检索结果-南通市图书馆

Limited tree richness effects on herb layer composition,richness and productivity in experimental forest stands

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 Plant Ecology 2017年第1期10卷 190-200页

作者： Markus S.Germany Helge Bruelheide alexandra Erfmeier Institute for Ecosystem Research GeobotanyKiel UniversityOlshausenstr.7524118 KielGermany Institute of Biology/Geobotany and Botanical Garden Martin Luther University Halle-WittenbergAm Kirchtor 106120 HalleGermany German Centre for Integrative Biodiversity Research(iDiv)Halle-Jena-Leipzig Deutscher Platz 5e04103 LeipzigGermany

Aims In forests,the herbaceous understory vegetation plays an important role for ecosystem functioning as it represents a significant component of total aboveground *** addition,the herb layer contributes to overall forest species richness and controls tree species *** versa,trees in the overstory control understory herb and shrub growth through competition for *** an experimental forest plantation with manipulated tree richness,we asked to which degree tree species richness and identity affect herb layer composition,richness and productivity and how these relationships across strata change with abiotic environmental conditions and competition *** In the context of the Biodiversity-Ecosystem Functioning project in subtropical China(BEF-China),we made use of the integrated BEFmod experiment arranged along a tree species richness gradient at two sites,with additional subplot treatments of phosphorus addition,herb layer weeding and no *** recorded the understory vegetation and determined herb layer biomass production on a total of 201 *** Findings We found only minor effects of tree layer richness on herb layer species composition and no significant effect on herb layer richness or productivity ***,there were strong tree layer identity effects on all response variables,which were partly explained by differences in leaf area index and by a high share of woody species both in total herb layer species richness and *** were strong treatment effects,which were largest in the‘no weeding’treatment but we did not find any treatment×tree layer richness interaction in herb layer ***,these effects are mainly explained by increased competition intensity within the herb layer in the absence of *** the young age of the experiment,the interactions between tree species identity,tree richness and the herb layer did already emerge and can be expected to become stronger with

关键词： experimental research platform of BEF-China functional biodiversity research forest understory biomass Jiangxi Province

Modeling Size-number Distributions of Seeds for Use in Soil Bank Studies

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 Integrative Plant Biology 2008年第5期50卷 531-535页

作者： Hugo Casco alexandra Soveral Dias Luís Silva Dias Chemical Ecology Unit Centre of Ecology and EnvironmentUniversidade de vora7002-554 vora Portugal

Knowledge of soil seed banks is essential to understand the dynamics of plant populations and communities and would greatly benefit from the integration of existing knowledge on ecological correlations of seed size and shape. The present study aims to establish a feasible and meaningful method to describe size-number distributions of seeds in multi-species situations. For that purpose, size-number distributions of seeds with known length, width and thickness were determined by sequential sieving. The most appropriate combination of sieves and seeds dimensions was established, and the adequacy of the power function and the Weibull model to describe size-number distributions of spherical, non-spherical, and all seeds was investigated. We found that the geometric mean of seed length, width and thickness was the most adequate size estimator, providing shape-independent measures of seeds volume directly related to sieves mesh side, and that both the power function and the Weibull model provide high quality descriptions of size-number distributions of spherical, non-spherical, and all seeds. We also found that, in spite of its slightly lower accuracy, the power function is, at this stage, a more trustworthy model to characterize size-number distributions of seeds in soil banks because in some Weibull equations the estimates of the scale parameter were not acceptable.

关键词： accuracy power function seeds shape seeds size size-number distributions Weibull model.

