检索结果-南通市图书馆

The Hardy-Weinberg principle and its applications in modern population genetics

在线全文

学校读者我要写书评

暂无评论

Frontiers in Biology 2010年第4期5卷 348-353页

作者： john j.CHEN Department of Preventive Medicine State University of New York at Stony BrookStony BrookNY 11794-8036USA

The discovery of the Hardy-Weinberg principle marked the beginning of the field of population *** the past hundred years,it has provided a starting point for many population genetic *** this review,the Hardy-Weinberg principle,its statistical testing,and several of its applications in various modern population genetic research areas,including allelic variability and selection in the human leukocyte antigen region,microsatellite genotyping error detection,and accuracy of haplotype estimation,are discussed.

关键词： the Hardy-Weinberg principle statistical testing population genetics human leukocyte antigens microsatellite genotyping haplotype estimation

Storylines of family medicine Ⅶ: family medicine across the lifespan

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Family Medicine and Community Health 2024年第S3期12卷 61-69页

作者： William B Ventres Leslie A Stone Katharine C Barnard Sara G Shields Mark j Nelson Maria Verónica Svetaz Clara M Keegan joel j Heidelbaugh Paige B Beck Lucille Marchand Family and Preventive Medicine University of Arkansas for Medical Sciences College of MedicineLittle RockArkansasUSA Family Medicine and Community Health UMass Chan Medical SchoolWorcesterMassachusettsUSA john Peter Smith Hospital Family Medicine Residency Fort WorthTexasUSA Family and Community Medicine Hennepin HealthcareMinneapolisMinnesotaUSA Family Medicine University of Vermont Larner College of MedicineBurlingtonVermontUSA Family Medicine University of Michigan Medical SchoolAnn ArborMichiganUSA Family Medicine and Community Health University of Wisconsin-Madison School of Medicine and Public HealthMadisonWisconsinUSA

Storylines of Family Medicine is a 12-part series of thematically linked mini-essays with accompanying illustrations that explore the many dimensions of family medicine as interpreted by individual family physicians and medical educators in the USA and elsewhere around the ***‘Ⅶ:family medicine across the lifespan’,authors address the following themes:‘Family medicine maternity care’,‘Seeing children as patients brings joy to work’,‘Family medicine and the care of adolescents’,‘Reproductive healthcare across the lifespan’,‘Men’s health’,‘Care of older adults’,and‘Being with dying’.May readers appreciate the range of family medicine in these essays.

关键词： life illustration family

Dielectric confinement on exciton binding energy and nonlinear optical properties in a strained Zn_(1-x_(in))Mg_(x(in))Se/Zn_(1-x(out))Mg_(x(out))Se quantum well

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 Semiconductors 2012年第9期33卷 1-7页

作者： j.Abraham Hudson Mark A.john Peter Department of Physics NPR Arts&Science CollegeNathamDindigul-624401India Department of Physics Government Arts CollegeMelur-625106MaduraiIndia

The band offsets for a Zn1-xin Mgxin Se/Zn1-xout Mgxout Se quantum well heterostructure are determined using the model solid theory. The heavy hole exciton binding energies are investigated with various Mg alloy contents. The effect of mismatch between the dielectric constants between the well and the barrier is taken into account. The dependence of the excitonic transition energies on the geometrical confinement and the Mg alloy is discussed. Non-linear optical properties are determined using the compact density matrix approach. The linear, third order non-linear optical absorption coefficient values and the refractive index changes of the exciton are calculated for different concentrations of magnesium. The results show that the occurred blue shifts of the resonant peak due to the Mg incorporation give the information about the variation of two energy levels in the quantum well width.

关键词： interband emission energy exciton binding energy quantum well

Potential influence of wildfire in modulating climate-induced forest redistribution in a central Rocky Mountain landscape

在线全文

学校读者我要写书评

暂无评论

Ecological Processes 2017年第1期6卷 52-68页

作者： john L.Campbell Douglas j.Shinneman Department of Forest Ecosystems and Society Oregon State UniversityCorvallisORUSA U.S.Geological Survey Forest and Rangeland Ecosystem Science CenterBoiseIDUSA.

