一种海藻倍半萜类化合物及其制备方法

本发明涉及海洋天然产物领域，具体地说是一种海藻倍半萜类化合物及其制备方法。具体结构式如（I）所示，其制备方法为将海洋褐藻叉开网翼藻经海水冲洗干净、除去表面附着的沙砾及杂藻，阴干、粉碎后浸取、溶剂分配和反复的层析分离，得到单体化合物。发明通过海洋褐藻叉开网翼藻经提取、分离获得的倍半萜类天然化合物，属于新的小分子天然有机化合物，容易制备获得。

Phylogeny of higher taxa of Hexapoda according to 12sRNA sequences

The phylogenetic relationship of Hexapoda has been debated for a long time, which will be resolved mainly depending on the settlement of monophyly, affinities and interrelationships among Protura, Collembola and Diplura. Mitochondrial 12sRNA gene about 35

云南新平哀牢山夜间捕获鸟类的多样性

2007-09-05-2007-11-05和2008-09-03-2008-11-07期间,在云南省新平县哀牢山金山丫口用灯光诱捕对秋季夜间迁徙鸟类组成进行了调查.共捕获鸟类129种,7943只,分属于14日23科.雀形目鸟类为网捕主要鸟类,占总网捕数量的58.9%.其中红尾伯劳(Lanius cristatus)、小杜鹃(Cuculus poliocephalus)和红喉歌鸲(Luscinia calliope)3种是该地夜间网捕优势种鸟类,三者数量皆超过网捕岛类总数的5%.每天夜间20:00-22:00和次日凌晨04:00-4)6:00是捕获鸟类数最的高峰时段.网捕期间,早期Shannon-Wiener指数和Pielou指数最低,优势指数C最高;中期Shannon-Wiener指数和Pielou指数最高,优势度指数C最低.2008与2007年相比,优势指数C和G-F指数较低.但Shannon-Wiener指数和Pielou指数较高.云南省不同"打雀山"仪问捕获鸟类的种类和数量存在差异.地理和气候可能是造成这些差异的主要因素.

三峡水库初次蓄水后干流库区桡足类的纵向分布与季节变化

作为大型水利工程,三峡水库于2003年6月开始蓄水,蓄水后库区水环境发生了变化。为了了解三峡水库水生态系统的演替规律,同时为环境保护、渔业资源开发利用以及水环境管理提供理论基础,我们对三峡水库第一阶段蓄水后桡足类的季节变化和空间分布进行了周年季节性研究。在三峡库区江津至茅坪的10个断面共采集到8种桡足类,其中哲水蚤目2种、猛水蚤目1种、剑水蚤目5种,北碚中剑水蚤(Mesocyclops pehpeiensis)、广布中剑水蚤(M.leuckarti)和汤匙华哲水蚤(Sinocalanus dorrii)分

斑点叉尾鮰几种疑难疾病的介绍

<正>当前养殖斑点叉尾鮰在我国方兴未艾,然而,和其它养殖动物一样,随着养殖范围的扩大、养殖密度的提高以及养殖时间的延长,斑点叉尾鮰的疾病问题也随之接踵而来,并成为进一步发展的重要制约因素。本文介绍斑点叉尾鮰几种疑难疾病的主要特征,以帮助斑点叉尾鮰养殖业者能够在生产实践中尽早发现和认识它们,并采取正确的控制对策,减少因病造成的损失。

苯丙胺对铜绿微囊藻的生物效应研究

研究了不同浓度苯丙胺在不同条件下对铜绿微囊藻的生长及毒性效应。结果表明 ,低浓度苯丙胺在弱碱性条件下促进铜绿微囊藻的生长 ;高浓度的苯丙胺则抑制其生长。苯丙胺对铜绿微囊藻 2 4、48、72、96h的EC50 值分别为 2 4 .52、1 6 .51、1 0 .76、9.60mg/L ,且其毒性随时间的延长而增加

生活污水对稀有鮈鲫的毒性效应研究

利用稀有鲫个体小、性成熟时间短、在实验室控制条件下容易饲养等特点 ,将其作为一种毒性实验材料 ,从形态学和组织学水平对生活污水可能产生的毒性效应进行了初步研究。研究结果表明 ,在早期生命阶段 ,高浓度的生活污水对稀有鲫有急性毒性效应。受排污口污水暴露的稀有鲫鱼卵根本无法孵化 ;对处于性腺发育期稀有鲫的暴露则引起肝脏细胞水平上的毒性效应 ,且随污水浓度的增高 ,对鱼体性发育的阻碍效应也越强 ,而整个生命期即使仅暴露于低浓度的生活污水中 ,其个体发育和性发育也均受到影响 ,肝细胞也表现出强烈的毒性效应

