脱落酸对UV-C胁迫下小麦幼苗光合特性及抗氧化酶活性的影响

研究了UV-C辐射下短期和长期脱落酸(ABA)处理对小麦幼苗CO2同化作用、羧化效率、光合CO2响应以及抗氧化酶活性等的影响.结果表明,在无UV-C辐射情况下,短期和长期ABA处理能提高光合速率,比对照增加14·69%和20·46%,降低气孔导度,比对照降低14·74%和17·31%,但对胞间CO2浓度和羧化效率影响不大.当受到UV-C辐射时,光合速率、羧化效率、气孔导度和胞间CO2浓度逐渐降低.长期ABA处理变化最小,其次为ABA短期处理,对照降低最大.ABA处理能够提高小麦光合对CO2的响应,UV-C辐射抑制光合对CO2的响应.ABA处理能够提高小麦抗氧化酶(CAT、SOD、POD)活性而降低MDA含量.在UV-C辐射下,CAT活性先升高随后降低,在辐射处理1h时活性达最大值,ABA处理的SOD和POD活性先升高后降低,且ABA长期处理比短期处理增加明显,对照则逐渐降低.ABA处理可能通过提高小麦CO2同化作用和抗氧化酶活性增强对UV-C胁迫的抗性,且ABA长期处理比短期处理效果更明显.

增强UV-C辐射作用下小麦和豌豆幼苗光合响应及其相对抗性

以小麦和豌豆为材料,研究了UV-C辐射(波长<280nm)对叶片光合特性及抗氧化酶活性的影响.结果表明:UV-C辐射增强,可使豌豆叶片光合速率减弱,气孔导度、胞间CO2浓度、蒸腾速率和羧化效率明显降低,而对小麦叶片上述各项指标的影响则是先增加、后降低;在UV-C辐射下,豌豆的CO2补偿点逐渐升高,而小麦的CO2补偿点先降低、后升高.UV-C辐射除了使豌豆的POD活性和小麦的SOD活性逐渐降低外,其他抗氧化酶活性则呈先升高、后降低的变化趋势.小麦对短时间UV-C辐射的抗性比豌豆强,但随着UV-C辐射时间的延长,小麦和豌豆的抗氧化酶活性均降低,光合作用减弱.

蛭弧菌J26发酵生产维生素C前体产物的鉴定

采用有机溶剂沉淀方法去除J26发酵液中杂蛋白，通过离子交换、活性炭吸附去除发酵液中杂质，最后蒸发浓缩获得无色透明结晶。通过对所获晶体的红外光谱分析、熔点测定、纸层析鉴定，证明所获晶体确为维生素C前体2－酮基－L－古龙酸（2－KGA）。

中国东北西部地区沙质荒漠化过程与植被动态关系的生态学研究——群落多样性与沙质荒漠化过程

依据东北西部沙质荒漠化地区植被的分类与排序,分析了不同演替梯度上植被群落多样性指数与DCA排序坐标值的相关关系,利用其探讨群落多样性与沙质荒漠化过程的关系;科尔沁沙地、呼伦贝尔沙地,1)植物群落的生态优势度λ、Renyi的均匀度E1与群落分布的地下水位有显著的相关关系;2)植物群落Hill的多样性指数H0,H1、Hill的均匀度Eh、Hill指数的均匀度E′1与海拔、湿润系数、Thornthwaite指数、降水量、地下水位、放牧干扰等有显著的相关关系;3)植物群落Renyi的多样性指数N0,N1、Heip修正的均匀度Ep、Alatalo修正的均匀度E′h与经度、温暖指数、冷暖指数、Thornthwaite指数、土壤有机质、地下水位、放牧等干扰有显著的相关关系。4)呼伦贝尔沙地的完工-海拉尔沙带,樟子松林、贝加尔针茅羊草草甸草原;科尔沁沙地的油松林、羊草草甸草原、丛生禾草草原具有较高的多样性,各群落类型随着沙质荒漠化过程的逐渐加剧,物种丰富度逐渐降低,其递减趋势分为旱生沙化系列、湿生沙化系列、盐水至水生系列。按各群落类型的物种丰富度递减顺序可分为6个级别,6个级别所含的群落类型分别对应着稳定沙地(A、B),固定沙丘(C),半固定沙丘(D),半流动沙丘(E),流动沙丘(F)。

