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Assessing Biomass Expansion Factor of Birch Tree <i>Betula utilis</i>D. DON 被引量:1
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作者 Khurshid Alam Syed Moazzam Nizami 《Open Journal of Forestry》 2014年第3期181-190,共10页
Biomass is the component of living organism and mostly obtained from plants, animals, insects and the residue of all the mentioned organisms. Biomass is the key source of energy present in the form of organic matter. ... Biomass is the component of living organism and mostly obtained from plants, animals, insects and the residue of all the mentioned organisms. Biomass is the key source of energy present in the form of organic matter. The study aimed to find out biomass and its variation in each component of Betula utilis D. Don (Birch Tree) with varying diameter at Kalam forest division Swat, Khyber Pakhtunkhwa (KPK) province, Pakistan. The biomass of different components was determined by non-destructive methods. Overall, 30 trees were selected from different diameter classes viz a viz up to 10, 11 - 20 and greater than 20 cm. Ten trees were selected from each class. The diameter of stem and large branches and their length were measured in the field. Later, the volumes of stem and branches were calculated and converted into biomass. The study revealed that stem contributes 42.65% biomass followed by large and sub branches as 39.22% and 13.54% respectively. Leaves contribute 4.59% only. The above tree biomass contribution by different components was arranged as stem was greater than large branches;these were greater than sub branches and the lowest was in leaves. The total above ground biomass of single tree was 20.59, 58.041 and 197.214 kg·tree-1 respectively for diameter up to 10, 11 - 20 and greater than 20 cm. The averaged biomass in all diameter classes was 91.95 ± 93.064 kg·tree-1. The total biomass of single tree of diameter class up to 10, 11 - 20 and greater than 20 cm was 24.71, 69.649 and 236 kg respectively. The below ground biomass of single tree of diameter class up to 10, 11 - 20 and greater than 20 cm was 4.11 ± 1.24 kg, 11.61 ± 3.56 kg and 39.44 ± 8.9 kg respectively. The biomass expansion factor was 1.34, 1.47, and 1.5 t·m-3 respectively for diameter classes up to 10 cm, 11 - 20 cm and greater than 20 cm respectively. The mean biomass expansion factor for all diameter classes was 1.44 t·m-3. 展开更多
关键词 BIOMASS Allocation BIOMASS expansion factor BIRCH TREE
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Construction land expansion and influencing factors of typical river valley cities in Northeast China: Taking Jilin City as an example
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作者 LI Ruiqi LI Hong YIN Jingbo 《Global Geology》 2023年第3期189-198,共10页
Jilin City is a typical river valley city in Northeast China.In this paper,the authors studied the spatial and temporal expansion characteristics of the built-up areas in Jilin City from 1990 to 2020 using the analysi... Jilin City is a typical river valley city in Northeast China.In this paper,the authors studied the spatial and temporal expansion characteristics of the built-up areas in Jilin City from 1990 to 2020 using the analysis of expansion speed and strength,fractal dimension,barycenter coordinate transfer index and sector analysis.The ultimate-goal is to analyze the driving and restrictive factors that affect the spatial expansion of river valley cities.The results indicate that(1)the expansion speed of urban land in Jilin City has been re-latively slow in the past 30 years,while only slightly faster in 2010–2020;(2)in the spatial dimension,Jilin City mainly expanded to the south,then to the west,and extensive expansion has resulted in complex mor-phology with little stability and compactness;(3)the expansion is affected by multiple factors,of which the positive factor is industrial development,while the restrictive factors include natural factors,population loss,etc.This study provides a case for the formulation of land use policies and land space planning in river valley cities. 展开更多
