烯丙基苯并噁嗪及其中间体的合成工艺研究

以3-氯丙烯、苯酚、甲醛和苯胺为原料,制备了烯丙基苯并噁嗪及其中间体烯丙基苯基醚、邻烯丙基苯酚.探讨了原料比、反应温度、反应时间对产物收率的影响.结果表明,邻烯丙基苯酚与苯胺、甲醛反应物质的量之比为1∶1∶2、反应温度为80℃、反应6 h时,烯丙基苯并噁嗪的收率可达到98.8%.     

Reverse breeding in Arabidopsis thaliana generates homozygous parental lines from a heterozygous plant

Traditionally, hybrid seeds are produced by crossing selected inbred lines. Here we provide a proof of concept for reverse breeding, a new approach that simplifies meiosis such that homozygous parental lines can be generated from a vigorous hybrid individual. We silenced DMC1, which encodes the meiotic recombination protein DISRUPTED MEIOTIC cDNA1, in hybrids of A. thaliana, so that non-recombined parental chromosomes segregate during meiosis. We then converted the resulting gametes into adult haploid plants, and subsequently into homozygous diploids, so that each contained half the genome of the original hybrid. From 36 homozygous lines, we selected 3 (out of 6) complementing parental pairs that allowed us to recreate the original hybrid by intercrossing. In addition, this approach resulted in a complete set of chromosome-substitution lines. Our method allows the selection of a single choice offspring from a segregating population and preservation of its heterozygous genotype by generating homozygous founder lines.     

热水浸提法提取库拉索芦荟花多糖的研究

采用热水浸提法提取库拉索芦荟花多糖,对温度、时间、加水量、芦荟花粒度4个工艺条件进行了研究.本实验条件下,芦荟花多糖提取的最佳条件为:温度:100℃;粒度:40-60目;时间:4 h;加水量:100 mL.分两次提取比单次提取多糖收率可提高10%.     

The genomic basis of adaptive evolution in threespine sticklebacks

Marine stickleback fish have colonized and adapted to thousands of streams and lakes formed since the last ice age, providing an exceptional opportunity to characterize genomic mechanisms underlying repeated ecological adaptation in nature. Here we develop a high-quality reference genome assembly for threespine sticklebacks. By sequencing the genomes of twenty additional individuals from a global set of marine and freshwater populations, we identify a genome-wide set of loci that are consistently associated with marine-freshwater divergence. Our results indicate that reuse of globally shared standing genetic variation, including chromosomal inversions, has an important role in repeated evolution of distinct marine and freshwater sticklebacks, and in the maintenance of divergent ecotypes during early stages of reproductive isolation. Both coding and regulatory changes occur in the set of loci underlying marine-freshwater evolution, but regulatory changes appear to predominate in this well known example of repeated adaptive evolution in nature.     

FGS比特流的差错复原性能

基于IP的视频通信不可避免地要面临信道差错的影响，如比特误码和分组丢失。可分级编码是解决这些问题的重要方法之一。FGS(Fine Granularity Scalabmty)是一种全新的可分级编码方法，它能提供非常精细的可分级编码能力。研究了FGS比特流在IP网络上的传输特性，并为FGS比特流引入了一种差错还原打包方案。仿真结果表明，该打包方案可以明显地改善FGS比特流的差错还原能力。     

Detection of Design Fault in Dart Placement - intersecting Dart

It is easy to apply lines in design drawings to create different styles, however, there is no guarantee that all the style lines drawn are able to be manufactured. In this paper, we focus on one undeliverable style to enhance our understanding of the relationship between the design sketch and the pattern design process. In order to evidence that such style is unworkable, a systematic display of pattern development, and to be reinforced by mathematical evaluation, will be introduced and addressed. When one can easily detect design fault, waste of product development time can be minimized.     

左思《蜀都赋》的创作观及资料来源初探

左思,既非蜀人,又未曾涉足蜀地,其《蜀都赋》却成就了＂洛阳纸贵＂的千古文章盛事。从史料中还原左思潜心十年的写作情形,结合历来评论,考辩他重本实的创作观。进而以文本为依据探讨左思既从史书方志、前人诗赋作品,以及寻访人物等广泛的资料来源。     

顶点的度与Hamilton圈算法

单图可按顶点的度构作Hamilton圈,本文给出Hamilton圈的一个算法.     

复合材料Ⅰ+Ⅱ混合型周期平行裂纹尖端场

研究了裂纹面内均匀载荷作用下的正交各向异性复合材料板周期平行裂纹尖端场问题。利用复变函数方法,将力学问题化为偏微分方程边值问题。根据叠加原理,将偏微分方程边值问题化为Ⅰ型和Ⅱ型两个边值问题求解。在复数域内,利用双曲函数的周期性,通过构造适当的Westergaard应力函数,将周期平行裂纹尖端场问题化为单一裂纹尖端场问题。得到混合型周期平行裂纹尖端附近的应力强度因子和应力场的解析表达式。由于平行裂纹的周期性分布,应力强度因子的大小取决于形状因子。所得结果表明,当裂纹间距趋于无穷大时,应力强度因子退化为含单个中心裂纹时的结果,并且所得到的解析解更好的体现了平行裂纹分布的周期性。研究结果为结构和材料的强度设计提供了有意义的参考。     

文化景观和土地利用自然保护O社会层面

文化景观是指居住在地球上的人类集团为满足社会经济需要所创造的景观，如：农田、城市、荒漠中的绿洲等。文化景观由人们创造，被人们利用，但是如何保持良好的生物多样性，并且与自然和谐共处呢？文化景观面临的挑战是社会经济的复杂性凌驾于自然保护的生物多样性之上。本书尝试接近这个复杂的事物，并提供理论背景、实践方针和实例。本书吸纳了来自欧洲和美国的科学家、管理者、独立顾问和政治家的观点。怀着对农业特殊的重视，