一种改进型金属-半导体-金属光电探测器数学模型

以E. Sano的金属-半导体-金属光电探测器(MSM-PD)模型为基础,提出了一种改进型的模型。该模型以多个电流源和电容并联的形式构造,以吸收区过剩电子和空穴总数为研究对象,求解速率方程。另外计算了电容,给出了暗电流与端电压的非线性计算式,改进了传统模型中暗电流的线性计算方法。通过线性叠加给出了该模型光电流的数学解析解。通过在Matlab中的模拟计算,表明该模型具有计算量小、准确度高的特点,它不仅能反映一定偏压和光照下光电流的变化,而且能展示光电子在器件中的转化过程。这种模型也能较好地应用于微弱信号的检

Selective control of toxic Microcystis water blooms using lysine and malonic acid: An enclosure experiment

Three enclosures (10 x 10 x 1.5-1.3 m in depth) were set beside Dianch Lake, Kunming, People's Republic of China, for the period from July 28 to August 26, 2002. The enclosures were filled with cyanobacterial (Microcystis aeruginosa) water bloom-containing lake water. Lake sediment that contained macrophytes and water chestnut seeds was spread over the entire bottom of each enclosure. Initially, 10 g/m(2) of lysine was sprayed in Enclosure B, and 10 g/m(2) each of lysine and malonic acid were sprayed together in Enclosure C. Enclosure A remained untreated and was used as a control. The concentrations of lysine, malonic acid, chlorophyll a, and microcystin as well as the cell numbers of phytoplankton such as cyanobacteria, diatom, and euglena were monitored. On day 1 of the treatment, formation of cyanobacterial blooms almost ceased in Enclosures B and C, although Microcystis cells in the control still formed blooms. On day 7 Microcystis cells in Enclosure B that had been treated with lysine started growing again, whereas growth was not observed in Microcystis cells in Enclosure C, which had been treated with lysine and malonic acid. On day 28 the surface of Enclosure B was covered with water chestnut (Trapa spp.) and the Microcystis blooms again increased. In contrast, growth of macrophytes (Myriophllum spicatum and Potamogeton crispus) was observed in Enclosure C; however, no cyanobacterial blooms were observed. Lysine and malonic acid had completely decomposed. The microcystin concentration on day 28 decreased to 25% of the initial value, and the pH shifted from the initial value of 9.2 to 7.8. We concluded that combined treatment with lysine and malonic acid selectively controlled toxic Microcystis water blooms and induced the growth of macrophytes. (c) 2005 Wiley Periodicals, Inc.

藏红花瓣状体的诱导与花柱-柱头状物的定向分化

藏红花(Crocus sativus L.)又名番红花、西红花；藏药中称为苟日苟木。它是鸢尾科草本植物，原产于欧洲、地中海地区。我国长期以来把它作为珍贵的中藏药。其药用部位是柱头，有效成分主要是藏红花素、藏红花酸、藏红花醛和藏红花苦素。丁葆祖等于1979年首次从藏红共的球茎获得完整的植株。Sano等人1987年在离体条件下，诱导花柱-柱头状物再生获得成功，此后国内外不断有相关报道。但试验大多集中在由外植体直接或由愈伤组织间接诱导柱头状物，且花柱-柱头状物的频率低和数量少。我们试图先由藏红花花瓣诱导瓣状体，再定向分化花柱-柱头状物，来提高花柱-柱头状物的诱导频率和数量。从而为以后的大规模生产奠定基础。