检索结果-南通市图书馆

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

云南国家重点保护陆生野生动物分布格局研究

西南林业大学学报（自然科学） 2024年第5期44卷 101-111页

作者：姜志诚任正涛曾熙雯段禾祥吴学灿云南省生态环境科学研究院云南省高原湖泊流域污染过程与管理重点实验室云南昆明650034

基于《云南省各州市分布的国家重点保护野生动植物名录(2021年)》,通过大量收集和整理科考资料、公民科学数据,结合一定野外调查和访问调查,以《中国生物物种名录2023版》为框架,形成了云南省国家重点保护陆生野生动物分布补充名录,对... 详细信息

基于《云南省各州市分布的国家重点保护野生动植物名录(2021年)》,通过大量收集和整理科考资料、公民科学数据,结合一定野外调查和访问调查,以《中国生物物种名录2023版》为框架,形成了云南省国家重点保护陆生野生动物分布补充名录,对新的名录采用属–科(G–F)多样性指数计算各州市保护物种多样性,并对云南省分布的国家重点保护陆生动物种类、各州市分布情况及分布格局等进行系统剖析。结果表明:补充后云南省分布国家重点保护陆生野生动物有403种,较2021年名录(385种)增加18种(4.68%)。云南省的G–F多样性指数为0.90,各州市平均值为(0.78±0.05),最高为怒江州(0.90),最低是曲靖市(0.56)。云南省国家重点保护陆生野生动物相似性形成6个区域,且物种多样性分布在经纬度上呈现西南高、东北低的格局。本研究可为云南省及各州(市)、县(区)分布的国家重点保护陆生野生动物名录更新及保护、管理提供参考。

关键词：国家重点保护物种陆生野生动物分布格局多样性云南省

Synthesis of Polymethacrylates Used as Multifunctional Lubricating Oil Additives

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

China Petroleum Processing & Petrochemical Technology 2015年第2期17卷 69-75页

作者： Liu Yinong Fan Lichuang duan Qinghua SINOPEC Research Institute of Petroleum Processing

In this paper, four kinds of polymethacrylates(PMAs) used as multifunctional additives were synthesized from quaternary C1—C14 methacrylate, among which sample 4 exhibited relatively better performance. According to the methacrylate ratio of sample 4, the optimized reaction conditions of PMA were explored by orthogonal experiments comprising 4 factors and 3 levels, and the optimized reaction conditions covered an initiator dosage of 0.8 %, a molecular weight regulator dosage of 0.4%, a reaction temperature of 95 ℃ and a reaction time of 8.5 h. When the optimized PMA samples were used to formulate the 75W/90 automotive gear base oil, they exhibited improved shear stability and good low temperature property. In comparison with foreign commercial polymethacrylate GP, the optimized PMA samples exhibited better thickening ability, similar shear stability and slightly weak low temperature property, with their performance being the same as GP's on the whole. The slight difference in the performance between the optimized PMA and GP was attributed to the difference of chain length of copolymers and the distribution of relative molecular mass between them.

关键词： polymethacrylate thickening ability shear stability low temperature property

基于无损检测和概率的古代石拱桥结构可靠度评估

在线全文

学校读者我要写书评

暂无评论

安全与环境工程 2024年第2期31卷 120-128页

作者：龚祝存王音智段凯悦史靖韬崔德山中国地质大学(武汉)工程学院湖北武汉430074

中国古代石拱桥由于其年代久远、结构复杂、露天保存以及可靠度评估过程中参数不易确定等特点,导致传统结构稳定性分析评估方法难以准确评估古代石拱桥结构实际响应和可靠度。提出一种基于无损检测和概率的古代石拱桥结构可靠度评估方... 详细信息

