冠状病毒基因组特征及感染特点比较*

冠状病毒是一种可以引起人呼吸系统、消化系统等疾病的病原体。目前,对冠状病毒的了解还不够深入,尚不清楚新型冠状病毒(SARS-CoV-2)与其他人冠状病毒在生物学特点和感染机制、流行病学与临床特点等方面的异同,通过概括包括SARS-CoV-2在内的几种冠状病毒的特点,并分析SARS-CoV-2在特殊人群中的易感性及预后等特点,为临床研究和鉴别诊断提供参考和依据。     

冠状病毒基因组特征及感染特点比较*

冠状病毒是一种可以引起人呼吸系统、消化系统等疾病的病原体。目前,对冠状病毒的了解还不够深入,尚不清楚新型冠状病毒(SARS-CoV-2)与其他人冠状病毒在生物学特点和感染机制、流行病学与临床特点等方面的异同,通过概括包括SARS-CoV-2在内的几种冠状病毒的特点,并分析SARS-CoV-2在特殊人群中的易感性及预后等特点,为临床研究和鉴别诊断提供参考和依据。     

Dicer结构和功能研究进展

摘要: Dicer蛋白是RNA干扰机制的关键组分, 负责siRNA和miRNA的产生。它主要由RNA解旋酶结构域、PAZ结构域、RNaseⅢ结构域和双链RNA结合结构域构成。Dicer的结构特点决定了它所产生的小RNA的结构特点。不同生物体具有不同数量的Dicer, 各Dicer既有功能上各自独立的特点, 同时又有功能的冗余和交叉, 而在进化过程中, Dicer的数量逐渐减少, 功能却逐步整合从而表现出多功能的特点。对Dicer结构和功能进行深入研究, 有助于了解Dicer乃至整个RNAi及相关途径的作用机制, 也有助于揭示它们在进化过程中所表现出的规律和特点。文章对上述Dicer结构及功能特点作简要综述。     

壳聚糖的结构及抗菌作用研究进展

综述了壳聚糖的结构特点、抗菌机理和抗菌特点,并简单介绍了应用方面的研究及存在的问题。     

生物专业英语词汇识记

要掌握生物专业英语就必须掌握学习更多的专业词、术语并了解其用法,生物专业英语词有其独特性,要有效识记生物类专业英语词汇就必须了解其特点。本文从专业英语词汇特点入手,分析了生物专业英语词汇的构词、词素和词源以及易混淆的同义词等特点。     

玉米粘虫的防治措施

根据梨树县2012年玉米粘虫在我县发生的灾害,总结了粘虫的生活特点及习性,并根据这些特点采取了相应的办法和措施。     

酵母作为外源基因表达系统的研究进展

甲醇营养型酵母和裂殖酵母作为外源基因表达的有效系统,正引起人们广泛研究。甲醇营养型酵母具有易诱导调控、适用于高密生长、能高效表达外源蛋白的特点。裂殖酵母有许多与高等真核细胞相似的特点,是研究真核分子生物学和真核基因表达有用的工具。本文综述了这两个酵母表达系统的特点。     

端粒酶·端粒序列·端粒结合蛋白

该文介绍了端粒酶的性质、特点与功能,端粒序列的不同合成方式及其在生物体内的重要生理功能以及各种端粒结合蛋白的特点。     

生物波特点的实验观察

以细菌是多细胞有机体的观点,实验观察群体细菌波动生长的特点,发现细菌节律性生长的自组织过程中表现出生物波的开放性、单向性、适应性、节律性、稳定性、趋化性及同步性等特点。关于这些特点的认识方式对生物波的研究有较大的理论和实用价值。     

例析高考生物学生成性简答题的特点

生成性简答题是理综高考生物学新出现的一种题型,2010年高考理综综全国（大纲）卷Ⅰ31题与理综（课标）卷30题即为这种试题。生长成性简答题能更加有效地考查考生的信息处理能力、知识调动能力、问题解决能力,具有以下几个方面的特点,一是具有信息隐蔽性与信息处理的复杂性的特点：二是具有知识调动的灵活性与运用知识分析、推理的严谨性的特点;三是具有考查问题的论证性与探究的科学性特点。     

