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Old-growth mixed beech-dominated forests continue accumulating carbon with advancing age
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作者 Katarína Markuljaková Marek Svitok +21 位作者 Martin Mikolás Jeňýk Hofmeister Wiliam S.Keeton Anders Alhströme Dheeraj Ralhan Jakob Pavlin Audrey Rose Salerno Daniel Kozák Daniela Dúhová Pavel Janda Stjepan Mikac Tzvetan Zlatanov Momchil Panayotov Elvin Toromani Srdjan Keren Abdulla Dikku Cǎtǎlin-Constantin Roibu Kresimir Begovic Radek Bace Ivo Pardus Martin Dusátko Miroslav Svoboda 《Forest Ecosystems》 2026年第1期230-238,共9页
Old-growth forests uniquely support biodiversity while serving as some of the planet's most important carbon stocks.The influence of tree and stand age on carbon flux dynamics remains debated—an urgent question a... Old-growth forests uniquely support biodiversity while serving as some of the planet's most important carbon stocks.The influence of tree and stand age on carbon flux dynamics remains debated—an urgent question as climate-driven disturbances may reshape forest age structures and in situ carbon storage.To clarify these relationships in Fagus sylvatica,systems,we examined a unique dataset of 3,503 tree ring series from 190 plots across some of the best preserved old-growth forests from five southern European countries.By employing a dendrochronological approach and integrating key environmental variables,including elevation,slope,temperature,and the presence of large-diameter trees(≥60 cm),we analyzed the complex relationships between tree/stand age within a plot(represented by plot-level mean values,hereafter“stand age”)and aboveground carbon stock across live,standing,and lying deadwood pools.The average stand age was 220 years,with 230 tC⋅ha^(-1) of carbon stored in aboveground biomass and necromass.We found a positive correlation between age and carbon storage at both the individual tree and plot levels.Notably,the presence of large-diameter trees was the strongest indicator of carbon stock,with carbon accumulation peaking at about 30%large-tree stems proportion before stabilising,while younger beech trees(below 100 years old)had a smaller contribution to carbon storage.We found no evidence of a decline in carbon stock with advancing stand age across the studied sites.Despite the ecological importance of old-growth forests,many of them remain unprotected and are disappearing across Europe.Our findings highlight the importance of preserving old-growth forests to maximize their role as long-term ecosystem carbon reservoirs. 展开更多
关键词 Old-growth forests Carbon stock Physiographic features Old trees Climate change mitigation Dendrochronology
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改进A^(*)算法融合动态窗口法的无人船路径规划 被引量:2
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作者 党宽 黄红武 +1 位作者 高秀晶 辛鹏 《交通工程》 2025年第6期29-35,共7页
