A novel hydroperoxyl substituted cembranolide diterpene from marine soft coral Lobophytum crassum

A new cembranolide diterpene with a hydroperoxyl substitution was isolated from the marine soft coral Lobophytum crassum. The structure was elucidated on the basis of chemical and spectral methods.

Responses of a coastal phytoplankton community to increased nutrient input from the Changjiang (Yangtze) River

Nutrient input from the Changjiang River (Yangtze River) has been increasing dramatically since the 1960s. At the mouth of the Changjiang River, the nitrate concentration has increased about three-fold in 40 years, from 20.5 mu mol/L in the 1960s to 59.1 mu mol/L in the 1980s and to 80.6 mu mol/L in 1990-2004. Phosphate concentration increased by a factor of 30%, from 0.59 mu mol/L in the 1980s to 0.77 mu mol/L in 1990-2004. The increasing nitrate input has arisen mostly from the mid and lower reaches of the Changjiang River, where the river meets one of the most strongly developed agriculture areas in China. Responses of the coastal phytoplankton community to the increasing nutrient inputs are also seen in the available monitoring data. First, a trend of increasing phytoplankton standing stock from 1984 to 2002 appeared in the Changjiang River estuary and adjacent coastal waters, especially in late spring. Secondly, the proportion of diatoms in the whole phytoplankton community showed a decreasing trend from about 85% in 1984 to about 60% in 2000. Finally, red tides/harmful algal blooms increased dramatically in this area in terms of both number and scale. About 30-80 red tide events were recorded each year from 2000 to 2005 in the East China Sea. The scale of some blooms has been in excess of 10,000 km(2). (c) 2008 Elsevier Ltd. All rights reserved.

A new diterpenoid, taibairubescensin C, from Isodon rubescens

A new kaurenoid, taibairubescensin C (1), was isolated from the ethanol extract of the leaves and tender branches of Isodon rubescens (Hemsl.) Hara. Its structure was designated as 2beta,6alpha-diacetoxy-3beta, 11beta-dihydroxy-ent-kaur-16-en-15-one (1) on the basis of detailed spectroscopic analysis.

利用计算机仿真与系统辨识求解导弹弹道轨迹

提出了求解某武器系统导弹弹道轨迹的两种方法：计算机仿真和系统辨识方法．详细介绍了导弹系统的计算机仿真模型，并利用控制理论和数值分析的方法对仿真模型求解；根据系统辨识理论，将整个系统看作“黑箱”，建立与输入、输出数据等价的模型，引入折息因子对模型进行辨识．最后分别给出了计算机仿真试验曲线和系统辨识试验曲线，证明了两种求解方法的有效性。

过程工业综合自动化的单元技术进展

本文概述了过程工业综合自动化各种单元自动化技术及各种支撑体系与工具的发展动态，从而肯定了综合自动化的技术基础与发展必然性。

大气活性气态汞采样和分析方法

改进了利用镀KCl扩散管采集大气活性气态汞分析方法。实验证明：在450℃条件下加热10min 被扩散管捕获的活性气态汞会被热解出。该法最低检出限为3 pg，具有成本低、分析方法简单、省时及采样管能多次使用等优点。

贵州红枫湖水体溶解有机质的剖面特征和季节变化

溶解有机氮(dissolved organic nitrogen , DON) 与溶解有机碳(dissolved organic carbon , DOC) 相结合在湖泊水体溶解有机质(dissolved organic matter , DOM) 的研究中少有报道. 本研究对贵州喀斯特地区高原性湖泊-红枫湖水体DOC 和DON 的含量进行了近2a 的测定,研究了DOM 的剖面特征和季节变化,并探讨了DOM 垂向分布和季节变化的影响因素. 结果表明,红枫湖DOC 的浓度范围为1160～3108 mg·L - 1 ,DON 的浓度范围为0110～0137 mg·L - 1 . 在湖水混合期表层和底层的DOC和DON 的浓度基本一致,在湖水分层期DOC 和DON 浓度表现出从表层往底层减小的趋势. 表层水体(0～2m 或3m) DOC 的浓度在春末夏初或夏季达到最大,DON 的浓度在春末夏初稍高于其它月份. 结合叶绿素和降雨的数据分析认为,藻类活动和陆源输入直接导致了表层水体DOM 的季节变化模式. DOM 的C/ N 在一般情况下向下增大,但在夏季南湖的垂向水柱上,DOC 和DON 的浓度在12m 以下增大,C/ N 从12m 的1811 下降为14m 的1419 ,并向下持续减小,这很有可能是颗粒态有机质发生降解释放出C/ N 较低的DOM ,成为水体内DOM 的一个内源.

光解水制氢半导体光催化材料的研究进展

自从Fujishima-Honda效应发现以来,科学研究者一直努力试图利用半导体光催化剂光分解水来获得既可储存而又清洁的化学能--氢能.近一二十年来,光催化材料的研究经历了从简单氧化物、复合氧化物、层状化合物到能响应可见光的光催化材料.本文重点描述了这些光催化材料的结构和光催化特性,阐述了该课题的意义和今后的研究方向.[

Optimal light regime for the cultivation of transgenic Laminaria japonica gametophytes in a bubble-column bioreactor

Fluctuating light intensity had a more significant impact on growth of gametophytes of transgenic Laminaria japonica in a 2500 ml bubble-column bioreactor than constant light intensity. A fluctuating light intensity between 10 and 110 mu E m(-2) s(-1), with a photoperiod of 14 h:10 h light:dark, was the best regime for growth giving 1430 mg biomass l(-1).