关键词 river valley city expansion of construction land influencing factors Jilin City
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Urban Expansion in Major Grain Producing Area from 1978 to 2017:A Case Study of Zhengzhou Metropolitan Area,China 被引量:1
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作者 YANG Yongju ZHANG Hebing +2 位作者 QIAO Xuning LIU Liang ZHENG Jinchan 《Chinese Geographical Science》 SCIE CSCD 2023年第1期1-20,共20页
The spatial form of urbanization in China has developed from single-core city expansion to a multi-center metropolitan area.However,little attention has been paid to the growth process of the emerging metropolitan are... The spatial form of urbanization in China has developed from single-core city expansion to a multi-center metropolitan area.However,little attention has been paid to the growth process of the emerging metropolitan area situated in major grain producing locations in the central China.Taking the Zhengzhou metropolitan area(ZZMA)as a case study,we developed an inverse S-shape model to characterize the spatial distribution of urban land density,and constructed an urban expansion core index,urban expansion intensity index,and urban compactness index to quantify the spatial structure change that has taken place from 1978 to 2017 during the process of urban expansion.Moreover,cropland contribution rate(CR)was constructed to evaluate the impacts of urban expansion on croplands.We uncovered four key findings.First,over the past 40 yr,the ZZMA has experienced dramatic expansion,and the central city of Zhengzhou expanded faster than other cities.The gravity centers of urban expansion of surrounding cities were moving toward to Zhengzhou City.Second,the urban land density decreased with the distance from the city center to the outskirts.As the only large city,Zhengzhou has experienced the fastest and most compact centralized urban expansion,especially after 2000,while other medium-and small-sized cities have experienced low-intensity decentralized expansion.Third,the urban core has been gradually expanding outward.From 1978 to 2017,the hot-zone of urban growth has moved progressively with the acceleration of urbanization.All cities except Jiaozuo had a single peak in different periods.Forth,the cities in national core grain-producing areas has higher cropland contribution rates and lower urban expansion areas,which was closely related to cropland protection.Further analysis showed that large city was relatively better positioned than smaller cities in the efficiency of their urban infrastructure and the effectiveness of wealth creation efficiency in the urbanized area could be tested in all cities,and the policy factor seemed to play an important role in the urban expansion process. 展开更多
关键词 urban expansion major grain producing area inverse S-shape cropland contribution rate(CR) policy factor Zhengzhou metropolitan area(ZZMA)
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The influencing factors of urban land expansion in Changsha 被引量:9
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作者 ZHOU Guohua HE Yanhua 《Journal of Geographical Sciences》 SCIE CSCD 2007年第4期487-499,共13页
