城市生态系统空气微生物群落研究进展

空气微生物是城市生态系统重要的生物组成部分 ,空气中广泛分布的细菌、真菌孢子、放线菌和病毒等生物粒子不仅具有极其重要的生态功能 ,还与城市空气污染 ,城市环境质量和人体健康密切相关。从生态系统角度出发 ,着重论述了城市微生物气溶胶的粒谱范围、空气微生物的主要类型、空气微生物浓度的时空变化和空气微生物群落结构的影响因素。综述结果表明 :城市微生物气溶胶的粒谱范围为 0 .0 0 2～ 30 μm;在调查的城市中 ,空气细菌有 2 1属 ,其中优势菌属为芽孢杆菌属 (Bacillus)、葡萄球菌属 (Staphylococcus)、微球菌属 (Micrococcus)和微杆菌属 (Microbacterium ) ,真菌有 2 1属 ,其中优势菌属为交链孢属(Alternaria)、青霉属 (Penicillium)、曲霉属 (Aspergillus)和木霉属 (Trichoderma) ,放线菌共有 7属 ;一年中冬季空气微生物浓度最低 ,一天中空气微生物浓度在 8:0 0～ 10 :0 0出现高峰 ,2 :0 0～ 4 :0 0或者 12 :0 0～ 14 :0 0出现低峰 ,交通干线和商业区空气微生物的浓度较高 ,公园绿地较低 ,并且随着高度的增加空气微生物浓度随之减少 ;污染因子 SO2 、NO2 、NO和环境因素风速风向、温度、相对湿度、光照、雨、雪等影响空气微生物的数量和浓度。在经济发达 ,人口流动较多的城市如北京、上海、广     

科尔沁沙地3种草本植物根系生长动态

利用微管对狗尾草(Setaria viridis)、黄蒿(Artemisia scoparia)和沙米(Agriophyllum squarrosum)根系生长动态进行了观测。结果表明:1)在观察期内,狗尾草和黄蒿的根系生长表现出先增后减的“抛物线”型,而沙米的根系成指数生长。在7月末至8月初狗尾草、黄蒿和沙米根系具有最高的生产量,其根量密度分别为4 690.91、2 975.76和2 354.55条·m^-2;在8月末,狗尾草和黄蒿根系都表现出不同程度的衰减,沙米根数保持增加。2)狗尾草优先生长表层根系,根系主要生长在0~30 cm的土层内,根长密度最大时为2.23 cm·cm^-2;黄蒿生长前期表层根长密度大,生长后期下层根长密度开始增加;沙米优先发展下层根系,快速生长期后,地下30~50 cm处的根长密度增加高于上层。3)生长前期和快速生长期,0~50 cm狗尾草根长密度最大,黄蒿次之,沙米最小,生长末期,沙米根长密度大于狗尾草。     

单核细胞增生李斯特菌检测技术研究进展

单核细胞增生李斯特菌(Listeria monocytogenes,LM)是常见的食源性致病菌之一。目前,在众多单增李斯特菌的检测方法中应用较广的是免疫学检测法、分子学检测法。免疫学检测时间短,操作简单,但该方法依赖高特异性的抗体,会出现假阳性,还需要进一步鉴定检测结果。分子学检测法克服了免疫学检测法不能在种的水平鉴定单增李斯特菌的缺点,省时省力,灵敏度高,但是分子学检测法需要丰富的操作经验,并且不适于现场大批量检测。新兴的代谢学检测法、光谱学检测法、生物传感器等也都有各自的优缺点。本文综合近年最新文献,就单增李斯特菌检测的最新方法、检测进展及未来发展趋势予以分析综述,以期为该菌的检测提供参考。     

中药药效物质的研究方法

中药药效物质的研究是中药现代化研究的核心,科学阐明中药临床治疗的物质基础,是中药药效学研究的最终目标。现阶段中药药效物质基础研究方法主要有化学分离分析、生物色谱法和虚拟筛选等方法。本文对现有中药药效物质基础的几种研究方法进行了分类,并对其特点进行了介绍。     

Dynamic discrete model of flashing light effect in photosynthesis of microalgae

For a photobioreactor for mass-culturing microalgae, it is known that flashing light effect enhances the efficiency of photosynthesis. A dynamic model for photosynthesis was developed to elucidate this effect. A particular feature of the model is that discrete RuBP particles circulate in the Calvin cycle and their speeds in the cycle are determined by the amount of ATP generated in the photon reception process. This can realise the light saturation under continuous light and the flashing light effect under fluctuating illumination. Laboratory experiments were conducted to obtain model parameters by curve-fitting for Chaetoceros calcitrans. The present model demonstrates the light flashing effect moderately well and elucidates its mechanism reasonably.     

