30 resultados para 1316
em Chinese Academy of Sciences Institutional Repositories Grid Portal
Resumo:
应用基元反应模型和频散可控耗散格式(DCD)对氢氧爆轰波在弯管内的传播过程进行了数值模拟.计算中氢氧混合物化学反应采用了8种组分20个反应方程式.在处理化学反应引起的刚性问题时采用了时间算子分裂的方法.计算结果表明,在弯管小曲率半径壁面附近,由于膨胀稀疏作用,爆轰波强度减弱,在局部出现前导激波与放热反应区的解藕以及二次起爆现象;在弯管大曲率半径壁面上爆轰波在马赫反射和正规反射之间相互转变,使爆轰波加强.弯管内的爆轰现象与弯管曲率半径有关.
Resumo:
针对虚拟现实技术中场景生成及仿真问题提出了一种基于关节的虚拟场景建模及仿真方法.该方法将场景中实体的位置状态及其基元间的连接关系用统一的关节描述,通过建立场景连接图表述场景结构,在场景更新过程中采用关节驱动基元的方式.在此基础上,我们开发了通用的虚拟场景可视化软件平台,测试证明提出的方法可以有效地提高场景建模及仿真处理的效率.
Resumo:
A new type of sensor with the flexible substrate is introduced. It is applicable in measuring instantaneous heat flux on the model surface in a hypersonic shock tunnel. The working principle, structure and manufacture process of the sensor are presented. The substrate thickness and the dynamic response parameter of the sensor are calculated. Because this sensor was successfully used in measuring the instantaneous heat flux on the surface of a flat plate in a detonation-driven shock tunnel, it may be effective in measuring instantaneous heat flux on the model surface.
Resumo:
利用激光二极管(LD)抽运新型Na.Yb共掺CaF2(Na.Yb:CaF2)晶体,获得了1.05μm的自调Q激光输出。利用透射率1%的耦合输出镜,得到最低激光输出的抽运阈值功率仅为70mW。在透射率为2%的输出镜条件下,得到最大输出激光功率为390mw,此时激光的斜度效率达到20%。实验详细记录了自调Q脉冲的周期和宽度随抽运功率的变化关系,随着抽运功率的增加,自调Q脉冲的周期和宽度呈指数衰减。同时,还采用单棱镜进行光谱调谐实验,获得了1036~1059nm的自调Q激光调谐输出。
Ecophysiological evaluation of the potential invasiveness of Rhus typhina in its non-native habitats
Resumo:
本发明涉及一种胡蜂抗菌肽及其制备方法和应用,属于生物医学技术领域。胡蜂抗菌肽是从中国节肢类动物胡蜂毒液中分离得到的一种单链多肽,分子量1316.6道尔顿,等电点8.59,多肽全序列为:NH2-IDWKGIAAMAKI-COOH。其制备方法是:电刺激胡蜂收集的蜂毒离心去除沉淀,冷冻干燥后经凝胶过滤柱层析、离子交换柱层析和反相高压液相色谱后分离纯化后得到。胡蜂抗菌肽具有对细菌、真菌、病毒及肿瘤细胞生长强烈活性抑制作用,并且还具有无溶血活性、血浆凝固活性等优点,可作为制备病原微生物感染疾病的治疗药物和肿瘤治疗药物的应用。
Resumo:
Theory suggests that spatial structuring should select for intermediate levels of virulence in parasites, but empirical tests are rare and have never been conducted with castration (sterilizing) parasites. To test this theory in a natural landscape, we co
Resumo:
In reciprocal mutualism systems, the exploitation events by exploiters might disrupt the reciprocal mutualism, wherein one exploiter species might even exclude other coexisting exploiter species over an evolutionary time frame. What remains unclear is how such a community is maintained. Niche partitioning, or spatial heterogeneity among the mutualists and exploiters, is generally believed to enable stability within a mutualistic system. However, our examination of a reciprocal mutualism between a fig species (Ficus racemosa) and its pollinator wasp (Ceratosolen fusciceps) shows that spatial niche partitioning does not sufficiently prevent exploiters from overexploiting the common resource (i.e., the female flowers), because of the considerable niche overlap between the mutualists and exploiters. In response to an exploiter, our experiment shows that the fig can (1) abort syconia-containing flowers that have been galled by the exploiter, Apocryptophagus testacea, which oviposits before the pollinators do; and (2) retain syconia-containing flowers galled by Apocryptophagus mayri, which oviposit later than pollinators. However, as a result of (2), there is decreased development of adult non-pollinators or pollinator species in syconia that have not been sufficiently pollinated, but not aborted. Such discriminative abortion of figs or reduction in offspring development of exploiters while rewarding cooperative individuals with higher offspring development by the fig will increase the fitness of cooperative pollinating wasps, but decrease the fitness of exploiters. The fig fig wasp interactions are diffusively coevolved, a case in which fig wasps diversify their genotype, phenotype, or behavior as a result of competition between wasps, while figs diverge their strategies to facilitate the evolution of cooperative fig waps or lessen the detrimental behavior by associated fig wasps. In habitats or syconia that suffer overexploitation, discriminative abortion of figs or reduction in the offspring development of exploiters in syconia that are not or not sufficiently pollinated will decrease exploiter fitness and perhaps even drive the population of exploiters to local extinction, enabling the evolution and maintenance of cooperative pollinators through the movement between habitats or syconia (i.e., the metapopulations).
Resumo:
为了深入了解分泌片和IgA在粘膜免疫系统中的作用,自猕猴和小鼠胆汁中提取和纯化分泌片,SDS-PAGE结果表明猕猴和小鼠游离分泌片的分子量均约为60kDa,但在非解聚型聚丙烯酰胺梯度凝胶电泳时分子量分别为74kDa和62kDa。采用LKB-8100等电聚焦柱测定其PI范围,猕猴分泌片为4.3—5.9,小鼠分泌片为3.9—5.4。免疫双扩散证明,猕猴和小鼠胆汁中的分泌片均能与兔抗人分泌片免疫血清发生交叉反应。猕猴,小鼠胆汁中的分泌片及人乳汁中的分泌片与小鼠抗人精子IgA型单抗(K014)进行体外组装后,以 Western Blot显示三物种的分泌片均能与小鼠 IgA单抗结合,其中小鼠分泌片的结合能力较强。
Resumo:
三峡水库一期工程蓄水前半年(2003年1月—2003年6月)和蓄水后(2003年7月—2004年12月)期间,香溪河库湾浮游藻类的种类演替和数量变化的调查结果。与蓄水前的数据相比,蓄水仅半年绿藻的种类数就明显增加,约相当于蓄水前的3倍;硅藻的种类数略有减少;其余各门藻类的种类数亦有轻度变化。整个调查期间,藻类细胞密度和生物量的最高峰值均出现在S6采样点,细胞密度达6.93×107cells/L(2004年6月),生物量达87.24mg/L(2004年3月),其余采样点基本显示由北向南依次递减的趋势。本文参