为让无人船具有正确的路径规划能力,并保证无人船能躲避实时障碍物到达目的地,提出一种结合改进A^(*)算法和改进动态窗口法的融合算法。首先,将A^(*)算法的8邻域搜索方向通过角度判断进行删减,减少路径搜索时间;其次,在A^(*)算法的估价... 为让无人船具有正确的路径规划能力,并保证无人船能躲避实时障碍物到达目的地,提出一种结合改进A^(*)算法和改进动态窗口法的融合算法。首先,将A^(*)算法的8邻域搜索方向通过角度判断进行删减,减少路径搜索时间;其次,在A^(*)算法的估价函数中引入人工势场算法进行路径修正,增加路径搜索的精确性,并通过节点斜率的关系,删除冗余路段。改进的A^(*)算法相比传统A^(*)算法在2个地图上路径分别缩短22.87%、4.54%,搜索时间分别减少57.66%、36.52%;接着,改进动态窗口法的评价函数,使无人船能更快到达目标点,改进的动态窗口法相比传统的动态窗口法在未知障碍物地图上搜索时间减少27.87%,路径长度减少3.78%;最后,把融合算法与其他算法比较,验证融合算法的实时避障能力。实验结果证明,融合算法规划的路径最短,能实时避障。 展开更多
关键词 无人船 改进A^(*)算法 改进动态窗口法 融合算法 实时避障
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1H NMR Quantification of Astaxanthin and Vitamin E in Nutritional Supplement
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作者 XIN Wenyuan ZHOU Yunbing +2 位作者 LIU Daixi WANG Cong SHERWIN K.B.Sy 《Journal of Ocean University of China》 2025年第6期1827-1833,共7页
Astaxanthin(AX)and vitamin E(VE)are widely consumed nutritional supplements in China,with its beneficial effects predominantly attributed to all-trans AX and VE.The aim of this study is to develop and validate a rapid... Astaxanthin(AX)and vitamin E(VE)are widely consumed nutritional supplements in China,with its beneficial effects predominantly attributed to all-trans AX and VE.The aim of this study is to develop and validate a rapid and accurate method for quantifying the content of AX and VE in nutritional supplement products using highly sensitive1H NMR method.Coumarin was chosen as the internal standard.Specific signals from AX was optimal at H-7,7'in the chemical shift range ofδ6.17–6.24 ppm,whereas the signals of VE atδ2.59 ppm.To demonstrate the reliability of this analytical approach the proposed method underwent rigorous validation,specificity,limit of detection(LOD),limit of quantitation(LOQ),linearity,accuracy,precision,and recovery.The accuracy of the validation method was 3.10%for AX and 1.99%for VE.The results indicated that the method was precise and reliable.The method has been successfully applied to simultaneous quantification of AX and VE in nutritional supplements products. 展开更多
关键词 1H NMR spectroscopy ASTAXANTHIN vitamin E quality control marine bioresource
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某新建大型水电站发电量预测研究分析
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作者 王利宁 《现代工业经济和信息化》 2025年第4期262-264,共3页
水电是我国电力工业的重要组成部分,作为清洁能源在节能减排中扮演着重要角色。因此,通过对黄河上游某新建混流式机组水电站年来水量、月平均流量、在运水电站负荷率等历史数据计算分析,以在运同地区水电站近年负荷率进行复核,对预测结... 水电是我国电力工业的重要组成部分,作为清洁能源在节能减排中扮演着重要角色。因此,通过对黄河上游某新建混流式机组水电站年来水量、月平均流量、在运水电站负荷率等历史数据计算分析,以在运同地区水电站近年负荷率进行复核,对预测结果进行综合分析,最终得出本电站多年平均发电量预测结果。 展开更多
关键词 水电站 年发电量 综合分析
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Fluid therapy strategies in acute pancreatitis:Randomized controlled trial comparing dextran and Ringer’s lactate
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作者 Nicolae Cristian Costea Stefan Vesa +2 位作者 Mariana Toma Cristina Pojoga Andrada Seicean 《World Journal of Gastrointestinal Surgery》 2025年第11期384-394,共11页
