检索结果-南通市图书馆

Determinants and rates of land degradation： Application of stationary time-series model to data from a semi-arid environment in Kenya

引用

Journal of Arid Land 2018年第1期10卷 1-11页

作者： kevin z mganga dickson m nyariki nashon k r musimba dorothy a amwata department of range and wildlife sciences south eastern kenya university170-90200 KituiKenya department of agricultural economics and agribusiness south eastern kenya university170-90200 KituiKenya school of business and economics murangáuniversity of technology75-10200 MurangaKenya

The causes of land degradation in the African drylands have been shown to vary. Some researchers consider climate to be the major contributor to degradation, with anthropogenic factors playing a minor role. Others reverse the significance of these two factors. A third group attributes land degradation to climate and anthropogenic factors equally. This study was undertaken to establish the factors influencing land degradation in a semi-arid environment in southeastern Kenya and the rate of change in vegetation types for a period of 35 years （1973-2007）. The reduction in grassland cover was used as an indicator of land degradation. Causes of land degradation were determined by a multiple regression analysis. A log-linear regression analysis was used to establish the rate of vegetation change. The multiple and log-linear regression analyses showed：（1） woody vegetation, livestock population and cultivated area to be the main contributors of reduction in grassland cover in the area, and （2） an increase in undesirable woody species, livestock population and cultivated area had a significant （P〈0.05） negative effect on grassland vegetation. Increased human population, low amounts of rainfall and drought showed no significant negative effect on grassland vegetation cover. In conclusion, human and livestock population growth and increased agricultural land have contributed to intensive crop cultivation and overgrazing in the semi-arid lands. This overuse of the semi-arid rangelands has worsened the deterioration of the natural grassland vegetation.

关键词： regression analysis land degradation grassland cover semi-arid Kenya Sub-Saharan Africa

来源：

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

mobility and sulfidization of heavy metals in sediments of a shallow eutrophic lake, Lake Taihu, China

引用

Journal of Environmental Sciences 2015年第5期27卷 1-11页

作者： Shouliang Huo Jingtian Zhang kevin m.Yeager Beidou Xi Yanwen Qin Zhuoshi He Fengchang Wu State Key Laboratory of Environmental Criteria and Risk Assessment Chinese Research Academy of Environmental Science Department Earth and Environmental Sciences University of Kentucky

The technique of DGT（diffusive gradients in thin films） using three diffusive gel thicknesses was applied to estimate the mobility and bioavailability of heavy metals in sediments and porewater of Lake Taihu, China. The DGT results showed significantly positive correlations between Co, Pb, Cd and mn, and Ni and Fe concentrations in porewater. Cu and Zn showed a significantly negative correlation with mn, due to Cu combination with carbonates and Zn derived from agricultural pollution, respectively. The rank order of average concentrations of Co, Ni and Cd at each station was DGT1.92〉DGT0.78〉 DGT0.39, suggesting stronger resupply from sediments to porewater when using thicker diffusive gels. Comparing centrifugation and DGT measurements, Co, Ni and Cd are highly labile; mn and Fe are moderately labile; and Cu, Zn and Pb are slightly labile. The variations of AVS concentrations in sediment cores indicate that metal sulfides in deeper layers are easily diffused into surface sediments.

关键词： Sulfidization process Heavy metals DGT(diffusive gradients in thin films)

来源：

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

A 60-year sedimentary record of natural and anthropogenic impacts on Lake Chenghai,China

引用

Journal of Environmental Sciences 2012年第4期24卷 602-609页

作者： Fengyu Zan Shouliang Huo Beidou Xi Jingtian Zhang Haiqing Liao Yue Wang kevin m.Yeager School of Environment Beijing Normal UniversityBeijing 100875China State Key Laboratory of Environmental Criteria and Risk Assessment Chinese Research Academy of Environmental ScienceBeijing 100012China College of Environmental Science and Engineering Anhui Normal UniversityWuhu 241000China Department of marine Science University of Southern MississippiStennis Space CenterMS 39529USA

Recent sediments from Lake Chenghai, China, were investigated at high temporal resolution to trace both natural and anthropogenic effects on the lake using total organic carbon （TOC）, total nitrogen （TN）, total phosphorus （TP）, organic phosphorus （Po）, inorganic phosphorus （Pi） and organic carbon and nitrogen stable isotopes （~13Corg and 615N） in a 137Cs-dated sediment core. The results indicated that the sedimentary record covers the last 60 years, during which the lake had undergone apparent changes in nutrient sources and productivity in response to nutrient loading. Prior to the late 1980s, the nutrient contents in sediments mainly originated from algae and lake productivity was relatively stable. Since the late 1980s, increasing TOC, TN and TP concentrations together with the change of 613Corg and 615N suggested anthropogenic perturbations in nutrient loading and lake productivity. Endogenic nutrients derived from algae and anthropogenic inputs were two important sources of sedimentary nutrients. The anthropogenic nutrients mainly originated from the discharge of industrial wastewater and artificial cultivation of Spirulina after the middle 1980s, and domestic wastewater discharged from Yongsheng County since 1993.