Phenolphthalein immobilized membrane for an optical pH sensor

A phenolphthalein immobilized cellulose membrane for an optical pH sensor was described. The phenolphthalein was first reacted with the formaldehyde to produce a series of prepolymers with many hydroxymethyl groups. In this paper, the prepolymers was abbreviated to phenolphthalein-formaldehyde (PPF). Then the PPF was covalently immobilized to the diacetylcellulose membrane via hydroxymethyl groups. Finally the membrane was hydrolyzed in the 0.1 M NaOH solution for 24 h to reduce the response time. Advantageous features of the pH-sensitive membrane include (a) a large dynamic range from pH 8.0 to 12.50, or even broader, (b) rapid response time (2-30 s), (c) easy of fabrication, and (d) a promising material for determination of high pH values. The immobilized PPF has a broader dynamic range from 8.0 to 12.50 than the free phenolphthalein from pH 8.0 to 11.0, and this was due to the newly produced methylenes in our investigation.

Preparation of a carbon supported Pt catalyst using an improved organic sol method and its electrocatalytic activity for methanol oxidation

The organic sol method for preparing ultrafine transition metal colloid particles reported for the first time by Bonnemann et al. [H. Bonnemann, W Brijoux, R. Brinkmann, E. Dinjus, T. Jou beta en, B. Korall, Angew. Chem. Int. Ed. Engl., 30 (1991) 1312] has been improved in this paper. The improved organic sol method uses SnCl2 as the reductant and methanol as the organic solvent. Thus, this method is very simple and inexpensive. It was found that the average size of the Pt particles in the Pt/C catalysts can be controlled by adjusting the evaporating temperature of the solvent. Therefore, the Pt/C catalysts prepared by the same method are suitable for evaluating the size effect of the Pt particles on electrocatalytic performance for methanol oxidation. The results of the X-ray diffraction (XRD) and transmission electron microscopy (TEM) showed that when the evaporating temperatures of the solvent are 65, 60, 50, 40, and 30 degrees C, the average sizes of the Pt particles in the Pt/C catalysts prepared are: 2.2, 3.2, 3.8, 4.3, and 4.8 nm, respectively. The X-ray photoelectron spectroscopic (XPS) results demonstrated that the small Pt particles are easily oxidized and the decomposition/adsorption of methanol cannot proceed on the surfaces of Pt oxides.

Hydrothermal synthesis and crystal structure of a novel layered compound [Ni(C10H8N2)(2)V3O8.5]

A novel layered compound, [Ni(C10H8N2)(2)V3O8.5], was hydrothermally synthesized and structurally characterized by single crystal X-ray diffraction. The compound crystallizes in monoclinic system, space group P21/c with a = 1.551 8(3) nm, b = 1.476 1(3) nm, c = 1.048 3(2) nm, beta = 92.02(3), V = 2.399 8(8) nm(3), Z = 4, R = 0. 046 7, wR(2) = 0. 085 9.

A phenomenological study of the structural relaxation of an inorganic glass (Li(2)O2SiO(2))

The structural relaxation process of an inorganic glass (Li(2)O2SiO(2)) has been studied by differential scanning calorimetry. The sample is subjected to different thermal ageing histories with isothermal stages at an ageing temperature of T-g - 30 degrees C for different ageing times and at an ageing time of 16 h for different ageing temperatures. A four-parameter Tool-Narayanaswamy-Moynihan (TNM) model, is applied to simulate the normalized specific-heat curves measured. The ageing-temperature and ageing-time dependence of the structural relaxation parameters in the TNM model is obtained. (C) 1998 Elsevier Science S.A. All rights reserved.

Crystallization behaviour of poly(ether ether ketone)/poly(ether sulfone) block copolymer

The crystallization and melting behaviours of a multiblock copolymer comprising poly(ether ether ketone) (PEEK) and poly(ether sulfone) (PES) blocks whose number average molecular weights <((M)over bar (n)'s)> were 10 000 and 2900, respectively, were studied. The effect of thermal history on crystallization was investigated by wide-angle X-ray diffraction measurement. A differential scanning calorimeter was used to detect the thermal transitions and to monitor the energy evolved during the isothermal crystallization process from the melt. The results suggest that the crystallization of the copolymer becomes more difficult as compared with that of pure PEEK. The equilibrium melting point of the copolymer was found to be 357 degrees C, about 30 degrees C lower than that of pure PEEK. During the isothermal crystallization, relative crystallinity increased with crystallization time, following an Avrami equation with exponent n approximate to 2. The fold surface free energy for the copolymer crystallized from the melt was calculated to be 73 erg cm(-2), about 24 erg cm(-2) higher than that of pure PEEK. Copyright (C) 1996 Elsevier Science Ltd.

