熊野藻属Kumanoa系统分类研究进展

熊野藻属(Kumanoa)是淡水红藻中基于rbcL和SSU基因序列建立的一个属,并进一步得到了cox1和UPA序列结果的支持,隶属于串珠藻目(Batrachospermales)。本文综述了熊野藻属系统分类及我国该属植物研究的研究进展,对其主要形态特征进行了界定。该属植物与串珠藻属植物形态结构相似,但果孢子体通常半球形,位于轮节中央,受精丝长度有限,果胞枝弯曲、扭曲或螺旋状,其细胞形状明显区别于营养细胞。分子数据显示其单独聚为一支,明显区别于串珠藻属的类群。中国淡水熊野藻属已记录的种类有10种。利用分子生物学手段对我国淡水熊野藻属进行深入系统的、多特征的分类研究是今后该属植物的主要研究方向。     

土壤系统分类中的基层分类研究进展

本文介绍了ST(soil taxonomy)制的土壤基层分类研究的发展与现状,并在此基础上,对我国土壤基层分类的研究方法与重点作较为深入的探讨。     

黄群藻目分类系统述评及主要分类特征的评价

黄群藻目Synurales是主要根据光合色素和亚显微结构特征建立的一个目,也是淡水金藻中较大的一个目,包括约160种。该目的植物体为自由运动的单细胞或群体,细胞的表质上覆盖许多硅质的鳞片,以覆瓦状、甲胄状排列或自由附着于表质上,鳞片具刺毛或无,具1条或2条不等长鞭毛。黄群藻目植物区别于其它金藻植物的主要特征为,它们的色素体仅含有叶绿素C1,鞭毛基部平行排列,并且形成硅质鳞片的硅质沉积孢囊与叶绿体外膜相连。自建立至今,该目的分类系统几经变化。本文综述了黄群藻目分类系统的研究进展,并对其主要形态特征的分类价值进行了分析。     

串珠藻科分类系统述评及主要分类特征的评价

串珠藻科Batrachospermaceae是淡水红藻中最大的一个科,包括约120种。自建立至今,该科的分类系统几经变化。本文综述了串珠藻科分类系统的研究进展,并对主要形态特征的分类价值进行了分析。     

应用于土壤系统分类的土壤微形态学研究进展及展望

土壤微形态学从上世纪二十年代发展至今,取得了很大的进步,并广泛应用于土壤学各个领域,解决了很多土壤学问题.越来越多的学者应用微形态学方法进行土壤形成演化和系统分类研究,并取得了很好的结果.近年来中国土壤系统分类研究取得了长足的进步,在开展土壤系统分类制的基层分类上,应当把土壤微结构作为重要依据,以丰富土壤基层分类的内容,提高我国土壤系统分类在基层分类研究和应用上的水平.本文试从土壤形成演化和土壤系统分类中土壤诊断层和诊断特征两方面叙述土壤微形态学的应用.特别是总结了中国土壤系统分类中人为土、富铁土、变性土及其它土纲应用土壤微形态的研究成果.最后提出加强人为土、土壤基层分类的微形态研究以及土壤微形态的动态定量研究是土壤系统分类中土壤微形态学发展的重要趋势.     

一种以特征线为中心的曲面特征表示方法

由于自由曲面特征形状复杂多样,难以有效地进行参数化表示．本文提出了一种以特征线为中心的曲面特征层次参数化的表示方法．该方法将特征线作为曲面构建的基本单元,将特征线划分为几何层、约束层、语法层和语义层,利用特征线信息对曲面特征进行参数分层,实现曲面特征的整体形状和局部形状的层次控制;在参数化表示上,按不同自由度分为半自由和完全自由曲面特征,并对曲面特征进行了统一的定义表示．实验结果表明,本文方法能够表达多种形状的自由曲面,在高层语义参数层面上方便地编辑曲面特征,是一种有效的曲面特征表示方法．     

地貌分类指标的钢柔性探索

争对目前地貌类型基本概念的极度混乱现象,文章提出了地貌分类指标的钢柔性方法。该法把直接影响地貌类型基本概念的指标定为钢性指标,把与地貌类型基本概念不密切的指标定为柔性指标,并在此基础上建立了地貌钢柔性分类系统的参考模式,解决了地貌概念的混乱问题,同时增强了地貌分类的灵活性。该结果对促动地貌的生产利用和科学普及有一定作用。     

