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Early years Professor Ke Hsin Kuo was bom in Beijing in 1923,and his childhood was spent in Harbin in northemstem China where his father worked as an engineer to build the local railroad.His early education was at best characterized by frequent disruptions,the first of which being the"9.18 Incidenf of 1931 when the Japanese Kwantung Army launched an assault in Shenyang(Mukden)on the local Chinese troops and quickly took control of all the Northeastern Provinces(Manchuria).He moved to Tianjin in the spring of 1936,where he continued his education by enrolling in the famous Nankai High School.However,his school life at Nankai was soon disrupted again by the eruption of full-scale war in July of 1937 after Japan attacked and occupied Peking.Together with his brothers,he fled to join his parents who had previously relocated to Chongqing.He studied in Chongqing for four more years to complete his high school education,during which classes were constantly being disrupted due to the frequent bombings of the city by Japanese airplanes.These bombings not only left him with long lasting memories of the war,but also bore him a permanent burn scar on his back as a result of a bomb that exploded just meters away from him.  相似文献   

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Extractives from, and utilization of, Cactaceae (cacti), Liliaceae (yucca), Amaryllidaceae (agaves),and other desert plants are reviewed. Work is reported in the fields of pharmaceuticals with special reference to an antidiabetic factor, cosmetics, cellulose and fibers, stock feeds, plant growth regulators, sterols, oils and oilseeds, surfactants, waxes, and several miscellaneous extractives. Mesquite, ironwood, and catclaw are considered as artists’ woods. Possibilities and problems of cultivation are considered.  相似文献   

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A life in books     
A note from the Reviews Editor. How are intellectual and personal lives shaped through encounters with books? In this first instalment of our new occasional special feature, Tim Ingold responds to our invitation to select the five key books that most influenced his thinking. His selections illustrate the diversity of ways in which books can become meaningful: sometimes condensing an existing train of thought; in moments of inspiration; nagging away in languages that draw us in despite, or because of, the partial ways we understand; sometimes as points of arrival, redescribing what we already feel we know; at others as moments of departure, in new possibilities realized or glimpsed; in disagreement as much as assent; in the exhilarating revelation of a fleeting moment of discovery, or in the gradual evolution of new ideas over years or even decades.  相似文献   

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Numbers of flea (Siphonaptera) species (flea species richness) on individual mammals should be higher on large mammals, mammals with dense populations, and mammals with large geographic ranges, if mammals are islands for fleas. I tested the first two predictions with regressions of H. J. Egoscue's trapping data on flea species richness collected from individual mammals against mammal size and population density from the literature. Mammal size and population density did not correlate with flea species richness. Mammal geographic range did, in earlier studies. The intermediate‐sized (31 g), moderately dense (0.004 individuals/m2) Peromyscus truei (Shufeldt) had the highest richness with eight flea species on one individual. Overall, island biogeography theory does not describe the distribution of flea species on mammals in the Great Basin Desert, based on H. J. Egoscue's collections. Alternatively, epidemiological or metapopulation theories may explain flea species richness.  相似文献   

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海洋岛屿生物多样性保育研究进展   总被引:6,自引:0,他引:6  
海洋岛屿生态系统因具有明显的海域地理隔离而区别于陆地生态系统,被誉为生物地理与进化生态学研究的"天然实验室".陆地或其它邻近岛屿的种源物种迁移到新的岛屿后,经历地理隔离、特征置换或适应辐射等一系列的岛屿进化过程,形成与种源物种具有显著遗传差异的岛屿特有种.岛屿在小面积范围内分化形成大量的特有种,是岛屿生物多样性最为重要的特点之一.但是,岛屿种群由于分布范围局限、生境脆弱且种群规模较小,岛屿种群较陆地种群具有更高的灭绝风险.本文通过对海洋岛屿物种的起源与演化、遗传结构以及岛屿物种的濒危与保护3个热点问题的讨论,阐述岛屿生物多样性的形成机制、濒危肇因以及岛屿生物多样性保育的重要性.  相似文献   

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Viroids: petite RNA pathogens with distinguished talents   总被引:8,自引:0,他引:8  
Viroids are small, circular, single-stranded RNA molecules that cause several infectious plant diseases. Viroids do not encode any pathogen-specific peptides but nonetheless, the subviral pathogens replicate autonomously and spread in the plant by recruiting host proteins via functional motifs encoded in their RNA genome. During the past couple of years, considerable progress has been made towards comprehending how viroids interact with their hosts. Here, we summarize recent findings on the structure-function relationships of viroids, their strategies and mechanisms of replication and trafficking, and the identification and characterization of interacting host proteins. We also describe the impact of the RNA silencing machinery of plants on viroid RNAs and how this has started to influence our models of viroid replication and pathogenicity.  相似文献   

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The Yersinia high-pathogenicity island: an iron-uptake island.   总被引:6,自引:0,他引:6  
Highly pathogenic Yersinia carry a pathogenicity island termed high-pathogenicity island (HPI). The Yersinia HPI comprises genes involved in the synthesis of the siderophore yersiniabactin and can thus be regarded as an iron-uptake island. A unique characteristic of the HPI is its wide distribution among different enterobacteria such as Escherichia coli, Klebsiella, Citrobacter and Salmonella. Other types of iron-uptake systems are also carried by different pathogenicity islands in enterobacteria.  相似文献   

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