BACKGROUND Acute pancreatitis(AP)is a frequent gastrointestinal emergency characterized by inflammation.It has the potential to progress to organ failure.Fluid therapy plays a critical role in early AP management,miti... BACKGROUND Acute pancreatitis(AP)is a frequent gastrointestinal emergency characterized by inflammation.It has the potential to progress to organ failure.Fluid therapy plays a critical role in early AP management,mitigating hypovolemia-induced ischemia and systemic inflammatory response syndrome(SIRS).AIM To evaluate dextran 40+Ringer’s lactate solution(RLS)vs RLS alone for fluid therapy in mild to moderate AP.METHODS We conducted a single-center,single-blind,randomized controlled trial involving 108 patients with mild to moderate AP.Participants were randomized to receive either dextran 40+RLS(1:3 ratio)or RLS alone.All patients underwent standardized,goal-directed fluid therapy and were monitored for clinical response,inflammatory markers,and complications.The primary outcomes were reduction in C-reactive protein(CRP)and resolution of SIRS at 72 hours.Secondary outcomes included organ failure,intensive care unit admission,mortality,and length of hospital stay.RESULTS The dextran 40+RLS group demonstrated significantly lower CRP levels.No differences were observed in SIRS changes,fluid overload,refractory status mortality,local complications,or organ failure rates.Hospitalization tended to be shorter in the dextran 40+RLS group(5 days vs 6 days)although not to a statistically significant level(P=0.1).Adverse events were mild and comparable in both groups.CONCLUSION Dextran 40+RLS improved the early CRP response in patients with AP without added complications.Although medium-term outcomes were similar,early benefits support its use in initial management. 展开更多
关键词 Acute pancreatitis Fluid therapy DEXTRAN Ringer’s lactate Randomized controlled trial Systemic inflammatory response syndrome C-reactive protein
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金刚烷胺对海带幼孢子体的毒性研究
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作者 鹿瑶 徐英江 +6 位作者 赵军强 何金霞 刘辉 孙琰晴 王小涵 李晓捷 任利华 《水产学杂志》 2025年第5期52-60,78,共10页
金刚烷胺作为一种流感病毒的防治药物曾广泛应用于畜禽养殖中,过度使用导致其在环境中不断累积,且随地表径流最终汇入海洋,成为一种新型海洋污染物。研究表明:金刚烷胺对刺参等海洋生物具有一定的毒性效应,但对大型藻类的毒性效应研究... 金刚烷胺作为一种流感病毒的防治药物曾广泛应用于畜禽养殖中,过度使用导致其在环境中不断累积,且随地表径流最终汇入海洋,成为一种新型海洋污染物。研究表明:金刚烷胺对刺参等海洋生物具有一定的毒性效应,但对大型藻类的毒性效应研究十分有限。本文以大型褐藻海带的幼孢子体为研究对象,采用实验室内模拟的方式,系统研究了金刚烷胺对海带幼孢子体生长、生理结构、氧化损伤及抗氧化酶活性的影响。研究发现:金刚烷胺对海带幼孢子体具有生长抑制作用,损伤叶片组织结构;海带幼孢子体可以耐受低剂量(≤1.0×10^(4) ng·L^(-1))金刚烷胺的胁迫,氧化损伤可逆,但随暴露剂量增加,机体抗氧化系统被抑制,氧化损伤加剧乃至死亡。结果表明:金刚烷胺对海带幼孢子体的生长和抗氧化防御系统具有负面影响,对海洋生态系统的健康构成潜在威胁,急需加强对金刚烷胺的环境监测和管控,以减轻其对海洋生物的危害。 展开更多
关键词 金刚烷胺 海带幼孢子体 抗氧化系统 氧化损伤 组织切片
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Assessing the effectiveness of acoustic signals in mark-recapture studies to estimate dolphins population
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作者 Elena Papale Maria Ceraulo +2 位作者 Martina Gregoriettid Clarissa De Vita Giuseppa Buscaino 《Current Zoology》 2025年第4期409-418,共10页