池塘水华与底层磷营养状态的关系

比较了武汉东郊相邻池塘间隙水、上覆水与沉积物中磷形态、水相中与不同大小颗粒相联系的碱性磷酸酶活性 (APA)、溶解态与沉积物APA动力学参数及沉积物有机质的含量。铜绿微囊藻 (Microcystisaeruginosa)出现或繁盛的池塘上覆水中正磷酸盐 (O—P)或间隙水中不同形态磷的浓度较高 ,而底层水相不同形态磷浓度较低的池塘叶绿素的浓度亦低 ,且未见铜绿微囊藻 ,故水华与底层磷营养之间联系紧密。各塘沉积物磷主要以铁结合态形式存在 ,铜绿微囊藻繁盛的池塘沉积物中铁结合态磷含量较低 ,而有机质含量较高

Feasibility of cyanobacterial inoculation for biological soil crusts formation in desert area

Practical testing of the feasibility of cyanobacterial inoculation to speed up the recovery of biological soil crusts in the field was conducted in this experiment. Results showed that cyanobacterial and algal cover climbed up to 48.5% and a total of 14 cyanobacterial and algal species were identified at the termination of inoculation experiment; biological crusts' thickness, compressive and chlorophyll a content increased with inoculation time among 3 years; moss species appeared in the second year; cyanobacterial inoculation increased organic carbon and total nitrogen of the soil; total salt, calcium carbonate and electrical conductivity in the soil also increased after inoculation. Diverse vascular plant communities composed of 10 and 9 species are established by cyanobacterial inoculation on the windward and leeward surface of the dunes, respectively, after 3 years. The Simpson index for the above two communities are 0.842 and 0.852, while the Shannon-Weiner index are 2.097 and 2.053, respectively. In conclusion, we suggest that cyanobacterial inoculation would be a suitable and effective technique to recover biological soil crusts, and may further restore the ecological system. (C) 2008 Published by Elsevier Ltd.

Use of microbial community to evaluate performance of a wetland system in treating Pb/Zn mine drainage

The performance of a wetland system in treating lead (Pb)/zinc (Zn) mine drainage was evaluated by using the polyurethane foam unit (PFU) microbial community (method), which has been adopted by China as a standardized procedure for monitoring water quality. The wetland system consisted of four cells with three dominant plants: Typha latifolia, Phragmites australis and Paspalum distichum. Physicochemical characteristics [pH, EC, content of total suspended solid (TSS) and metals (Pb, Zn, Cd, and Cu)] and PFU microbial community in water samples had been investigated from seven sampling sites. The results indicated that the concentrations of Pb, Zn, Cd, Cu, and TSS in the mine drainage were gradually reduced from the inlet to the outlet of the wetland system and 99%, 98%, 75%, 83%, and 68% of these metals and TSS respectively, had been reduced in concentration after the drainage passed through the wetland system. A total of 105 protozoan species were identified, the number of protozoa species and the diversity index (DI) gradually increased, while the heterotrophic index (HI) gradually decreased from the inlet to the outlet of the wetland system. The results indicated that DI, HI, and total number species of protozoa could be used as biological indicators indicating the improvement of water quality.

Toxicity of cypermethrin to Daphnia magna HB

The acute toxic effect of the pesticide cypermethrin to Daphnia magna HB was examined. D. magna HB was exposed to cypermethrin at concentrations of 0, 1, 3, 5, 7, and 9 mg/L for 24 In. Data showed that the 24 h-LC50 of cypermthrin on D. magna HB was 4.81 mg/L. In contrast, the 24 h-LC50 of K2Cr2O7 (the national standard toxicant) to Daphnia magna was 0.38 mg/L in the current study. Results indicated that the Daphnia magna was very sensitive to pesticides. In addition, the effects of the culture condition(such as hardness, temperature and DO etc.) on Daphnia magna HB was also studied.

Impact of hydrogen dilution on microstructure and optoelectronic properties of silicon films deposited using tirisilane

We explored the deposition of hydrogenated amorphous silicon (a-Si: H) using trisilane (Si3H8) as a gas precursor in a radiofrequency plasma enhanced chemical vapour deposition process and studied the suitability of this material for photovoltaic applications. The impact of hydrogen dilution on the deposition rate and microstructure of the films is systematically examined. Materials deposited using trisilane are compared with that using disilane (Si2H6). It is found that when using Si3H8 as the gas precursor the deposition rate increases by a factor of similar to 1.5 for the same hydrogen dilution (R = [H-2]/[Si3H8] or [H-2]/[Si2H6])- Moreover, the structural transition from amorphous to nanocrystalline occurs at a higher hydrogen dilution level for Si3H8 and the transition is more gradual as compared with Si2H6 deposited films. Single-junction n-i-p a-Si: H solar cells were prepared with intrinsic layers deposited using Si3H8 or Si2H6. The dependence of open circuit voltage (V-oc) on hydrogen dilution was investigated. V-oc greater than 1 V can be obtained when the i-layers are deposited at a hydrogen dilution of 180 and 100 using Si3H8 and Si2H6, respectively.