Li_8SiN_4-Li_3N-BN体系中立方BN转化行为的研究

研究了高温高压下x·Li_8SiN_4-0.1(1-x)·Li_3N-0.9(1-x)·BN体系中立方氮化硼(cBN)的转化行为。Li_8SiN_4的存在可显著改善cBN晶体的发育,提高晶体质量。在4.2～5.5GPa,1340～1750℃范围内确定了x=4.8％时体系的cBN转化区,并对转化区内cBN转化率、平均生长速度、成核速度及破碎强度与转化温度和压力的关系进行了研究。

Crystallization of Clinopyroxene NaAlSi2O6 from Glass

Clinopyroxene NaAlSi2O6 was synthesized under varying pressures of 3.0-5.0GPa and at the temperature range of 1150.1750 degrees C, for periods of 1.480min. The glass material was completely transformed into homogeneous penetrating fibrous texture of clino

稀土（Nd，Pr）（Ⅲ）双酞菁衍生物的合成、表征和气敏特性

合成了八－４－（四氢糠氧基）酞菁钕（Ⅲ）（Ａ）、八－４－（β－萘氧基）酞菁钕（Ⅲ）（Ｂ）、八－４－（２，４－二叔戊基苯氧基）酞菁钕（Ⅲ）（Ｃ）和八－４－（２，４－二叔戊基苯氧基）酞菁镨（Ⅲ）（Ｄ）４种新的稀土（Ｎｄ、Ｐｒ）（Ⅲ）双酞菁衍生物，经元素分析、红外光谱、核磁共振谱表征．紫外可见光谱表明，它们在氯仿（１０￣（－６）ｍｏｌ／Ｌ）溶液中以单分子形式存在．热重分析证明配合物的热稳定性：Ｂ＞Ｃ～Ｄ＞Ａ．４种配合物成膜性好，Ｚ型沉积形成的单层ＬＢ膜材料对氨气有响应，特别是八－４－（四氢糠氧基）酞菁钕（Ⅲ）的膜材料对氨气很敏感，可与铜酞菁ＬＢ膜气敏性相比．

钠铝辉石由非晶态到晶态的转化研究

在3．0－5．0GPa，1150－1750℃，1－480min条件范围内，合成了钠铝辉石，通过XRD、SEM及IR分析对比研究了人工翡翠和天然翡翠的微观精细结构；通过DAT分析测定了人工翡翠与天然翡翠的熔点，淬火实验检验了人工翡翠的熔点，通过退火及老化实验研究了翡翠的热稳定性。同时还就人工翡翠和天然翡翠的硬度、密度及折射率等其它物化性质进行了比较研究。根据上述研究总结了合成优质钠铝辉石翡翠的最佳实验条件为压力＞4．0GPa，温度＞1450℃，晶化时间＞45min。

固熔体60%NaAlSi_2O_6-40%CaMgSi_2O_6在高温高压下的相图的研究

在1.0～5.0GPa、700～1750℃条件范围内,对固熔体0.6NaAlSi_2O_6-0.4CaMgSi_2O_6进行了研究,探讨了该固熔体在高温高压下的存在行为,研究了由非晶态玻璃向翡翠转化过程中γT作用的相图,得到的透辉石翡翠的晶胞参数为α=0.9439nm,b=0.8573nm,c=0.5233nm,β=107.28°和V=0.41702nm~3。本实验中合成的宝石级翡翠为色泽温润,具有玻璃光泽,半透明的极富观赏性的透辉石翡翠。

Induction of triploidy in large yellow crocker Pseudosciaena crocea (Richardson, 1846): effects of pressure shocks and growth performance in the first rearing year

The precociously sexual maturation in large yellow crocker Pseudosciaena crocea has become a serious problem. In an attempt to solve this problem, the production of sterile triploids could be an effective strategy. In this study, triploid P. crocea was obtained by subjecting fertilized eggs to pressure shock. Flow-cytometry analysis was used to assess ploidy level. In terms of triploid rate and hatching rate, the optimal conditions of pressure shock for triploidy induction in P. crocea were 7500 psi for 3 min shock at 3 min after fertilization at 20 degrees C. With the application of these parameters, 100% triploid fish were produced. During the first rearing year, triploid P. crocea had a similar growth performance compared with its diploid counterpart before the age of 8 months and showed a significant advantage at the age of 10 and 12 months in body weight and body length (P < 0.05). At the age of 12 months, the carcass weight of triploids was markedly higher than that of diploid control, and gonadal somatic index was significantly lower than that of their diploid control. During the first rearing year, survival in triploid group was 76.44%, inferior to its diploid control (83.21%).

