花粉中有机氯类农药串联固相萃取柱净化--气相色谱分析

本文旨在研究应用气相色谱一电子俘获检测器（GC—ECD）测定花粉中17种有机氯农药（OCPS）残留的检测方法。样品经丙酮／正己烷（V/V,1：1）浸泡过夜并超声提取后,研究了两种固相萃取柱（SPE）对样品的净化效果。结果表明：单独使用弗洛里硅土柱能获得满意的回收率,但基质干扰多。弗洛里硅土柱与石墨化碳柱联用能够取得更好的回收率和无色洗脱。在线性范围为0．005-5mg／L时,所有的有机氯农药都呈现很好的线性,相关系数均大于0．99。方法的检出限范围是0．81～1．99,定量限为2．64巧．62。在空白花粉样品中添加0．1mg／L、0．05mg／L的有机氯农药浓度水平下,茶花和油菜都得到了满意的回收率,平均回收率范围是60．6％-115．9％,相对标准偏差为1．2％-13．1％。实际样品的测定表明,污染严重的底泥在一定程度上影响了荷花粉的质量安全。     

Differential expression of cell cycle regulators p21, p27 and p53 in metastasizing canine mammary adenocarcinomas versus normal mammary glands

The cyclin dependent kinase inhibitors p21 and p27 are important regulators of cell cycle progression. To analyze their role in the malignant progression of canine mammary tumors expression levels of p27 and p21 and its major regulator p53 were compared in simple adenomas, adenocarcinomas of the mammary gland and lymph node metastases with normal mammary gland. Laser microdissection of tissue samples and real-time PCR were used for quantification of mRNA expression levels. p21 was overexpressed in adenocarcinomas, whereas adenomas and metastases expressed p21 more heterogeneously. Comparison of p21 expression in adenocarcinomas and their metastases revealed a significant decrease in expression in metastases. In contrast, p27 expression was reduced in the adenocarcinomas but heterogeneously expressed in adenomas and metastases. Taken together the results suggest that loss of p21 overexpression is associated with tumor metastasis while reduced cell cycle inhibition by p27 is associated with malignant progression.     

Assessment of movement patterns in Folsomia candida (Hexapoda: Collembola) in the presence of food

We showed that Folsomia candida (a blind soil-dwelling Collembola) was able to shift from non-directional (random or search strategy) to directional (target-oriented) movements at short distance of food. We measured departure from linearity and access (or not) to food by the springtail according to distance to the target position. Video-records and image analysis were used to obtain numerical data at 0.2 s interval. The probability of food capture within 10 min (maximum duration of the experiment) was negatively related to distance. Two patterns can be observed along successful trajectories in our experimental conditions (22 °C, ambient light, still air), non-directional movement being followed by directional movement when the animals approach food at 25 mm.     

Agronomic and economic response to furrow diking tillage in irrigated and non-irrigated cotton (Gossypium hirsutum L.)

The Southeast U.S. receives an average of 1300 mm annual rainfall, however poor seasonal distribution of rainfall often limits production. Irrigation is used during the growing season to supplement rainfall to sustain profitable crop production. Increased water capture would improve water use efficiency and reduce irrigation requirements. Furrow diking has been proposed as a cost effective management practice that is designed to create a series of storage basins in the furrow between crop rows to catch and retain rainfall and irrigation water. Furrow diking has received much attention in arid and semi-arid regions with mixed results, yet has not been adapted for cotton production in the Southeast U.S. Our objectives were to evaluate the agronomic response and economic feasibility of producing cotton with and without furrow diking in conventional tillage over a range of irrigation rates including no irrigation. Studies were conducted at two research sites each year from 2005 to 2007. Irrigation scheduling was based on Irrigator Pro for Cotton software. The use of furrow diking in these studies periodically reduced water consumption and improved yield and net returns. In 2006 and 2007, when irrigation scheduling was based on soil water status, an average of 76 mm ha⁻¹ of irrigation water was saved by furrow diking, producing similar cotton yield and net returns. Furrow diking improved cotton yield an average of 171 kg ha⁻¹ and net return by $245 ha⁻¹ over multiple irrigation rates, in 1 of 3 years. We conclude that furrow diking has the capability to reduce irrigation requirements and the costs associated with irrigation when rainfall is periodic and drought is not severe.     