Accurate estimations of animal population size are pivotal for implementing management strategies properly.Recapture technique based on sounds as a specimen identifcation mark has barely been used for marine mammals.H... Accurate estimations of animal population size are pivotal for implementing management strategies properly.Recapture technique based on sounds as a specimen identifcation mark has barely been used for marine mammals.However,inferring abundance estimates from acoustic methods could enhance the accuracy and precision of population size assessments.Here,we tested the possibility of using signature whistles as individual marks for estimating the size of common bottlenose dolphin(Tursiops truncatus)populations.Data were continuously collected for 326 days in 2015–2016,by using a fxed acoustic device located in the Sicily Strait(Italy).The SIGID method was applied to identify Signature Whistles Types(SWTs)over 7,000 h of recordings.Eighty SWTs were detected as long as their stereotyped fundamental frequency contours were repeated in bouts of at least 6 renditions.The mean SWTs monthly recording rate resulted in 0.19(Standard deviation=0.16),with 20 SWTs recorded over 5 or more different encounters(until a maximum of 30 encounters).The Jolly–Seber model(with POPAN formulation)was run in Mark software to estimate the population size.The estimated population size resulted in 171 bottlenose dolphins(95%confdence interval=137–215).Even if the detection and identifcation of signature whistles required crucial precautions,and animals could be detected differently from visual techniques,the population size estimate obtained was comparable with previous results based on physical marks data.These outcomes demonstrated that signature whistles can be considered a strongly effective tool for integrating traditional mark-recapture techniques with fnely estimated dolphins’population abundances. 展开更多
关键词 modeling methods passive acoustic monitoring signature whistles specimen identifcation mark Tursiops truncatus
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Large-scale and long-term spatiotemporal patterns of disturbances in primary beech-dominated forests in the Carpathian Mountains of Europe
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作者 Pavel Janda Arne Buechling +22 位作者 Marek Svitok Thomas A.Nagel Martin Mikolas Radek Bace Kresimir Begovic Martin Dusatko Daniela Duhova Matej Ferencik Michal Frankovic Rhiannon Gloor Ondrej Kameniar Tomas Knir Daniel Kozak Jana Agh Labusova Katarina Markuljakova Jakob Pavlin Ion Catalin Petritan Catalin-Constantin Roibu Audrey Rose Salerno Karol Ujhazy Antonin Veber Lucie Vitkova Miroslav Svoboda 《Forest Ecosystems》 2025年第5期987-997,共11页
Extreme disturbance activity is a signature of anthropogenic environmental change. Empirical information describing the historical normative limits of disturbance regimes provides baseline data that facilitates the de... Extreme disturbance activity is a signature of anthropogenic environmental change. Empirical information describing the historical normative limits of disturbance regimes provides baseline data that facilitates the detection of contemporary trends in both disturbances and community-level responses. Quantifying the attributes of historical disturbances is challenging due