and landscape scales must necessarily be considered for environmental management and the conservation of Andean lotic ecosystems.

关键词： Andean lotic systems Andean agroecosystems Instream habitat Landcover Turnover Nestedness

A hypothesis for a novel role of RIN1-the modulation of telomerasefunction by the MAPK signaling pathway

在线全文

学校读者我要写书评

暂无评论

BIOCELL 2020年第4期44卷 525-534页

作者： PATRIC HAMBLETON manuel ALEJANDRO BARBIERI Department of Biological Sciences Florida International UniversityMiami33199USA Biomedical Science Institute Florida International UniversityMiami33199USA Fairchild Tropical Botanic Garden Miami33156USA International Center of Tropical Botany Florida International UniversityMiamiFL33199USA

Cancerous cells display abnormalities in the signal transduction pathways responsible for responding to extracellular growth factors,or *** that alter proteins involved in these types of pathways can lead to inappropriate or unregulated cell growth,and therefore predispose the cell to become *** critical role of the Ras/mitogen-activated protein kinase(MAPK)pathway in transducing growth signals to the interior of the cell and subsequently stimulating cell growth and proliferation is underscored by the fact that roughly one quarter of all human tumors contain mutant forms of Ras proteins.A particular focus on the signaling and membrane trafficking adaptor protein known as Ras interference 1(RIN1)will reveal how this protein can potentially play a significant role in the development of the cancerous phenotype in certain cell *** equal interest is the possible connection between the Ras/MAPK pathway,and subsequent expression and enzymatic activity of telomerase–a key enzyme known to be overexpressed in roughly 85%of all ***1 is a 783 amino acid(84 kDa)cytosolic protein that is involved in key steps of growth factor receptormediated endocytosis and can potentially moderate signaling through the MAPK ***1,with its unique ability to compete directly with Raf for activation by Ras,could potentially influence signaling through more than one of the MAPK *** so,RIN1 may then be able to exert a precise and selective effect on the downstream signal(s)of a MAPK target such as telomerase.

关键词： Cancer Regulation Pathway Telomere

Virtual Conductance Based Cascade Voltage Controller for VSCs in Islanded Operation Mode

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Modern Power Systems and Clean Energy 2022年第6期10卷 1704-1713页

作者： Francisco Jesús Matas-Díaz manuel Barragán-Villarejo Juan Carlos Olives-Camps Juan manuel Mauricio JoséMaría Maza-Ortega Department of Elec‐trical Engineering Universidad de SevillaSeville 41092Spain

Voltage source converters have become the main enabler for the integration of distributed energy resources in *** the case of islanded operation,these devices normally set the amplitude and frequency of the network voltage by means of a cascade controller composed of an outer voltage control loop and an inner current control *** strategies to compute the gains of both control loops have been proposed in the literature in order to obtain a fast and decoupled response of the voltages at the point of common *** paper proposes an alternative and simple methodology based on the introduction of a virtual conductance in the classic cascade *** strategy allows to design each control loop independently,obtaining a closed-loop response of a first-order *** this way,the gains of each control loop are easily derived from the parameters of the LC coupling filter and the desired closed-loop time ***,a state observer is included in the controller to estimate the inductor current of the LC filter in order to reduce the number of required measurements.A laboratory testbed is used to validate and compare the proposed *** experimental results demonstrate the effectiveness of the proposal both in steady-state and transient regimes.

