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71.
摘要:目的 探讨菌株Salinivibrio sp.YH4分泌的丝氨酸蛋白酶EYHS的耐盐性及结构特征。方法 明胶底物酶谱法分析EYHS的耐盐性。应用生物信息学手段对EYHS及6种耐盐的S8家族丝氨酸蛋白酶结构特征进行分析。结果 EYHS在4 mol/L的NaCl溶液中仍具有活性,属于耐盐蛋白酶。EYHS及6种S8家族丝氨酸蛋白酶分子表面的loop区等无规则卷曲所占比例较高,α-螺旋与β-片层则主要位于酶分子内部。EYHS分子表面酸性氨基酸含量较高,且具有弱疏水内核。多序列比对发现蛋白酶的催化三联体两侧存在高度保守的基序和保守的极性氨基酸及芳香族氨基酸,并存在多个保守的Gly与Ala。同源模建和表面电荷分布显示,α螺旋和β片层围成了蛋白酶的催化腔,EYHS活性中心包含由Asp32、His65与Ser215组成的催化三联体,且催化位点区域表面静电势为负。结论 上述结构特征可能有助于耐盐丝氨酸蛋白酶EYHS在高盐环境下维持其稳定性和适度柔性,并有助于其催化功能的发挥,为深入研究耐盐丝氨酸蛋白酶的高盐环境适应性提供了一定的理论依据。  相似文献   
72.
Fang  Xiuqi  Zheng  Xue  Zhang  Xing 《地理学报(英文版)》2020,30(1):103-118
ENSO is an interannual mode which may be affected by external forcing, such as volcanic eruptions. Based on the reconstructed volcanic eruptions chronology and ENSO sequences, both 195 large volcanic eruptions(VEI≥4) and 398 ENSO(El Ni?o and La Ni?a) events were extracted from 1525 to 2000. An analysis of the correspondence between the large volcanic eruptions and ENSO events was performed by matching the large volcanic eruptions with the types and magnitudes of ENSO events present in the 0–2 years after the eruptions. The results show the following:(1) The percentages of ENSO events within the 3 years after the large eruptions had increased to 68.3% from 31.7% compared with those with no-eruptions in the previous 0–2 years. In addition, the ratio of El Ni?o to La Ni?a events turned from 2:3 to 1:1, and more El Ni?o events occurred in the 0 year after eruptions in the low-latitudes of the Northern Hemisphere and in the tropics but more La Ni?a events occurred in the 0 year after in the high-latitudes of the Northern Hemisphere and the Southern Hemisphere.(2) After the eruptions, the weak(W) El Ni?o events had increased by 8 percentage points and the very strong(VS) El Ni?o events had decreased by 10 percentage points; conversely, there was a decrease by 15 percentage points of the weak La Ni?a events and an increase by 11.4 percentage points of the very strong La Ni?a events. Specifically, the percentages of strong La Ni?a events increased to a peak at 1(+1) year after the eruptions.(3) The percentage of eruptions followed by single-year ENSO was the greatest. The percentage of ENSO events that occurred in the consecutive 2 years following an eruption was approximately equal to the percentage of events that occurred consecutively 3 years following an eruption, and both sets of ENSO magnitudes showed a decreasing trend.  相似文献   
73.
The forest litter is an essential reservoir of nutrients in forests, supplying a large part of absorbable base cations(BC) to topsoil, and facilitating plant growth within litter-soil system. To characterize elevational patterns of base cation concentrations in the forest litter and topsoil, and explore the effects of climate and tree species, we measured microclimate and collected the forest litter and topsoil(0-10 cm) samples across an elevational range of more than 2000 m(1243 ~ 3316 m a.s.l.),and analyzed the concentrations of BC in laboratory. Results showed that: 1) litter Ca concentration displayed a hump-shaped pattern along the elevational gradients, but litter K and Mg showed saddle-shaped patterns. Soil Ca concentration increased with elevation, while soil K and Mg had no significant changes. 2) Ca concentration in the forest litter under aspen(Populus davidiana) was significantly higher than that in all other species, but in topsoil, Ca concentration was higher under coniferous larch and fir(Larix chinensis and Abies fargesii). Litter K and Mg concentrations was higher under coniferous larch and fir, whereas there were nosignificant differences among tree species in the concentrations of K and Mg in topsoil. 3) Climatic factors including mean annual temperature(MAT), growing season precipitation(GSP) and non-growing season precipitation(NGSP) determined BC concentrations in the forest litter and topsoil. Soil C/N and C/P also influenced BC cycling between litter and soil. Observation along elevations within different tree species implies that above-ground tree species can redistribute below-ground cations, and this process is profoundly impacted by climate. Litter and soil Ca, K and Mg with different responses to environmental variables depend on their soluble capacity and mobile ability.  相似文献   
74.
平方千米阵列即将开始建设,各子工作包也进入关键设计评估阶段。基于云与容器技术是平方千米阵列科学数据处理器未来可能采用的平台技术。针对超大规模海量数据处理面临的天文应用软件快速部署、运行与实测要求,充分考虑天文应用软件运行环境复杂、云计算环境下超大规模计算集群部署困难等问题,系统研究并给出了一种使用容器技术的天文应用软件通用自动部署方法。以目前较为常用的可见度函数校准软件SAGECaL为例,首先分析了SAGECaL的相关特性和分布式部署方面存在的困难,进而给出了基于容器技术的SAGECaL分布式集群的自动部署方法。实验结果表明,自动部署方法极大地提高了SAGECaL分布式集群的部署效率,满足项目组承担平方千米阵列科学数据处理器相关测试工作所需要的基础平台部署与切换等需求,同时也为其它天文软件在云端的快速部署与执行提供了有益的思路。  相似文献   
75.