to their transient episodic nature, with decades-to centurieslong intervals between recurrences. Unmanaged primary forests that support centuries-old trees therefore serve as unique reference systems for quantifying past disturbance regimes. We surveyed relict stands of primary beech-dominated forests over wide environmental gradients in the Carpathian Mountains of Europe. We collected core samples from 3,026 trees in 208 field survey plots distributed across 13 forest stands in two countries. We used dendrochronological methods to analyze time-series of annually-resolved ring-width variation and to identify anomalous growth patterns diagnostic of past forest canopy removal. A 180-year record(1810–1990) of spatially and temporally explicit disturbance events(n =333) was compiled and used to derive s tatistical attributes of the disturbance regime. We quantified disturbance severity(canopy area lost), patch size, and return intervals. Our analyses describe a complex regime where a background of relatively frequent, smallscale, low-to intermediate-severity disturbance was punctuated by episodic large-scale high-severity events. Even the most severe events were non-catastrophic at a stand level, leaving significant residual tree cover that supported a continuity of ecological function. We did not detect evidence for an expected climate-induced intensification of disturbance with time, but methodological limitations precluded an assessment of disturbance activity in the decades since 1990. 展开更多
关键词 Canopy gap Climate change Disturbance regime Ecosystem resilience Natural range of variability Baseline conditions Tree mortality
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A maximum sea surface salinity tongue in the North Brazil continental shelf
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作者 Maria Cadima Paola Castellanos +2 位作者 Estrella Olmedo Joaquim Dias Edmo J.D.Campos 《Atmospheric and Oceanic Science Letters》 2025年第3期41-46,共6页
The variability of the sea surface salinity measurements provided by the Soil Moisture and Ocean Salinity mission reveals the presence of a local salinity maximum(a salty tongue)in the northwestern tropical Atlantic.T... The variability of the sea surface salinity measurements provided by the Soil Moisture and Ocean Salinity mission reveals the presence of a local salinity maximum(a salty tongue)in the northwestern tropical Atlantic.The sea surface salinity positive anomaly starts increasing in July,reaches its maximum in January,and then disappears.The local maximum of salinity appears in the late boreal autumn/winter,when the Amazon discharge is minimal and the salty water from the South Atlantic is transported by the North Brazil Current along the shelf break across the equator.The authors validate the satellite observations in this area and assess the vertical structure of the salinity maximum by using in situ measurements and an in situ-interpolated product. 展开更多
关键词 Tropical Atlantic ocean Salty tongue North Brazil current
