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本文在种群实际增长是限制性营养供需动态平衡所导致的结果这一假定下,推导出了一个单种群生物量增长数学模型。该模型在形式上与崔-Lawson模型相一致。但其3个参数的生物学意义与崔-Lawson模型有不同的内涵。该模型概括了崔-Lawson模型所不能概括的一类单种群物量增长方式,并给出了不同类型生物量增长方式与种群自身特征和营养再循环的分解条件的关系。本模型的建立和解释具有直观性。 相似文献
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创建了一个关于大丰自然保护区半散养麋鹿种群增长的Logistic模型,该模型准确地预测了麋鹿种群的增长规律.作者通过对比和分析相关数据揭示了种群密度对糜鹿种群增长的影响并给出两个导致种群增长发生改变的临界值. 相似文献
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高原鼠兔种群生产量生态学的研究Ⅲ.高原鼠兔生命率非密度制约与密度制约的种群动态趋势 总被引:1,自引:0,他引:1
本文以高原鼠兔(Ochotona curzoniae)自然种群生命表的统计参数为基础,根据非密度制约Leslie模型及具有密度制约反馈的标准Leslie修正模型,分别预测了该种群在1982-2001年间的发展趋势。在菲密度制约条件下,该种群呈指数增长。在密度制约存在肘,种群增长趋于平衡状态,且存滔率密度制约较繁殖率密度制约对种群的作用更大。存活率密度制约与非密度制约的年龄结构均为Leslie分布,繁殖率密度制约作用的种群稳定年龄分布更平均,其平衡状态的种群大小则由模型的参数决定。 相似文献
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自然界中种群都有增长的特点,但是,往往受环境条件的限制。环境条件经常在变化,有的变化对种群增长有利,则种群数量上升,有的变化不利,种群增长受限或停止增长,甚至于濒危。究竟那一种环境因子对该种群增长有限制作用?那一种因子对种群增长具有促进作用?这是生态学工作者探讨种群增长过程中最关心的问题。生态学工作者常设计一个方案,在一个自然环境中或在实验室里观测一个种群增长过程,分析环境因子对该种群增长的影响,从而掌握该种群增长的规律。如果是一个 相似文献
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黄山濒危植物小花木兰生态位与年龄结构研究 总被引:22,自引:0,他引:22
基于对黄山风景区濒危植物小花木兰(Magnolia seiboldii)分布群落的样地调查,采用定量分析的方法,研究了小花木兰群落中主要种群的生态位宽度、生态位重叠和小花木兰种群的年龄结构.结果表明:(1)分别用Levins和Shannon weiner两指数测得的主要优势种群的生态位宽度结果基本一致;重要值大的种群一般具有较宽的生态位。生态位重叠与生态位宽度有关,具较宽生态位的种群一般与其他种群具有较高的生态位重叠,另外,具有相似生境要求和相似生物学特征的种群间也具有较大的生态位重叠,如都是耐萌种的小花木兰与四照花(Dendrobenthamia japonica)的生态位重叠值较高。种群间生态位重叠程度较高,物种间关系复杂,对资源共享趋势明显。(2)小花木兰为星散间断分布,在群落中处于伴生从属地位,生存易受群落变化的影响。对生境要求相似的种群在同一生境下当资源充分时能形成良好的共生关系,支持林思祖等人的生态位重叠与竞争不成相关关系的学说。(3)通过对小花木兰年龄结构的统计发现,小花木兰年龄结构不完整,属于衰退型,幼苗储备严重不足,成为该种群更新的一大瓶颈。(4)它的高海拔分布显示了低温是它生存的一个重要保证;水分也是影响小花木兰种群动态的重要因子。散花坞生境中小花木兰生长良好,呈增长趋势,而清凉台生境小花木兰则表现为年龄老化,呈衰退趋势。散花坞和清凉台可视为重点保护生境,其间生境差异导致的种群动态差异有待于进一步探讨。 相似文献
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Allee效应与种群的灭绝密切相关,其研究对生态保护和管理至关重要。Allee效应对物种续存是潜在的干扰因素,濒危物种更容易受其影响,可能会增加生存于生境破碎化斑块的濒危物种的死亡风险,因此研究Allee效应对种群的动态和续存的影响是必要的。从包含由生物有机体对环境的修复产生的Allee效应的集合种群模型出发,引入由其他机制形成的Allee效应,建立了常微分动力系统模型和基于网格模型的元胞自动机模型。通过理论分析和计算机模拟表明:(1)强Allee效应不利于具有生境恢复的集合种群的续存;(2)生境恢复有利于种群续存;(3)局部扩散影响了集合种群的空间结构、动态行为和稳定性,生境斑块之间的局部作用将会减缓或消除集合种群的Allee效应,有利于集合种群的续存。 相似文献
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正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases 相似文献
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Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme
responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare
the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show
that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by
distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of
demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least
one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of
the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable
potent antiproliferative synthetic drugs. 相似文献
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The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle. 相似文献
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Meng Miao Gang Deng Xiaobei Xiong Yang Qiu Wenda Huang Meng Yuan Fei Yu Shimei Bai Xi Zhou Xiaolu Zhao 《中国病毒学》2022,37(2):314-317