This research systematically analyses land-use map of Changsha city in different periods of time. The spatial form and structural evolution was analysed by studying indices such as city land-use structure proportion, ... This research systematically analyses land-use map of Changsha city in different periods of time. The spatial form and structural evolution was analysed by studying indices such as city land-use structure proportion, expansion intensity, economic flexibility, population flexibility, changing compactness index and so on. The dynamic mechanism of urban land expansion has been discussed by integrating the regional social economy development situation and many aspects such as the physiographical surrounding, population and economic development, traffic infrastructure, planning and regional development tactic and system innovation. The research indicates that the urban land expansion speed and intensity have steadily increased in Changsha from 1949 to 2004. The expansion form has been from a single external expansion to a combination form of external and internal expansion, from a circular or linear continuous form to a blocky or agglomeration shape. Overall, the urban land expansion of Changsha city is a phasic, diversified and complex process. And no matter what the stage is, it is an organic system containing multiple speed, pattern and shape, which are driven by multiple impetuses. The dominant feature at different stages was highlighted because of the balance and fluctuation between different forces, and the existing urban land border and shape have resulted from the joint efforts of these phasic forces. 展开更多
关键词 Changsha urban land expansion influencing factors dynamic mechanism
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The Factorizational Theory of Finite Asymptotic Expansions in the Real Domain: A Survey of the Main Results 被引量:4
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作者 Antonio Granata 《Advances in Pure Mathematics》 2015年第1期1-20,共20页
After studying finite asymptotic expansions in real powers, we have developed a general theory for expansions of type (*) ,x → x0 where the ordered n-tuple forms an asymptotic scale at x0 , i.e. as x → x0, 1 ≤ i ≤... After studying finite asymptotic expansions in real powers, we have developed a general theory for expansions of type (*) ,x → x0 where the ordered n-tuple forms an asymptotic scale at x0 , i.e. as x → x0, 1 ≤ i ≤ n – 1, and is practically assumed to be an extended complete Chebyshev system on a one-sided neighborhood of x o. As in previous papers by the author concerning polynomial, real-power and two-term theory, the locution “factorizational theory” refers to the special approach based on various types of factorizations of a differential operator associated to . Moreover, the guiding thread of our theory is the property of formal differentiation and we aim at characterizing some n-tuples of asymptotic expansions formed by (*) and n -1 expansions obtained by formal applications of suitable linear differential operators of orders 1,2,…,n-1. Some considerations lead to restrict the attention to two sets of operators naturally associated to “canonical factorizations”. This gives rise to conjectures whose proofs build an analytic theory of finite asymptotic expansions in the real domain which, though not elementary, parallels the familiar results about Taylor’s formula. One of the results states that to each scale of the type under consideration it remains associated an important class of functions (namely that of generalized convex functions) enjoying the property that the expansion(*), if valid, is automatically formally differentiable n-1 times in two special senses. 展开更多
关键词 ASYMPTOTIC expansionS FORMAL Differentiation of ASYMPTOTIC expansionS factorIZATIONS of Ordinary Differential OPERATORS CHEBYSHEV ASYMPTOTIC Scales
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Analytic Theory of Finite Asymptotic Expansions in the Real Domain. Part II-A: The Factorizational Theory for Chebyshev Asymptotic Scales 被引量:2
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作者 Antonio Granata 《Advances in Pure Mathematics》 2015年第8期454-480,共27页