CRYSTALLIZATION OF POLY(ARYL-ETHER-ETHER-KETONE)S BLENDS

The crystallization and melting behaviour of poly(aryl-ether-ether-ketone) (PEEK) in blends with another polymer of the same family containing a bulky pendant phenolphthalein group (PEK-C) have been investigated by thermal methods. The small interaction energy density of the polymer pair (B = -8.99 J/cm3), evaluated from equilibrium melting point depression, is consistent with the T(g) data that indicate partial miscibility in the melt. Two conjugated phases are in equilibrium at 430-degrees-C: one is crystallizable and contains about 35 wt% of PEK-C; the other, containing only 15 wt% of PEEK, does not form crystals upon cooling and it interferes with the development of spherulites in the sample. The analysis of kinetic data according to nucleation theories shows that crystallization of PEEK in the explored temperature range takes place in Regime III and that a transition to Regime II might be a consequence of an increase in the amount of non-crystallizable molecules in the PEEK-rich phase. A composition independent value of the end surface free energy of PEEK lamellae has been derived from kinetic data (sigma-e = 40 +/- 4 erg/cm2) in excellent agreement with previous thermodynamic estimates. A new value for the equilibrium melting temperature of PEEK (T(m)-degrees = 639 K) has been obtained; it is about 30-degrees-C lower than the commonly accepted value and it explains better the "memory effect" in the crystallization from the melt of this high performance polymer.

Formation and early development of tetraspores of Gracilaria lemaneiformis (Gracilaria, Gracilariaceae) under laboratory conditions

Morphological and culture studies of tetraspores of Gracilaria lemaneiformis were carried out under laboratory conditions. Relationships of germination rate, diameter and survival rate of tetraspores from 1st generation branches with grads of temperature and irradiance were determined, respectively. The result showed that 1st generation branches is in the majority of the tetraspores shedding and tetraspores from which had highest survival rates than other parts of the sporophytic plant. The time tetraspores used developing from giant unicells to diads, which both existed on the epidermis, then to tetraspores off the matrix, was only approximately 3 weeks all through. However, tetraspores spent more than two months developing into germlings of gametophytes. It was shown that temperature variation (10, 15, 25, 30 degrees C) with the light of 30 mu mol m(-2) s(-1) had significant effects on the germination rate and diameter, but had no apparent effect on survival rate (ANOVA, P < 0.01). Germination rates of tetraspores reached the maximum at 20 degrees C, which was significantly higher than those at other temperature levels (P < 0.01), whereas 15 degrees C seemed to be optimal temperature for the diameter. All the three growth parameters (germination rate, diameter and survival rate) yield highly significant variations with irradiance treatments at room temperature (ANOVA, P < 0.01). The optimal germination rate was detected at the irradiance of 30 mu mol m(-2) s(-1) (P < 0.01). The photon flux density which exceeds 480 nnol m(-2) s(-1) have apparently negative effect on diameter and survival rate. (c) 2005 Elsevier B.V. All rights reserved.

