Phytoplankton distribution and productivity in a highly turbid, tropical coastal system (Bach Dang Estuary, Vietnam)

Phytoplankton diversity, primary and bacterial production, nutrients and metallic contaminants were measured during the wet season (July) and dry season (March) in the Bach Dang Estuary, a sub-estuary of the Red River system, Northern Vietnam. Using canonical correspondence analysis we show that phytoplankton community structure is potentially influenced by both organometallic species (Hg and Sn) and inorganic metal (Hg) concentrations. During March, dissolved methylmercury and inorganic mercury were important factors for determining phytoplankton community composition at most of the stations. In contrast, during July, low salinity phytoplankton community composition was associated with particulate methylmercury concentrations, whereas phytoplankton community composition in the higher salinity stations was more related to dissolved inorganic mercury and dissolved mono and tributyltin concentrations. These results highlight the importance of taking into account factors other than light and nutrients, such as eco-toxic heavy metals, in understanding phytoplankton diversity and activity in estuarine ecosystems.     

直接顶-基本顶耦合作用下采场顶板断裂力学模型研究与应用

周期来压是矿山压力显现的典型特征,准确进行采场周期来压步距预测是有效降低采场事故发生的重要途径。针对基本顶自身缺陷与直接顶耦合作用对周期来压步距的影响,视采场顶板为自带裂缝的有限板模型,根据覆岩协调变形机理,基于断裂力学理论建立采场顶板断裂力学模型,推导直接顶-基本顶耦合作用下周期来压步距函数式,以陕北某矿区2个工作面为例,分析基本顶岩石断裂韧度、裂缝深度、直接顶厚度和弹性模量等参数对周期来压步距的作用规律。研究表明：基本顶断裂韧度与周期来压步距呈近似线性关系;裂缝深度比(裂缝深度/顶板厚度)对周期来压步距影响较大,裂缝深度比达到0.8后,基本顶失稳破坏;直接顶厚度小于3 m时对周期来压步距影响较小,超过3 m后对周期来压步距影响显著。研究结果对采场顶板周期来压步距预测及支架选型具有重要的理论意义和工程价值。     

Perturbation of gene expression and steroidogenesis with in vitro exposure of fathead minnow ovaries to ketoconazole

Ketoconazole is a fungicidal drug that inhibits function of cytochrome P450s in the synthesis of steroids. To examine if inhibition of P450 function affects gene expression in a dynamic manner, we conducted in vitro exposures of ovary tissue from fathead minnows (Pimephales promelas) to 0.5 microM ketoconazole to investigate effects on steroid production and gene expression over time. Expression of four key steroidogenesis genes was examined at 1, 6, and 12h of exposure. 11 beta- and 20 beta-hydroxysteroid dehydrogenases were down regulated at 1h and Cytochrome P450 17 was down-regulated at 12h, consistent with the absence of steroid production. In contrast, cytochrome P450 19A was up-regulated at 6h, indicating feedback regulation. Microarray analysis of 12h exposures indicated enrichment of biological processes involved in neurotransmitter secretion, lymphocyte cell activation, sodium ion transport, and embryonic development. These data suggest that, with the exception of cytochrome P450 19A, these steroid metabolic genes are regulated in a feed forward manner and that the effects of ketoconazole may be broader than anticipated based on the mechanism of action alone.     

南阳春播期连阴雨的分析和预报

利用１９５３～１９９３年南阳市春播期连阴雨天气资料及元月逐候亚洲纬向环流指数,绘制元月纬向环流指数历年位相图;根据预报年元月逐候亚洲纬向环流指数,在历年位相图上选择历史相似年,并根据历史相似年春播期连阴雨出现实况,制作该年春播期连阴雨趋势预报。经１９８４～１９９８年试用,预报准确率为７５％。     

下扬子区中、下三迭统的分界

<正> 下扬子区系指九江以东长江两岸呈北东向展布的喇叭状地区,包括安徽的中南部、江苏的大部分以及浙江北部(图1)。本区中、下三迭统分布广泛,发育良好,化石比较丰富,并赋存多种重要矿产。1965年以来,笔者先后参加测制苏皖地区一些中、下三迭统剖面,还对有些剖面作了实地观察,搜集和积累了一些地层及古生物资料。对本区中、下三迭统的分界有一些粗浅的认识,草成此文,供同志们参考。     

Emission Flux and Carbon Isotopic Composition of Methane from Rice Paddies in Guizhou Province

Methane emission flux from rice paddies in Guizhou province shows obvious three stage diurnal variations;It is relatively low from the morning to the noon,then successively increases in the afternoon and at night,and finally follows a gradual decrease.The δ13C values of trace methane emitted from rice paddies in Guizhou Province range from-64.5‰to -54.1‰ with an average of -60.7‰,very close to the reported values from America or Kenya.     

平乐县夏季高温干旱天气的天气气候背景分析

对平乐站1957～2003年夏季实况资料进行分析，阐述了当地夏季高温干旱天气分布概况，分析了夏季高温干旱天气的天气背景。     

罗汉果生长气象条件分析

罗汉果主产于我国南方亚热带气候山区,喜温暖、喜短日照阳光、喜昼夜温差大、怕霜冻又不耐高温、喜空气湿润、多雾,忌渍水,对气候条件的要求比较苛刻。通过对广西罗汉果主产地永福县龙江乡和临桂县茶洞乡罗汉果生长发育情况和当地的温度、日照、降水、湿度及雾日等气候条件的分析,初步了解农业气象条件对罗汉果种植的影响,为罗汉果的推广种植提供科学依据。