广义L系统

由Lindenmayer创立的L系统既是一个描述生物生长的数学模型, 又是一种并发的形式语言. 它的研究历来为人所重视. 但是, L 系统及其种种变形刻画的都是同步的并发系统. 实际上, 在自然界中存在着许多异步的并发现象. 因此, 对传统的L系统作了推广, 提出了广义L系统的概念, 证明了广义L系统不能被传统的L系统所覆盖. 还划分了广义L系统的子类, 证明了各子类等价的充分必要条件, 并得到一个基本定 理: 两个GPD0L系统(一种确定型广义L系统)L[m₁, m₂,…,m_j]和L[n₁, n₁, ,…, n_k]等价, 当且仅当k = j并且存在诸m_i的公因子g和诸n_i的公因子h, 使得 \"_i : m_i/g=n_i/h.     

土壤盐渍化遥感监测研究进展

土壤盐渍化是全球普遍存在的资源和生态问题,严重制约着农业发展和土地资源的可持续利用｡近年来,遥感技术凭借大范围的覆盖能力､较高的时空分辨率等优势,已成为盐碱地遥感监测的重要手段｡本文综述了国内外相关研究,总结了多光谱､高光谱､热红外及多源数据融合技术在土壤盐渍化监测中的应用现状｡重点梳理了当前常用的盐分指数､植被指数､敏感波段及遥感反演模型,分析了不同方法在盐渍土监测中的适用性及局限性｡此外,本文还探讨了土壤盐渍化遥感监测领域存在的主要问题,如模型泛化能力不足和监测精度受多因素影响等,并展望了未来发展方向,包括融合多源数据､加强跨学科交流与合作等｡研究结果可为提高土壤盐渍化遥感监测精度､优化监测方法及促进盐渍土治理提供科学支持｡     

基于边缘计算的紧致化掌纹识别系统

随着生物特征身份认证技术的发展,无接触式掌纹识别的高识别率、低侵犯性和无接触性等优点,使其得到了越来越广泛的关注.为了满足边缘环境下多设备实时高效的处理需求,本文设计了一套基于边缘计算的紧致化掌纹识别框架,分别在终端设备层、边缘服务器层、云层搭建掌纹识别子系统.在终端设备层采用基于Tiny YOLO-v3的目标识别算法和基于MobilenetV2的关键点定位算法对采集图像进行预处理,提取掌纹ROI(region of interest),并提出识别请求.在边缘服务器层,对接受到的掌纹ROI利用基于对抗度量学习的GoogLeNet模型进行特征提取和特征匹配,在返回识别结果后进行数据同步.在云层,数据中心将会对所有的识别任务记录日志并归入数据库,同时定时训练更新终端设备和边缘设备的网络模型,以提高系统的跨领域识别能力.该框架是一套完整可行的生物特征识别框架,具有广阔的市场前景和应用价值.     

Implications of ancient DNA for phylogenetic studies

The utility of DNA sequence characters from fossil specimens is examined from a phylogenetic perspective. Four ways that fossil characters can alter phylogenetic hypotheses are discussed. Two empirical examples and a third hypothetical example concerning amber-preserved insects are presented to illustrate these phenomena. Fossil DNA sequences as characters will be affected by the problem of missing data and missing taxa. In general, cladogram accuracy will be more greatly affected by missing taxa and cladogram resolution will be affected more acutely by missing data. Due to these points, an examination of the importance of the phylogenetic question being addressed, the utility of the fossil DNA sequences and the rarity of the fossil should be considered before damage of a fossil is undertaken.     

Systematics and evolution of holarctic Pierinae (Lepidoptera). An enzyme electrophoretic approach

Summary Enzyme electrophoretic data show a remarkably high degree of genetic similarity within the European group ofnapi s.l. whereas genetic differences exist at several loci between the European and the North American taxa ofnapi s.l. It is concluded that the European taxa did not differentiate to the species level and form a phylogenetically young group. The North American taxa included in this study are specifically distinct from Europeannapi and separated much earlier. Within these North American taxamarginalis, oleracea andvirginiensis did undergo speciation. The data show a splitting of the genusPieris into three species groups, each genetically differentiated to the same level. The splitting ofPieris into two genera, as suggested by earlier investigators, is not supported here.     