Flux and fate of Yangtze river sediment delivered to the East China Sea

Numerous cores and dating show the Yangtze River has accumulated about 1.16 x 10(12) t sediment in its delta plain and proximal subaqueous delta during Holocene. High-resolution seismic profiling and coring in the southern East China Sea during 2003 and 2004 cruises has revealed an elongated (similar to 800 km) distal subaqueous mud wedge extending from the Yangtze River mouth southward off the Zhejiang and Fujian coasts into the Taiwan Strait. Overlying what appears to be a transgressive sand layer, this distal clinoform thins offshore, from similar to 40 in thickness between the 20 and 30 m water depth to < 1-2 in between 60 and 90 m water depth, corresponding to an across shelf distance of less than 100 km. Total volume of this distal mud wedge is about 4.5 x 10(11) m(3), equivalent to similar to 5.4 x 10(11) t of sediment. Most of the sediment in this mud wedge comes from the Yangtze River, with some input presumably coming from local smaller rivers. Thus, the total Yangtze-derived sediments accumulated in its deltaic system and East China Sea inner shelf have amounted to about 1.7 x 10(12) t. Preliminary analyses suggest this longshore and across-shelf transported clinoform mainly formed in the past 7000 yrs after postglacial sea level reached its mid-Holocene highstand, and after re-intensification of the Chinese longshore current system. Sedimentation accumulation apparently increased around 2000 yrs BP, reflecting the evolution of the Yangtze estuary and increased land erosion due to human activities, such as fanning and deforestation. The southward-flowing China Coastal Current, the northward-flowing Taiwan Warm Current, and the Kuroshio Current appear to have played critical roles in transporting and trapping most of Yangtze-derived materials in the inner shelf, and hence preventing the sediment escape into the deep ocean. (c) 2006 Elsevier B.V. All rights reserved.

滤食性贝类养殖活动对海域生态系统的影响及生态容量评估

滤食性贝类以水体中的浮游植物和有机碎屑为主要食物，养殖海域的初级生产力水平、水动力学特性等生态环境因子的差异，不仅直接影响养殖贝类的产量，而且也与贝类养殖活动对生态环境的压力密切相关。由于养殖的种类、密度、方式及养殖海域的特性不同，关于贝类对生态环境的影响往往有不同的结果。本文以我国北方大连獐子岛扇贝底播海区和荣成桑沟湾贝类筏式养殖区为研究对象，采用现场调查、室内受控实验及生态数值模型模拟方法，分析研究了滤食性贝类对海域生态系统的影响，对这两个海域贝类养殖的生态容量进行了初步的评价。 主要结果： 1. 獐子岛海域底播贝类养殖活动对该海域生态系统的影响较小。非参数统计—符号检验的结果显示，养殖区与非养殖区之间的溶解性无机氮、磷酸盐浓度、氮磷摩尔比及浮游植物群落结构没有统计学上的差异（p>0.05）。但是从变化的趋势上来看，贝类养殖活动对水域环境的某些参数有一定程度的影响。例如，獐子岛底播贝类养殖海域的溶解性无机氮以氨氮为主，可能与贝类的代泄活动有关；不论是叶绿素浓度，还是网采浮游植物的生物量都是贝类高密度养殖区<贝类低密度养殖区<非养殖区（7月份除外），这种趋势可能与贝类的摄食压力有关。 桑沟湾各环境指标表现出明显的区域性。除春季外，非养殖区的DIN浓度高于各养殖区。在春季和冬季，贝类区的磷酸盐浓度显著降低；而硅酸盐浓度在夏季和秋季显著增大。综合分析DIN、PO4-P及SiO3-Si三个参数的四季变化，海带区、贝藻区及贝类区发生显著性变异的概率分别为25%，42%和50%，贝类区的变异较大。浮游植物、小型浮游动物的生物多样性指数都是以非养殖区为最高，贝类区的多样性指数最低。尤其是浮游动物的丰度，贝类区显著低于非养殖区。 2. 利用挪威的MOM (Modelling-Ongrowing fish farms-Monitoring)评价系统，评价了桑沟湾长期大规模的贝藻筏式养殖活动对底质环境的压力。在桑沟湾设10个取样站位，共获得66个底泥样品。比较了MOM－B评价系统的3组参数的季节变化特性。结果显示，底质条件属于1级，说明桑沟湾贝藻长期大规模的养殖活动对底质环境的压力较低。结合桑沟湾的环境及养殖特点，分析了压力较低的原因。 3. 经计算，2006年中国海水养殖的贝类和藻类使用浅海生态系统的碳可达396万吨，并通过收获从海中移出至少136.9万吨的碳。从1995年至2006年，养殖大型藻类和贝类累计移出的碳分别约为365万吨和893万吨，总计达1258万吨。证明了浅海的贝类和藻类养殖活动直接或间接地使用了大量的海洋碳，提高了浅海生态系统吸收大气CO2的能力。 4. 采用模拟现场生物沉积法测定了虾夷扇贝的滤水率、摄食率等生理指标及其与贝类个体大小、水温的关系。虾夷扇贝单位个体的滤水率与组织干重的关系符合幂函数方程CR=a×DWb，b值在0.45～0.65范围内；水温对虾夷扇贝滤水率的影响极其显著(p<0.01)，温度（T）与滤水率（CR）呈抛物线的关系：CR=-0.0009T2+0.0188T-0.0306，水温为10℃时，虾夷扇贝的滤水率、摄食较大。 5. 采用模拟现场流水法测定了3种滤食性贝类的食物选择性。紫贻贝、长牡蛎及栉孔扇贝分别对直径4m, 6m 和 8m颗粒的保留效率达到最大值；对小颗粒（直径2m）的保留效率分别为17%, 19% 和 8％。栉孔扇贝对食物数量和质量浓度的变化相对敏感，随着数量浓度的增加，栉孔扇贝倾向于摄食较大的颗粒；随着颗粒食物质量浓度的增加，倾向于摄食较小的颗粒。 6. 獐子岛海域四个航次的调查结果显示，叶绿素浓度在1.23～2.85mg.m-3范围内，均值为1.78±0.57 mg.m-3；初级生产力的变化范围为30.4～117.0 mg C. m-2.d-1，平均值为76.6±41.9 mg C. m-2.d-1。通过虾夷扇贝生物量断面调查，获得了虾夷扇贝的壳高频率分布情况，7月份的众数值出现在100 mm，10月份壳高的众数值为80 mm。利用以上测定的虾夷扇贝的滤水率等基本生物学特性，结合虾夷扇贝的年产量、海域面积和有关的水文状况等数据，计算了滤水效率、摄食压力、调节比率3个食物限制性指标参数，全年的均值分别为0.048, 0.31和 0.16，都小于1，说明目前该海域虾夷扇贝的养殖量未达到养殖容量。 7. 利用STELLA软件，建立的桑沟湾贝藻养殖的数值模型，模拟了叶绿素a浓度及氮磷营养盐的周年变化情况，及其对贝类养殖生物量变化的响应。以叶绿素a浓度为指标，初步探讨了桑沟湾贝类的生态容量。