中国古代石拱桥由于其年代久远、结构复杂、露天保存以及可靠度评估过程中参数不易确定等特点,导致传统结构稳定性分析评估方法难以准确评估古代石拱桥结构实际响应和可靠度。提出一种基于无损检测和概率的古代石拱桥结构可靠度评估方法。该方法首先提出利用无损检测技术或工程地质类比法获取石拱桥结构物理力学参数并建立数值模型;然后基于无损检测数据或《工程地质手册》,利用敏感性分析方法确定对石拱桥整体结构响应影响较大的关键参数,即第一类关键参数,并根据参数先验分布提出不同的抽样方法,生成随机样本实现贝叶斯更新过程;最后通过ANSYS软件对桥梁结构的响应进行有限元分析,并利用可靠度分析方法计算出石拱桥结构可靠度指标,并根据相关标准对石拱桥结构安全与可靠度进行评估。以全国重点文物保护单位隋代赵州桥(大石桥)为研究对象建立简化模型,采用本文提出的可靠度评估方法计算得到目前赵州桥的可靠度为3.42,该桥梁安全等级为二级,该评估结果与实际情况基本相符,从而验证了本文方法的可靠性和可行性。该方法可规避传统物理力学检测过程中对石拱桥古建筑的损害,筛选出的关键参数合理,且数据更新处理充分考虑模型参数的不确定性,从而可更精确地计算出古代石拱桥可靠度指标,可为古建筑文物的预防性保护提供科学依据。

关键词：古代石拱桥结构可靠度评估无损检测技术概率贝叶斯更新赵州桥

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

罗田垂枝杉子代生长性状遗传变异及早期选择

广西师范大学学报（自然科学版） 2024年第5期42卷 193-200页

作者：杨姝琦许业洲袁慧周瑜段爱国杜超群湖北省林业科学研究院湖北武汉430075 湖北省钟祥市盘石岭林场湖北钟祥431900 中国林业科学研究院林业研究所国家林业和草原局林木培育重点实验室北京100091

罗田垂枝杉独特的形态特征使其成为林木理想的株型,具有较高经济利用价值和较大的推广应用前景,但其子代测定工作不够完善,各性状的遗传参数未知,这不利于垂枝杉的遗传改良工作。本研究分析杉木遗传变异规律,从而进行优良家系的早期选择... 详细信息

罗田垂枝杉独特的形态特征使其成为林木理想的株型,具有较高经济利用价值和较大的推广应用前景,但其子代测定工作不够完善,各性状的遗传参数未知,这不利于垂枝杉的遗传改良工作。本研究分析杉木遗传变异规律,从而进行优良家系的早期选择,以期为垂枝杉种质资源的保护和选择育种提供理论依据。以罗田垂枝杉子代测定林为研究对象,比较分析不同家系间3年生、4年生林木树高、胸径的生长差异及其遗传规律,并展开优良家系的早期选择。结果显示:子代测定林3年生平均树高、胸径分别为3.11 m和4.07 cm,4年生平均树高、胸径分别为4.16 m和5.35 cm。各家系间生长性状在3年生和4年生时均存在极显著差异(P<0.01);表型变异系数为26.24%~41.83%,遗传变异系数为5.37%~9.15%,单株遗传力为0.3052~0.4318,家系遗传力为0.6099~0.7021,均受到中强程度的遗传控制。不同来源家系中,垂枝杉半同胞家系的生长性状均表现较好,且均为最大值。按照15%的入选率选出5个优良家系,分别为1-17、1-21、1-20、2-3和3-6,其入选均值分别为3.43 m(3年生树高)、4.74 cm(3年生胸径)、4.64 m(4年生树高)和6.20 cm(4年生胸径),平均遗传增益分别为6.71%、10.25%、7.92%和11.13%,选择效果明显,选育出的优良家系可以为垂枝杉种质资源的保护和选择育种提供极佳的种质材料。

关键词：罗田垂枝杉生长性状遗传变异早期选择子代测定

Microphysical Properties of Rainwater in Typhoon Usagi(2013):A Numerical Modeling Study

在线全文

学校读者我要写书评

暂无评论

Advances in Atmospheric Sciences 2019年第5期36卷 510-526页

作者： Lin DENG wenhua GAO Yihong duan Yuqing WANG Nanjing University of Information Science and Technology State Key Laboratory of Severe Weather Chinese Academy of Meteorological Sciences International Pacific Research Center and Department of Atmospheric Sciences School of Ocean and Earth Science and Technology University of Hawai'i at Mānoa