Mental health of the Slovak population during COVID-19 pandemic:A cross-sectional survey

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

World Journal of Clinical Cases 2022年第25期10卷 8880-8892页

作者： Maria Kralova.alexandra Brazinova Veronika Sivcova Lubomira Izakova Department of Psychiatry Faculty of Medicine Comenius University and University Hospital BratislavaBratislava 81369Slovakia Institute of Epidemiology Faculty of Medicine Comenius University BratislavaBratislava 81372Slovakia

BACKGROUND Population’s mental health surveillance is essential for knowing the distribution of mental well-being and mental disorders in the *** allows for the establishment,evaluation,and revision of preventive measures and curative *** results of such monitoring should serve as a database for evidencebased mental health *** disorders are among the top ten causes of burden globally and crisis situations such as the pandemic increase the risk of mental health problems,as they cause constant fear of contagion and the implementation of restrictive *** impact of the coronavirus disease 2019(COVID-19)pandemic on the general population of the Slovak Republic has not yet been *** hypothesis was that more than one fifth of the population(women to a greater extent)will have symptoms of anxiety and *** To assess the mental health of the general Slovak population aged 15 years and older in the summer of 2021 by determining the prevalence of depressive and anxiety *** An anonymous cross-sectional survey was implemented in a sample of 1501 respondents in the summer of 2021 during the COVID-19 *** inclusion criteria were age of 15 years and older and ability to complete the survey questionnaire online or in a face-to-face *** survey assessed anxiety symptoms by the seven-item general anxiety disorder and depressive symptoms by the nine-item patient health questionnaire *** cut-off scores of 10 or greater were used for *** Anxiety symptoms were present in 19.32%and depression in 24.65%of the *** of both disorders were more common in females:15.00%of males and 24.00%of females experienced anxiety symptoms,and 19.00%of males and 30.00%of females experienced symptoms of *** of both disorders were the most common in the youngest age group(15-25 years old):One fifth of males(20.29%)and one third of females(35.32%)had symptoms of anxiety,and 2

关键词： Mental health COVID-19 pandemic Anxiety Depression Slovak Republic

Moving of a submarine under an ice cover in fluid of finite depth

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 Hydrodynamics 2019年第3期31卷 562-569页

作者： alexandra V. Pogorelova Vitali L. Zemlyak Victor M. Kozin Sholom-A leichem Priamursky State University Birobidzhan Russia Institute of Machining and Metallurgy FEB RAS Komsomolsk-na-Amure Russia

The influence of a basin depth on ice cover deflections, when a submarine moves under it in fluid, is experimentally and theoretically analyzed. For a theoretical research the ice cover is modelled by an elastic floating plate, and the submarine is modelled by a source-sink system in a fluid flow. The problem is solved by means of asymptotic analysis and integral transformations. The experimental study is conducted with submarine models in the pool with the sizes L*B*H= 10m*3m*lm . The ice cover for experiments is modelled in two ways. The first way is the thin ice plate received by freezing of the surface layer of water at low temperatures. In the second case the rubber sheet floating on a reservoir surface is used. The special velocity (the velocity at which maximum values of the wave height are reached) is analyzed. It is obtained that the decrease of the basin depth leads to decrease of the special speed. For small speeds (less than the special speed) there is the fact that the basin depth decrease leads to the increase of the height of the flexural-gravity wave.

关键词： Ice cover submarine flexural gravity wave source-sink system

Role of circulating free DNA in colorectal cancer

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 Gastrointestinal Oncology 2016年第12期8卷 810-818页

作者： Alexios Matikas alexandra Voutsina Maria Trypaki Vassilis Georgoulias Laboratory of Tumor Cell Biology School of MedicineUniversity of Crete

The gradual elucidation of the underlying biology of colorectal cancer has provided new insights and therapeutic options for patients with metastatic disease which are selected according to predictive biomarkers. This precision medicine paradigm, however, is incomplete since not all eligible patients respond to these agents and prognostic stratification is largely based on clinicopathologic variants. Importantly, no robust data exist to help properly select patients with localized disease at high risk for recurrence and most likely to benefit from adjuvant chemotherapy. There is a rapidly expanding body of literature regarding the role of the qualitative and quantitative analysis of circulating free DNA in various neoplasms, which consistently outperforms traditional tumor markers both as a predictive and as a prognostic marker. Several lines of evidence suggest that circulating free DNA may exhibit a complementary role to existing modalities for the early diagnosis of colorectal cancer, the selection of patients for adjuvant chemotherapy, for the followup of treated patients, for the selection of treatment for advanced disease and the assessment of response and for determining the prognosis of patients. These data, which are reviewed here, illustrate the important role that circulating biomarkers may soon have at the daily clinical practice.