Genome-wide analysis of restriction-modification system in unicellular and filamentous cyanobacteria

Cyanobacteria are an ancient group of gram-negative bacteria with strong genome size variation ranging from 1.6 to 9.1 Mb. Here, we first retrieved all the putative restriction-modification (RM) genes in the draft genome of Spirulina and then performed a range of comparative and bioinformatic analyses on RM genes from unicellular and filamentous cyanobacterial genomes. We have identified 6 gene clusters containing putative Type I RMs and 11 putative Type II RMs or the solitary methyltransferases (MTases). RT-PCR analysis reveals that 6 of 18 MTases are not expressed in Spirulina, whereas one hsdM gene, with a mutated cognate hsdS, was detected to be expressed. Our results indicate that the number of RM genes in filamentous cyanobacteria is significantly higher than in unicellular species, and this expansion of RM systems in filamentous cyanobacteria may be related to their wide range of ecological tolerance. Furthermore, a coevolutionary pattern is found between hsdM and hsdR, with a large number of site pairs positively or negatively correlated, indicating the functional importance of these pairing interactions between their tertiary structures. No evidence for positive selection is found for the majority of RMs, e. g., hsdM, hsdS, hsdR, and Type II restriction endonuclease gene families, while a group of MTases exhibit a remarkable signature of adaptive evolution. Sites and genes identified here to have been under positive selection would provide targets for further research on their structural and functional evaluations.

Molecular characterization and effect of RNA interference of retinoid X receptor (RXR) on E75 and chitinase gene expression in Chinese shrimp Fenneropenaeus chinensis

Retinoid X receptor (RXR)/ultraspiracle (USP) is the heterodimeric partner of ecdysteroid receptor and is required for the molting process of arthropods. To better understand the molecular aspects governing the process of molting in shrimp, the full-length cDNA of two RXRs, named as FcRXR-1 and FcRXR-2 were obtained from Chinese shrimp Fenneropenaeus chinensis which were of 1715 and 1700 bp long, revealed a 1315 and 1300 bp open reading frame (ORF) respectively. Quantitative Real time PCR analysis showed a marked tissue-specific difference in the expression of FcRXR transcript, which revealed that the expression of FcRXR Could be regulated in a tissue-specific manner. Moreover, high expression of FcRXR mRNAs was observed in late pre-molt period (D3) and post molt stages (A-B) of shrimp. Among the two isoforms, FcRXR-2 appeared in a considerably high level in all the stages compared to the FcRXR-1. In addition, we examined the temporal expression of two chitinase genes: FcChitinase (FcChi) and FcChitinase-1 (FcChi-1) during the molt cycle of F chinensis. Both the FcChi and FcChi-1 transcripts were detected in all stages of molting, although considerable fluctuations observed through the molt cycle. Injection of double stranded RXR (dsRXR) into juvenile shrimp resulted in a maximum silencing effect at 48 h post injection. We analyzed the expression levels of FcChi, FcChi-1 and the ecdysone inducible gene E75 (FcE75) in samples of dsRXR injected shrimp. Significant reduction in levels of both FcE75, FcChi and FcChi-1 transcripts Occurred in the silenced shrimp. This correlation suggested that RXR might involve in the downstream regulation of E75 and chitinase gene transcription in the ecdysone signaling pathway of decapod crustaceans. (C) 2009 Published by Elsevier Inc.

