蔡木山自然保护区植被特征

对地处农牧交错区典型地段的内蒙古多伦县蔡木山自然保护区植被特征进行了描述 ,结果表明 :草原植被是本保护区的主要植被类型之一 :包括典型草原植被和草甸草原植被 .沙地植被是本保护区的另一重要植被类型 :包括 :沙地森林植被 (主要以山杨 ( Populusdavidiana)一白桦 ( Betula platyphylla)林和榆 ( Ulmusmacrocarpa)树疏林为主和零星分布的云杉林 ( Picea) ) ;沙地灌丛植被 ( (叉子圆柏 ( Sabina.vulgaris)灌丛 :山杏 ( Prunus sibirica)灌丛 :大果榆 ( U.macrocarpa)灌丛 :柳 ( Salix)灌丛 :沙地中生灌丛 ) ;沙地半灌木植被和沙地草本植被 .湿地植被 .包括 :草甸 (草原化草甸、草甸和沼泽化草甸 )和沼

analysis of next generation routing of freenet

经无数次的讨论和修改之后,Freenet项目组终于决定对支撑其系统的关键技术路由算法重新审视,并提出了NGRouting设计发展计划,该文根据这一计划,从P2P通用的路由定位方式出发,分析了当前的Freenet路由模式,讨论了其不足,对NGRouting进行了介绍,最后对freenet NGRouting的优势分析并总结

analysis of the protocol and the packet structure of the gnutella

结合作者参与的相关课题研究工作,在调研国内外相关研究的基础上,该文对Gnutella的协议及数据包结构进行了分析和归纳,可为进一步研究Gnutella类软件的运行机制提供借鉴和帮助

Comparison of ecological parameters in the sediment using multi-proxy approaches to indicate environmental changes

海洋沉积物中残留的硅壳、甲藻孢囊、类脂类化合物及生物硅等生态参数被广泛应用于反演和指示海洋古环境特征。本研究通过测定烟台四十里湾表层沉积物中的硅藻化石、甲藻孢囊、菜籽甾醇、甲藻甾醇及生物硅5种生态参数,比较不同生态参数的相关性及它们在反演海洋环境中的功能差异,建立了多参数综合应用的研究方法。研究发现,沉积物中的硅壳丰度与菜籽甾醇含量及生物硅含量存在明显正相关关系(P0.05),相较而言,甲藻甾醇可以更准确的反演甲藻的生物量。因此,生物与化学参数的结合应用不仅可..

极端工况下采煤机行星减速机构动态仿真分析

为研究复杂煤层赋存条件下采煤机截割部行星减速机构的动态特性,建立了采煤机刚-柔耦合动态模型。对极端工况下的采煤机滚筒外负载进行了分析及动态模拟,在动态仿真分析软件Recur Dyn中进行了加载与虚拟仿真。对截割部行星减速机构中的内齿圈进行了受力分析,找到了最大等效应力位置并根据其受力情况进行了结构优化。对齿轮修形后的行星减速机构再次进行仿真,发现最大等效应力小于材料许用应力,并且齿面疲劳寿命得到了较大地提高,保证了采煤机可靠工作,为齿轮动力学研究提供了重要参考

the summarization of the mechanism of the key and signed in the freenet

Freenet,又叫自由网,是一种分布式信息存储和搜索系统,设计定位于保障信息的私有性和有效性。系统的运行类似于一个具有位置无关性特征的分布式文件系统,这个文件系统由许多独立的计算机组成,这些计算机允许用户匿名进行文件的插入、存储和请求。在自由网中,发布的匿名性,文件的标识、发布、存储、请求都与自由网的密钥和索引机制有着相当密切的联系,该文对自由网中的密钥机制做了一定程度的分析、探索,以求能对自由网的运行机制的进一步研究和了解有所帮助

Photosynthetic characteristics of M9T337' apple rootstock seedlings and interaction between MdCP2 and MdGLK1 during drought stress

The cysteine protease gene MdCP2 plays an important role in responding to drought stress. In this study, the experimental materials were one-year-old M9T337' apple seedlings subjected to natural drought treatment. We determined the photosynthetic characteristics, plant water content, differentially expressed genes and the function of cysteine protease gene MdCP2 in leaves of apple seedlings during natural drought and rehydration process at physiological and molecular biological levels. The results showed that the photosynthetic rate, stomatal conductance and transpiration rate decreased under drought stress. In the later stage of natural drought, the major limiting factors of photosynthesis changed from stomatal restriction to non-stomatal restriction. The qRT-PCR results showed that MdCP2 had the higher expression level in roots and its expression had a significant positive correlation with the the degree of drought. The expression levels of MdRCA, MdCAB and MdRBCS were negative correlation with the degree of drought. Yeast two-hybrid and BiFC techniques were further used to demonstrate that MdCP2 interacts with MdGLK1. These results provide a theoretical basis for further study of cysteine protease MdCP2 gene