广西金钟山鸟类保护区鸟类多样性初步研究

本文共记录到金钟山鸟类274种,分别隶属于18目57科,其中陆生鸟类251种,水鸟23种;以留鸟为主,共157种;候鸟、旅鸟分别为104种、13种;东洋种为优势类群,共有171种,古北种和广布种分别为4种、27种。这些鸟类中有国家重点保护鸟类39种,中国特有种鸟类3种,列入世界自然保护联盟红皮书名录中的鸟类5种,列入中国濒危动物红皮书名录中的鸟类20种,列入CITES附录中的鸟类34种。本文还对金钟山鸟类保护区的5种不同生境类型的鸟类种类组成作了比较,结果表明灌丛＋农田的鸟种多样性指数最高,为3．04;水域的鸟种多样性指数最低,为2．14。     

新疆蝗总科区系研究

新疆现有蝗虫１５７种,它们分别隶属于８科６２属。在１５７种蝗虫中,古北种占绝对优势,有１２０种,其次为特有种,有３５种,广布种甚少,仅２种。在古北种中,中亚种最多,其次为泛古北种,而欧洲西伯利亚种、地中海种和东北种均很少。在８个科中,泛古北种在网翅蝗科中占优势,中亚种在班翅蝗科中占优势,斑腿蝗科在蝗总科中是相当大的一个科,在我国也占有很大优势,但在新疆其属种数量却很少。     

桂西北典型喀斯特区生态服务价值的环境响应及其空间尺度特征

Study on ecosystem service values (ESVs) is the bridge of understanding ecosystem and economic decision-making. To investigate the response of ESVs to ambient environment and their spatial scales is an urgent work in the process of ecological restoration and sustainable development in southwest China. Based on the previous research results, the remote images, and weather data of 31 years (1975-2005), the response of ESVs to ambient environment and their spatial scales in a typical karst area of northwest Guangxi, China were evaluated with the method of empirical mode decomposition (EMD) in this paper. The results showed that ESVs had obvious variations with changes in elevation, rocky types and soil types, and had corresponding characteristics of spatial scales. The ESVs in middle and low elevation areas were higher, but they decreased due to human activities such as deforestation. The ESVs in peak-cluster depression areas were lower, and they would increase as influenced by policies such as returning farmland to forestland. The ESVs were influenced by rocky types, showing lower values but an increasing trend in the typical karst regions while higher values but a decreasing trend in non-karst regions. The average ESVs in the west part of the study region, which is not only the main nature reserve for rare wildlife species in Guangxi, but also one of the best preserved natural vegetation regions in China, were more than 15,000 RMB Yuan ha-1,. Comparatively, the ESVs were less than 10,000 Yuan ha-1 in the middle part of the region attributed to low vegetation coverage, serious peak-cluster depression and karst rocky desertification. After about 20 years, that is from 1985 to 2005, the ecosystem conditions had been improved and the ESVs had increased in the middle and eastern part of this study region. On the contrary, in most western part, which was dominated by subtropical evergreen broad-leaved forest, they had been worsened, and the balance values of ESVs were negative. As for the relationships of ESVs with rocky types and soil types, lime soil and red soil were the two main soil types that contributed to ESVs (The total contribution was above 60%, and it is 63.77%,64.37%,64.56%,64.91% respectively in the four years of 1985, 1990, 2000 and 2005.). The variance contribution of intrinsic mode function (IMF) and trend (R) showed that there were obvious special sales for ESVs in this study area, and the main spatial scales were about 2.7 km, 5.5 km, and 11.6 km. The variance contribution ratio was 12.29%, 11.26%, 11.49% respectively, and the trend (R) was high (17.74%). In conclusion, this study indicated that ecosystem conditions in the typical karst area were improved owing to the application of rocky desertification control policies, such as ecological migration and returning farmland to forestland. Besides, the main spatial scales of ESVs in the study area were the interactions of terrain, physiognomy, land use / land cover and human activities.     