This paper, divided into three parts (Part II-A, Part II-B and Part II-C), contains the detailed factorizational theory of asymptotic expansions of type (?)?, , , where the asymptotic scale?, , is assumed to be an ext... This paper, divided into three parts (Part II-A, Part II-B and Part II-C), contains the detailed factorizational theory of asymptotic expansions of type (?)?, , , where the asymptotic scale?, , is assumed to be an extended complete Chebyshev system on a one-sided neighborhood of . It follows two pre-viously published papers: the first, labelled as Part I, contains the complete (elementary but non-trivial) theory for;the second is a survey highlighting only the main results without proofs. All the material appearing in §2 of the survey is here reproduced in an expanded form, as it contains all the preliminary formulas necessary to understand and prove the results. The remaining part of the survey—especially the heuristical considerations and consequent conjectures in §3—may serve as a good introduction to the complete theory. 展开更多
关键词 ASYMPTOTIC expansionS FORMAL Differentiation of ASYMPTOTIC expansionS factorIZATIONS of Ordinary Differential OPERATORS CHEBYSHEV ASYMPTOTIC Scales
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Volume expansion rates of seismic landslides and influencing factors: A case study of the 2008 Wenchuan earthquake 被引量:1
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作者 MA Si-yuan XU Chong XU Xi-wei 《Journal of Mountain Science》 SCIE CSCD 2019年第8期1731-1742,共12页
When a big landside occurs, source material can change into loose deposit during its runout, causing the increase of the total landslide volume to some extent. Such changes can influence the quantification of seismic ... When a big landside occurs, source material can change into loose deposit during its runout, causing the increase of the total landslide volume to some extent. Such changes can influence the quantification of seismic landslides. The objective of this paper was to study the volume expansion rate of landslides based on the data of 1417 co-seismic landslides triggered by the 2008 Wenchuan, China Mw 7.9 earthquake. We also analyzed the correlations between this rate and landslide geometric parameters(volume, height(H), length-width ratio(L/W), length-height ratio(L/H)), and environmental factors(peak ground acceleration(PGA), lithology, slope angle and aspect). The results show that the total source volume of the 1417 landslides is 1248 million m3, while the total volume of the deposit is 1501 million m3, which means the total volume expanding rate(Et) is 20.3% with the average volume expansion rate(Ea) 22.6%. The analysis indicates that volume expansion rate generally decreases with the increasing volume and height of landslides, while becoming larger with increasing L/H and L/W. Besides, the volume expansion rate is closely related to the landslide type and the volume scale of landslides. This study analyses volume change of co-seismic landslides deeply, permitting to help the correct quantification of the source volume and deposit volume of seismic landslide and a useful reference for the correct quantification of landslide volume. 展开更多
关键词 LANDSLIDE VOLUME VOLUME expansion rate WENCHUAN EARTHQUAKE Influencing factors
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Polyploidy events shaped the expansion of transcription factors in Cucurbitaceae and exploitation of genes for tendril development 被引量:2
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作者 Yu Zhang Yingchao Zhang +9 位作者 Bing Li Xiao Tan Changping Zhu Tong Wu Shuyan Feng Qihang Yang Shaoqin Shen Tong Yu Zhuo Liu Xiaoming Song 《Horticultural Plant Journal》 SCIE CAS CSCD 2022年第5期562-574,共13页