Introduction:Climate change is expected to impose significant tension on the geographic distribution of tree ***,tree species range shifts may be delayed by their long life spans,capacity to withstand long periods of physiological stress,and dispersal *** could theoretically break this biological inertia by killing forest canopies and facilitating species redistribution under changing *** investigated the capacity of wildfire to modulate climate-induced tree redistribution across a montane landscape in the central Rocky Mountains under three climate scenarios(contemporary and two warmer future climates)and three wildfire scenarios(representing historical,suppressed,and future fire regimes).Methods:Distributions of four common tree species were projected over 90 years by pairing a climate niche model with a forest landscape simulation model that simulates species dispersal,establishment,and mortality under alternative disturbance regimes and climate ***:Three species(Douglas-fir,lodgepole pine,subalpine fir)declined in abundance over time,due to climate-driven contraction in area suitable for establishment,while one species(ponderosa pine)was unable to exploit climate-driven expansion of area suitable for *** fire frequency accelerated declines in area occupied by Douglas-fir,lodgepole pine,and subalpine fir,and it maintained local abundance but not range expansion of ponderosa ***:Wildfire may play a larger role in eliminating these conifer species along trailing edges of their distributions than facilitating establishment along leading edges,in part due to dispersal limitations and interspecific competition,and future populations may increasingly depend on persistence in locations unfavorable for their establishment.

关键词： Forest disturbance Wildfire Climate change Central Rocky Mountains Climate niche Species migration Species distribution

Structural and functional roles of ether lipids

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Protein & Cell 2018年第2期9卷 196-206页

作者： john M. Dean Irfan j. Lodhi Division of Endocrinology Metabolism and Lipid Research Department of Medicine Washington University School of Medicine Saint Louis MO 63110 USA

Ether lipids, such as plasmalogens, are peroxisome- derived glycerophospholipids in which the hydrocarbon chain at the sn-1 position of the glycerol backbone is attached by an ether bond, as opposed to an ester bond in the more common diacyl phospholipids. This seem- ingly simple biochemical change has profound structural and functional implications. Notably, the tendency of ether lipids to form non-lamellar inverted hexagonal structures in model membranes suggests that they have a role in facilitating membrane fusion processes. Ether lipids are also important for the organization and stability of lipid raft microdomains, cholesterol-rich membrane regions involved in cellular signaling. In addition to their structural roles, a subset of ether lipids are thought to function as endogenous antioxidants, and emerging studies suggest that they are involved in cell differentiation and signaling pathways. Here, we review the biology of ether lipids and their potential signifi- cance in human disorders, including neurological diseases, cancer, and metabolic disorders.

关键词： ether lipids plasmalogen phospholipid peroxisomes cancer metabolic disorders

Continued development of azithromycin as a neuroprotective therapeutic for the treatment of spinal cord injury and other neurological conditions

在线全文

学校读者我要写书评

暂无评论

Neural Regeneration Research 2021年第3期16卷 508-509页

作者： Timothy j.Kopper john C.Gensel Spinal Cord and Brain Injury Research Center Department of PhysiologyUniversity of KentuckyLexingtonKYUSA

Spinal cord injury(SCI)induces a robust inflammatory response largely mediated by resident microglia and infiltrating macrophages across the blood-brain *** these cell populations are capable of promoting repair and regenerative responses,in the days and weeks after SCI they predominately adopt pro-inflammatory profiles known to inhibit recovery and potentiate secondary injury pathways.

关键词： protective injury therapeutic

What are extreme environmental conditions and how do organisms cope with them？

在线全文

学校读者我要写书评

暂无评论

Current Zoology 2011年第3期57卷 363-374页

作者： john C. WINGFIELD j. Patrick KELLEY Frederic ANGELIER Department of Neurobiology Physiology and Behavior University of California One Shields Avenue Davis CA 95616 U.S.A