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中国海域波浪能资源分布及波浪能发电装置适用性研究 被引量:14
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作者 胡聪 毛海英 +2 位作者 尤再进 石洪源 高松 《海洋科学》 CAS CSCD 北大核心 2018年第3期142-148,共7页
首先全面综述了国内外波浪能资源开发利用现状,系统总结了目前国内外海洋波浪能资源发电技术中应用的主要波浪能资源开发装置及存在问题;基于ERA-Interim再分析数据,给出了中国海域的平均波浪能流密度和季节特征,从而获取高波能资源分... 首先全面综述了国内外波浪能资源开发利用现状,系统总结了目前国内外海洋波浪能资源发电技术中应用的主要波浪能资源开发装置及存在问题;基于ERA-Interim再分析数据,给出了中国海域的平均波浪能流密度和季节特征,从而获取高波能资源分布区域,得到了中国海域波浪能资源分布富集区域;结合不同海岸岸线及海底类型,综合给出了中国波能资源富集区域中发电装置适用建议、高峰发电季节。对提高我国波浪能资源开发利用、推动海洋可再生能源行业的发展具有重要意义,也为实用化、商业化海洋波浪能资源选址提供了科学依据。 展开更多
关键词 波浪能资源 中国海域 ERA-INTERIM 发电装置
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东营三角洲演化特征与岩性圈闭分布规律<英文> 被引量:5
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作者 方勇 邓宏文 +2 位作者 Massimo SARTI 万晓樵 冯晓杰 《石油勘探与开发》 SCIE EI CAS CSCD 北大核心 2003年第5期123-126,共4页
东营三角洲是东营凹陷古近系沙河街组沙三段的主要沉积体系之一,为一大型复合三角洲。该三角训形成的浊积砂体岩性圈闭是东营凹陷沙三段重要的勘探目标,近几年平均每年发现的岩性油藏石油储量超过千万吨。为了给东营三角洲隐蔽油气藏进... 东营三角洲是东营凹陷古近系沙河街组沙三段的主要沉积体系之一,为一大型复合三角洲。该三角训形成的浊积砂体岩性圈闭是东营凹陷沙三段重要的勘探目标,近几年平均每年发现的岩性油藏石油储量超过千万吨。为了给东营三角洲隐蔽油气藏进一步的勘探提供科学依据,运用高分辨率层序地层学理论和分析方法,在建立高频层序地层格架的基础上,研究东营三角洲演化过程、古构造坡折发育类型及不同期次三角洲与构造坡折的配置关系,分析这些因素对岩性圈闭形成的重要作用,认为在进积时期推进距离较远(三角洲进积作用大于加积作用)、退积时期湖泛规模较大条件下发育的三角洲朵叶体易形成具有一定规模的浊积扇。 展开更多
关键词 东营三角洲 基准面 岩性圈闭 层序地层学
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Cu-25Ni-25Ag三元合金在600℃和700℃空气中的氧化 被引量:1
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作者 赵泽良 牛焱 +1 位作者 F.Gesmundo 吴维 《中国有色金属学报》 EI CAS CSCD 北大核心 2001年第2期183-186,共4页
研究了Cu 2 5Ni 2 5Ag合金在 6 0 0℃和 70 0℃空气中的氧化。合金由富Ag的α相与Cu Ni固溶体 β相组成。氧化速率大致服从抛物线规律 ,除短时间的加速氧化外 ,随着氧化的进行氧化速率逐渐减小。尽管存在Ag和Ni,但合金成膜速率与纯Cu的... 研究了Cu 2 5Ni 2 5Ag合金在 6 0 0℃和 70 0℃空气中的氧化。合金由富Ag的α相与Cu Ni固溶体 β相组成。氧化速率大致服从抛物线规律 ,除短时间的加速氧化外 ,随着氧化的进行氧化速率逐渐减小。尽管存在Ag和Ni,但合金成膜速率与纯Cu的相近。在不同温度下合金都形成了外层为CuO ,内层为Cu2 O ,NiO和Ag颗粒组成的复杂氧化膜。同时 ,氧化膜最前沿的Cu Ni固溶体颗粒仅表面部分氧化 。 展开更多
关键词 三元合金 Cu-Ni-Ag 双相合金 氧化 铜合金
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基于能量平衡原理的机床结构动态优化 被引量:1
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作者 刘江 王兆涛 阮业康 《制造技术与机床》 北大核心 2021年第3期31-34,共4页
提出了一种基于能量平衡原理的机床结构动态优化的方法,通过提高机床部件能量分布的均匀性来提高机床动态性能。以数控雕铣机龙门架的动态性能优化设计为例,对这一方法做了具体的阐述。首先,利用有限元软件模态分析确定出部件危险模态... 提出了一种基于能量平衡原理的机床结构动态优化的方法,通过提高机床部件能量分布的均匀性来提高机床动态性能。以数控雕铣机龙门架的动态性能优化设计为例,对这一方法做了具体的阐述。首先,利用有限元软件模态分析确定出部件危险模态的固有频率及振型;然后,根据能量分布确定出动能和势能集中的区域,再根据能量平衡原理对零件结构进行优化;最后,使用标准差对能量分布的均匀性进行评价,最终达到提高机床部件动态特性的目的。 展开更多
关键词 动态特性 能量平衡 动能 势能 标准差
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海南岛海砂资源的分类特征及成矿特点分析 被引量:15
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作者 仝长亮 《中国地质调查》 2018年第3期74-80,共7页
海南岛海砂资源丰富,质量较好,储量位居全国前列,其中钛铁矿、锆英石和独居石是海南岛的优势滨海砂矿资源。根据其用途主要分为3类:锆钛砂矿、石英砂矿和建筑用砂矿。通过资料收集和整理,分别研究了海南岛不同类型海砂资源的分布范围、... 海南岛海砂资源丰富,质量较好,储量位居全国前列,其中钛铁矿、锆英石和独居石是海南岛的优势滨海砂矿资源。根据其用途主要分为3类:锆钛砂矿、石英砂矿和建筑用砂矿。通过资料收集和整理,分别研究了海南岛不同类型海砂资源的分布范围、勘查程度、资源储量、形成环境和资源潜力等。研究结果表明:锆钛砂矿开发程度最高,主要分布于琼东沿海及水下阶地一带的全新统,规模较大,品位较高,开发条件较好;琼西则以建筑用砂矿和石英砂矿为主,海砂质量好,杂质含量较低;位于浅海区的潮流沙脊和河口三角洲,工作程度不高,但其海砂分布广、厚度大、砂质好,是今后海砂勘查的重点区域,具有良好的资源开发前景。总结海南岛海砂资源的主要成矿特点为:(1)分布广泛,规模巨大,开发条件好;(2)主要产于全新世地层;(3)沉积厚度较大,纵向连续性好;(4)海砂质量较好,并富含重矿物。 展开更多
关键词 海南岛 海砂资源 分类特征 成矿特点