关键词： Cell-free DNA Circulating tumor DNA Colorectal cancer Biomarker KRAS

Factors Influencing the Attitude to Mobile Payment Usage ——The Significance of Culture

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Factors Influencing the Attitude to Mobile Payment Usage —...

作者： alexandra Ochs 上海交通大学

学位级别：硕士

In recent years,the importance of mobile payment has risen across the globe,showcasing fast-growing profit and user *** payment describes all payments fulfilled by using internet-enabled equipment such as phones and has started primarily as a payment method for online purchases before developing into both online and physical *** penetration rates of mobile payment still differ significantly between markets *** China has been dubbed as a mobile payment nation with mobile payment being the preferred payment method,while many western countries such as Germany still lack behind in the development with cash being the primary payment *** from this development,there is a growing need to understand the factors influencing the usage behavior of *** on the topic of mobile payment acceptance often uses the TAM model from Davis as a ground work that was developed to explain information technology *** the TAM model,consisting of the independent variables perceived ease of use and perceived usefulness,and the two additional independent variables subjective norm and perceived security which have been introduced by other researcher,this paper tries to understand the moderating effect of the factor culture in the mobile payment usage *** do so,the paper utilizes the dependent variable attitude towards *** is a difficult concept to measure but is nevertheless one of the crucial factors when explaining a person's behavior as they are heavily influenced by the culture,they find themselves *** measurement model introduced for culture are Hofstede's *** dimensions of Collectivism and Uncertainty Avoidance are especially interesting to this thesis,that will be utilized when analyzing the moderating effect of *** a deductive approach,this paper utilizes data from a survey distributed in China and Germany to test the moderating *** survey contains measurement items introd

关键词： Mobile payment culture Hofstede's dimensions TAM model

Small-scale genotypic richness stabilizes plot biomass and increases phenotypic variance in the invasive grass Phalaris arundinacea

同方学位论文库评论

在线全文

同方学位论文库

学校读者我要写书评

暂无评论

Journal of Plant Ecology 2018年第1期11卷 47-55页

作者： alexandra R.Collins Brian Beckage Jane Molofsky Division of Information Technology and Science Champlain College163 South WillardBurlingtonVermont05401USA Department of Plant Biology University of Vermont111 Jeffords Hall63 Carrigan DriveUniversity of VermontBurlingtonVermont 05405USA

Aims We aim to understand how small-scale genotypic richness and gen-otypic interactions influence the biomass and potential invasiveness of the invasive grass,Phalaris arundinacea under two different dis-turbance treatments:intact plots and disturbed plots,where all the native vegetation has been ***,we address the following questions(i)Does genotypic richness increase biomass production?(ii)Do genotypic interactions promote or reduce bio-mass production?(iii)Does the effect of genotypic richness and gen-otypic interactions differ in different disturbance treatments?Finally(iv)Is phenotypic variation greater as genotypic richness increases?Methods We conducted a 2-year common garden experiment in which we manipulated genotype richness using eight genotypes planted under both intact and disturbed conditions in a wetland in Burlington,Vermont(44°27′23″N,73°11′29″W).The experiment consisted of a randomized complete block design of three blocks,each containing 20 plots(0.5 m2)per disturbed *** calculated total plot biomass and partitioned the net biodiversity effect into three com-ponents:dominance effect,trait-dependent complementarity and trait-independent *** calculated the phenotypic variance for each different genotype richness treatment under the two disturbance *** Findings Our results indicate that local genotypic richness does not increase total biomass production of the invasive grass *** in either intact or disturbed ***,genotypic interactions underlying the responses showed very different patterns in response to increasing genotypic *** the intact treatment,genotypic interactions resulted in the observed biomass being greater than the predicted biomass from monoculture plots(e.g.,overyielding)and this was driven by ***,facilitation was reduced as genotypic richness *** the disturbed treatment,genotypic interactions resulted in underyielding w

