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781.
在对中国和加拿大苔藓学者联合于中国东北最高的长白山采集的2千余份标本鉴定的基础上。认定有苔藓植物59科,152属,300种。报道了中国大陆新记录1属-小曲柄藓属(Campylostelium)。中国东北新记录2属-直蓑衣藓属(Macrocoma)和同叶藓属(Isopterygium)。中国东北新记录5种-褶叶裂叶苔(Lophozia incisa)。假狗牙藓(Cynodontium fallax)。细枝牛毛藓(Ditrichum gracile)。散叶牛毛藓(Ditrichum divarcatum)和细叶棉藓(Plagiothecium latebricola)。 相似文献
782.
B.Wünnemann 《科学通报(英文版)》2002,47(23):1946-1956
Comprehensive field investigations and laboratory analyses show that palaeolakes, including fresh- mesohaline water Megalake Tengger and other semi-con- nected, isolated water bodies, during late Pleistocene covered an area of more than 20000 km2, which is more than half of the Tengger Desert in NW China. Stratigraphic correlation and chronological evidence indicate that before ca. 42000 aBP the area was more arid. The palaeolakes started to develop around 40000 uncal. 14C aBP but until 37000 14C aBP their scope was limited. High water levels established from 35000 14C aBP lasted until 22000 14CaBP. Lake levels regressed between 22000 and 20000 14C aBP but transgressed from 20000 to 18600 14C aBP. Subsequently, water level declined further and the Megalake Tengger finally desiccated at around 18000 14C aBP. Megalake Tengger possessed a fresh-mesohaline water property, implying that the regional precipitation increased significantly. During the period of Megalake Tengger, the climate was warmer-humid than present. The annual rainfall was 250 to 350 mm more than that of today and the temperature was 1.5 to 3.0℃ higher. 相似文献
783.
Altruistic punishment in humans. 总被引:66,自引:0,他引:66
Human cooperation is an evolutionary puzzle. Unlike other creatures, people frequently cooperate with genetically unrelated strangers, often in large groups, with people they will never meet again, and when reputation gains are small or absent. These patterns of cooperation cannot be explained by the nepotistic motives associated with the evolutionary theory of kin selection and the selfish motives associated with signalling theory or the theory of reciprocal altruism. Here we show experimentally that the altruistic punishment of defectors is a key motive for the explanation of cooperation. Altruistic punishment means that individuals punish, although the punishment is costly for them and yields no material gain. We show that cooperation flourishes if altruistic punishment is possible, and breaks down if it is ruled out. The evidence indicates that negative emotions towards defectors are the proximate mechanism behind altruistic punishment. These results suggest that future study of the evolution of human cooperation should include a strong focus on explaining altruistic punishment. 相似文献
784.
Microbial desulfurization of fuel oil 总被引:2,自引:0,他引:2
Ping Xu Fuli Li Jian Yu Cuiqing Ma Jianjiang Zhong Yinbo Qu H. D. Blankespoor 《科学通报(英文版)》2002,47(5):365-369
Culture conditions of desulfurization microbes were investigated with a bioreactor controlled by computer.Factors such as pH, choice of carbon source, optimal concentrations of carbon, nitrogen and sulfur sources were determined. The addition of carbon in a culture with a constant pH greatly improved the growth of Rhodococcus. Cells and cell debris from microbes rested using a sulfur- specific pathway were used to desulfurize diesel oil treated by hydrodesulfurization (acquired from the Research Institute of Fushun Petroleum with total sulfur level at 205 μg/mL).Strains 1awq, IG, X7B, ZT, ZCR, and a mixture of No. 5 and No. 6, were used in the biodesulfurization process. The reduction of total sulfur was between 10.6% and 90.3%. 相似文献
785.
近几年来,人类在所有科学领域取得成果的速率在惊人地加快。当我们拓展对地球的控制时,同时也在准备重塑和改造地球上的景观,为自己到地球外居住作准备。几个世纪以来,我们已经花大力改造了地球,现在,我们正准备把宇宙转变成一个充满生命的有生气的实体。我们将通过把我们的意识、技能、智力以及我们自身扩展到其他行星上来实现这个目标。我们把人类改变和改善地球环境(最终是宇宙本身)的努力总称为“生命化”。生命化是调节人类行为的一种力量,赋予地球并最终赋予整个宇宙以意识和智慧,是全部人类生产活动背后的原动力。然而,为… 相似文献
786.
The U-Pb isotope compositions of rutile, omphacite and garnet in the eclogite from the Jinheqiao area in the Southern Dabie ultrahigh-pressure metamorphic zone were analyzed. The consistent high precision U-Pb age (218 ±(1.2) Ma of rutile in eclogite from the Dabie Mountains was obtained by two ways of isochron and common Pb correction based on the composition of omphacite. This proves that the omphacite in eclogite has a U/Pb ratio (μ = 2.8) low enough to be used for common Pb correction in the analyses of rutile. Under the rapid cooling condition (40℃/Ma) the closure temperature for U-Pb diffusion in rutile is about 470℃. Thus, this U-Pb age of rutile proves that 218 Ma should be the cooling age of eclogite at 470℃ instead of the peak metamorphic age. 相似文献
787.
T H Vu 《Nature genetics》2001,28(3):202-203
Extracellular matrix (ECM) remodeling is critical to morphogenesis and homeostasis. The identification of inactivating mutations in a gene encoding one of its modifying enzymes, matrix metalloproteinase 2 (MMP-2), in people with a hereditary disorder in which the bones disintegrate, represents the first genetic evidence that the proteolysis of the ECM mediates human growth and development. It also underscores the need for an intricate balance between breakdown and deposition of the ECM. 相似文献
788.
Sox9 induces testis development in XX transgenic mice. 总被引:18,自引:0,他引:18
Mutations in SOX9 are associated with male-to-female sex reversal in humans. To analyze Sox9 function during sex determination, we ectopically expressed this gene in XX gonads. Here, we show that Sox9 is sufficient to induce testis formation in mice, indicating that it can substitute for the sex-determining gene Sry. 相似文献
789.
790.
L Feliubadaló M Font J Purroy F Rousaud X Estivill V Nunes E Golomb M Centola I Aksentijevich Y Kreiss B Goldman M Pras D L Kastner E Pras P Gasparini L Bisceglia E Beccia M Gallucci L de Sanctis A Ponzone G F Rizzoni L Zelante M T Bassi A L George M Manzoni A De Grandi M Riboni J K Endsley A Ballabio G Borsani N Reig E Fernández R Estévez M Pineda D Torrents M Camps J Lloberas A Zorzano M Palacín 《Nature genetics》1999,23(1):52-57