A 2-km resolution simulation using the Weather Research and Forecasting model with Morrison microphysics was employed to investigate the rainwater microphysical properties during different stages of Typhoon Usagi(2013) in the inner-core and outer region. The model reproduced the track, intensity, and overall structure of Usagi(2013) reasonably. The simulated raindrop size distribution showed a rapid increase in small-size raindrop concentration but an oscillated decrease in large-size ones in the inner-core region, corresponding well with the upward motion. It was found that there existed two levels(1.25 and 5.25 km) of maximum number concentration of raindrops. The ice-related microphysics at high levels was stronger than the warm-rain processes at low levels. The larger raindrops formed by self-collection in the inner-core suffered from significant breakup, but the raindrops outside the eyewall did not experience evident breakup. Model results indicated that the dominant terms in the water vapor budget were the horizontal moisture flux convergence(HFC) and local condensation and deposition. The evaporation from the ocean surface(PBL) was ~10% of the HFC in the inner core, but up to 40% in the outer region as the air therein was far from saturation. Furthermore, water vapor in the outer region was obtained equally through evaporation from the cloud and inward transportation from the environment. An earlier start of cloud microphysical processes in the inner-core region was evident during the intensification stage, and the continuous decreasing of condensation in both the inner-core and outer regions might imply the beginning of the storm weakening.

关键词： raindrops microphysical properties typhoon simulation

Characterization of a collection of Chinese fir elite genotypes using *** amplified polymorphism markers

在线全文

学校读者我要写书评

暂无评论

Journal of Forestry Research 2016年第5期27卷 1105-1110页

作者： Hongjing duan Dehuo Hu Yun Li Huiquan Zheng National Engineering Laboratory for Tree Breeding Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental Plants Ministry of Education College of Biological Sciences and Technology Beijing Forestry University Beijing 100083 People's Republic of China Guangdong Provincial Key Laboratory of Bio-control for the Forest Disease and Pest Guangdong Academy of ForestryGuangzhou 510520 People's Republic of China

Chinese fir [Cunninghamia lanceolata （Lamb.） Hook] is a major timber tree species in China. In the pre- sent study, sequence-related amplified polymorphism （SRAP） markers were used to evaluate the polymorphisms, diversity, and relationships in a collection of Chinese fir elite genotypes （n = 103） from the Lechang provenance, an endangered provenance. Thirty-five SRAP primer combinations produced 620 bands among the tested 103 Lechang provenance genotypes and 17 nonSLechang provenance genotypes; 577 （93.1%） of these were polymorphic, yielding an average of 16.5 polymorphic bands per primer combination. Of the SRAP primer combinations （n = 35）, I4 ones identified 〉70.0 % of the 120 genotypes. The Mel2-Eml9 combination had the strongest discriminatory ability with 93.3 % of the genotypes iden- tified. An UPGMA dendrogram further showed that most of the Lechang provenance genotypes （87.4 %） grouped together （Cluster A）. The Lechang genotypes had a con- siderable amount of genetic variation with genetic simi- larity from 0.40 to 0.81. The current work may facilitate the management of the endangered Lechang Chinese fir provenance.

关键词： Chinese fir SRAP Germplasm Geneticvariation - Dendrogram

Experimental study of bed-load transport using particle motion tracking

在线全文

学校读者我要写书评

暂无评论

International Journal of Sediment Research 2017年第1期32卷 73-81页

作者： Jaeho Shim Jennifer G.duan Department of Civil Engineering and Engineering Mechanics University of Arizona

A series of experiments were conducted in a flume to study bed-load *** motion of bed-load particles was captured by a series of images taken by a high-speed camera.A novelparticle motion tracking method was developed to automatically detect all the moving particles and calculate the instantaneous particle *** instantaneous bed load transport rate was calculated based on particle velocity and the volume of moving *** verify this method,bed load transport rate based on the image processing technique was compared to the manually measured ones as well as data from other *** showed that the new technique made it possible to quantify the spatial and temporal variations of bed load transport rate at the individual particle scale.