关键词： invasive grass genotypic diversity Phalaris arundinacea tripartite method phenotypic variance

Prevalence of anti-HAV antibodies in multitransfused patients with beta-thalassemia

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 2008年第10期14卷 1559-1563页

作者： Dimitrios Siagris alexandra Kouraklis-Symeonidis Irini Konstantinidou Myrto Christofidou Ioannis Starakis alexandra Lekkou Christos Papadimitriou Alexandros Blikas Nicholas Zoumbos Chryssoula Labropoulou-Karatza Department of Internal Medicine Patras University HospitalPatras 26504 Greece

AIM: To detect the prevalence of anti-HAV IgG antibodies in adult multitransfused beta-thalassemic patients. METHODS: We studied 182 adult beta-thalassemic patients and 209 controls matched for age and sex from the same geographic area, at the same time. Anti-HAV IgG antibodies, viral markers of hepatitis B virus (HBV) and hepatitis C virus (HCV) infection were evaluated. RESULTS: Anti-HAV IgG antibodies were detected more frequently in thalassemic patients (133/182; 73.1%) than in healthy controls (38/209; 18.2%, P < 0.0005). When we retrospectively evaluated the prevalence of anti-HAV IgG antibodies in 176/182 (96.7%) thalassemic patients, whose medical history was available for the previous ten years, it was found that 83 (47.2%) of them were continuously anti-HAV IgG positive, 16 (9.1%) acquired anti-HAV IgG antibody during the previous ten years, 49 (27.8%) presented anti-HAV positivity intermittently and 28 (15.9%) were anti-HAV negative continuously. CONCLUSION: Multitransfused adult beta-thalassemic patients present higher frequency of anti-HAV IgG antibodies than normal population of the same geographic area. This difference is difficult to explain, but it can be attributed to the higher vulnerability of thalassemics to HAV infection and to passive transfer of anti-HAV antibodies by blood transfusions.

关键词： Hepatitis A virus Anti-HAV antibodies Beta-thalassemia Multiple transfusions Hepatitis C virus

Inhibition of IKK-NFκB pathway sensitizes lung cancer cell lines to radiation

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Cancer Biology & Medicine 2017年第3期14卷 293-301页

作者： Avgi Tsolou Maria Liousia Dimitra Kalamida Stamatia Pouliliou alexandra Giatromanolaki MichaelKoukourakis Department of Radiotherapy/Oncology Democritus University of Thrace and University General Hospital of AlexandroupolisAlexandroupolis 68100Greece Department of Pathology Democritus University of Thrace and University General Hospital of AlexandroupolisAlexandroupolis 68100Greece

Objective:Cancer cell radioresistance is a stumbling block in radiation *** activity in the nuclear factor kappa B(NFκB)pathway correlates with anti-apoptotic mechanisms and increased *** IKK complex plays a major role in NFκB activation upon numerous *** this study,we examined the interaction between ionizing radiation(IR)and different members of the IKK-NFκB pathway,as well as upstream activators,RAF1,ERK,and ***:The effect of 4 Gy of IR on the expression of the RAF1-ERK-IKK-NFκB pathway was examined in A549 and H1299 lung cancer cell lines using Western blot analysis and confocal *** examined changes in radiation sensitivity using gene silencing or pharmacological inhibitors of ERK and IKKβ.Results:IKKα,IKKγ,and IκBαincreased upon exposure to IR,thereby affecting nuclear levels of NFκB(phospho-p65).ERK inhibition or si RNA-mediated down-regulation of RAF1 suppressed the post-irradiation survival of the examined lung cancer cell lines.A similar effect was detected on survival upon silencing IKKα/IKKγor inhibiting IKKβ.Conclusions:Exposure of lung cancer cells to IR results in NFκB activation via *** genetic or pharmacological blockage of the RAF1-ERK-IKK-NFκB pathway sensitizes cells to therapeutic doses of ***,the IKK pathway is a promising target for therapeutic intervention in combination with radiotherapy.

关键词： IKK NFκB ionising radiation lung cancer radiosensitization