DETERMINATION OF TRACE AMOUNT OF 14 RARE-EARTH IMPURITIES IN HIGH-PURITY YTTRIUM-OXIDE WITH ICP-AES

A method of analysis of high purity yttrium oxide with ICP-AES was described with emphasis on the study of Y_2O_3 matrix effects. The results showed that the line intensities of ana]ytes decreased with the increase of Y_2O_3 concentration in solution because of following factors. (1) The presence of matrix resulted in the decrease of the amount of analytes reaching ICP. (2) Matrix Y_2O_3 entering the plasma decreased the excitation temperature of the plasma and depressed the ionization of analytes in the pl...

NdP_5O_(14)晶体的光谱强度参数

关于高稀土浓度化学计量比的稀土五磷酸盐晶体已为人们所熟知，国内外NdP_3O_(14)晶体已用作微小型激光器的工作物质。但对稀土五磷酸盐晶体的光谱参数报告得不多。我们生长

Er_(3x)~(3+):Y_(3-3x)Al_5O_(12)和Er_x~(3+)Yb_(1-x)P_5O_(14)晶体的光谱强度参数

本文报道了用J-O理论计算的Er_(3x)~(3+):Y_(3-3x)A_5O_(12)和Er_x~(3+)Yb_(1-x)P_5O_(14)两种晶体中Er~(3+)五种浓度的振子强度、Ω_λ参数、辐射跃迁几率与荧光分支比。并观察了这些参数的变化规律。

Ce_(0.9)RE_(0.1)P_5O_(14)晶体中Ce~(3+)的发光寿命研究

利用时间相关单光子计数方法系统地测定了Ce_(0.9)RE_(0.1)P_5O_(14)晶体中Ce~(3+)的发光寿命。发现荧光寿命数值能够较好地说明双掺晶体中除Ce而外的其它稀土离子对Ce~(3+)的发光强度的增强或猝灭现象。

YP_5O_(14):Er~(3+),Tm~(3+)晶体的合成

研究了水热法合成晶体,浓度配比、生长温度对晶体生长习性的影响.合成了一系列化学计量比的Y_(1-x-0.3)Er_(0.3)Tm_xP_5O_(14)(x=0.01～0.1)晶体,观察和分析了晶体的缺陷及成因,测定和讨论了晶体结构.

Ho~(3+)离子及HoP_5O_(14)晶体的光谱性质

根据HoP_5O_(14)的吸收光谱和荧光光谱,用Judd-Ofelt理论计算了Ho~(3+)的强度参数.并计算了激发能级的辐射跃迁速率、辐射寿命、荧光分支比和积分发射截面等光谱参数.

SmP_5O_(14)晶体中Sm~(3+)离子的能级和晶场参数

本文利用光谱方法测定了SmP_5O_(14)晶体中Sm~(3+)离子的能级,通过拟合定出晶场参数,利用这些参数所计算的能级和实验能级符合得很好。

Sm_xLa_(1-x)P_5O_(14)和Dy_xY_(1-x)P_5O_(14)晶体的荧光寿命研究

本文用脉冲衰减法和时间分辨荧光光谱法测量了六种不同稀土离子浓度的Sm_xLa_(1-x)P_5O_4晶体的~4G_(5/2)→~6H_J(J=5/2,7/2,9/2,11/2)四个能级和七种不同稀土离子浓度的Dy_xY_(1-x)P_5O_(14)晶体的~4F_(9/2)→~6H_J(J=15/2,13/2,11/2,9/2)四个能级的荧光寿命和荧光强度。结果指出,在这类晶体中,Sm~(3+)和Dy~(3+)的荧光寿命随着离子的浓度增加而变短,存在着严重的荧光浓度猝灭现象。最后还讨论了浓度与寿命,寿命与荧光强度的关系。

Ce_(0.9)Yb_(0.1)P_5O_(14)晶体的光电压光谱

前文在研究五磷酸铈晶体中Ln~(3+)对Ce~(3+)发光强度的影响时,发现当加入少量的Eu~(3+)和Yb~(3+)离子到CeP_5O_(14)晶体中能使Ce~(3+)的发射产生严重的猝灭现象,以致于用Ce~(3+)的302nm吸收带激发晶体时,观察不到Ce~(3+)的发射,或者十分微弱。令人费解的是Yb~(3+)离子在紫外和可见区无吸收带,Yb~(3+)离子的加入应该成为一个稀释离子,现却使Ce~(3+)的发射产生严

控制气氛光谱法测定纯氧化钬中14个稀土杂质元素

本文介绍的是:使溶液干渣样品在Ar/O_2气氛中交流电弧激发,以基体钬为内标,测定高纯氧化钬中微量稀土杂质。其被测元素的测定下限是:铕、镱和钇各为0.0004％,镧、钐、铒,镝和铥各为0.0016％,铈、钕、钆和铽各为0.0031％,镨和镥各为0.0063％,相对标准偏差均小于7.1％。

Cytoglobosins A-G, Cytochalasans from a Marine-Derived Endophytic Fungus, Chaetomium globosum QEN-14

Financial support from the Ministry of Science and Technology of China (2010CB833802 and 2007AA09Z446) and from the National Science Foundation of China (30910103914) is gratefully acknowledged.