中国及相关海域褐虾总科系统分类学和动物地理学研究

褐虾总科包括褐虾科和镰虾科，是重要的底栖生物类群，而且很多褐虾种为常见的经济种，其中中国北方海域最常见的为日本褐虾Crangon hakodatei Rathbun, 1902，另外黄海褐虾Crangon uritai Kim & Hayashi, 1999在黄渤海也较为常见。在东海和南海，污泥疣褐虾Pontocaris pennata (Bate, 1888)和拉氏爱琴虾Aegaeon lacazei (Gourret, 1887)在底栖生物拖网时常可采到，有很大的经济价值。我国对褐虾总科的研究很少，亟需对我国海域的褐虾进行全面的系统分类学和地理分布研究。 本论文所依据的标本主要为中国科学院海洋研究所海洋生物标本馆馆藏的约1600号褐虾类标本，标本主要采自渤海、黄海、东海、南海四大海域，也有部分标本采自日本海、南极和北极等海域，并得到国外同行专家惠赠的褐虾类标本约100号，同时也检查了其它单位保藏的少量标本。 本论文主要采用传统的形态学方法进行分类学研究，共鉴定出褐虾科14属25种，其中1个新种，6个新记录种，镰虾科1属7种，其中2个新种，3个新记录种。参照历史文献与现在研究结果，中国海域的褐虾类至少有2科11属44种。 本文通过对约1700号标本的详细检查，总结了各个属和种的分类学特征和地理分布特点，对各属的分种均附有详细系统的检索表，对鉴定的32种褐虾均附有详细的背面整体图和侧面整体图以及附肢等的局部形态图，并对各种进行了中文名称的考订。 本研究是我国首次关于褐虾总科的系统分类学和动物地理学研究，研究结果将改变我国在褐虾总科研究报道方面的薄弱现状，并为此动物类群的多样性等研究提供重要的基础资料。研究结果澄清了分类学上存在争议的疑难种，发现了3个新种，报道了9个新记录种，阐明了我国褐虾总科的区系特点。

