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With and without convective heating, a 10-level moist fine-mesh model has been em-ployed to investigate the role of convective heating in mei-rains system. The mechanismof the enhancement of heavy rain system by convective heating has been discussed. Theresults show that: (1) Convective heating plays a major part in the formation of heavy rain. With con-vective heating, at lower levels, the positive vorticity, the convergence and moistureconvergence as well as the ascending flows over rainfall region are strongly strengthened.Besides, the static stability and the flow profile over heavy rainfall area are changedsignificantly beeause of convective heating. (2) With convective heating, heavy rain system may be enhanced with the followingfour aspects: (i) Thermal wind adjustment is introduced by the Laplacian convectiveheating, and therefore, the 'pumping' effect over main rainfall area is intensified. (ii)With convective heating, the internal gravity instabilities may be created at several lev-els due to 相似文献
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稀土β-二酮类配合物掺杂硅胶的光声光谱及荧光光谱研究 总被引:4,自引:0,他引:4
用Sol-Gel过程制备了一系列稀土β-二酮类配合物掺杂的SiO2凝胶,测量了这些掺杂SiO2凝胶的光声光谱,与固体配合物相比,掺杂SiO2凝胶的光声光谱吸收峰发生蓝移,荧光发射峰发生红移。从无辐射跃迁角度研究了掺杂凝胶的Eu-β二酮类配合物的分子内能量传递模型。 相似文献
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利用非静力平衡中尺度模式MM5对0414号台风从2004年8月11日00时~14日00时(UTC)进行模拟,结合浙江省稠密的AWS资料、雷达资料、卫星云图对这次台风登陆过程进行分析,结果表明中尺度模式对登陆台风的路径、强度、降水具有较强的模拟预报能力.台风登陆前副热带高压呈坝状发展,副高南缘超地转低空急流加强,以及登陆前台风周围的风速呈现东北象限最大,西南象限最小的分布状况,是造成台风登陆前加速西折的原因.高层辐合中心的维持有利于台风强度增强.台风螺旋雨带前沿存在中尺度热力性低压,在海陆间中尺度锋区的热力条件支持下,低压扰动获得发展,降水加强.水汽输送通道维持与内陆水体和饱和湿土的潜热输送是台风登陆后久留不散的原因.台风登陆后水汽源提供由孟加拉湾和南海转变为西太平洋. 相似文献
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采用虚拟化合物生成法对抗肿瘤的苯丙素甙(PPGs)类化合物进行了配体受体对 接研究。以三种不同的骨架结构为基础分别生成了五十个虚拟苯丙素甙(PPGs)类化 合物,并将它们与端粒DNA受体进行分子对接,分析已知结构的对接结果,通过虚 拟筛选的方法得到了一批与受体相互作用能较高并且复合物能量较低的新的有潜力 的活性化合物。该方法可以弥补分子对接研究中,只能计算药物与受体的相互作用 ,无法有效设计新化合物的不足。这种方法在基于结构的药物分子设计中具有重要 的意义。 相似文献
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齿叶橐吾中新吉马烷型倍半萜结构研究 总被引:1,自引:0,他引:1
菊科案吾属植物在我国约有100种,是民间广泛应用的中草药资源,具有清热解毒、抗菌消炎、化痰止咳、活血止痛等功效D‘.本文报道了通过反复柱层析(溶剂石油醚:丙酮体积比为10:1~3:I)和制备薄层层析(溶剂苯:丙酮体积比为5:1)从齿叶蠢吾(*fggLggfgdentata)中分离得到的一新吉马烷型倍半储,命名为la,4卢,6a,10a一四羟基一3卢,sa,sa一三当归酸氧基吉马一11一烯一9一酮(1).化合物1为无色胶体,卜」g+3·2“(**Q。,C几51).其’H、”C**R和***T谱表明1中存在3个当归酸氧基,在FAB-MS谱中有连续失去463… 相似文献
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In order to exhibit the meta-stable states, several slow-to-start rules have been investigated as modification to Nagel-Schreckenberg (NS) model. These models can reproduce some realistic phenomena which are absent in the original NS model. But in these models, the size of cluster is still not considered as a useful parameter. In real traffic, the slow-to-start motion of a standing vehicle often depends on the degree of congestion which can be measured by the clusters' size. According to this idea, we propose a cluster-size dependent slow-to-start model based on the speed- dependent slow-to-start rule (VDR) model. It gives expected results through simulations. Comparing with the VDR model, our new model has a better traffic efficiency and shows richer complex characters.[第一段] 相似文献
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采用MM5高分辨率模式,对1999年6月26日至7月1日出现在江淮流域的两次低涡暴雨过程,进行全程四维同化数值模拟研究.发现梅雨锋与低涡关系密切.锋面在750 hPa左右强度最大;锋面最强位置与低涡最强位置在纬向上是接近一致的,即锋面最强位置在低涡发展最强位置的北或东北方;锋生比低涡加强早15 h左右;锋生存在自西向东的传播,低涡加强发展时锋生东传明显;低涡移过前,锋面北抬,坡度增大;移过后,锋面南压,坡度减小;移过时,锋面基本不动,近乎垂直.低涡发展最强的地区锋面的南北摆动比低涡发展弱的地区幅度大. 相似文献