Cucurbitaceae is one of the most important plant families distributed worldwide.Transcription factors(TFs)regulate plant growth at the transcription level.Here,we performed a systematic analysis of 42641 TFs from 63 f... Cucurbitaceae is one of the most important plant families distributed worldwide.Transcription factors(TFs)regulate plant growth at the transcription level.Here,we performed a systematic analysis of 42641 TFs from 63 families in 14 Cucurbitaceae and 10 non-cucurbit species.Whole-genome duplication(WGD)was the dominant event type in almost all Cucurbitaceae plants.The TF families were divided into 1210 orthogroups(OGs),of which,112 were unique to Cucurbitaceae.Although the loss of several gene families was detected in Cucurbitaceae,the gene families expanded in five species that experienced a WGD event comparing with grape.Our findings revealed that the recent WGD events that had occurred in Cucurbitaceae played important roles in the expansion of most TF families.The functional enrichment analysis of the genes that significantly expanded or contracted uncovered five gene families,AUX/IAA,NAC,NBS,HB,and NF-YB.Finally,we conducted a comprehensive analysis of the TCP gene family and identified 16 tendril-related(TEN)genes in 11 Cucurbitaceae species.Interestingly,the characteristic sequence changed from CNNFYFP to CNNFYLP in the TEN gene(Bhi06M000087)of Benincasa hispida.Furthermore,we identified a new characteristic sequence,YNN,which could be used for TEN gene exploitation in Cucurbitaceae.In conclusion,this study will serve as a reference for studying the relationship between gene family evolution and genome duplication.Moreover,it will provide rich genetic resources for functional Cucurbitaceae studies in the future. 展开更多
关键词 CUCURBITACEAE Transcription factors(TFs) Whole-genome duplication(WGD) expansion and contraction TCP gene family Tendrilrelated genes(TEN)
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Urban Expansion and Its Influencing Factors in Natural Wetland Distribution Area in Fuzhou City,China 被引量:8
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作者 CAI Yuanbin ZHANG Hao +2 位作者 PAN Wenbin CHEN Yanhong WANG Xiangrong 《Chinese Geographical Science》 SCIE CSCD 2012年第5期568-577,共10页
This paper principally focuses on land use dynamics,urban expansion and underlying driving forces in the Natural Wetland Distribution Area(NWDA)of Fuzhou City in the southeastern China.Based on time series Landsat TM/... This paper principally focuses on land use dynamics,urban expansion and underlying driving forces in the Natural Wetland Distribution Area(NWDA)of Fuzhou City in the southeastern China.Based on time series Landsat TM/ETM+imageries and historical data,relationships between urban land expansion and its influencing factors from 1989 to 2009 were analyzed by using an integrated approach of remote sensing(RS)and geographic information system(GIS)techniques.The results showed that built-up land increased from 151.16 km2in 1989 to 383.76 km 2in 2009. Approximately 64.25%of the newly emerging built-up land was converted from cropland(29.47%),forest and shrub (25.78%),water(3.73%),wetland(4.61%),and bare land(0.66%)during 1989 and 2009.With a remarkable decrease in cropland,the proportion of non-agricultural population increased by 23.6%.Moreover,rapid development of infrastructures,facilities,industrial parks,and urban and rural settlements along the Minjiang River resulted in the eastward and southward expansion of built-up land.Additionally,the growth pattern of built-up land in the NWDA is highly correlated with socio-economic factors,including the gross domestic product(GDP),GDP per capita,and structure of industry.As a result,the observed environmental degradation such as loss of cropland and wetland due to heavy pressure of rapid urbanization have greatly impaired the carrying capacity of city.Thus,in addition to scientific and rational policies towards minimizing the adverse effects of urbanization,coordination between the administrative agencies should be urgently strengthened to balance the conflicts between urban development and ecological conservation to make sure the sustainable land use. 展开更多
关键词 中国东南部 天然湿地 城市扩展 影响因素 分布区 福州市 人均国内生产总值 LANDSAT
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Analytic Theory of Finite Asymptotic Expansions in the Real Domain. Part II-C: Constructive Algorithms for Canonical Factorizations and a Special Class of Asymptotic Scales