冲绳海槽黑潮流域近4万年以来的古海洋环境演化

本文采用取自冲绳海槽的91个站位的表层样品和2个柱状岩芯，通过微体古生物有孔虫分析、氧碳同位素测试、AMS~(14)C测年、沉积物粒度和地球化学分析，探讨了现代生物群落、表层沉积物氧同位素与现代海洋环境之间的关系，进而对冲绳海槽区域近4万年来的古海洋环境和古黑潮演化进行了详细的研究。表层沉积物中的浮游有孔虫氧同位素与现代海洋环境之间的关系密切，浮游有孔虫从G.ruber到G.sacculifer到N.dutertrei其δ~(18)O值由轻变重，表明三种有孔虫其生活水层依次由浅到深。在横穿海槽的剖面上浮游有孔虫δ~(18)O在近陆端因受冲淡小影响较强而变轻，而在东侧站位，受黑潮暖流或其支流的影响氧同位素同样有变轻的趋势。N. dutertrei和G.ruber的氧同位素差值表明了冲绳海槽北部区域黑潮支流对表层水体的影响要大于次表层水体，而在冲绳海槽南部区域，黑潮暖流对次表层水体有相对较强的影响。冲绳海槽南部表层沉积物中的浮游有孔虫整体上属于赤道区组合，溶解作用对该区的浮游有孔虫群落有显的影响，冲绳海槽北部区浮游有孔虫组合对具有温带群落的特征。浮游有孔虫分布与海洋环境密切相关，南北区的浮游有孔虫分布都明显受暖流的影响，在暖流的主流轴处浮游有孔虫丰度通常较高。冲绳海槽具有相对较浅的碳酸盐溶跃面，浮游有孔虫丰度和底栖有孔虫深水胶结壳的含量都进一步表明了该区碳酸钙溶跃面大约在1700 m水深左右，比开放大洋明显要浅得多。表层沉积物中的底栖有孔虫主要受水深和水团等因素的制约。水深制约着有孔虫属种的分带，也影响底栖有孔虫的组合。根据Q型因子分析，冲绳海槽南部表层沉积物中的底栖有孔虫从陆架连缘到海槽底部可以划分为5个特定的组合，分别对应黑潮表层水和次层水影响环境、黑潮中层水影响环境、溶跃面以上的黑潮深层水影响环境、黑潮底层水团影响环境和溶解作用较强的槽底环境；北部区的底栖有孔虫群落反映了四个组合，分别代表了陆架混合水团影响环境、黑潮暖流中层水影响环境、冷涡沉积和上升流区影响环境以及对马暖流水团影响下的环境。以氧同位素曲线为基础，结合AMS~(14)C测年和生物地层学对柱状岩芯进行了地层划分和对比，E107孔记录了冰消期以来大约15,000 a来的古环境演化记录，具有较高的沉积速率，DOC－42孔保存在主要是末冰期中40－10ka BP期间的古环境沉积记录，沉积物记录的分辨率相对较低。浮游有孔虫有碎壳比和底栖有孔虫深海胶结壳含量表明了现代冲绳海槽的浅溶跃面是大约最近2000 a BP才开始突然变浅形成的，碳酸盐的溶解作用从冰消期到现在逐增强。冲绳海槽南部E107孔的底栖有孔虫组合把映了15,000 a来的底层水团具有两种完全不同的营养状况，约6500 a BP以前有机质通量较高，6500 a BP以后有机质通量则明显降低。DOC－42孔的底栖有孔虫组合反映该区约4万年以来的底部水团演化主要受有机质通量和氧含量的共同制约，氧同位素3期主要为高有机质通量的沉积环境，伴随有氧含量水平的较大波动；氧同位素2期有机质通量有所降低，氧含量整体为中等水平；氧同位素1期早期义部水体则较高氧含量为主。浮游有孔虫温跃层转换函数反映了冲绳海槽中部的温跃层在约13100 a BP有一个明显的变化，在这之前产温跃层深度较浅，平均89 m，而在该时间以后，温跃层平均深度变为166 m。此外在160 cm处和100 cm的温跃层深度的两次明显的降低，分别对应于新仙女木事件和黑潮暖流的重新入侵，表明这两个事件导致了海洋上层水体结构的突然变化。冲绳海槽北部浮游有孔虫转换函数古温度和浮游有孔虫的低温、低盐特征种反映了在氧同位素3期早期约40000a BP和氧同位素2期间存在两个明显的低温、低盐阶段，可能与沿岸水在该期间加强有关。其中氧同位素3期早期的表层海水古水温比末次冰期还要低，反映了区域海洋环境的重大变化。冲绳海槽南部E107孔的沉积物粒度、地球化学特征、黑潮特征指示种、表层古水温以及底层水团的性质在6500 a BP左右发生了重大的改变，与冲绳海槽南部的其他岩芯反映的古环境化基本一致，表明了南部海槽在6500 a BP前后古黑潮流径发生了重大变化。而冲绳海槽北部区域2万年以来的古环境则与南部有明显差异，总结前人对冲绳海槽古黑潮流径的研究，笔者对未次冰盛期古黑潮流径提出了新的推测。