关键词： stable isotope C/N ratio organic matter lake productivity anthropogenic impacts

来源：

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

Behavioural and energetic consequences of competition among three overwintering swan(Cygnus spp.)species

引用

Avian Research 2021年第4期12卷 707-721页

作者： kevin A.Wood Julia L.Newth Geoff m.Hilton Eileen C.Rees Wildfowl&Wetlands Trust SlimbridgeGloucestershire GL27BTUnited Kingdom Centre for Ecology and Conservation/Environment and Sustainabil-ity Institute College of Life and Environmental SciencesUniversity of ExeterExeter TR109EZUnited Kingdom Department of Zoology University of CambridgeDowning StreetCambridge CB23EJUnited Kingdom

Background:Winter numbers of the northwest European population of Bewick's Swans(Cygnus columbianus bewickii)declined recently by c.40%.During the same period,numbers of two sympatric and ecologically-similar congeners,the mute Swan(Cygnus olor)and Whooper Swan(Cygnus cygnus)showed increases or *** has been suggested that these opposing population trends could have a causal relationship,as mute and Whooper Swans are larger and competitively dominant to Bewick's Swans in foraging *** so,effects of competition of mute and Whooper Swans on Bewick's Swans should be detectable as measurable impacts on behaviour and ***:Here,we studied the diurnal behaviour and energetics of 1083 focal adults and first-winter juveniles("cygnets")of the three swan species on their winter grounds in eastern *** analysed video recordings to derive time-activity budgets and these,together with estimates of energy gain and expenditure,were analysed to determine whether individual Bewick's Swans altered the time spent on key behaviours when sharing feeding habitat with other swan species,and any consequences for their energy expenditure and net energy ***:All three swan species spent a small proportion of their total time(0.011)on aggressive interactions,and these were predominantly intraspecific(≥0.714).mixed-effects models indicated that sharing feeding habitat with higher densities of mute and Whooper Swans increased the likelihood of engaging in aggression for cygnet Bewick's Swans,but not for *** levels of interspecific competition decreased the time spent by Bewick's Swan cygnets on foraging,whilst adults showed the opposite *** among low densities of conspecifics(m^(2)),individual Bewick's Swans spent more time on vigilance in the presence of higher densities of mute and Whooper Swans,whilst individuals within higher density Bewick's Swan flocks showed the opposite ***,we found no evide

关键词： Avian behaviour Energy expenditure Ethology Interference competition Interspecific interactions Time activity budgets Video observations

来源：

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

Partial epithelial-mesenchymal transition in keloid scars: regulation of keloid keratinocyte gene expression by transforming growth factor-β1

引用

Burns & Trauma 2016年第3期4卷 199-215页

作者： Jennifer m.Hahn kevin L.mcFarland Kelly A.Combs Dorothy m.Supp Research Department Shriners Hospitals for Children-CincinnatiCincinnatiOHUSA Research Department Shriners Hospitals for Children-CincinnatiCincinnatiOHUSA Department of Surgery University of Cincinnati College of MedicineCincinnatiOHUSA

Background:Keloids are an extreme form of abnormal scarring that result from a pathological fibroproliferative wound healing *** molecular mechanisms driving keloid pathology remain incompletely understood,hindering development of targeted,effective *** studies in our laboratory demonstrated that keloid keratinocytes exhibit adhesion abnormalities and display a transcriptional signature reminiscent of cells undergoing epithelial-mesenchymal transition(EmT),suggesting a role for EmT in keloid *** the current study,we further define the EmT-like phenotype of keloid scars and investigate regulation of EmT-related genes in ***:Primary keratinocytes from keloid scar and normal skin were cultured in the presence or absence of transforming growth factor beta 1(TGF-β1)+/-inhibitors of TGF-β1 and downstream signaling *** expression was measured using quantitative polymerase chain *** was analyzed using an in vitro wound healing *** in keloid scar and normal skin sections were localized by *** analyses utilized SigmaPlot(SyStat Software,San Jose,CA)or SAS?(SAS Institute,Cary,NC).Results:In keloid and normal keratinocytes,TGF-β1 regulated expression of EmT-related genes,including hyaluronan synthase 2,vimentin,cadherin-11,wingless-type mmTV integration site family,member 5A,frizzled 7,ADAm metallopeptidase domain 19,and *** of canonical TGF-β1 signaling in keloid keratinocytes significantly inhibited expression of these genes,and TGF-β1 stimulation of normal keratinocytes increased their *** inhibition of the extracellular signal-regulated kinase 1/2(ERK1/2)signaling pathway or the p38 mitogen-activated protein kinase pathway attenuated TGF-β1-induced expression of subsets of these *** of keloid keratinocytes,previously shown to be increased compared with normal keratinocytes,was significantly reduced by inhibition of TGF-β1 or E