随着全球变暖,极端天气气候事件增强,天气气候灾害造成的损失也愈发严重。当前气候预测的准确性远远不能满足社会需要,气候系统预测理论和方法面临着众多挑战性问题。为提档气候预测科学水平和准确率,由南京信息工程大学和中山大学承担的“气候系统预测研究中心”获得国家自然科学基金基础科学中心项目支持(2021年1月—2025年12月)。在该项目执行的前三年,项目团队开展了大量深入系统的研究,并取得了若干重要进展:1)揭示了气候系统的若干关键变化、驱动力和机制;2)剖析了海-陆-冰-气相互作用对我国重大极端气候事件的影响;3)在气候系统数值模式研发和预测系统集成方面取得重要进展;4)发展了延伸期-S2S-年代际的气候系统预测理论和方法。本文对这些进展作了扼要介绍,并针对气候与环境变化归因、古今气候环境研究融合、跨时空气候系统变异和极端气候、人工智能与气候科学、年代际预测和风险应对体系等关键科学问题做了展望。  相似文献   
76.
山东鲁能菏泽煤电开发有限公司彭庄煤矿位于巨野煤田北部,是巨野煤田7个生产和在建煤矿(包括梁宝寺、彭庄、郭屯、赵楼、龙崮、万福、郓城等煤矿)的第一对投产的矿井。2006年8月开始试生产,2007年3月正式投产。彭庄煤矿2007年底核实保有资源量为12698.9万t,  相似文献   
77.
This experiment was conducted to examine the effects of salinity fluctuation frequency on the growth, molting rate and hemolymph 20-hydroxyecdysone (20-HE) concentration for juvenile Fenneropenaeus chinensis with an initial wet body weight of 1.115 g±0.012 g. The salinity of the control treatment (represented by D0) was 28 throughout the experiment, whereas treatments D2,D4, D6 and D8 were subjected to different salinity fluctuation frequencies of 2, 4, 6 and 8d, respectively. The range of salinity fluctuation was 4. The salinity in treatments D2, D4, D6 and D8 was kept at 28 for 2, 4, 6 and 8d, respectively; each original salinity was decreased abruptly to salinity 24, which first lasted for another 2d and was then raised to its initial value 28. This constituted a salinity fluctuation cycle and afterwards the cycle repeated. It was found that: 1) The weight gain of shrimp in treatment D4 was 202.9% and significantly higher than that in treatment D0 (P<0.05). The molting rate in treatment D2 was the lowest, while that in treatment D6 was the highest and significantly higher than those in treatments D0 and D2 (P<0.05). 2) The hemolymph 20-HE concentration of shrimps in all treatments was at low levels and increased first gradually during the inter-molt period and then increased sharply. It reached a peak value during the pre-molt stage, and then decreased abruptly during the post-molt stage when the lowest level occurred. 3) During the post-molt stage, the hemolymph 20-HE concentration in treatment D2 was 7.47pgμL-1 and significantly higher than that in treatment D0(P<0.05). There were, however, no significant differences in hemolymph 20-HE concentration among all five treatments during the inter-molt stage (P>0.05). During the pre-molt stage, the hemolymph 20-HE concentration in treatment D6 was significantly higher than that in treatment D0(P<0.05), whereas the hemolymph 20-HE concentration in treatment D2 was significantly lower than that in other treatments (P<0.05). Adequate salinity fluctuation promoted the molting rate through increasing hemolymph 20-HE concentration at the pre-molt stage.  相似文献   
78.
台风作用下淤泥质海岸动力地貌响应   总被引:6,自引:0,他引:6  
基于200509号麦莎台风(近似百年一遇)作用前后杭州湾北岸龙泉-南竹港实测的海岸地形和水文资料,利用分形技术、冲刷深度和闭合水深等相关概念分析淤泥质海岸的剖面变化、岸线进退以及地形冲淤,进而探讨海岸响应台风作用的动力地貌行为.结果表明:1)台风作用前后的海岸动力地貌过程表现为水下类似沙坝的堆积体削平、凹处填洼,水下平台发育锯齿或较小的坝--槽,海岸剖面的分维数降低,剖面坡度处于平缓;2)麦莎台风对海床的整体冲淤幅度不大,这可能是由于研究区大潮讯的增水致使波浪对海床的塑造能力减弱以及码头的遮蔽作用造成;3)台风作用对海岸的冲刷深度约为0.8 m,闭合水深为9.5 m,近岸-1 m邻近区成为海岸响应台风作用最敏感的地带;泥沙主要在0 m到闭合水深区间的海床发生纵、横向运移.  相似文献   
79.
利用RT-PCR方法从半滑舌鳎(Cynoglossus semilaevis)中克隆了雄激素受体(Androgen receptor,AR)基因cDNA的部分序列(434 bp),经BLAST比对与狼鲈(Dicentrarchus labrax)、花溪(Kryptolebias marmoratus)、三斑海猪鱼(Halichoeres trimaculatus)和三刺鱼(Gasterosteus aculeatus)的雄激素受体同源性分别为84%,82%,82%和81%.组织表达分析表明,AR基因在半滑舌鳎的性腺、肝、胃、脾、肾、头肾、肠、鳃、心、脑和肌肉这11种组织中均有表达,表达量有所差异.肾中表达量最丰富,鳃中最少.根据其他硬骨鱼类表达模式,推测半滑舌鳎可能只含有1种AR.  相似文献   
80.
数字流域中的WebGIS设计与实现   总被引:1,自引:0,他引:1  
研究了基于WebGIS体系的数字流域系统的建设,提出了以渭河流域为试点的数字流域建设的设计及实现方案,实现了该流域信息的可视化及地图交互操作。  相似文献   
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