Cloning and sequencing of the phycocyanin gene from Spirulina maxima and its evolutionary analysis (vol 14, pg 307, 2002)

The geneswere cloned for the two apoprotein subunits, alpha and beta, of phycocyanin from the cyanobacterium Spirulina maxima (=Arthrospira maxima) strain F3. The alpha- and beta-subunit gene-coding regions contain 489 bp and 519 bp, respectively. The beta-subunit gene is upstream from the alpha-subunit gene, with a 111-bp segment separating them. Similarities between the alpha-subunits of S. maxima and nine other cyanobacteria were between 58% and 99%, as were those between the beta-subunits. The maximum similarity between the alpha- and beta-subunits from S. maxima was 27%.

贝藻混养系统中贝类食物来源的定量分析

应用稳定碳、氮同位素比值法和脂肪酸标志分析法，较为系统地研究了贝藻混养系统中滤食性贝类的食物来源，评估了大型藻类对混养系统及滤食性贝类的物质贡献。主要研究结果如下： 1.综述了典型生态系统中大型藻类和滤食性贝类各自的生态学地位和作用，大型藻类与滤食性贝类不仅在水体营养盐方面存在互利关系，二者在物质循环与收支方面同样具有耦合性，大型藻类提供的颗粒态有机质可以为滤食性贝类提供饵料来源。 2.总结了稳定同位素比值法和脂肪酸标志法在海洋生态系统食物来源及食物网分析中的应用，并建立了两种方法的具体操作规程。 3.分析了栉孔扇贝Chlamys farreri和海带Laminaria japonica混养系统中海带碎屑形成及释放不同阶段的生态学特征，评估了碎屑对扇贝的饵料贡献。海带在6周内释放了自身约27％的碳；碎屑形成及释放过程中C:N比值显著下降，同时伴随着旺盛的细菌降解，碎屑中也发现有大量硅藻类和原生动物存在。稳定同位素分析证实海带碎屑是混养期间扇贝的主要食物来源。 4.查明了春季胶州湾潮间带自然分布的长牡蛎Crassostrea gigas、紫贻贝Mytilus galloprovincialis和湾内浅海筏式养殖栉孔扇贝的可能食物来源。湾内栉孔扇贝饵料组成中浮游硅藻类为最主要部分，同时混杂有陆源有机质和细菌类物质；潮间带自然生长的牡蛎和贻贝饵料组成中，浮游植物占86.2-89.0％，种类组成中除硅藻外还包括一定比例的金藻和甲藻类；潮间带繁盛的孔石莼Ulva pertusa藻床为两种贝类提供了8.7-11.0％的补充食物来源。 5.揭示了桑沟湾贝藻混养海区春、夏季栉孔扇贝饵料来源组成情况及其季节变化，评估了海带养殖区碎屑碳量季节变化及海带来源碳对扇贝组织碳的贡献。结果表明，湾内贝藻混养区碎屑碳量为75.52-265.19 μg l-1，其在水体总颗粒态有机碳中的比例为25.6-73.8％。海带来源碎屑碳对栉孔扇贝组织碳的贡献比例为14.1-42.8％，且与水体碎屑碳比例的季节变化存在极显著相关性(F=0.992, P=0.004)。5月份湾外海带养殖区水体碎屑碳量为110.12-144.71 μg l-1，显著高于湾内无海带区（75.52 μg l-1），湾外养殖的扇贝组织中海带来源碳比例为22.0-24.1％，显著高于湾内单养区扇贝（9.6％）。估算结果表明，桑沟湾每年收获的6967吨（总湿重）栉孔扇贝中，海带提供了约57.1吨碳，换算为海带干物质为219.6吨。脂肪酸标志分析结果表明，2月份至8月份硅藻类在扇贝饵料组成中比例逐渐下降，而细菌类比例逐渐升高。整个采样期间，EPA/DHA比例较低，说明扇贝饵料组成中可能包括高DHA含量的组分。

Uniformity of karyotypes in Ligularia (Asteraceae : Senecioneae), a highly diversified genus of the eastern Qinghai-Tibet Plateau highlands and adjacent areas