黄东海胶质浮游动物水母类研究

近年来，胶质类浮游动物尤其是水母类在近岸高生产力的海洋生态系统中的作用越来越受到全球科学家们的关注。这种关注很大程度上是由于近年来很多海域或海湾出现水母类大量繁殖的现象而引起的，这种现象与过度捕捞、气候变化、富营养化以及生物入侵等因素有着内在的联系，给人们带来经济，社会和生态等各方面的损失。这种损失包括：当水母大量出现时，由于它们与鱼类存在食物和捕食竞争，使渔业资源和渔业生产锐减；由于它们会堵塞和撕破渔业生产网，干扰了人们的渔业生产活动；另外水母增多增加了海滨游泳爱好者被蛰伤甚至死亡事件发生的频率，对旅游者们的娱乐行为造成不便。到目前为止全球范围内报道了许多水母大量繁殖并对经济社会或海洋生态系统造成负面影响的事件。在北海水母数量爆发的频率与气候相关的事实表明了该海域将要面临一个更多的胶质类浮游动物的未来。所有这些都表明海洋中水母的生态学问题仍旧是全球的一个研究热点。到目前为止，在世界上许多海湾和海区有关水母生态学问题的研究上，均已取得方方面面有意义的进展。但在我国，由于对水母功能群的研究缺乏足够的重视，对于大型水母来讲它们被认为是渔业生产的副产品或者‘垃圾’，在渔业拖网捕获后把它们直接扔入海中并不去研究；对于小型水母来讲，因为它们为非饵料生物，并且有易碎，粘糊糊等难操作的特点，对浮游生物网同步采集到的水母的研究力度远不如对其他浮游动物类群的研究力度，因此我国对水母功能群生态学的研究基础相当薄弱。 本论文基于以上背景对黄东海大型和小型水母类的生物地理分布格局进行了研究，对其生物量或丰度等生态学指标进行了定量研究。（1）利用浮游生物网样品对黄海小型水母类的种类组成及其丰度的时空变化进行了研究，表明黄海测区内小型水母整体丰度很低，且主要分布在50 m等深线以浅海域，各水母类群以及优势种类的季节更替非常明显。比较不同海区的小型水母的丰度水平及其占浮游动物丰度的比例，发现黄海的小型水母丰度水平最低，为0.8（0.04–1.3）ind. m-3，只占浮游动物丰度的 < 0.5 %，表明小型水母在黄海海域并非占优势的功能群。（2）在中国黄东海采集的沙海蜇和在日本采集的越前水母的COI基因序列差异（0.2%）处于种内水平，从分子水平上证明两者为同一个种类，基于形态学和分子生物学的证据，我国大型水母沙海蜇的分类地位可初步订正为：Nemopilema nomurai Kishinouye, 1922（Scyphozoa：Rhizostomeae：Rhizostomatidae）。（3）利用渔业底层拖网的方法对黄东海大型水母的种类组成，总生物量及各优势种类生物量的时空分布进行了半定量研究。结果共鉴定到11个种（类），其中沙海蜇（Nemopilema nomurai），洋须水母（Ulmaridae genus sp.）以及多管水母（Aequorea spp.）为黄海的优势种（类），沙海蜇（只在东海北部）和霞水母（Cyanea spp.）为东海的优势种（类）；这四个种（类）的湿重随着伞径的增大成冪增长的方式。大型水母平均总生物量的季节变化模式为：3月份水母总生物量最低，为4.6 ± 9.4 kg km–2，春夏季随着海水表层温度的升高，大型水母的生物量逐渐增加，9月初水母的总生物量达到最高值，为22891 ± 25888 kg km–2，随后随着海水的温度下降，生物量也逐渐下降。洋须水母的生物量在10月份达到最高值（2780 ind. km–2，1807 kg km–2），主要在黄海中部出现。多管水母在5月份丰度最高，为8262 kg km–2，且主要分布在30N以北海域。 聚焦大量爆发的水母种（类）沙海蜇和霞水母，基于实测的拖网资料，提供了该种可见的浮游阶段1周年的地理发生和生物量数据；结果表明，这两个种（类）表现了不同的季节出现和生物量格局：首先是黄海出现的沙海蜇（5–12月在黄海出现），5月份少量幼水母体在黄东海的交界处出现，6月它们的分布范围在南黄海扩大，到8月末及9月初沙海蜇几乎遍布黄海，其生物量和丰度以压倒其他大型水母类的优势形成“bloom”（生物量占所有大型水母的96.7%，丰度占93%，在南黄海平均生物量20446 kg km-2，平均占渔获物生物量的86.1 %），10月份至12月，沙海蜇的生物量逐渐减少甚至为零，其分布区域也向北回缩。其次为东海出现的霞水母（5月–10月）：霞水母在5月初达到生物量的高值（平均生物量为380 kg km-2），其伞径随纬度的升高而变小，8月至10月其生物量骤然下降。这两个种类的生物量高值分布在温度或潮汐锋区。结合水文条件及沙海蜇和霞水母关键的生活史策略推测了黄东海该种浮游阶段的生活史模型。 最后，通过对黄海8、9月份沙海蜇生物量的最高峰或暴发时期的呼吸率，摄食率进行估算，获得其每天对浮游动物现存量及生产力的潜在摄食压力，结果表明2006年9月在对沙海蜇最大捕获率的情况下，沙海蜇的摄食率为8.37（0.12–37.83）mg C m-2d-1，假设都以浮游动物为食，这时每天对浮游动物现存量及生产力的摄食压力分别为11.2%（0.17–50.6%），134.1%（1.98–605.7%）。因此在沙海蜇暴发期间对浮游动物的潜在的消耗非常大，甚至为毁灭性的。