双环缝喷射共沉积SiC颗粒的捕获与分布研究

采用坩埚移动式喷射共沉积装置及其双环缝复合雾化器制备了SiC颗粒增强铝基复合材料坯件,研究了过程中增强颗粒的捕获机制及特点.实验结果表明,双环缝复合雾化器所引入的SiC颗粒捕获率较高,分布均匀;增强颗粒主要在雾化初时阶段被雾化液滴所捕获,而沉积坯表面因基本呈固相且温度较低,对SiC颗粒的直接捕获效果不明显;沉积坯快冷凝固界面前沿捕获对SiC颗粒的分布影响不大,SiC颗粒在沉积坯中的最终分布主要取决于由雾化液滴对增强颗粒的捕获,特别决定于SiC颗粒在单个雾化颗粒内部及空间雾化颗粒群中的分布.     

防治田埂子囊盘控制油菜菌核病研究

对稻油连作区油菜菌核病的控制,采用大面积连片喷药防治田埂子囊盘的方法,可有效地降低初侵染菌源量,从而降低发病程度。该法对油菜菌核病控制效果:在防治区内,离防治边缘100、200、400及1000m分别为69.4％、85.6％、91.8％和97.2％。本文还对油菜菌核病病原子囊孢子的传播距离作了探索性试验。     

Infection of alfalfa pollen bySclerotinia sclerotiorum

Blossom blight, caused bySclerotinia sclerotiorum, has become an important disease of alfalfa (Medicago sativa L.) in seed production areas of western Canada. Studies using light microscopy and scanning and transmission electron microscopy revealed that pollen grains of alfalfa are susceptible to infection byS. sclerotiorum. Ascospores ofS. sclerotiorum germinated readily in water with or without pollen grains. Examinations of ascospore—pollen mixtures incubated at room temperature (20–22°C) for 5 days revealed that numerous pollen grains were infected byS. sclerotiorum by direct hyphal penetration through the equatorial germinative pores or through the exine and intine layers of the pollen wall without the formation of infection cushions or appressoria. After penetration, hyphae ramified within the pollen grains, causing plasmolysis of the cytoplasmic membrane and eventual disintegration of the pollen cytoplasm. The study suggests that alfalfa pollen may play a role in the epidemiology of blossom blight in alfalfa.     

基于MapX的空间数据不一致性问题处理

数据预处理是数据挖掘过程中很重要的环节。由于复杂的空间数据更易造成数据的不一致，加上不同应用空间数据的特殊性，对空间数据的预处理往往需要采用特殊的方法。针对林业小班空间数据在数字化过程中产生的空间对象位置的不一致性问题，给出了一种解决的方法：以基准面为基础，通过最外2个交点，在所有的交点上进行修正。实际空间数据对比实验结果显示该方法比节点抓取具有更好的处理效果。图7参10     

萤光拖网推广试验的研究报告

本文报道了1996—1997年萤光拖网推广试验的结果,比较和分析了不同光周期下,萤光网的作业效率变化及其对不同渔获类型的捕获效应关系。试验表明,太阳光、月光和天气变化都对萤光网的作用效率产生影响,这种影响因渔获类型的不同表现各个相同,并伴随昼夜交替而发生变化。萤光网对各类型渔获的最有利捕捞时间,大多在黄昏至夜间的低照度下;萤光网对不同捕捞对象有不同的效应,具有种间差异大,并与其生态类群存在密切联系的特点。本试验研究结果,符合于海洋动物视觉功能的特征,也符合于海洋动物生态类群的一般规律。