关键词： Voltage source converter microgrid cascade controller virtual conductance

Plant geranylgeranyl diphosphate synthases: every (gene) family has a story

在线全文

学校读者我要写书评

暂无评论

aBIOTECH 2021年第3期2卷 289-298页

作者： M.Victoria Barja manuel Rodriguez-Concepcion Centre for Research in Agricultural Genomics(CRAG)CSIC-IRTA-UAB-UB Campus UAB Bellaterra08193 Barce-lonaSpain Institute for Plant Molecular and Cell Biology(BMCP) CSIC-Universitat Politecnica de Valencia46022 ValenciaSpain

Plant isoprenoids(also known as terpenes or terpenoids)are a wide family of primary and secondary metabolites with multiple *** particular,most photosynthesis-related isoprenoids(including carotenoids and chlorophylls)as well as diterpenes and polyterpenes derive from geranylgeranyl diphosphate(GGPP)produced by GGPP synthase(GGPPS)enzymes in several cell *** genomes typically harbor multiple copies of differentially expressed genes encoding GGPPS-like *** sequence comparisons allow to identify potential GGPPS candidates,experimental evidence is required to ascertain their enzymatic activity and biologi cal ***,functional analyses of the full set of potential GGPPS paralogs are only available for a handful of plant *** we review our current knowledge on the GGPPS families of the model plant Arabidopsis thaliana and the crop species rice(0ryza sativa),pepper(Capsicum annuum)and tomato(Solanum lycopersicum).The results indicate that a major determinant of the biological role of particular GGPPS paralogs is the expression profile of the corresponding genes even though specific interactions with other proteins(including GGPP-consuming enzymes)might also contribute to *** some species,however,a single GGPPS isoforms appears to be responsible for the production of most if not all GGPP required for cell *** the mechanisms regulating GGPPS activity in particular cell compartments,tissues,organs and plant species will be very useful for future metabolic engineering approaches aimed to manipulate the accumulation of particular GGPP-derived products of interest without negatively impacting the levels of other isoprenoids required to sustain essential cell functions.

关键词： Geranylgeranyl diphosphate GGPP GGPP synthase Isoprenoid Isoprenyl transferase

Steatosis and insulin resistance in hepatitis C: A way out for the virus?

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2009年第40期15卷 5014-5019页

作者： José A Del Campo manuel Romero-Gómez Unit for The Clinical Management of Digestive Diseases and CIBERehd Hospital Universitario de Valme

The hepatitis C virus (HCV) induces lipid accumulation in vitro and in vivo. The pathogenesis of steatosis is due to both viral and host factors. Viral steatosis is mostly reported in patients with genotype 3a, whereas meta-bolic steatosis is often associated with genotype 1 and metabolic syndrome. Several molecular mechanisms responsible for steatosis have been associated with the HCV core protein, which is able to induce gene expres-sion and activity of sterol regulatory element binding protein 1 (SREBP1) and peroxisome proliferator-activat-ed receptor γ (PPARγ), increasing the transcription of genes involved in hepatic fatty acid synthesis. Steatosis has been also implicated in viral replication. In infected cells, HCV core protein is targeted to lipid droplets which serve as intracellular storage organelles. These studies have shown that lipid droplets are essential for virus assembly. Thus, HCV promotes steatosis as an eff icient mechanism for stable viral replication. Chronic HCV in-fection can also induce insulin resistance. In patients with HCV, insulin resistance is more strongly associated with viral load than visceral obesity. HCV seems to lead to insulin resistance through interference of intracellular insulin signalling by HCV proteins, mainly, the serine phosphorylation of insulin receptor-1 (IRS-1) and im-pairment of the downstream Akt signalling pathway. The HCV core protein interferes with in vitro insulin signal-ling by genotype-specif ic mechanisms, where the role of suppressor of cytokine signal 7 (SOCS-7) in genotype 3aand mammalian target of rapamycin (mTOR) in geno-type 1 in IRS-1 downregulation play key roles. Steatosis and insulin resistance have been associated with f ibrosis progression and a reduced rate of sustained response to peginterferon plus ribavirin.