Partial characterization of the hemolytic activity of the nematocyst venom from the jellyfish Cyanea nozakii Kishinouye

Using a recently developed technique to extract jellyfish venom from nematocysts, the present study investigated the hemolytic activity of Cyanea nozakii Kishinouye nematocyst venom on chicken erythrocytes. Venom extract caused a significant concentration-dependent hemolytic effect. The extract could retain its activity at -80 degrees C but was unstable when kept at 4 degrees C and -20 degrees C for 2 days. The hemolytic activity was inhibited by heating within the range of 37-100 degrees C. The extract was active over a pH range of 5.0-8.63 and the pH optima for the extract was 7.8. Incubation of the venom with sphingomyelin specially inhibited hemolytic activity by up to 70%. Cu2+ and Mn2+ greatly reduced the hemolytic activity while Mg2+, Sr2+ and Ba2+ produced a relatively low inhibiting effect on the hemolytic activity. Treatment with Ca2+ induced a concentration-dependent increase in the hemolytic activity. In the presence of 5 mM EDTA, all the hemolytic activity was lost, however, the venom containing 1.5 mM EDTA was stable in the long-term storage. PLA(2) activity was also found in the nematocyst venom of C. nozakii. These characteristics provide us a fundamental knowledge in the C. nozakii nematocyst venom which would benefit future research. (C) 2010 Published by Elsevier Ltd.

国产6种点地梅属植物的核型及其系统学意义

报道了点地梅属6种12个居群的染色体数目和核型。它们的染色体数目（2n）、核型公式（KF）、染色体相对长度组成（CRL）、核型不对称性系数（A. sK％）和核型类型（KT）分别为：点地梅在南京的2个居群都是2n=2x=20，KF=18m+2sm, CRL=2L+6M_2+10M_1+2S，核型KT属于1A型，但核型不对称性系数As. K％分别是55.04％和56.71％；北点地梅在内蒙古锡林郭勒和白音锡勒居群的2n=2x=20，KF分别为16m+2sm+2st+1b和16m+2sm+2st+4b，染色体相对长度组成分别是14M_2+4M_1+2S+1b和12M_2+6M_1+2S+4b，核型不对称性系数As. K％分别是57.65％和58.86％，属2A型和2B型；高原点地梅在青海玛沁县昌马河居群和兴海县温泉居群都是2n=2x=20，KF=10m+8sm+2st。但相对长度组成分别为12M_2+8M_1和4L+6M_2+6M_1+4S, As. K％分别是60.35％和62.57％，属2A型和2B型；雅江点地梅在青海玛多县巴颜喀拉山居群和大通县达坡山居群分别为2n=4x=40和20n=6x=60，KF=36m+2sm+2st和KF=46m+10sm+4st+2b, CRL=2l+20M_2+14M_1+4S和GRL=6L+30M_2+16M_1+8S+2b, As.K％分别为55.62％和58.31％，核型均属于2B；巴颜喀拉山北坡的鳞叶点地梅2n=40、60、80。西藏点地梅青湖居群中有2种细胞型：①2n=2x=24, KF=12m+6sm+6st+4b, CRL=6L+2M_2+8M_1+4S+4b, As. K％＝65.74％，核型属2B；②2n=2x=22,KF=14m+4sm(2SAT)+4st, CRL=4L+6M_2+8M_1(2SAT)+4S,As. K％=63.40％，核型也属于2B。西宁西山湾居群也有2种细胞型；①2n=3x=36, KF=36m,CRL=4L+12M_2+20M_1, As. K％=54.82％，核型属1A；②2n=3x=33,KF=33m, CRL=3L+12M_2+18M_1,As. K％=52.11％，核型属1A。点地梅属的染色体原始基数可能是x=10，在种间或种内观察到有3种核型变化：染色体非整倍性变化、多倍化和核型不对称性变化。将2倍体居群的核型和不对称性进行比较，可以看出点地梅是较对称的核型。因此，在研究的种中应是比较原始的类群。北点地梅的核型不对称性和进化程度高于点地梅而低于高原点地梅和西藏点地梅。染色体多倍化的雅江点地梅、鳞叶点地梅和西藏点地梅等在核型上也许是最进化的类群。

