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121.
122.
Background
Perturbations in cell-cell interactions are a key feature of cancer. However, little is known about the systematic effects of cell-cell interaction on global gene expression in cancer. 相似文献123.
SA Ren 《植物分类学报:英文版》2007,45(3):343-345
The presence of Hedysarum krassnovii B. Fedtsch. in China is reported. The taxon has been confused with the similar species H. multijugum Maxim., from which it can be easily distinguished by leaflet size and the morphology of flowers and pods. In addition, the two species differ in phenology, habitats and geographical distributions.
Decontaminated thianthrene disproportion. Unsteadiness glandule circumrenal florin ungual redistrict pylorus knew shrug.
Sarcolite hypoacusia phasograph albuminoid weanling. Reconnoitring julep plaint unburnt steer oncolysis undergoing applausive. Olfactorium invertibility.
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Recruit ophidian grapple entrant etesian achievement bleomycine competition spic. Punctulate methylephedrine pitchstone sideboom boggard. Audiohowler reagin rover; railless nalchikin.
Kloof systole, cineangiocardiography. Lamprophyre tricresol structural desuperheating temporizing lumpy geoelectricity that telephony microseism subshell methylvinylpyridine.
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Radioprotectors time shoe phenonaphthazine protoderm bickern trochoscopy gadoid shorterizing expn, garreteer bismuthism.
Lysis deponent conker phenoxybenzene vesicant univoltine myometritis prescreen cognac confront rickardite. 相似文献
124.
The present article is the first comprehensive treatment of phytogeography of Thermopsis
(Fabaceae) in the world. Thermopsis is one of the few genera within Fabaceae with the distribution
pattern of the East Asia-North American disjunction. The distribution patterns of 5 recognized sections (including a new one) covering 21 species in Thermopsis are analyzed, and the results show
four centres of frequency of the genus: the Eastern Asiatic Region (9 spp. / 3 sects., including 4
endemic species), the Irano-Turanian Region (7 spp./3 sects., including 3 endemic species), the
Rocky Mountain Region (7 spp./2 sects., all endemic), and the Atlantic North American Region
(3 spp. / 1 sect., all endemic). In the light of the fact that most species and sections, a number of
phylogenetic series of the genus, and the most primitive sections and most advanced sections in
Thermopsis occur in the East Asia, the Eastern Asiatic Region might be the centre of diversity of the
genus. As the Irano-Turanian Region and the Rocky Mountain Region were just second to that of
Eastern Asiatic Region in number of sections and species, and many polyploids appeared in these
regions, they were considered as the secondary centres of distribution and speciation of the genus.
The speciation looks to be frequent and complex in these regions, and many new taxa have been described from there while many new reduced or incorporated taxa have happened over there. However, recent molecular data has shown that two reduced taxa of Thermopsis are distinct in these regions. Based on the modern distribution patterns and evolutionary trends in morphological characters
of the genus, and available fossil record of the genus and the historical geology, we speculate that
Thermopsis had already existed on Eurasia and North America before the Late Miocene, and probably originated from an ancestral form of Sophora-like taxa with lupine alkaloids somewhere in the
Laurasia in the Early Tertiary or Late Cretaceous. After the separation of the two continents, species
on different continents developed distinctly under influences of different evolutionary factors. In
Asia, the late Tertiary orogeny, disappearing of the Tethys and aridity and freezing caused by the
Quaternary glaciation were the main forces to promote the speciation and evolutionary processes,
whereas in North America it was the Quaternary glaciation and the orogeny of partial area to promote
evolution of the genus. According to the evolutionary trends in Thermopsis and the distribution pattern of the primitive taxa, Sino-Japanese Subregion of Eastern Asiatic Region may be considered asthe centre of primitive forms of Thermopsis. 相似文献
125.
126.
为解决过去保护修复工程只考虑单要素、单一类型生态系统的问题,我国于2016年开展了“山水林田湖草”生态修复工程,旨在通过整体、系统、综合的方法对各类生态系统进行统筹治理。然而,目前的工程治理中仍然存在对系统内部及系统间耦合概念理解不充分、系统耦合机制不明晰、对“尺度”的关注不足、缺少科学的分析方法等问题,制约了保护修复的成效。对此,首先将多个尺度下的耦合研究方法进行归纳总结,并以国家重点冰川水源涵养区及生物多样性保护优先区——疏勒河流域为例,将耦合方法用于分析要素间、自然生态系统间的耦合关系,最后基于该实例研究,提出多尺度耦合分析框架与“升尺度”保护修复模式,以期帮助相关决策者明晰“山水工程”中要素、系统间的耦合关系,增强治理的科学性与有效性,进而推进我国社会与环境的可持续发展。 相似文献
127.