关键词： Keloid Keratinocyte Epithelial-mesenchymal transition Wound healing Scar Fibrosis

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

A review of UHmWPE wear-induced osteolysis:the role for early detection of the immune response

引用

Bone Research 2016年第2期4卷 72-84页

作者： Adrese m Kandahari Xinlin Yang kevin A Laroche Abhijit S Dighe Dongfeng Pan Quanjun Cui Department of Orthopaedic Surgery University of Virginia Department of Radiology and medical Imaging University of Virginia

In a world where increasing joint arthroplasties are being performed on increasingly younger patients, osteolysis as the leading cause of faiIure after total joint arthroplasty （TJA） has gained considerable attention. Ultra-high molecular weight polyethylene wear-induced osteolysis is the process by which prosthetic debris mechanicaIly released from the surface of prosthetic joints induces an immune response that favors bone catabolism, resulting in loosening of prostheses with eventual failure or fracture. The immune response initiated is innate in that it is nonspecific and self-propagating, with monocytic cells and osteoclasts being the main effectors. To date, detecting disease early enough to implement effective intervention without unwanted systemic side effects has been a major barrier. These barriers can be overcome using newer in vivo imaging techniques and modules linked with fluorescence and/or chemotherapies. We discuss the pathogenesis of osteolysis, and provide discussion of the challenges with imaging and therapeutics. We describe a positron emission tomography imaging cinnamoyl-Phe-（D）-Leu-Phe-（D）-Leu-Phe-Lys module, specific to maerophages, which holds promise in early detection of disease and localization of treatment. Further research and increased collaboration among therapeutic and three-dimensional imaging researchers are essential in realizing a solution to clinical osteolysis in TJA.

关键词： UHmWPE RANKL A review of UHmWPE wear-induced osteolysis

来源：

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

Development and evaluation of corrosion resistant coating for expandable rock bolt against highly corrosive ground conditions

引用

International Journal of mining Science and Technology 2018年第1期28卷 145-151页

作者： kevin Jinrong ma John Stankus Dakota Faulkner Keystone mining Services LLC of Jennmar Corporation Inc

Expandable rock bolts are widely used in hard rock mines as an efficient ground control ***, capacity and service life can be significantly reduced if the metallic body is subjected to *** some hard rock mines in the U.S., highly corrosive ground conditions exist, and it has been reported that inflatable rock bolts have corroded within a few months after *** provide mining industry a cost-effective inflatable bolt and combat the corrosion issues, Jennmar Corporation, Inc.,and its subsidiary Keystone mining Services, LLC(KmS), analyzed corroded bolt samples, identified root causes, evaluated properties of various coating materials, and developed a new inflatable rock bolt,Python m3^(Tm), that is protected with an innovative PyFlexU2^(Tm)*** new generation Python m3^(Tm) features improved steel chemistry for reliable performance, modified profile for better inflation, and surface preparation and coating *** PyFlexU2^(Tm)is impervious to liquid and air, durable, and UV *** a flexible, adhesive, and highly corrosion-resistant undercoating, and a very hard sacrificial surface coating, the PyFlexU2^(Tm)coating system provides the Python m3^(Tm)superior protection against chemical corrosion and physical scratch *** under-coating has exceptional flexibility and adhesion to prevent coating micro-cracks or fractures after bolt inflation and possesses excellent corrosion resistance to acids(pH 11), fuels, and salt *** corrosion and scratch resistant PyFlexU2^(Tm)coating offers very effective bolt protection for extra longevity in highly corrosive *** Python m3^(Tm)coated with PyFlexU2^(Tm)has been tested in the most challenging conditions,including laboratory corrosion tests in extreme acidic and basic solvents, rock slurry, and borehole scratch insertion *** demonstrated corrosion and scratch resistance, the product has been greatly welcomed by hard rock min

关键词： Rock bolt Hard rock Corrosive ground condition Bolt corrosion

来源：

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

A thin Si nanowire network anode for high volumetric capacity and long-life lithium-ion batteries

