5年模拟增温后矮蒿草草甸群落结构及生产量的变化

5年模拟增温后观察表明,植物生长期4～9月暖室内10 cm、20 cm地下土壤平均增温1.86℃,10 cm、20 cm地上空气平均增温1.15 ℃,地表0 cm平均增温1.87 ℃,且增温在植物生长初期大于生长末期及枯黄期.在模拟增温初期年生物量比对照高,增温5年后生物量反而有所下降.增温使禾草类植物种增加,杂草减少.从表面来看,增温可使植物生长期延长,利于增大生物量,实际受热效应作用,植物发育生长速率加快,植物成熟过程提早,生长期反而缩短,加之玻璃纤维的存在使暖室内外温度交换减缓,减少了温度日变化,限制干物质积累,终久导致生物量减少.这说明小气候的作用,环境条件诱发土壤结构变化,植被的种群结构也随之改变,甚至出现演替的过程,全球变暖不仅对植物的生物生产力影响较大,而且对植被类型的演替有着不可忽视的作用.

毛冠菊属系统位置的核形态证据(英文)

首次记载了毛冠菊属 2种 4居群的核形态资料。两种植物的染色体间期和前期染色体为复杂型和中间型。狭舌毛冠菊两居群的染色体数目与核型公式为 2n =1 8=1 4m + 2sm + 2st( 2SAT) ;毛冠菊两居群的染色体数目与核型公式为 2n =1 8=1 4m + 2sm( 2SAT) + 2st。它们分别代表了整个毛冠菊属的两组植物 ,并包含了形态学上最原始的种类 ,因此 ,该属的染色体基数可能为x =9。核形态证据表明毛冠菊属放在紫菀族比放在旋覆花族和千里光族中更为合理。

根田鼠身体大小的性二型

在雌雄异体的有性生物中，反映身体结构和功能特征的某些变量在两性之间常常出现固有的和明显的差别，使得人们能够以此为根据判断一个个体的性别，这种现象被称为性二型 (sexualdimorphism)。国外大量研究表明 ,哺乳动物性二型现象十分普遍 ,并且 ,在大多数情况下 ,雄性个体大于雌性个体；国内同类研究还不多，仅见周立等 、盛和林、陈国芳、杜铭章分别对高原鼠兔(Ochotonacurzoniae)、黄鼬 (Mustelasibirica)、摇蚊和海蛇的性二型现象作过报道 ,但均未分析其产生原因。本研究试图从两个方面探讨根田鼠 (Microtusoeconomus)身体大小的性二型现象。其一 ,检验成年根田鼠体重的性别差异 ,并在实验室饲养条件下 ,繁殖后代, 分析个体发育中根田鼠体重的性别差异, 目的在于检验性二型出现时间与青春期性发育相关的假设; 其二, 根据自然条件下雌雄根田鼠繁殖期间的能量需求差异以及由此产生的后果, 分析捕食压力与性二型现象的关系, 以探讨性二型现象的进化原因。

Genetic variation and phylogeographic history of Picea likiangensis revealed by RAPD markers

Repeated cycles of retreat and recolonization during the Quaternary ice ages are thought to have greatly influenced current species distributions and their genetic diversity. It remains unclear how this climatic oscillation has affected the distribution of genetic diversity between populations of wind-pollinated conifers in the Qinghai-Tibetan region. In this study, we investigated the within-species genetic diversity and phylogenetic relationships of Picea likiangensis, a dominant forest species in this region using polymorphic DNA (RAPD) markers. Our results suggest that this species has high overall genetic diversity, with 85.42% of loci being polymorphic and an average expected heterozygosity (H (E)) of 0.239. However, there were relatively low levels of polymorphism at population levels and the differences between populations were not significant, with percentages of polymorphic bands (PPB) ranging from 46.88 to 69.76%, Nei's gene diversity (H (E)) from 0.179 to 0.289 and Shannon's indices (Hpop) from 0.267 to 0.421. In accordance with our proposed hypothesis, a high level of genetic differentiation among populations was detected based on Nei's genetic diversity (G (ST) = 0.256) and AMOVA analysis (Phi (st) = 0.236). Gene flow between populations was found to be limited (Nm = 1.4532) and far lower than reported for other conifer species with wide distribution ranges from other regions. No clusters corresponding to three morphological varieties found in the south, north and west, respectively, were detected in either UPGMA or PCO analyses. Our results suggest that this species may have had different refugia during the glacial stages in the southern region and that the northern variety may have multiple origins from these different refugia.

Analysis of saturated free fatty acids from pollen by HPLC with fluorescence detection

A sensitive method for the determination of free fatty acids using 2-(2-(anthracen-10-yl)-1H-naphtho[2,3-dimidazol-1-yl) ethyl-p-toluenesuIfonate (ANITS) as tagging reagent with fluorescence detection has been developed. ANITS could easily and quickly label fatty acids in the presence of the K2CO3 catalyst at 90 degrees C for 40 min in N,N-dimethylformamide solvent. From the extracts of rape bee pollen samples, 20 free fatty acids were sensitively determined. Fatty acid derivatives were separated on a reversed-phase Eclipse XDB-C8 column by HPLC in conjunction with gradient elution. The corresponding derivatives were identified by post-column APCI/MS in positive-ion detection mode. ANITS-fatty acid derivatives gave an intense molecular ion peak at mlz [M+H](+); with MS/MS analysis, the collision-induced dissociation spectra of m/z [M+H](+) produced the specific fragment ions at mlz [M-345](+) and mlz 345.0 (here, m/z 345 is the core structural moiety of the ANITS molecule). The fluorescence excitation and emission wavelengths of the derivatives were lambda(ex) = 250 nm and lambda(em) = 512 nm, respectively. Linear correlation coefficients for all fatty acid derivatives are > 0.9999. Detection limits, at a signal-to-noise ratio of 3 : 1, are 24.76-98.79 fmol for the labeled fatty acids.