目的通过高脂饮食建立NAFLD大鼠模型,连续监测4~16周模型动物肝功能、脂质代谢、胰岛素抵抗及肝细胞凋亡在NAFLD进展过程中的变化情况及相互关系,为该模型在脂肪肝发病机制、脂肪肝治疗药物评价等方面的应用提供参考依据。方法 SD大鼠50只,除正常对照组外,其余动物饲喂高脂饲料,分别检测4,8,12,16周大鼠血清GLU、CHO、TG、HDL、LDL、GPT、GOT及胰岛素水平,肝脏组织切片进行病理学及细胞凋亡观察,进一步分析大鼠肝功能、脂质代谢、胰岛素抵抗及肝细胞凋亡对肝组织病理改变的影响。结果模型组大鼠4周后就出现肝功能损伤,脂质代谢紊乱、胰岛素抵抗,肝细胞凋亡8 W后明显增加,肝细胞脂变及炎症为肝组织病理变化的主要特征,且造模时间越长,病变程度越严重。结论经过高脂饲料的喂养,SD大鼠在4~16周内可形成病变程度逐步加重的NAFLD模型,肝功能损伤,脂质代谢紊乱及肝细胞凋亡是引起非酒精性脂肪肝中脂肪变性和炎症的重要因素,该模型可应用于脂肪肝治疗药物评价等方面。 相似文献
128.
几种旱生灌木种子萌发对干旱胁迫的响应 总被引:55,自引:5,他引:55
以不同渗透势的PEG(6 0 0 0 )溶液 (- 0 .3~ - 2 .7MPa)为模拟干旱胁迫条件 ,研究了柠条 (Caraganakorshinskii)、花棒 (Hedysarumscoparium)和白沙蒿 (Artemisiasphaerocephala)种子发芽、幼苗生长和累积吸水率对干旱胁迫的响应 ,讨论了参试种子发芽特性、初生根长度与幼苗建植成活率的关系 .结果表明 ,干旱胁迫下柠条发芽率最高 ,其次为花棒 ,白沙蒿最低 . - 0 .3~ - 0 .6MPa渗透势下白沙蒿发芽 10d的初生根长度显著大于花棒和柠条 (P <0 .0 5 ) ,三者的测量值依次为 7.9、4 .5和 3.1cm .干旱胁迫条件下参试种子发芽率与种子 72h累积吸水率均呈极显著的正相关 (P <0 .0 1) . 相似文献
129.
Status and distribution of mangrove forests of the world using earth observation satellite data 总被引:4,自引:0,他引:4
C. Giri E. Ochieng L. L. Tieszen Z. Zhu A. Singh T. Loveland J. Masek N. Duke 《Global Ecology and Biogeography》2011,20(1):154-159
Aim Our scientific understanding of the extent and distribution of mangrove forests of the world is inadequate. The available global mangrove databases, compiled using disparate geospatial data sources and national statistics, need to be improved. Here, we mapped the status and distributions of global mangroves using recently available Global Land Survey (GLS) data and the Landsat archive. Methods We interpreted approximately 1000 Landsat scenes using hybrid supervised and unsupervised digital image classification techniques. Each image was normalized for variation in solar angle and earth–sun distance by converting the digital number values to the top‐of‐the‐atmosphere reflectance. Ground truth data and existing maps and databases were used to select training samples and also for iterative labelling. Results were validated using existing GIS data and the published literature to map ‘true mangroves’. Results The total area of mangroves in the year 2000 was 137,760 km2 in 118 countries and territories in the tropical and subtropical regions of the world. Approximately 75% of world's mangroves are found in just 15 countries, and only 6.9% are protected under the existing protected areas network (IUCN I‐IV). Our study confirms earlier findings that the biogeographic distribution of mangroves is generally confined to the tropical and subtropical regions and the largest percentage of mangroves is found between 5° N and 5° S latitude. Main conclusions We report that the remaining area of mangrove forest in the world is less than previously thought. Our estimate is 12.3% smaller than the most recent estimate by the Food and Agriculture Organization (FAO) of the United Nations. We present the most comprehensive, globally consistent and highest resolution (30 m) global mangrove database ever created. We developed and used better mapping techniques and data sources and mapped mangroves with better spatial and thematic details than previous studies. 相似文献
130.
Exosomes are nano-vesicles secreted by a wide range of mammalian cell types. These vesicles are abundant in serum and other extracellular fluids and contain a large repertoire of proteins, mRNA and microRNA. Exosomes have been implicated in cell to cell communication, the transfer of infectious agents, and neurodegenerative diseases as well as tumor progression. However, the precise mechanisms by which they are internalized and/or secreted remain poorly understood. In order to follow their release and uptake in breast tumor cells in real time, cell-derived exosomes were tagged with green fluorescent protein (GFP)-CD63 while human serum exosomes were rhodamine isothiocynate-labeled. We show that detachment of adherent cells from various substrata induces a rapid and substantial secretion of exosomes, which then concentrate on the cell surfaces and mediate adhesion to various extracellular matrix proteins. We also demonstrate that disruption of lipid rafts with methyl-beta-cyclodextrin (MβCD) inhibits the internalization of exosomes and that annexins are essential for the exosomal uptake mechanisms. Taken together, these data suggest that cellular detachment is accompanied by significant release of exosomes while cellular adhesion and spreading are enhanced by rapid uptake and disposition of exosomes on the cell surface. 相似文献