关键词： Bed-load transport Particle tracking Particle velocity

Effects of minor Sr addition on as-cast microstructure and mechanical properties of a Mg-3Sn-2Ca(wt.%) magnesium alloy

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

China Foundry 2014年第2期11卷 108-114页

作者： Yang Mingbo Li Hongliang duan Chengyu School of Materials Science & Engineering Chongqing University of Technology Key Laboratory of Manufacture and Test Techniques for Automobile Parts Ministry of EducationChongqing University of Technology

Minor Sr was introduced to the Mg-3Sn-2Ca （wt.%） alloy in this paper, and the effects of minor Sr addition on the as-cast microstructure and mechanical properties of the Mg-3Sn-2Ca （wt.%） alloy were investigated by using of optical and electron microscopies, differential scanning calorimetry （DSC） analysis, and tensile and creep tests. The results indicate that, after adding 0.034wt.%, 0.065wt.% or 0.10wt.% Sr to the Mg- 3Sn-2Ca alloy, the morphology of the primary CaMgSn phase changes from the initial coarse needle-like net to relatively fine short block and/or particle-like shapes. At the same time, the additions of 0.034wt.% or 0.065wt.% Sr suppress the formation of the primary CaMgSn phase, and the addition of 0.10wt.% Sr not only suppresses the formation of the primary and eutectic CaMgSn phases but also promotes the formation of Mg2Ca phase. Furthermore, the addition of minor Sr to the Mg-3Sn-2Ca alloy can improve the tensile properties of the alloy both at room temperature and 150 ℃. The creep property of the Mg-3Sn-2Ca alloy at 150 ~C is also improved by the additions of 0.034wt.% and 0.065wt.% Sr; however, the addition of 0.10wt.% Sr is not beneficial to the creep properties of the Mg-3Sn-2Ca alloy.

关键词： magnesium alloys Mg-Sn-Ca alloys CaMgSn phase Sr addition

多孔腹腔镜手术与开腹手术治疗妊娠早中期卵巢良性肿瘤蒂扭转的效果及对妊娠结局的影响

在线全文

学校读者我要写书评

暂无评论

临床和实验医学杂志 2024年第5期23卷 512-515页

作者：王瑶陈琳琳段微首都医科大学附属北京妇产医院妇瘤科北京100026 清华大学附属第一医院妇科北京100016

目的探讨多孔腹腔镜手术(MILS)与开腹手术在治疗妊娠早中期卵巢良性肿瘤蒂扭转(BOTT)的效果及对妊娠结局的影响。方法将2013年2月至2023年1月首都医科大学附属北京妇产医院及清华大学第一附属医院收治的92例妊娠早中期BOTT孕妇纳入本次... 详细信息

目的探讨多孔腹腔镜手术(MILS)与开腹手术在治疗妊娠早中期卵巢良性肿瘤蒂扭转(BOTT)的效果及对妊娠结局的影响。方法将2013年2月至2023年1月首都医科大学附属北京妇产医院及清华大学第一附属医院收治的92例妊娠早中期BOTT孕妇纳入本次回顾性研究,根据手术方式的不同分为开腹组(n=40)和MILS组(n=52)。比较2组患者围术期指标[包括肿瘤直径、扭转角度、缺血等级、手术时间、术中出血量、术后通气时间和住院时间]、术后病理结果、并发症发生情况和妊娠结局。结果2组的肿瘤直径、缺血等级比较,差异均无统计学意义(P>0.05);MILS组的扭转角度、手术时间、术中出血量、排气时间和住院时间分别为(436.0±189.0)°、(50.73±20.19)min、(18.84±5.42)mL、(16.48±7.08)h和(5.23±1.32)d,均显著低于开腹组[(590.0±202.0)°、(69.41±25.63)min、(46.61±18.30)mL、(26.05±12.57)h和(7.78±1.20)d],差异均有统计学意义(P0.05)。2组术后并发症发生率比较,差异无统计学意义(P>0.05)。2组的早产、流产、引产、分娩方式、分娩孕周和新生儿出生体重比较,差异均无统计学意义(P>0.05)。结论MILS治疗妊娠早中期BOTT的术后并发症发生情况和妊娠结局与开腹手术治疗相当,但MILS手术效果优于开腹组。

关键词：腹腔镜手术妊娠早中期卵巢良性肿瘤蒂扭转妊娠结局