铁同位素测定化学前处理方法初步研究

样品纯化分离的效果对铁同位素比值的精确测定起着至关重要的作用.本文通过对GSB Fe试剂标准、重金属混和标准、水系沉积物标准、植物标准及自然样品(包括湖泊水、沉积物和颗粒物等)预处理实验研究,并在Bio-Rad AGMP-1 100～200目氯化物型阴离子交换柱上进行分离,回收率达104%,基质的去除较为彻底,初步建立了铁同位素测定的化学纯化分离方法.

恩施鱼塘坝自然硒的发现及其初步研究

在湖北恩施渔塘坝发现了罕见的自然硒矿物，同一地域内产出自然硒矿物的规模和多种成因类型并存的现象为首次报道。按自然硒的形成环境和赋存条件将其分为三种，分别是碳质硅质岩和硅质碳质页岩中的原生自然硒，表生环境氧化还原作用形成的自然硒和“石煤”自燃形成的自然硒晶体。自然硒矿物的发现将为硒的矿物学、矿床地球化学、环境地球化学提供新的认识和研究空间。

峨眉山大火成岩省Cu—Ni—PGE成矿作用－－几个典型矿床岩石地球化学特征的分析

峨眉山大火成岩省岩浆型Cu—Ni—PGE矿化岩体广泛分布，构成峨眉山地幔柱成矿系统中一个非常重要的成矿系列。本文剖析了峨眉山大火成岩省该类矿床的分布及部分典型矿床的地质地球化学特征和矿化特征，揭示了成矿岩体统一的地 幔柱成因，阐述了Cu—Ni—P( E成矿作用与峨眉山地幔柱岩浆活动体系的关系，探讨了由于岩浆演化过程及硫化物熔离富集过程的差异所导致的矿化类型变异。指出Cu—Ni—PGE矿床成矿岩体原始岩浆为地幔柱高程度熔融的高镁玄武岩浆，成矿岩体与峨眉山低钛玄武岩同源，矿化岩体主要产于峨眉山地幔柱活动模型的内带低钛玄武岩分布区；金宝山、朱布、力马河、杨柳坪矿床分别代表峨眉山地幔柱Cu—Ni—PGE成矿作用不同成矿机制的端员类型。

岩石学混合计算在岩浆结晶分异作用研究中的应用——以云南白马寨镍矿区煌斑岩为例

公式C^1L=C^1O,LF^(D-1)岩浆结晶分异过程中的微量元素地球化学模型，但如何确定式中残余熔体的重量百分比(F)和熔体中分离出来的矿物相的总分配系数(D^1)一直是个难题。本文介绍了一种直接计算出残余熔体比例(F)和岩浆结晶矿物比例(以此计算出D^1)的方法——岩石学混合计算法的基本原理，以云南白马寨镍矿区煌斑岩为例，介绍了该方法在岩浆结晶分异作用研究中的应用。

陆相热水沉积成因硅质岩与超大型锗矿床的成因—— 以临沧锗矿床为例

临沧锗矿床的硅质岩中存在大量的热水沉积构造和植物化石, 该硅质岩富SiO2 , 低TiO 2和Al2O3, Al/(Al+Fe+Mn)比值平均为0.010, 明显富集Ge, Sb, As, W; 其次Cs, U, Mo和Tl有不同程度的富集, 稀土总量一般小于1 μg/g, 最大2.324 μg/g , 相对富集LREE; δ Eu为0.452 ~ 5.141, δ Ce为 0.997 ~ 1.174; 稀土元素北美页岩标准化模式呈平坦状或向左倾斜; 氧同位素组成与热泉硅华类似. 上述特征表明本区硅质岩属陆相热水沉积成因. 硅质岩作为中寨锗矿体的顶板或夹层, 在空间上与锗矿体紧密接触. 硅质岩中含锗5.6 ~ 360 μg/g, 平均78 μg/g. 靠近硅质岩的煤中锗含量明显升高. 随着煤中锗含量的不断升高, 含矿煤的特征微量元素比值及稀土元素的球粒陨石标准化分配模式与硅质岩越来越相似. 临沧锗矿床煤中锗可能主要由与煤层形成近同时的、以热水成因硅质岩为标志的热水活动带入.

The chemical nature of carbonaceous deposits and their role in methane dehydro-aromatization on Mo/MCM-22 catalysts

Various carbonaceous deposits are formed during the course of methane dehydro-aromatization (MDA) under non-oxidative conditions on Mo/MCM-22 catalysts. These carbon species were investigated by various temperature-programmed techniques such as TPH and TPCO2, combining with TPO and TGA results in order to reveal their chemical nature and determine their amounts. The TPO profiles recorded from coked Mo/MCM-22 catalysts show two temperature peaks: one at about 756 K and the other at about 876 K. The coke amounts related to these two peaks were determined on the basis of the corresponding corrected and deconvoluted TPO profiles, combining with the TGA profiles concerned.