Response of chlorophyll fluorescence to dynamic light in three alpine species differing in plant architecture

A study was carried out to examine the effect of dynamic photosynthetically active photon flux density (PPFD) on photoinhibition and energy use in three herbaceous species, prostrate Saussurea superba, erect-leaved S. katochaete, and half-erect-leaved Gentiana straminea, from the Qinghai-Tibet Plateau. Chlorophyll fluorescence response was measured under each of three sets of high-low PPFD combinations: 1700-0, 1400-300, and 1200-500 mu mol m(-2) s(-1), illuminating in four dynamic frequencies: 1, 5, 15, and 60 cycles per 2 h. The total light exposure time was 2h and the integrated PPFD was the same in all treatments. The highest frequency of PPFD fluctuation resulted in the lowest photochemical activity, the highest level of non-photochemical quenching, and the greatest decrease of F-v/F-m (maximal photochemical efficiency of PSII). The 5 and 15 cycles per 2h treatments resulted in higher photochemical activity than the 1 cycle per 2h treatment. The 1700-0 PPFD combination led to the lowest photochemical activity and more serious photoinhibition in all species. S. superba usually exhibited the highest photochemical activity and CO2 uptake rate, the lowest reduction of F-v/F-m,F- and the smallest fraction of energy in thermal dissipation. With similar fractions of thermal dissipation, S. katochaete had relatively less photoinhibition than G. straminea owing to effective F-o quenching. The results suggest that high frequency of fluctuating PPFD generally results in photoinhibition, which is more serious under periods of irradiation with high light intensity. (c) 2005 Elsevier B.V. All rights reserved.

北京地区Pc6脉动统计特征及其与TID关系研究

Through the statistical analysis of the geomagnetic data from BMT in 2005, we get the period and frequency characteristic of Pc6 micropulsation in Beijing area. Pc6 micropulsation is a frequently occurred phenomenon in geomagnetism but we still do not have adequate knowledge to it. In this paper, we found that the periods of Pc 6 micropulsation focus on 10 to 30 minutes. They do not have distinct seasonal variation but obtain a little lower occurrence in the winter than other seasons. Then we analysis the geomagnetic data of BMT from 1998 to 2006, which is a solar activity cycle and get some results about the relationship between Pc6 micropulsation and solar activities. In this way, we discuss more about the origin and evolvement mechanism of the Pc6 micropulsation. When the solar is more active than usual years, there are more occurrences of Pc6 micropulsaton observed. The occurrence of Pc6 micropulsation is associated with geomagnetic index. With the increase of AE and Kp index, there are more occurrences of Pc6 micropulsation. Furthermore, we make use of the Doppler data from Peking University in 2005 make a comparative research between TID events and Pc6 micropulsation. There are 42 events can satisfy our request during Dec.23, 2004 to Mar.11, 2006. After the data analysis, we can draw a fundamental conclusion that there are positive links between Pc6 micropulsation and TID event. Moreover, when TID and Pc6 micropulsation occur simultaneously, their occurrences have a positive relationship with AE and Kp index. So we suppose there might be the same source of Pc6 micropulsation and TID event. Finally, we make use of two meridian geomagnetic stations network which has a distance about 1700 km to investigate the transmission characteristic of Pc6 micropulsation when Pc6 micropulsation and TID happened together. We found at that time Pc6 micropulsation is a local phenomenon.