Severe environmental conditions affect organisms in two major ways. The environment may be predictably severe such as in deserts, polar and alpine regions, or individuals may be exposed to temporarily extreme conditions through weather, presence of predators, lack of food, social status etc. Existence in an extreme environment may be possible, but then to breed or molt in addition can present major bottlenecks that have resulted in the evolution of hormone-behavior adaptations to cope with unpredictable events. Examples of hormone-behavior adaptations in extreme conditions include attenuated testosterone secretion because territoriality and excess courtship may be too costly when there is one opportunity to reproduce. The individual may even become insensitive to testosterone when target areas of the brain regulating reproductive behavior no longer respond to the hormone. A second example is reduced sensitivity to glucocorticoids following acute stress during the breeding season or molt that allows successful reproduction and/or a vital renewal of the integument to endure extreme conditions during the rest of the year. Reduced sensitivity could involve：（a） modulated response of the hypothalamo-pituitary-adrenal axis, （b） reduced sensitivity to high glucocorticoid levels, or （c） a combination of （a） and （b）. Moreover, corticosteroid binding proteins （CBP） buffer responses to stress by reducing the movement of glucocorticoids into target cells. Finally, intracellular enzymes （11 β-hydroxysteroid dehydrogenase and variants） can deactivate glucocorticoids entering cells thus reducing interaction with receptors. These mechanisms have important implications for climate change and increasing extremes of weather [Current Zoology 57 （3）： 363-374, 2011].

关键词： Extreme environment Habitat configuration Glucocorticoids Stress response Corticosteroid-binding proteins Behavior

Alternative expressions for stand diameter in complex forests

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Forest Ecosystems 2023年第3期10卷 328-336页

作者： Mark j.Ducey john A.Kershaw jr. Department of Natural Resources and the Environment University of New HampshireDurhamNHUSA Faculty of Forestry and Environmental Management University of New BrunswickFrederictonNBCanada

Quadratic mean diameter is the most frequently reported descriptor of the diameter distribution of *** such,it is often used as an indicator of forest stand structure,developmental stage,and ecological and economic ***,quadratic mean diameter can be heavily influenced by the presence or absence of large numbers of small stems in lower canopy strata,and it is also sensitive to left-truncation of the diameter distribution,making its interpretation across inventories with different protocols ***,we examine three alternative expressions of stand diameter:the arithmetic and quadratic mean diameter of the thickest 100 trees per hectare,and the basal area-weighted mean *** data from the United States Forest Inventory and Analysis program for New York and New England,these alternative expressions showed closer correlation with multiple stand structural variables than did quadratic mean diameter,including merchantable cubic and board foot volume per hectare,aboveground live tree carbon per hectare,and total number of live and dead standing trees greater than 40 cm diameter at breast height per hectare(previously proposed as an index of old-growth structure).Arithmetic and quadratic mean diameter of the thickest 100 trees per hectare showed nearly identical performance,and the strongest correlations across the *** develop closed-form expressions for these variables when the diameter distribution is a Weibull,and illustrate their behavior relative to quadratic mean diameter for that *** the reasons for prevalence of quadratic mean diameter as an indicator remain valid,we suggest that these alternative measures should be more widely reported and analyzed to give a more informative depiction of stand structure and development in complex forests.

关键词： Forest structure Diameter at breast height Weibull distribution

Update on the management of the gastrointestinal effects of radiation

在线全文

学校读者我要写书评

暂无评论

World journal of Gastrointestinal Oncology 2021年第5期13卷 400-408页

作者： Hannah McCaughan Stephen Boyle john j McGoran Department of Gastroenterology Altnagelvin Area HospitalLondonderry BT476SBUnited Kingdom

Radiation therapy is a long-established and essential modality in the treatment of many *** is well known that tissue within a field of radiation can suffer indiscriminate effects,leading to acute and chronic *** gastrointestinal tract may be adversely affected by *** the mouth to the rectum,patients can experience troublesome symptoms that require the concerted input of specialist *** range from nursing care,dietetic optimization,pharmacological management,and mechanical procedures through endoscopy and *** evidence exists mainly for radiation induced effects in four distinct areas of the gastrointestinal tract:oral mucosa,esophagus,small bowel,and *** review explores the experiences of oncology and gastrointestinal teams in managing the most common conditions and some of the different practices for radiation associated morbidity.

关键词： Radiation Stricture Endoscopy