引用

Journal of Energy Chemistry 2023年第6期81卷 20-27,I0002页

作者： Ibrahim Saana Amiinu Sumair Imtiaz Hugh Geaney Tadhg Kennedy Nilotpal Kapuria Shalini Singh kevin m Ryan Bernal Institute University of LimerickLimerick V94 T9PXIreland Department of Chemical Sciences University of LimerickLimerick V94 T9PXIreland

Silicon nanowires(Si NWs)have been widely researched as the best alternative to graphite anodes for the next-generation of high-performance lithium-ion batteries(LIBs)owing to their high capacity and low discharge ***,growing binder-free Si NW anodes with adequate mass loading and stable capacity is severely limited by the low surface area of planar current collectors(CCs),and is particularly challenging to achieve on standard pure-Cu substrates due to the ubiquitous formation of Li+inactive silicide ***,the growth of densely-interwoven In-seeded Si NWs is facilitated by a thin-film of copper-silicide(CS)network in situ grown on a Cu-foil,allowing for a thin active NW layer(m thick)and high areal loading(≈1.04 mg/cm^(2))binder-free electrode *** electrode exhibits an average Coulombic efficiency(CE)of>99.6%and stable performance for>900 cycles with≈88.7%capacity *** significantly,it delivers a volumetric capacity of≈1086.1 m A h/cm^(3)at *** full-cell versus lithium manganese oxide(LmO)cathode delivers a capacity of≈1177.1 m A h/g at 1C with a stable rate *** electrode architecture represents significant advances toward the development of binder-free Si NW electrodes for LIB application.

关键词： Si NW anode Silicidation LmO cathode Amorphous ligaments Volumetric capacity Lithium-ion batteries

来源：

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

Enduring legacy of coal mining on the fungal community in a High Arctic soil after five decades

引用

Pedosphere 2022年第5期32卷 698-706页

作者： Dorsaf KERFAHI kevin K.NEWSHAm Ke DONG Hokyung SONG mark TIBBETT Jonathan m.ADAmS School of Natural Sciences Department of Biological SciencesKeimyung UniversityDaegu 42601(Republic of Korea) NERC British Antarctic Survey Madingley RoadCambridge CB3 OET(UK) Department of Life Science Kyonggi UniversitySuwon-si 16227(Republic of Korea) School of Earth and Environmental Sciences The University of ManchesterManchester M139PL(UK) Department of Sustainable Land management&Soil Research Center School of AgriculturePolicy and DevelopmentUniversity of ReadingReading RG66AR(UK) School of Geographic and Oceanographic Sciences Nanjing UniversityNanjing 210008(China)

mineral extraction is known to affect soil fungi in polar environments,but it is unknown how long these effects ***,by amplifying the internal transcribed spacer regions of rRNA genes in soil fungi,we compared soil fungal community in intact natural tundra with that in a nearby former coal mining area,abandoned 52 years previously,on Svalbard in the High *** with those in intact tundra,soils in the former mining area were more acidic and had lower plant *** of similar diversity in the two areas,the fungal community was dominated by Basidiomycota in the intact tundra,but by Ascomycota in the former mining *** genera formed a major part of the tundra community,but were notably less abundant in the mining *** principal variation among samples was soil ***,network connectivity analysis indicated that the fungal community in the former mining area had greater network connectivity than that in the tundra ***,the ecosystem in the former mining area has made only limited recovery towards the natural tundra state even after more than five *** is unclear whether the recovery of the fungal community is limited more by the low primary productivity,slow migration of fungi and plants,or slow changes in soil *** findings emphasize the susceptibility of polar ecosystems to disturbance,given their particularly slow recovery back towards the natural state.

关键词： abandoned mining site ectomycorrhizal fungi intact tundra mine tailings mineral extraction polar ecosystem recovery

来源：

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

Associations of preorchiectomy hormone levels to testicular germ cell tumor pathology,clinical stage,and size

引用

Asian Journal of Andrology 2021年第2期23卷 224-226页

作者： kevin G Pineault Joseph G Cheaib Amin S Herati Phillip m Pierorazio The James Buchanan Brady Urological Institute Johns Hopkins Hospital600 N Wolfe StBaltimoreMD 21287USA

Dear Editor,Despite the substantial body of evidence describing the alternations in and impact of hormones after treatment of unilateral testicular germ cell tumors(GCTs),only a few studies have examined hormone levels before radical orchiectomy.1 This letter details our investigation of the relationship between preorchiectomy hormone levels and surgical pathology,clinical stage,and tumor size among patients with *** in GCT presentation were expected based on varying preorchiectomy hormone levels.

关键词： pathology clinical size

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：