模拟增温对短穗兔耳草生长特征的影响

[目的]探讨短穗兔耳草个体对模拟增温的响应。[方法]采用国际冻原计划（ITEX）模拟增温对植物影响的研究方法,将温棚从小到大的顺序依次设为A、B、C、D、E5个温度梯度,分析不同温度梯度下短穗兔耳草个体生长特征的变化,研究模拟增温对短穗兔耳草生长特征的影响。[结果]随着温棚直径的减小,温度（地表温度和土壤温长）逐渐升高。与对照相比,A、B、C、D、E5个处理分别提高了2.68、1.57、1.20、1.07和0.69℃（地表气温）,1.74、1.06、0.80、0.60和0.30℃（土壤温度）。短穗兔耳草从对照至A温室随着温度的升高,叶片数、叶片高度逐渐增加,而匍匐茎逐渐减少。[结论]叶片数变化与温度（地表温度和地温）呈正相关关系,增温促进了短穗兔耳草的营养生长,抑制了它的克隆繁殖能力。

Dissection of rye B chromosomes, and nondisjunction properties of the dissected segments in a common wheat background

The rye B chromosome is a supernumerary chromosome that increases in number in its host by directed postmeiotic drive. Two types of rye B chromosomes that had been introduced into common wheat were dissected into separate segments by the gametocidal system to produce a number of rearranged B chromosomes, such as telosomes, terminal deletions and translocations with wheat chromosomes. A total of 13 dissected B chromosomes were isolated in common wheat, and were investigated for their nondisjunction. properties. Rearranged B chromosomes, separated from their B-specific repetitive sequences on the distal part of the long arm, did not undergo nondisjunction, and neither did a translocated wheat chromosome carrying a long-arm distal segment containing the B-specific repetitive sequences. However, such rearranged B chromosomes, missing their B-specific sequences could undergo nondisjunction when they coexisted with the standard B chromosome or a wheat chromosome carrying the B-specific sequences. Deficiencies of the short arm did not completely abolish the nondisjunction properties of the B chromosome, but did reduce the frequency of nondisjunction. These results confirmed previous suggestions that the directed nondisjunction of the rye B chromosome is controlled by two elements, pericentromeric sticking sites and a trans-acting element carried at the distal region of the long arm of the B chromosome. Additionally, it is now shown that the distal region of the long arm of the B chromosome which provides this function is that which carries the B-specific repetitive sequences.