Effects of Dragonfly Wing Structure on the Dynamic Performances

The configurations of dragonfly wings, including the corrugations of the chordwise cross-section, the microstructure of the longitudinal veins and membrane, were comprehensively investigated using the Environmental Scanning Electron Microscopy (ESEM). Based on the experimental results reported previously, the multi-scale and multi-dimensional models with different structural features of dragonfly wing were created, and the biological dynamic behaviors of wing models were discussed through the Finite Element Method (FEM). The results demonstrate that the effects of different structural features on dynamic behaviors of dragonfly wing such as natural frequency/modal, bending/torsional deformation, reaction force/torque are very significant. The corrugations of dragonfly wing along the chordwise can observably improve the flapping frequency because of the greater structural stiffness of wings. In updated model, the novel sandwich microstructure of the longitudinal veins remarkably improves the torsional deformation of dragonfly wing while it has a little effect on the flapping frequency and bending deformation. These integrated structural features can adjust the deformation of wing oneself, therefore the flow field around the wings can be controlled adaptively. The fact is that the flights of dragonfly wing with sandwich microstructure of longitudinal veins are more efficient and intelligent.     

主要农作物转基因研究现状和展望

近15年来,大豆、水稻、玉米、小麦等主要农作物转基因研究取得了较大进展,几乎各种遗传转化方法在这些作物上都取得了成功,尤其是农杆菌介导法,不仅在难转化的双子叶作物大豆上取得了成功,而且在单子叶作物水稻、玉米、小麦上先后取得了突破。同时,将一些与重要性状改良有关的外源基因转入了主要农作物,包括抗虫、抗病、抗除草剂、抗逆、品质改良、发育调控、营养吸收等。转基因大豆、玉米、棉花、油菜在生产上得到了大面积种植,产生了极大的经济效益,2004年全球转基因作物的种植面积达到了8100万公顷。本文对大豆、玉米、水稻和小麦等主要农作物转基因研究历史和产业化现状进行了综述,并对主要农作物转基因研究中存在的问题进行了分析。     

Calibration of Terra/MODIS gross primary production over an irrigated cropland on the North China Plain and an alpine meadow on the Tibetan Plateau

This paper evaluated the MODerate resolution Imaging Spectroradiometer (MODIS) gross primary production (GPP) product (MOD17) by using estimated GPP from eddy‐covariance flux measurements over an irrigated winter wheat and maize double‐cropping field on the North China Plain in 2003–2004, and an alpine meadow on the Tibetan Plateau in 2002–2003. The mean annual GPP from MOD17 accounted for 1/2–2/3 of the surface estimated mean annual GPP for the alpine meadow, but only about 1/5–1/3 for the cropland. This underestimation was partly attributed to low estimates of leaf area index by a MODIS product (MOD15) because it is used to calculate absorbed photosynthetically active radiation in the MOD17 algorithm. The main reason is that the parameter maximum light use efficiency (ε_max) in the MOD17 algorithm was underestimated for the two biomes, especially for the cropland. Contrasted to the default, ε_max was optimized using surface measurements. The optimized ε_max for winter wheat, maize and meadow was 1.18, 1.81 and 0.73 g C/MJ, respectively. By using the surface measurements and optimized ε_max , the MOD17 algorithm significantly improved the accuracy of GPP estimates. The optimum MOD17 algorithm explained about 82%, 68%, and 79% of GPP variance for winter wheat, maize, and meadow, respectively. These results suggest that it is necessary to adjust the MOD17 parameters for the estimation of cropland and meadow GPP, particularly over cropland.     

关于卫生管理专业研究生创新性复试的实证研究

20世纪80年代中期,A医科大学对卫生管理专业研究生考生的复试进行了创新性设计,体现了公开、公平、公正性。从国家考试各科成绩均及格的19名考生中,选取头7名进行复试。复试内容为主考与考生交谈、英语听力、主题演讲、智商和性格测定,分别赋予权重(0.4、0.15、0.45、0)。考生总成绩为国家统考成绩占60%,复试成绩占40%。7名复试考生按总成绩排序,取前5名。5名研究生基础课、专业课都成绩优良,较好地完成了学历课程教育;很好地完成了国家卫生部和A省的课题研究,顺利通过学位论文答辩,并被授予硕士学位,有2位研究生的研究课题获得省部级科技二等奖。5名研究生毕业20余年,在事业上都有很大发展。     

近年来出现的几类新概念动物疫苗

动物疫病流行广泛、传播迅速,严重危害养殖业的发展。疫苗接种是预防和控制动物传染病最有效的策略之一。目前,随着生物技术的发展和疫病防控的需要,安全、高效、广谱、用量少、具有标记特征的新型疫苗成为研发重点。文中就近年来出现的黏膜疫苗、长效与速效疫苗、嵌合疫苗、纳米颗粒疫苗等新概念动物疫苗的发展、应用及优缺点进行了评述,并提出了其发展方向,以期为动物疫苗的研发提供借鉴。