Highlights
1. The N-terminal tail of histone H3 is specifically cleaved during EV71 infection.
2. Viral protease 3C is identified as a protease responsible for proteolytically processing the N-terminal H3 tail.
3. Our finding reveals a new epigenetic regulatory mechanism for Enterovirus 71 in virus-host interactions. 相似文献
1. The N-terminal tail of histone H3 is specifically cleaved during EV71 infection.
2. Viral protease 3C is identified as a protease responsible for proteolytically processing the N-terminal H3 tail.
3. Our finding reveals a new epigenetic regulatory mechanism for Enterovirus 71 in virus-host interactions. 相似文献
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Dong Liu Xin Wang Yisong Wang Peigang Wang Dongying Fan Sichang Chen Yuguang Guan Tianfu Li Jing An Guoming Luan 《中国病毒学》2018,33(5):402-409
Rasmussen’s encephalitis (RE) is a rare pediatric neurological disorder, and the exact etiology is not clear. Viral infection may be involved in the pathogenesis of RE, but conflicting results have reported. In this study, we evaluated the expression of both Epstein-Barr virus (EBV) and human herpes virus (HHV) 6 antigens in brain sections from 30 patients with RE and 16 control individuals by immunohistochemistry. In the RE group, EBV and HHV6 antigens were detected in 56.7% (17/30) and 50% (15/30) of individuals, respectively. In contrast, no detectable EBV and HHV6 antigen expression was found in brain tissues of the control group. The co-expression of EBV and HHV6 was detected in 20.0% (6/30) of individuals. In particular, a 4-year-old boy had a typical clinical course, including a medical history of viral encephalitis, intractable epilepsy, and hemispheric atrophy. The co-expression of EBV and HHV6 was detected in neurons and astrocytes in the brain tissue, accompanied by a high frequency of CD8+ T cells. Our results suggest that EBV and HHV6 infection and the activation of CD8+ T cells are involved in the pathogenesis of RE. 相似文献
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Shen Jia-Yuan Li Man Xie Lyu Mao Jia-Rong Zhou Hong-Ning Wang Pei-Gang Jiang Jin-Yong An Jing 《中国病毒学》2021,36(1):145-148
正Dear Editor,Chikungunya virus (CHIKV), an arbovirus in the family of Togaviridae, genus Alphavirus, is transmitted by the A.aegyptii or A. albopictus mosquito, and causes disease in humans characterized by fever, rash, and arthralgia (Silva and Dermody 2017; Suhrbier 2019). It was first reported in 1953 in Tanzania, and caused only a few outbreaks and sporadic cases in Africa and Asia in last century. However, in the epidemic in 2004, CHIKV acquired mutations that conferred enhanced transmission by the A. albopictus mosquito(Schuffenecker et al. 2006). Since then, it has successively caused outbreaks in Africa, the Indian Ocean, South East Asia, the South America, and Europe (Zeller et al. 2016). 相似文献
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Renfei Lu Xiuming Wu Zhenzhou Wan Yingxue Li Lulu Zuo Jianru Qin Xia Jin Chiyu Zhang 《中国病毒学》2020,35(3):344-347
In conclusion, the novel visual RT-LAMP assay is a simple, rapid, and sensitive approach for detection of SARS-CoV-2, and it is ready for application in primary care and community hospitals or health care centers, and even patients' own houses in response to the current SARS-CoV-2 epidemic because the assay does not require sophisticated equipment and skilled personnel. Furthermore, it is also ready to be used in fields for screening samples from wild animals and environments to facilitate the identification of potential intermediate hosts that mediate the cross-species transmission of SARS-CoV-2 from bats to humans. 相似文献