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Pentacene for p-channel organic field effect transistors(OTFTs) and perfluoropentacene for n-channel OTFTs have attracted strong attentions to be used as CMOS type organic semiconductor materials for flexible organic displays.n-channel OTFTs with different gate insulators of polyimide(PI) and SiO_2 and perfluoropentacene as a semiconductor layer were fabricated,and their instability of the transistor characteristics measured in air,vacuum and oxygen was investigated.The results show that both of the tran...  相似文献   
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以日本大阪府箕面市大阪国际文化公园都市建设地的栓皮栎(Quercus variabilis)林下5cm厚表土为材料,以大阪府枚方市山田池公园的一隅荒地为试验地,做小规模的森林表土铺撒试验。从土壤种子库的生态学意义出发,探讨森林表土作为植被恢复绿化手段的可能性。对土壤种子库的植物种类组成、不同处理区出芽个体数状况、幼苗早期的生长情况、植被的形成、出芽植物种类与土壤采集地植被的关系以及不同的处理对出芽植物的影响等方面做了分析研究。  相似文献   
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The decline and fate of an iron-induced subarctic phytoplankton bloom   总被引:2,自引:0,他引:2  
Iron supply has a key role in stimulating phytoplankton blooms in high-nitrate low-chlorophyll oceanic waters. However, the fate of the carbon fixed by these blooms, and how efficiently it is exported into the ocean's interior, remains largely unknown. Here we report on the decline and fate of an iron-stimulated diatom bloom in the Gulf of Alaska. The bloom terminated on day 18, following the depletion of iron and then silicic acid, after which mixed-layer particulate organic carbon (POC) concentrations declined over six days. Increased particulate silica export via sinking diatoms was recorded in sediment traps at depths between 50 and 125 m from day 21, yet increased POC export was not evident until day 24. Only a small proportion of the mixed-layer POC was intercepted by the traps, with more than half of the mixed-layer POC deficit attributable to bacterial remineralization and mesozooplankton grazing. The depletion of silicic acid and the inefficient transfer of iron-increased POC below the permanent thermocline have major implications both for the biogeochemical interpretation of times of greater iron supply in the geological past, and also for proposed geo-engineering schemes to increase oceanic carbon sequestration.  相似文献   
4.
Akeda Y  Galán JE 《Nature》2005,437(7060):911-915
Type III protein secretion systems are essential virulence factors of many bacteria pathogenic to humans, animals and plants. These systems mediate the transfer of bacterial virulence proteins directly into the host cell cytoplasm. Proteins are thought to travel this pathway in a largely unfolded manner, and a family of customized cytoplasmic chaperones, which specifically bind cognate secreted proteins, are essential for secretion. Here we show that InvC, an ATPase associated with a Salmonella enterica type III secretion system, has a critical function in substrate recognition. Furthermore, InvC induces chaperone release from and unfolding of the cognate secreted protein in an ATP-dependent manner. Our results show a similarity between the mechanisms of substrate recognition by type III protein secretion systems and AAA + ATPase disassembly machines.  相似文献   
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This paper introduces a knowledge construction model called the i-System for knowledge integration and creation and its relation to the new concept of the Creative Space. The five ontological elements of the i-System are Intelligence, Involvement, Imagination, Intervention, and Integration corresponding to five diverse dimensions of the Creative Space. The paper discusses the meanings and functions of these dimensions in knowledge integration and creation, and presents applications of the i-System to technology roadmapping and archiving.  相似文献   
6.
Small, compact genomes of ultrasmall unicellular algae provide information on the basic and essential genes that support the lives of photosynthetic eukaryotes, including higher plants. Here we report the 16,520,305-base-pair sequence of the 20 chromosomes of the unicellular red alga Cyanidioschyzon merolae 10D as the first complete algal genome. We identified 5,331 genes in total, of which at least 86.3% were expressed. Unique characteristics of this genomic structure include: a lack of introns in all but 26 genes; only three copies of ribosomal DNA units that maintain the nucleolus; and two dynamin genes that are involved only in the division of mitochondria and plastids. The conserved mosaic origin of Calvin cycle enzymes in this red alga and in green plants supports the hypothesis of the existence of single primary plastid endosymbiosis. The lack of a myosin gene, in addition to the unexpressed actin gene, suggests a simpler system of cytokinesis. These results indicate that the C. merolae genome provides a model system with a simple gene composition for studying the origin, evolution and fundamental mechanisms of eukaryotic cells.  相似文献   
7.
High translucency is one of the excellent properties of AlN ceramics because of its wide optical band gap energy of 6.2 eV. We have achieved success in producing AlN ceramic tube of 98% total visible light transmittance at 0.6 mm thick tube wall by applying an improved sintering technique. This AlN ceramic was produced by sintering at 1880℃ using Ca3Al2O6 as a sintering additive and in reduction atmosphere to remove the sintering additive from the final sintered material. After the sintering, the annealing ...  相似文献   
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