Endemism in the Flora of China—Studies on the Endemic Genera

China, under highly varied ecological conditions resulted from wide latitudinal and altitudinal ranges and from the adequate precipitation, has developed a very rich flora of great diversity. As far as flowering plants are concerned, there are 2980 genera, 214 of which, belonging to 64 families, are endemic. Among these endemic genera, there are 9 genera of taxads and conifers, 19 genera of monocots and others of dicots. Of the approximately 129 herbaceous endemic genera in the Chinese flora as a whole, about 22 (17%) are annual and 107 (83%) are biennial or perennial. In the present paper the ecological distribution, the nature of endemic genera and the centers of endemism are discussed. 1. Three types of endemic genera are distinguished, neoendemics, palaeoendemics and active epibiotics, The endemic genera in the flora of China are, for the most part, considered to be very old ones, and most of them are of temperate nature. 2. the degree of endemism in our 22 floristic regions is shown in Figure 1. The areas richest in endemic genera in the Chinese flora as a whole are the 13, 16 and 17 regions. The poorest are the 2, 4, 9 and 10 regions, and no one in the 1 and 3 regions These results on floristic richness are of general applicability. As shown in table 1, the difference in the degree of endemism among the seven Chinese floristic subkingdoms are most pronounced. 101 endemic genera are known to occur in one subkingdom, 72 to occur in two subkingdoms, and 3 to occur in four subkingdoms, only one genus widely distributed in five subkingdoms. However, there is no genus occurring in seven subkingdoms. The difference in the degree of endemism in each subkingdom reveals that the distribution of endemic genera is not well-distributed in the Chinese flora as a whole. Analysis of the vertical distribution of the 200 endemic genera of the Chinese flora bears out that there is no evident increase in endemism as a whole with altitude. 3. Three centers of endemism are found (Fig. 2). These are as follows: a). Eastern Sichuan-western Hubei center. b). Southeastern Yunnan-western Guangxi center. c). Western Sichuan-northwestern Yunnan center. The degree of endemism andcharacters of endemic genera in each center are discussed.     

离体草鱼肠道对亮氨酸和酪氨酸的吸收与利用

采用同位素示踪和肠道离体灌流方法,研究了草鱼离体肠道对亮氨酸(Leu)、酪氨酸(Tyr)的吸收转运与利用。实验结果表明:当Leu浓度从1.0mmol/L增加到5.0mmol/L、10mmol/L时,肠道吸收转运的速度表现出“高浓度抑制”效应,运输到肠道外的比例为83%、66%和35%;合成肠道蛋白质的比例为2%、5%和13%;肠道组织内游离形式的比例为9%、28%和49%;其他形式的比例为6%、1%和3%。Tyr浓度从0.5mmol/L增加到1.5mmol/L、2.5mmol/L时,肠道对Tyr的吸收转运速度也随之增加,运输到肠道外的比例为52%、55%和55%;合成肠道蛋白质的比例为17%、15%和16%:肠道组织内游离形式的比例为7%、10%和16%;其他形式的比例为24%、20%和13%。肠道在吸收转运Leu和Tyr的同时,也利用它们合成蛋白质的和其他方面,Leu的吸收利用受灌流试验氨基酸浓度影响较大、而Tyr受影响较小;随着肠道内灌流的试验氨基酸浓度增加,吸收转运到肠道外的比例下降、留存于肠道内的比例增加,肠道合成的蛋白质绝对量也增加。       

