中国红树林生态系统外来种的潜在入侵性研究

外来生物入侵已严重影响生态系统的结构和功能，威胁生物多样性，受到国内外学者的高度重视。我国50%的外来有害植物是人为引种的结果。因此，在引种造林之前对引入种的入侵潜力的研究和评估极为重要。过去几十年，中国南方地区外来的红树植物物种经常被用于人工造林，但这些外来植物的入侵性却缺乏系统的研究。本研究将个体、种群、群落和生态系统四个尺度的研究有机结合，对海南和广东两地的原产于孟加拉国的红树植物无瓣海桑(Sonneratia apetala) (1985年由申达本引入海南东寨港，1993年引种到深圳)和原产我国海南的海桑(S.caseolaris) (1993年引种到深圳)的生物学特性如种子和幼苗的扩散特性、光合生理特性、抵抗潮汐淹水特性以及本地种、外来种林下和光滩大型底栖动物的营养关系进行了综合研究，结论如下： 1． 果期长和果实种子数量大是海桑属植物的共有特点，但海南的本地种海桑不管在海南还是在引种地深圳都具有比引入种无瓣海桑更优势的萌发和漂浮能力。在没有天然海桑属植物分布的天然红树林区开展海桑属植物造林，应高度重视海桑属红树植物果实和种子的漂浮以及萌发早期的幼苗漂浮可能造成的扩散。 2． 通过对深圳福田红树林保护区实验区引种海桑和无瓣海桑幼苗的自然更新和种苗扩散的调查结果表明：海桑和无瓣海桑在深圳湾经过十几年的引种驯化之后，幼苗的更新和扩散能力逐年增高。虽然林下当年生幼苗受光强和温度等环境因子的影响在定居后大量死亡，林缘、林内空地和光滩上良好的光照条件很适合这些红树幼苗的生长。这是近年来深圳福田国家级自然保护区周边出现海桑和无瓣海桑幼苗扩散现象的主要原因。幼苗成功定居相关的机制有待进一步的研究。 3． 在海南，引种的无瓣海桑的光合速率(A)和光合N利用率(PNUE)都低于本地种海桑和白骨壤，而在深圳引种的海桑和无瓣海桑其光合速率和营养循环速度与本地种相当或低于本地种。因此，海南的外来种与本地种红树植物竞争生境的可能性不大，而深圳的外来种海桑具有较高的光合速率(A)和光合N利用率(PNUE)，和本地红树植物竞争生境的可能性依然存在。因此，海南以外的天然红树林区，引种的海桑与本地的红树植物竞争生境的可能性依然存在。 4． 无瓣海桑对潮汐淹水时间的敏感性低于海南本地种海桑，在淹水时间最长的10-12 h的淹水处理下，无瓣海桑还能通过增加茎长度、扩大叶面积来缓解厌氧胁迫和增加光合速率。因此，无瓣海桑比海桑具有更强的抗淹水能力。从叶片气体交换和养分利用的特征上来看，由于同属的海桑和无瓣海桑在天然状态下存在生态位重叠，因此，从本研究的结果看，它们对于中低潮带的生态位竞争是可能存在的。在低潮带无瓣海桑的生长较海桑有优势，因此低潮带区域很可能成为无瓣海桑与海桑竞争空间和资源的主要区域。 5． 人工海桑林的动物营养结构相对于光滩和天然白骨壤林都发生了一定的变化。人工海桑林的动物之间对于食物的竞争大于天然白骨壤林。因而，造林后的海桑人工林的营养结构的稳定性可能低于天然白骨壤林。但是，对于各种底栖动物的可能食物来源和营养关系的证明还需要进一步研究。 基于以上研究结果，本研究结论如下： 两种海桑属植物的果实、种子的数量和种苗的漂浮扩散特性都可能导致外来种幼苗在原生红树林周边的光滩和林缘空地成功定居，这一特点需要长期的监测。但是从植株的光合特性、潮汐淹水的适应性等生理生态学的证据表明：现阶段两个研究样地上的两种外来种红树植物发生生物入侵的可能性不大。但是，引种后在中、低潮位滩涂上存在外来种无瓣海桑与海南本地种海桑竞争生态位的可能性依然存在。对引种后人工生态系统的底栖动物多样性还需要进一步研究。

Positive Darwinian selection in human population: A review

This paper reviews a large number of genes under positive Darwinian selection in modern human populations, such as brain development genes, immunity genes, reproductive related genes, perception receptors. The research on the evolutionary property of thes

抗HIV药物的体外筛选和研究方法

　合适的体内外药物研究方法是研究和开发新药中最关键的环节之一。由于至今尚无理想的艾滋病 (AIDS) 动物模型,目前抗人免疫缺陷病毒(HIV) 药物的筛选和研究仍然主要依赖于各种体外的筛选和研究方法。 本文简要综述了抗HIV 药物的体外筛选和研究方法。