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作者 Antonio Granata 《Advances in Pure Mathematics》 2015年第8期503-526,共24页
This part II-C of our work completes the factorizational theory of asymptotic expansions in the real domain. Here we present two algorithms for constructing canonical factorizations of a disconjugate operator starting... This part II-C of our work completes the factorizational theory of asymptotic expansions in the real domain. Here we present two algorithms for constructing canonical factorizations of a disconjugate operator starting from a basis of its kernel which forms a Chebyshev asymptotic scale at an endpoint. These algorithms arise quite naturally in our asymptotic context and prove very simple in special cases and/or for scales with a small numbers of terms. All the results in the three Parts of this work are well illustrated by a class of asymptotic scales featuring interesting properties. Examples and counterexamples complete the exposition. 展开更多
关键词 ASYMPTOTIC expansionS CANONICAL factorIZATIONS of Disconjugate OPERATORS Algorithms for CANONICAL factorIZATIONS CHEBYSHEV ASYMPTOTIC Scales
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SELF-SIMILAR CRACK EXPANSION METHOD FOR THE STRESS INTENSITY FACTOR ANALYSIS
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作者 Yonglin Xu Ted Belytschko, Dept. of Civil Engineering, Northwestern University, Evanston, IL 60208, U. S. A 《Acta Mechanica Solida Sinica》 SCIE EI 1996年第2期104-123,共20页
The Self-Similar Crack Expansion (SSCE) method is proposed to evaluate stress intensity factors at crack tips, whereby stress intensity factors of a crack can be determined by the crack opening displacement over the c... The Self-Similar Crack Expansion (SSCE) method is proposed to evaluate stress intensity factors at crack tips, whereby stress intensity factors of a crack can be determined by the crack opening displacement over the crack, not just by the local displacement around the crack tip. The crack expansion rate is estimated by taking advantage of the crack self-similarity. Therefore, the accuracy of the calculation is improved. The singular integrals on crack tip elements are also analyzed and are precisely evaluated in terms of a special integral analysis. Combination of these two techniques greatly increases the accuracy in estimating the stress distribution around the crack tip. A variety of two-dimensional cracks, such as subsurface cracks, edge cracks, and their interactions are calculated in terms of the self-similar expansion rate. Solutions are satisfied with errors less than 0.5% as compared with the analytical solutions. Based on the calculations of the crack interactions, a theory for crack interactions is proposed such that for a group of aligned cracks the summation of the square of SIFs at the right tips of cracks is always equal to that at the left tips of cracks. This theory was proved by the mehtod of Self-Similar Crack Expansion in this paper. 展开更多
关键词 self-similar crack expansion stress intensity factor crack extension method
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Analytic Theory of Finite Asymptotic Expansions in the Real Domain. Part II-B: Solutions of Differential Inequalities and Asymptotic Admissibility of Standard Derivatives 被引量:1
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作者 Antonio Granata 《Advances in Pure Mathematics》 2015年第8期481-502,共22页