Ligularia, a highly diversified genus in the eastern Qinghai-Tibet Plateau and adjacent areas, was chosen as a suitable subject in which to study speciation patterns in this 'hot spot' area at the chromosomal level. Chromosome numbers and karyotypes were studied in 23 populations of 14 species, most of which are endemic to this area. The basic number x = 29 was confirmed for all species. Ligularia virgaurea was found to have diploid and triploid cytotypes, 2n = 58 and 87. Other species are only diploid, with 2n = 58. The karyotypes of all populations within any species, and all species spanning most sections and covering most of the morphological range in Ligularia, are very similar to each other, belonging to type 2A according to Stebbin's classification. This karyotype was also found in its close allies, e.g. Cremanthodium, Ligulariopsis, Parasenecio, and Sinacalia. Aneuploid reduction of chromosome number from 2n = 60 to 58 and karyotypic variation was found in Ligularia and its allies. Such a chromosomal pattern with few polyploids infers that variation of karyotype structure at the diploid level seems to be the predominant feature of chromosomal evolution in this group and sympatric speciation via hybridization and polyploidization has played a minor role in its species diversity. (C) 2004 The Linnean Society of London

末次盛冰期以来中国陆地生态系统碳储量变化研究

Carbon is an essential element for life, food and energy. It is also a key element in the greenhouse gases and therefore plays a vital role in climatic changes. The rapid increase in atmospheric concentration of CO_2 over the past 150 years, reaching current concentrations of about 370 ppmv, corresponds with combustion of fossii fuels since the beginning of the industrial age. Conversion of forested land to agricultural use has also redistributed carbon from plants and soils to the atmosphere. These human activities have significantly altered the global carbon cycle. Understanding the consequences of these activities in the coming decades is critical for formulating economic, energy, technology, trade, and security policies that will affect civilization for generations. Under the auspices of the International Geosphere-Biosphere Programme (IGBP), several large international scientific efforts are focused on elucidating the various aspects of the global carbon cycle of the past decade. It is only possible to balance the global carbon cycle for the 1990s if there is net carbon uptake by terrestrial ecosystems of around 2 Pg C/a. There are now some independent, direct evidences for the existence of such a sink. Policymarkers involved in the UN Framework Convention on Climate Change (UN-FCCC) are striving to reach consensuses on a 'safe path' for future emissions, the credible predictions on where and how long the terrestrial sink will either persist at its current level, or grow/decline in the future, are important to advice the policy process. The changes of terrestrial carbon storage depend not only on human activities, but also on biogeochemical and climatological processes and their interaction with the carbon cycles. In this thesis, the climate-induced changes and human-induced changes of carbon storage in China since the past 20,000 years are examined. Based on the data of the soil profiles investigated during China's Second National Soil Survey (1979-1989), the forest biomass measured during China's Fourth National Forest Resource Inventory (1989-1993), the grass biomass investigated during the First National Grassland Resource Survey (1980-1991), and the data collected from a collection of published literatures, the current terrestrial carbon storage in China is estimated to -144.1 Pg C, including -136.8 Pg C in soil and -7.3 Pg C in vegetation. The soil organic (SOC) and inorganic carbon (SIC) storage are -78.2 Pg C and -58.6 Pg C, respectively. In the vegetation reservoir, the forest carbon storage is -5.3 Pg C, and the other of-1.4 Pg C is in the grassland. Under the natural conditions, the SOC, SIC, forest and grassland carbon storage are -85.3 Pg C, -62.6 Pg C, -24.5 Pg C and -5.3 Pg C, respectively. Thus, -29.6 Pg C organic carbon has been lost due to land use with a decrease of -20.6%. At the same time, the SIC storage also has been decreased by -4.0 Pg C (-6.4%). These suggest that human activity has caused significant carbon loss in terrestrial carbon storage of China, especially in the forest ecosystem (-76% loss). Using the Paleocarbon Model (PCM) developed by Wu et al. in this paper, total terrestrial organic carbon storage in China in the Last Glacial Maximum (LGM) was -114.8 Pg C, including -23.1 Pg C in vegetation and -86.7 Pg C in soil. At the Middle Holocene (MH), the vegetation, soil and total carbon were -37.3 Pg C, -93.9 Pg C and -136.0 Pg C, respectively. This implies a gain of-21.2 Pg C in the terrestrial carbon storage from LGM to HM mainly due to the temperature increase. However, a loss of-14.4 Pg C of terrestrial organic carbon occurred in China under the current condition (before 1850) compared with the MH time, mainly due to the precipitation decrease associated with the weakening of the Asian summer monsoon. These results also suggest that the terrestrial ecosystem in China has a substantial potential in the restoration of carbon storage. This might be expected to provide an efficient way to mitigate the greenhouse warming through land management practices. Assuming that half of the carbon loss in the degraded terrestrial ecosystem in current forest and grass areas are restored during the next 50 years or so, the terrestrial ecosystem in China may sequestrate -12.0 Pg of organic carbon from the atmosphere, which represents a considerable offset to the industry's CO2 emission. If the ' Anthropocene' Era will be another climate optimum like MH due to the greenhouse effect, the sequestration would be increased again by -4.3 - 9.0 Pg C in China.