关键词： Steatosis Insulin resistance Hepatitis Cvirus

Normozoospermic versus teratozoospermic domestic cats： differential testicular volume, sperm morphometry, and subpopulation structure during epididymal maturation

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Asian Journal of Andrology 2016年第6期18卷 871-878页

作者： Miguel Angel Gutierrez-Reinoso manuel Garcia-Herreros National Secretariat of Higher Education Science Technology and Innovation (SENESCYT) Quito Ecuador

Teratozoospermia （〈40% morphologically normal spermatozoa/ejaculate） is a frequent phenomenon in feline species. This research was carried out to study the possible differences in testicular volume, differential sperm morphometric traits, and potential differences regarding the sperm subpopulational structure during epididymal sperm maturation in teratozoospermic feline donors. Epididymal sperm samples were collected from the caput （R1）, corpus （R2）, and cauda （R3） epididymidis in two donor groups （N： normozoospermic; T： teratozoospermic）. Aliquots were assessed for concentration, viability, motility, and acrosomal integrity. Sperm morphometric descriptors from CASA-Morph analysis were analyzed by the Principal Component Analysis （PCA） and clustering analyses. Irrespective of the group analyzed, PCA revealed two Principal Components （PCs） for each epididymal region explaining more than the 93% of the variance. Surprisingly, the number of subpopulations remained constant in regions R1-R2-R3 irrespective of the donor group analyzed. However, the distribution of these subpopulations was found to be structurally different and strongly influenced by the epididymal region and the donor group. In conclusion, testicular morphometry and the sperm subpopulation structure were different in N and T donors. The alterations in subpopulations during epididymal maturation could be used as a potential clinical indicator of teratozoospermic individuals since an important influence of teratozoospermia on sperm subpopulation structure has been demonstrated.

关键词： epididymis feline sperm morphometry sperm subpopulations teratozoospermia testicular volume

Catenoidal Layers for the Allen-Cahn Equation in Bounded Domains

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Annals of Mathematics,Series B 2017年第1期38卷 13-44页

作者： Oscar AGUDELO manuel DEL PINO Juncheng WEI Department of Mathematics Zapadocescka Univerzita v PlzniPlzenCzech Republic Departamento de Ingenieria Matematica and CMM Universidad de ChileCasilla 170 Correo 3SantiagoChile Department of Mathematics University of British ColumbiaVancouver BC V6T 1Z2Canada

This paper presents a new family of solutions to the singularly perturbed Allen-Cahn equation α~2Δu + u(1- u^2) = 0 in a smooth bounded domain Ω R^3, with Neumann boundary condition and α > 0 a small parameter. These solutions have the property that as α→ 0, their level sets collapse onto a bounded portion of a complete embedded minimal surface with finite total curvature intersecting ?Ω orthogonally and that is non-degenerate respect to ?Ω. The authors provide explicit examples of surfaces to which the result applies.

关键词： Allen-Cahn equation Critical minimal surfaces Critical catenoid Infinite dimensional gluing method Neumann boundary condition

Neuroplastin in Ca^(2+)signal regulation and plasticity of glutamatergic synapses

在线全文

学校读者我要写书评

暂无评论

Neural Regeneration Research 2023年第8期18卷 1705-1706页

作者： Ayse Malci Xiao Lin Yun Stone Shi Rodrigo herrera-Molina Center for Neuroscience Research Children’s National Medical CenterWashingtonDCUSA Guangdong Institute of Intelligence Science and Technology ZhuhaiGuangdong ProvinceChina Combinatorial Combinatorial NeuroImaging Leibniz Institute for NeurobiologyMagdeburgGermany Centro Integrativo de Biología y Química Aplicada Universidad Bernardo O’HigginsSantiagoChile

The main function of neurons is information transmission in the form of action *** fulfill this duty,neurons are connected functionally with each other via synapses,the microscopic structures where specialized molecular machinery is strategically placed to release and receive neurotransmitters and to generate and extinguish calcium(Ca^(2+))*** synaptic molecular components are highly dynamic and they influence each other to confer structural and functional adaptability(plasticity)to neuronal communication(Biederer et al.,2017).

关键词： plasticity specialized structural