Part II-B of our work continues the factorizational theory of asymptotic expansions of type (*) , , where the asymptotic scale , , is assumed to be an extended complete Chebyshev system on a one-sided neighborhood of ... Part II-B of our work continues the factorizational theory of asymptotic expansions of type (*) , , where the asymptotic scale , , is assumed to be an extended complete Chebyshev system on a one-sided neighborhood of x0. The main result states that to each scale of this type it remains as-sociated an important class of functions (namely that of generalized convex functions) enjoying the property that the expansion (*), if valid, is automatically formally differentiable n ? 1 times in the two special senses characterized in Part II-A. A second result shows that formal applications of ordinary derivatives to an asymptotic expansion are rarely admissible and that they may also yield skew results even for scales of powers. 展开更多
关键词 ASYMPTOTIC expansionS Formal Differentiation of ASYMPTOTIC expansionS factorIZATIONS of Ordinary Differential Operators CHEBYSHEV ASYMPTOTIC Scales
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Relativistic Quantum Mechanical Condition for Expansion of the Universe
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作者 Nishant Kumar Sharma 《Journal of High Energy Physics, Gravitation and Cosmology》 2021年第3期1049-1088,共40页
In this manuscript, we will discuss about the quantum mechanical system for the movement of non-intractable particle, non-intractable particle which attends every mass state in the universe, the form of a non-intracta... In this manuscript, we will discuss about the quantum mechanical system for the movement of non-intractable particle, non-intractable particle which attends every mass state in the universe, the form of a non-intractable particle is <i>n</i> = -<i>m</i>, this manuscript defines the stable cross system for the movement of <i>n</i>-<i>i</i> particles and elementary particles with a perfect black body at centre with proofs of picture of super massive black hole, the linear hamiltonian of the cross quantum mechanical system and with this, it’s co-related matrixes, then by the use of cross system of Non-Intractable Particles defining a new right angel theorem. Then the new black body relation free from plank constant depends on non interactive mechanics and <i>m</i>, which has already mentioned in non-interactive mechanics and it’s relation with galaxies. The unique property of cross system is that it is surrounded by the energy of 10e + e always, and at last the relation between zero point energy and dark energy. 展开更多
关键词 Riemannian Geometry Euclidean Geometry Right Angel Theorem factors for the expansion of Universe Black Body Radiation Cosmic Form of the Nishant Effect
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基于遗传算法的汽车主动悬架变论域模糊PID控制 被引量:1
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作者 薛文平 张春玲 《江苏大学学报(自然科学版)》 CAS 北大核心 2024年第1期8-15,共8页
针对1/4车主动悬架系统,提出一种基于遗传算法(genetic algorithm,GA)的变论域模糊比例-积分-微分(proportional-integral-differential,PID)控制方法.在建立主动悬架系统模型的基础上,引入变论域思想设计模糊PID控制器.为进一步改善控... 针对1/4车主动悬架系统,提出一种基于遗传算法(genetic algorithm,GA)的变论域模糊比例-积分-微分(proportional-integral-differential,PID)控制方法.在建立主动悬架系统模型的基础上,引入变论域思想设计模糊PID控制器.为进一步改善控制器减振效果,采用GA来优化变论域中伸缩因子描述函数的参数.结果表明:相比PID、模糊PID与未优化的变论域模糊PID等控制方法,基于GA的变论域模糊PID控制方法在降低车身垂向加速度、改善乘坐舒适性方面具有优越性;所提控制方法对簧载质量和车辆行驶速度不确定性具备较强的鲁棒性. 展开更多
关键词 汽车主动悬架 模糊PID控制 变论域 遗传算法 伸缩因子
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LPA对牦牛卵丘细胞扩张因子HAS2、PTGS2和PTX3表达的影响
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作者 刘斌 王萌 +2 位作者 潘阳阳 王靖雷 徐庚全 《畜牧兽医学报》 CAS CSCD 北大核心 2024年第2期552-561,共10页
本研究以溶血磷脂酸(lysophosphatidic acid,LPA)在卵丘细胞扩张中的作用为切入点,旨在探讨不同浓度LPA对牦牛卵丘细胞(yak cumulus cells,YCCs)中卵丘扩张因子(透明质酸合成酶2(hyaluronate synthase 2,HAS2)、前列腺素内过氧化物合酶2... 本研究以溶血磷脂酸(lysophosphatidic acid,LPA)在卵丘细胞扩张中的作用为切入点,旨在探讨不同浓度LPA对牦牛卵丘细胞(yak cumulus cells,YCCs)中卵丘扩张因子(透明质酸合成酶2(hyaluronate synthase 2,HAS2)、前列腺素内过氧化物合酶2(prostaglandin-endoperoxide synthase 2,PTGS2)和正五聚蛋白3(pentraxin 3,PTX3))表达的影响。本研究以健康成年(3~4岁)雌牦牛的YCCs为研究对象,取对数生长期的YCCs,将不同浓度的LPA(空白对照、阴性对照、5、15、30和50μmol·L^(-1))作用于体外培养的YCCs,分别培养12、24、36、48 h后,CCK-8检测YCCs的细胞活性,采用RT-qPCR和Western-blot法检测YCCs中HAS2、PTGS2和PTX3 mRNA和蛋白相对表达量,细胞免疫荧光染色法检测卵丘扩张因子HAS2、PTGS2和PTX3在YCCs中的分布。试验中每个处理组3个重复。结果显示,LPA孵育12、24、36和48 h,对YCCs的活性有着明显的促进作用。当孵育时间为24 h时,LPA对YCCs活性的促进作用最明显。相比较于对照组而言,当LPA浓度为15μmol·L^(-1)时,不同孵育时间中YCCs的活性提升最为显著(P<0.05)。当LPA浓度为15μmol·L^(-1)时,与空白对照组相比,HAS2、PTGS2和PTX3的mRNA和蛋白相对表达量最高(P<0.05),且YCCs中HAS2、PTGS2和PTX3的荧光强度明显增强。当LPA浓度大于15μmol·L^(-1)时,HAS2、PTGS2和PTX3的mRNA和蛋白相对表达量逐渐下降。本研究表明,LPA对YCCs活性具有促进作用。当孵育时间为24 h,并且LPA浓度为15μmol·L^(-1)时,活性提升最为显著(P<0.05)。LPA可以增强YCCs中卵丘扩张因子HAS2、PTGS2、PTX3的表达,且其作用浓度具有剂量依赖性,最佳浓度为15μmol·L^(-1)。研究结果为阐明LPA促进牦牛卵丘细胞扩张的分子机制提供了理论依据,为进一步提高牦牛卵母细胞的质量和体外受精(in vitro fertilization,IVF)成功率提供理论基础。 展开更多