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Practical recommendations on stretching exercise:A Delphi consensus statement of international research experts
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作者 Konstantin Warneke Ewan Thomas +17 位作者 Anthony J.Blazevich José Afonso David G.Behm Paulo H.Marchetti Gabriel S.Trajano Masatoshi Nakamura Francisco Ayala Stefano Longo Nicolas Babault Sandro R.Freitas Pablo B.Costa Andreas Konrad Antoine Nordez Arnold Nelson Astrid Zech Anthony D.Kay Olyvia Dontit Jan Wilke 《Journal of Sport and Health Science》 2025年第5期110-123,共14页
Background:Stretching has wide appeal,but there seems to exist some mismatch between its purported applications and what the evidence shows.There is compelling evidence for some stretching applications,but for others,... Background:Stretching has wide appeal,but there seems to exist some mismatch between its purported applications and what the evidence shows.There is compelling evidence for some stretching applications,but for others,the evidence seems heterogeneous or unsupportive.The discrepancies even affect some systematic reviews,possibly due to heterogeneous eligibility criteria and search strategies.This consensus paper seeks to unify the divergent findings on stretching and its implications for both athletic performance and clinical practices by delivering evidence-based recommendations.Methods:A panel of 20 experts with a blend of practical experience and scholarly knowledge was assembled.The panel meticulously reviewed existing systematic reviews,defined key terminologies(e.g.,consensus definitions for different stretching modes),and crafted guidelines using a Delphi consensus approach(minimum required agreement:80%).The analysis focused on 8 topics,including stretching's acute and chronic(long-term)effects on range of motion,strength performance,muscle hypertrophy,stiffness,injury prevention,muscle recovery,posture correction,and cardiovascular health.Results:There was consensus that chronic and acute stretching(a)improves range of motion(although alternatives exist)and(b)reduces muscle stiffness(which may not always be desirable);the panel also agreed that chronic stretching(c)may promote vascular health,but more research is warranted.In contrast,consensus was found that stretch training does not(a)contribute substantively to muscle growth,(b)serve as an allencompassing injury prevention strategy,(c)improve posture,or(d)acutely enhance post-exercise recovery.Conclusion:These recommendations provide guidance for athletes and practitioners,highlighting research gaps that should be addressed to more comprehensively understand the full scope of stretching effects. 展开更多
关键词 Range of motion Strength Movement preparation Recovery Evidence-based practice STRETCH
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高产岩藻黄素的海洋硅藻筛选及光照条件优化 被引量:7
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作者 侯红焰 向威鹏 +2 位作者 张金荣 程鹏飞 周成旭 《水生生物学报》 CAS CSCD 北大核心 2020年第4期912-919,共8页