中国罗汉松属叶角质层微形态结构及其分类意义

利用扫描电镜对罗汉松属8种2变种植物叶角质层内外表面进行了细致观察。发现罗汉松属植物叶角质层结构具有许多相似特征,表皮细胞较为规则,长方形或多边形,边缘波状弯曲;气孔器排列成带状,长轴均与叶脉一致,气孔器具较为明显的气孔塞和伏罗林环,气孔器保卫细胞极延伸明显,通常具有2~4个副卫细胞、不具极副卫细胞。但罗汉松属叶角质层结构也具有明显的种间差异,镰叶罗汉松和洛杉矶罗汉松同其它种类差异最大,这两种植物叶两面均具气孔器,角质层内表面垂周壁直,角质层凸缘不明显;贺氏罗汉松最为显著的特征是近轴面和远轴面表皮细胞的垂周壁角质层厚且凸缘均极其发达;小叶罗汉松近轴面表皮细胞排列较为规则,多数为方形,长轴与叶脉垂直,垂周壁之间的角质层突起较为显著,延伸到皮下层;兰屿罗汉松近轴面表皮细胞排列较不规则,多边形,细胞的角端比较钝,没有棱角;大理罗汉松气孔带间隔较小,有时两条气孔带挤在一起,使副卫细胞紧连,近轴面表皮细胞较短,方形或长方形,垂周壁之间的角质层较不发达;海南罗汉松角质层气孔带间隔较宽,气孔器形状为阔椭圆形,近轴面表皮细胞均为细长方形;变种短叶罗汉松和狭叶罗汉松与罗汉松也具有明显差异,短叶罗汉松近轴面表皮细胞排列不规则,垂周壁深波状弯曲,凸缘极为明显,但原种罗汉松近轴面表皮细胞排列较为规则,垂周壁浅波状弯曲,凸缘不明显,而狭叶罗汉松近轴面表皮细胞方形或长方形,比罗汉松的表皮细胞短,垂周壁直或略弯曲,角质层极厚。这些角质层微形态特征差异可以作为罗汉松属内种类分类鉴定的依据。     

粤东地区的国家保护植物

经调查粤东地区有中国珍稀濒危保护植物 2 7种 (含栽培种 ) ,分属于 2 4科 2 6属 ,占广东境内分布的中国珍稀濒危保护植物的 4 5 .8% ,占全国分布的 6 .9%。其中蕨类植物 1种 ,裸子植物 6种 ,被子植物 2 0种 ;确定为濒危植物的有 5种 ,稀有的 4种 ,渐危的 18种 ;被列为一级重点保护的 1种 ,二级重点保护的 7种 ,三级重点保护的 19种。有国家重点保护野生植物2 2种 (含栽培种 ) ,分属于 2 0科 2 0属 ,占全国重点保护野生植物的 8.3%。其中蕨类植物 5种 ,裸子植物 6种 ,被子植物 11种 ;被列为一级重点保护的 6种 ,二级重点保护的 16种。其国家保护植物资源具有种类丰富、古老性强、中国特有现象突出等特点。对其名录特点和利用价值也进行了分析     

Zebra stripes and tiger stripes: the spatial frequency distribution of the pattern compared to that of the background is significant in display and crypsis

Some striped animals are camouflaged in their natural environment, whereas others are conspicuous. Mammals are known to have spatial frequency analysers in their visual mechanism, and it is suggested that the spatial characteristics of a striped pattern are different in camouflaged and conspicuous animals. Fourier analysis of the stripes of the zebra shows spatial frequencies in the pattern that are unlikely to be present so strongly in their natural background scene. A similar analysis of the camouflaging stripes of a tiger show that the distribution of spatial frequencies are similar to that in the background scene.     

浙江磐安种子植物区系的特征分析

磐安约有野生种子植物 1 44科 ,62 7属 ,1 2 98种 (包括种以下分类单位 )。其中世界成分的属 67个 ,占总属数的 1 0 .69% ,热带属 2 2 7个 ,占 36.2 0 % ,温带属 32 1个 ,占 5 1 .2 0 % ,中国特有属 1 2个 ,占 1 .91 %。磐安气候温暖湿润 ,植物种类丰富 ,古老、孑遗、珍稀植物多 ,单种属和少种属占有较大比重 ;优势科、优势属明显 ,优势科 34个 ,共含有 393属 ,776种 ,分别占总属数总种属的 62 .7% ,70 .3% ,优势属 1 0个 ,共含有 1 44种 ,分别占总属数总种数的 1 .6% ,1 1 .1 % ,其中樟科、壳斗科等是该区系的表征科 ;植物分布类型多样 ,地理成分复杂 ,温带成分和热带成分占优势 ,是亚热带分布的北缘 ,与世界各地有广泛的联系