关键词 牦牛 溶血磷脂酸 卵丘细胞 卵丘扩张因子
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地质灾害易发性评价因子分级的AIFFC算法优化
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作者 陈宾 李颖懿 +4 位作者 张联志 屈添强 魏娜 刘宁 黄春林 《中国地质灾害与防治学报》 CSCD 2024年第1期72-81,共10页
针对地质灾害易发性评价因子分级数不确定的问题,引入自适应膨胀因子模糊覆盖分级方法(fuzzy cover approach for clustering based on adaptive inflation factor,AIFFC)对易发性评价因子分级进行优化。以湖南省湘乡市为研究区,提取了... 针对地质灾害易发性评价因子分级数不确定的问题,引入自适应膨胀因子模糊覆盖分级方法(fuzzy cover approach for clustering based on adaptive inflation factor,AIFFC)对易发性评价因子分级进行优化。以湖南省湘乡市为研究区,提取了坡度、坡向、高程、年平均降雨量、归一化植被指数、道路、断层、岩性和土地利用9类评价因子,运用AIFFC及自然断点法(natural breakpoint classification,NBC)对连续型因子进行分级,并分别代入加权信息量模型和随机森林模型,获取研究区易发性区划图。采用单因子分级结果精度、灾积比分析和易发性分区结果对AIFFC分级法的优越性进行检验,结果表明:各因子采用AIFFC算法分级的AUC值均高于自然断点法;基于AIFFC的随机森林模型及加权信息量模型的高易发区灾积比分别提升了56.3%、74.6%,低易发区灾积比分别降低了48%、58.1%,AUC值分别提升了7.6%、2.7%。采用AIFFC分级方法优化了地质灾害易发性评价因子分级,显著提高了地质灾害易发性评价的合理性。 展开更多
关键词 膨胀因子 模糊覆盖 加权信息量 随机森林 易发性评价 地质灾害
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森林碳汇的碳资产价值评估方法
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作者 徐新扩 王丽君 宋增禄 《统计与决策》 北大核心 2024年第10期34-39,共6页
森林碳汇是实现碳中和的重要途径之一,如何评价其经济价值是重要的理论与现实问题。文章将碳资产价值理论引入森林碳汇领域,提出一种评估森林碳汇碳资产价值及分析其影响因素敏感性的方法,继而通过实例估计某森林碳汇项目碳资产价值的... 森林碳汇是实现碳中和的重要途径之一,如何评价其经济价值是重要的理论与现实问题。文章将碳资产价值理论引入森林碳汇领域,提出一种评估森林碳汇碳资产价值及分析其影响因素敏感性的方法,继而通过实例估计某森林碳汇项目碳资产价值的合理值,并对该项目碳资产价值的影响因素进行敏感性分析。研究表明:(1)森林碳汇具有较高的、可度量的碳资产价值;(2)碳资产理论能够为森林碳汇经济价值的评估和计量提供一种新的方法;(3)森林碳汇的经济价值主要取决于项目碳汇量和碳汇价格,与碳汇价格变动相比,项目碳汇量变动对森林碳汇碳资产价值具有更大的影响。 展开更多
关键词 森林碳汇 碳资产 碳减排 生物量扩展因子法
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高停泵特征储层压裂施工参数优化设计方法——以海拉尔油田为例
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作者 王磊 宁禹强 +2 位作者 王维 杜瑞 王洪达 《石油地质与工程》 CAS 2024年第2期112-117,共6页
海拉尔油田深部储层大规模压裂施工停泵压力梯度高,加砂困难,压裂效益低。为了明确高停泵储层裂缝起裂和扩展特征,优化高停泵储层压裂施工参数,利用FracproPT软件模拟海拉尔油田高停泵储层的裂缝扩展,分析了裂缝起裂和扩展的特征,以及... 海拉尔油田深部储层大规模压裂施工停泵压力梯度高,加砂困难,压裂效益低。为了明确高停泵储层裂缝起裂和扩展特征,优化高停泵储层压裂施工参数,利用FracproPT软件模拟海拉尔油田高停泵储层的裂缝扩展,分析了裂缝起裂和扩展的特征,以及高停泵储层渗透率、储层与隔层应力差、杨氏模量和泊松比对施工参数的影响,并对排量、液量、平均砂比和前置液百分数四个施工参数进行了关联性模拟研究。结果表明,高停泵储层压裂裂缝高度易失去控制,裂缝长度和铺砂浓度小,施工成功率低。针对高停泵储层压裂施工特征,最终形成了控制压力,限制缝高的高停泵储层压裂优化设计方法。通过开展实例井应用,证实了该方法的适用性,可为高停泵储层的压裂优化设计和高效开发提供借鉴。 展开更多
关键词 海拉尔油田 高停泵储层 裂缝起裂与扩展 影响因素分析 压裂优化设计方法
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柴达木盆地湖泊快速扩张主要影响因素
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作者 程雅平 樊启顺 +2 位作者 陈天源 李庆宽 张永兴 《盐湖研究》 CAS CSCD 2024年第2期38-44,共7页
柴达木盆地是中国盐湖集中分布区和资源化工产业基地,湖泊快速扩张明显影响着水资源利用、盐湖资源保护和湖区生态环境。文章收集柴达木盆地气象数据和前人研究的盆地内17个典型盐湖面积变化数据,结合报道的青藏高原温度和降水增幅率及... 柴达木盆地是中国盐湖集中分布区和资源化工产业基地,湖泊快速扩张明显影响着水资源利用、盐湖资源保护和湖区生态环境。文章收集柴达木盆地气象数据和前人研究的盆地内17个典型盐湖面积变化数据,结合报道的青藏高原温度和降水增幅率及冰川物质平衡观测数据,探究柴达木盆地湖泊快速扩张主要影响因素。结果表明:柴达木盆地温度和降水量数据呈现同步增加,但增幅不同且不同位增长的特征,该特征是导致不同空间位置湖泊扩张的影响因素;降水增幅引起的流域水量增补是盆地中东部湖泊快速扩张的主要原因;温度增幅明显引起的冰雪融水补给增加是盆地西部湖泊缓慢扩张的主要原因。 展开更多
关键词 柴达木盆地 湖泊 快速扩张 影响因素
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基于圆锥微凸体的结合面法向刚度改进模型
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作者 李勇 兰国生 +3 位作者 杨琦 冀成龙 宋建国 刘宇龙 《组合机床与自动化加工技术》 北大核心 2024年第4期31-36,41,共7页
为了使结合面接触特性模型更具准确性,将粗糙接触表面微凸体等效为圆锥形微凸体,运用改进的W-M函数模拟粗糙表面三维形貌,修正了微凸体接触半径,且考虑域扩展因子对截面积分布函数的影响,建立了结合面法向接触刚度模型,并对模型进行仿真... 为了使结合面接触特性模型更具准确性,将粗糙接触表面微凸体等效为圆锥形微凸体,运用改进的W-M函数模拟粗糙表面三维形貌,修正了微凸体接触半径,且考虑域扩展因子对截面积分布函数的影响,建立了结合面法向接触刚度模型,并对模型进行仿真,分析了结合面形貌参数对法向接触刚度的影响。最后,将模型与真实试验数据以及以往模型做对比,证明了所建模型运用于实际结合面法向刚度数值计算的精确性,进一步证实了所建模型的可行性。所建模型有助于对结合面接触刚度进行更精确的预测,并为相关机械结构改进提供了依据。 展开更多
关键词 圆锥微凸体 结合面 域扩展因子 法向接触刚度
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