为提高岩藻黄素(Fucoxanthin)提取效率,对16株海洋硅藻岩藻黄素的检测含量和实际含量进行了分析,并以一株牟氏角刺藻(Chaetoceros muelleri)为对象,研究了岩藻黄素与另外两种关键光合色素(即叶绿素a和β-胡萝卜素)的含量及其消长受光强... 为提高岩藻黄素(Fucoxanthin)提取效率,对16株海洋硅藻岩藻黄素的检测含量和实际含量进行了分析,并以一株牟氏角刺藻(Chaetoceros muelleri)为对象,研究了岩藻黄素与另外两种关键光合色素(即叶绿素a和β-胡萝卜素)的含量及其消长受光强和光质影响的特征。研究结果显示,不同种或同种不同株的海洋硅藻,在相同的培养条件、收获时期、提取方法下,其提取率差异大,可从不足1%到89.78%;岩藻黄素的检出含量各异,从0.03到5.02 mg/g。受不同光照强度[低:50μmol/(m^2·s);中:100μmol/(m^2·s);高:200μmol/(m^2·s)和光质(红光、蓝光)]的影响,岩藻黄素产量呈现不同特征。在低光照强度下,单位细胞岩藻黄素的含量相对较高。在红光条件下,岩藻黄素的产量高于蓝光。在相同光强条件下,岩藻黄素含量随增殖周期变化;在单色光质条件下,几种光合色素均在生长平台期后期含量增加。岩藻黄素的含量变化与叶绿素a和β-胡萝卜素的含量及其消长关系密切。研究为筛选藻株、优化硅藻培养条件以累积岩藻黄素提供了参考。 展开更多
关键词 岩藻黄素 海洋硅藻 提取率 光合色素 光照条件
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上海城市水网地区电火花震源地震探测隐伏断裂的应用探索 被引量:7
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作者 宋春华 施刚 +2 位作者 巫虹 张浩 郁飞 《地质力学学报》 CSCD 北大核心 2021年第6期938-948,共11页
人工地震勘探是目前公认最为有效的城市地区隐伏断裂探测手段之一,但其受限于激发震源和城市高干扰环境背景,在高度城市化区域往往难以获取良好的地震勘探资料。文章通过利用上海市城市水网发育的优势,在大治河水域开展大功率电火花震... 人工地震勘探是目前公认最为有效的城市地区隐伏断裂探测手段之一,但其受限于激发震源和城市高干扰环境背景,在高度城市化区域往往难以获取良好的地震勘探资料。文章通过利用上海市城市水网发育的优势,在大治河水域开展大功率电火花震源激发方式的地震探测,对电火花震源激发能量、放电水深、不同震源的地震成像效果等对比试验,获得了上海地区内河水域(大治河东段)最佳地震勘探激发参数,确认了在城市水网开展电火花震源激发地震勘探方式的有效性。与其他常规激发方式相比,电火花激发地震勘探资料具有较高的信噪比,并且可以达到较深的勘探深度,对城市地区隐伏断裂探测具有良好效果。 展开更多
关键词 城市水网 大功率电火花震源 地震勘探 隐伏断裂 不同震源对比 激发能量 地震时间剖面
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双作用液压打桩锤液压系统建模及动态特性研究 被引量:2
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作者 冯小星 李泽 +3 位作者 梅卫东 季鹏 彭熙伟 张百海 《机床与液压》 北大核心 2024年第24期178-183,共6页
针对液压打桩锤打击过程中流量、压力动态变化较大及流量、压力的非线性耦合特性,建立双作用液压打桩锤液压系统的动力学模型,采用数值法求解液压打桩锤运动的动力学模型,以超大型液压打桩锤的相关数据为基础,研究液压系统参数匹配对锤... 针对液压打桩锤打击过程中流量、压力动态变化较大及流量、压力的非线性耦合特性,建立双作用液压打桩锤液压系统的动力学模型,采用数值法求解液压打桩锤运动的动力学模型,以超大型液压打桩锤的相关数据为基础,研究液压系统参数匹配对锤芯位移、速度、加速度等动态特性的影响。仿真结果表明:通过合理匹配蓄能器充气压力、液阻、液压油源流量等关键参数,可优化打桩锤的动态特性,实现打击速度快、系统稳定性好的控制效果。 展开更多
关键词 液压传动 双作用液压打桩锤 动态特性 动力学模型
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基于Modelica的潜液泵系统建模与仿真分析 被引量:6
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作者 徐永坤 陈立平 +1 位作者 刘伟 朱江森 《机床与液压》 北大核心 2021年第14期142-147,共6页
为研究潜液泵系统的动态特性以及速度限制扭矩控制阀(STC阀)结构参数对阀芯动态性能的影响,在分析其工作原理、数学模型的基础上,采用多领域统一建模语言Modelica,在MWorks仿真软件中构建STC阀子系统、遥控阀组子系统等模型,并将所建立... 为研究潜液泵系统的动态特性以及速度限制扭矩控制阀(STC阀)结构参数对阀芯动态性能的影响,在分析其工作原理、数学模型的基础上,采用多领域统一建模语言Modelica,在MWorks仿真软件中构建STC阀子系统、遥控阀组子系统等模型,并将所建立的子系统模型与恒压变量泵、离心泵模型相结合,构造出完整的潜液泵系统模型。利用该模型进行系统仿真,分析STC阀节流孔直径和阀芯质量对阀芯动态性能的影响。研究结果表明:潜液泵系统具有良好的动态特性;STC阀节流孔直径越小,阀芯的运动速度越平稳、速度振荡越小,越能更快达到稳定状态;STC阀阀芯质量越大,阀芯的速度振动越小,运动速度越平稳。 展开更多
关键词 潜液泵系统 MODELICA语言 仿真分析 MWorks仿真 阀芯动态性能
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基于CFD方法分析端板对摆线推进器性能的影响 被引量:2
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作者 杨玉良 冯峰 +2 位作者 王玉娟 赖昱兴 章小松 《船舶工程》 CSCD 北大核心 2020年第8期75-79,共5页
基于FLUENT求解器,对摆线推进器叶梢末端加装端板前后水动力性能变化进行研究。根据摆线推进器工作时的旋转规律,编写相应UDF控制程序,运用滑移网格技术进行数值模拟。采用结构网格与非结构网格相结合的方式对模型进行网格划分,结合FLU... 基于FLUENT求解器,对摆线推进器叶梢末端加装端板前后水动力性能变化进行研究。根据摆线推进器工作时的旋转规律,编写相应UDF控制程序,运用滑移网格技术进行数值模拟。采用结构网格与非结构网格相结合的方式对模型进行网格划分,结合FLUENT求解器的计算结果,来分析水动力性能及叶梢涡的变化。进而得出结论,摆线推进器加装端板比未加端板的水动力性能更优、叶梢涡强度得到减弱和转矩振荡系数减小。因此在摆线推进器叶片末端加装端板,可提高推进器性能,工作更为安全和稳定。 展开更多
关键词 FLUENT求解器 摆线推进器 滑移网格 水动力性能 端板 叶梢涡
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