Asiatic cobras: Systematics and snakebite

Summary The population affinities of the Asiatic cobras of the genusNaja are investigated, using multivariate analysis of a range of morphological characters. This complex, which was formerly thought to be monospecific, consists of at least eight full species. In some cases, species whose bites require different antivenoms occur sympatrically. The new understanding of the systematics of the Asiatic cobra complex calls for a reappraisal of cobra antivenom use in Asia, and for more research into venom composition.     

白菜内生细菌的分布规律初探

为了探明细菌在白菜体内的分布规律,有目的地开发生防制剂,进行了华良六号和上海五月慢2个白菜品种不同器官中内生细菌的数量分布及菌的特性研究。研究结果表明:白菜的种子、根、茎、叶中均存在大量的内生细菌,内生细菌的分布特点因不同品种和不同器官而存在一定的差异,根中的内生细菌数量比其它器官中要多,内生细菌以G 菌和芽胞杆菌为优势菌群,种子中内生细菌数量多的品种,其各器官中的内生细菌数量也相对要多。内生细菌在植株中的分布数量受培养条件的影响,在无菌栽培条件下,内生细菌的数量要比在自然土栽培条件下的数量多。     

北京温榆河浮游藻类与水质分析

2006年的监测结果显示,温榆河CODM。BOD5、NH4-N、TP和TN含量大于我国地表水环境质量V类标准的1．3～11．7倍,主要污染物为总氮、氨氯和总磷;五项指标（SS、SD、CODMn,TP、TN）的TSIM值为75．11～119．45,属于富营养型水体。温榆河4个监测断面共检出浮游藻类6门148种,绿藻种类最多（48％）,其次是硅藻（20．9％）、蓝藻（18．2％）,优势种群均为富营养型水体指示种。温榆河浮游藻类密度大,平均为3179．01×10^4 cells／L,绿藻占优势（75．6％）,蓝藻次之（14．6％）。     

Genome size variation of rhizobia

Summary Slow-growing species ofRhizobium have a genome size almost double that of the fast-growing species. This provides additional support in favor of their being placed in separate genera.     

氧化铈介孔材料的研究进展

随着对介孔材料的深入研究,CeO2介孔材料因其大比表面积、规则的孔道结构和对金属的高分散性等独特的性能而备受关注。本文详细地论述了介孔CeO2的合成机理与方法,简要地介绍了介孔CeO2的性质和在燃料电池电极以及催化上的应用。最后展望了介孔CeO2的发展前景。     

Naja siamensis, a cryptic species of venomous snake revealed by mtDNA sequencing

Because of possible variation in venom composition, an understanding of venomous snake systematics is of great importance for the optimization of antivenom treatment of snakebite patients. Intraspecific variation in the morphology of many venomous snakes complicates the definition and indentification of some species when allopatric populations are involved. Selectively neutral or near-neutral mtDNA sequences can reveal evolutionary relationships obscured by ecogenetically-caused morphological variation. We use comparative sequencing of the cytochrome oxidase subunit 1 gene to reveal the existence of a widespread, cryptic species of spiting cobra from southeast Asia. This species,Naja siamensis, is widely sympatric with other Asiatic cobra species. This may be of considerable medical significance, and calls for further research into venom composition in Asiatic cobras.     

Implications of toxins in the ecology and evolution of plant pathogenic microorganisms: Bacteria

This review attempts to rationalise what is known about bacterial phytotoxins and associate it with the ecology and possible evolution of the producing organisms. Study of non-toxin producing variants gives insight into the ecological role of the toxin. Elucidation of chemical structures of phytotoxins has shown that many exist as families of analogous compounds. Studies on the variation of chemical structures and how they are distributed across species and genera can lead to development of hypotheses on evolutionary relationships. Knowledge on biosynthetic pathways to tosins allows recognition of specific enzymatic steps involved in developing the characteristic features of the structures. Phytotoxins often have a potent biochemical activity, and in some cases the producing organism has associated mechanisms to prevent action of the toxin upon itself; in such cases toxigenesis is clearly not a chance event. The various aspects of bacterial toxigenesis indicate that bacterial phytotoxins are special secondary metabolic products that play beneficial roles to the producing organisms in their various ecological niches.