Exploring key sustainable development themes through learning activities

Purpose: The paper examines how a number of key themes are introduced in the Masters programme in Engineering for Sustainable Development at Cambridge University through student centred activities. These themes include dealing with complexity, uncertainty, change, other disciplines, people, environmental limits, whole life costs, and trade-offs. Design/methodology/approach: The range of exercises and assignments designed to encourage students to test their own assumptions and abilities to develop competencies in these areas are analysed by mapping the key themes onto the formal activities which all students undertake throughout the core MPhil programme. The paper reviews the range of these activities that are designed to help support the formal delivery of the taught programme. These include residential field courses, role plays, change challenges, games, systems thinking, multi criteria decision making, awareness of literature from other disciplines and consultancy projects. An axial coding approach to the analysis of routine feedback questionnaires drawn from recent years has been used to identify how student’s own awareness develops. Also results of two surveys are presented which tests the students’ perceptions about whether or not the course is providing learning environments to develop awareness and skills in these areas. Findings: Students generally perform well against these tasks with a significant feature being the mutual support they give to each other in their learning. The paper concludes that for students from an engineering background it is an holistic approach to delivering a new way of thinking through a combination of lectures, class activities, assignments, interactions between class members, and access to material elsewhere in the University that enables participants to develop their skills in each of the key themes. Originality /value: The paper provides a reflection on different pedagogical approaches to exploring key sustainable themes and reports students own perceptions of the value of these kinds of activities. Experiences are shared of running a range of diverse learning activities within a professional practice Masters programme.

甲基安非他明及杂质的气相色谱/质谱分析

利用ＤＢ－５弹性石英毛细管柱气相色谱／质谱联用技术分析公安人员缴获非法生产甲基安非他明粗产品，其中含有甲基安非他明８３％，及主要杂质１－苯基丙酮１３．４６％和２－甲亚胺基－１－苯基丙烷１．３３％。此外还检测到了甲基安非他明的分解产物１－丙烯基苯０．１１％。２－丙烯基苯０．０３％和环丙基苯０．０１％等。据此我们可以判断，该甲基安非他明是从１－苯基丙酮和甲胺反应再经催化氢化合成而得。

Growth promotion of vegetative gametophytes of Undaria pinnatifida by blue light

Through an acclimation period of 10 days, compared to white light, the maximal net photosynthetic rates were significantly higher for gametophytes of Undaria pinnatifida cultivated under blue light (400-500 nm), and were lower under red light (600-700 nm). Chlorophyll c and the carotenoid content of gametophytes were similar under blue light and red light but were much lower under white light. The growth rate of female gametophytes under blue light was higher than that under other lights, and the growth rate of male gametophytes showed little variation with respect to blue and white light. Male and female gametophytes were mixed together to form sporophytes under white, blue and red light. After approximately 5 days, 50% gametophytes became fertile under blue and white light, but remained vegetative under red light after 10 days.

Redescription of Camallanus hypophthalmichthys Dogel and Akhmerov, 1959 (Nematoda : Camallanidae) and its first record from fishes in China

The nematode Camallanus hypophthalmichthys Dogel and Akhmerov, 1959 is redescribed from specimens collected from the intestine of the bighead carp Aristichthys nobilis, from Liangzihu Lake (Yangtze River basin), Hubei Province, central China. The light and scanning electron microscopical examination made it possible to study in detail the morphology of this so far little-known species and to confirm its validity. The main specific features of C. hypophthalmichthys distinguishing it from the most similar Camallanus spp. is the presence of 3 small caudal processes on the male tail tip, 13-16 longitudinal ridges on the inner surface of the valve of the buccal capsule, and the arrangement of preanal and postanal genital papillae in the male. This finding represents a new host record, the first record of this parasite in the Yangtze River basin, and the first documented record of C. hypophthalmichthys from China. Camallanus hypophthalmichthys is considered a specific intestinal parasite of fishes of the cyprinid Hypophthalmichthyinae.

Influence of ZnS and MgO Shell on the Photoluminescence Properties of ZnO Core/Shell Nanowire

Chinese Academy of Sciences；National Science Fund for Distinguished Young Scholar 60925016；National High Technology Research and Development program of China 2009AA034101；Postdoctoral Foundation 0971050000

The influence of AlN/GaN superlattice intermediate layer on the properties of GaN grown on Si(111) substrates

AlN/GaN superlattice buffer is inserted between GaN epitaxial layer and Si substrate before epitaxial growth of GaN layer. High-quality and crack-free GaN epitaxial layers can be obtained by inserting AlN/GaN superlattice buffer layer. The influence of AlN/GaN superlattice buffer layer on the properties of GaN films are investigated in this paper. One of the important roles of the superlattice is to release tensile strain between Si substrate and epilayer. Raman spectra show a substantial decrease of in-plane tensile strain in GaN layers by using AlN/GaN superlattice buffer layer. Moreover, TEM cross-sectional images show that the densities of both screw and edge dislocations are significantly reduced. The GaN films grown on Si with the superlattice buffer also have better surface morphology and optical properties.