140 resultados para B-1 Fields


Relevância:

80.00% 80.00%

Publicador:

Resumo:

本研究用线粒体细胞色素b 基因全序列和ND4 基因序列探讨了哀牢髭蟾 (Vibrissaphora ailaonica)分子亲缘地理学和保护遗传学,利用线粒体细胞色素b、 控制区全序列和部分12SrRNA 基因序列研究了分布于中国的红瘰疣螈 (Tylototriton verrucosus)分子亲缘地理学和保护遗传学。 哀牢髭蟾为生活于高海拔生境(大约2000-2600m)的濒危蛙类。各种致危因 素引起了关于对小的、隔离种群长期存活的关注,然而迄今没有关于该物种遗传 多样性的报道。本论文首次研究了分布于中国云南省的哀牢髭蟾的亲缘地理学和 保护遗传学。对采自于9 个种群81 个个体,我们应用线粒体mtDNA cyt b 和 ND4 基因共计1990bp, 获得了51 个单倍型。系统发育分析显示三个分化较深且互为单 系的族群,大致相应于分别被元江和藤条江河谷分开的三个地理单元(元江以东、 金平和藤条江以西地理单元),暗示了长期的地理隔离分化。分子变异等级分析 (AMOVA)显示遗传变异主要为三个地理单元之间(81.68%)和种群内的个体之 间(11.26%)。三个地理单元显著的地理分布暗示在空间和时间上的隔离,这与中 国西南地区在晚中新世到上新世的哀牢山的造山运动和隆升所引起的重要的气候 和古地质变化时间相一致。我们推测低海拔干热河谷可能是三个地理单元之间基 因交流受限的主要生态障碍。根据上述研究结果,我们建议对这三个遗传分化显 著的地理单元,元江以东地区、金平地区、藤条江以西地区作为独立的管理单元 分别加以保护。 本研究通过测定中国横断山区的红瘰疣螈(Tylototriton verrucosus)17个采集 点的123个红瘰疣螈标本的线粒体mtDNA Cyt b、D-loop和12SrRNA三个基因片段 (2347 bp)序列,首次研究了红瘰疣螈在横断山区的群体遗传结构和分子系统地理格 局,并讨论了T. shanjing的物种有效性。基于123个样品定义的49个单倍型的贝叶 斯和NJ系统发育分析表明:(1) T. verrucosus和T. shanjing均未各自构成单系,而是 共同构成一个单系群;(2) 横断山区的红瘰疣螈分为3个线粒体DNA地理单元,即滇 东南、滇中-滇西和片马地理单元,并且地理单元间不存在共享单倍型,说明红瘰 疣螈具有明显的系统地理分布格局。AMOVA分析同样表明3个地理单元之间存在 显著差异,并且分子变异主要发生在3个地理单元间(62.4%)。T. shanjing与T.verrucosus的mtDNA cyt b 序列差异平均值仅为1.1%,明显小于它们与两外群(贵 州疣螈和大凉疣螈)及外群间的遗传距离(6.5-9.9%)。因此,根据T. verrucosus和 T.shanjing的遗传差异以及系统发育分析结果都不支持T. shanjing的物种地位,T. shanjing为T. verrucosus的同物异名,并建议恢复T. verrucosus的中文名红瘰疣螈。 基于上述结果,我们建议将分布于滇东南、滇中-滇西、片马地区的红瘰疣螈作 为三个独立的管理单元分别加以保护。

Relevância:

80.00% 80.00%

Publicador:

Resumo:

研究了双子带占据的In0.52Al0.48As/In0.53Ga0.47As单量子阱中磁电阻的Shubnikov-de Haas(SdH)振荡效应和霍耳效应,获得了不同子带电子的浓度、迁移率、有效质量和能级位置.低磁感应强度(B〈1.5T)下由迁移率谱和多载流子拟合相结合的方法得到的各子带电子浓度与通过SdH振荡得到的结果一致.在d^2ρ/dB^2-1/B的快速傅里叶变换谱中,观察到除了通常强烈依赖温度的对应于各子带的频率f1和f2以及f1的倍频(2f1)外,还观察到对温度不敏感的频率f1-f2.这是由于量子阱中不同子带的电子具有相近的有效质量,两个子带之间发生了强烈的磁致子带间散射.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

长白山是北温带寒冻地区苔藓植物的典型代表场所,苔藓种类敏多,遍布各垂直分布带,在生态系统的能量流动和物质循环中起着重要作用。本文从苔藓的光合生理和水分关系入手,着重探讨了苔藓植物的光合生理过程与生态适应机制的关系。获得的结果表明:1、苔藓植物有很强的利用弱光能力,叶绿素含量高,叶绿素a/b在1.1-1.9之间,测得的五种苔藓光补偿为30-45μmolm~(-2)s~(-1),光饱和点在300-360μmolm~(-1)s~(-1)。最适条件下,光合速率最大的是提灯藓约为4.69(mgCO_2/gdm·h),最小的是垂枝藓为0.94。苔藓CO_2补偿点在44-103ppm之间。2、阔叶红松林中苔藓的光合最适温度为20 ℃针叶林中苔藓的光合最适温度为15 ℃。苔藓的光合及呼吸能力随海拔升高而降低。3、大部分苔藓的光合作用最适含水量为5(gH_2O/dw)左右。垂枝藓在含水量下降至4.0(gH_2O/dw)时净光合为零,塔藓为1.5-2.0左右,其他种小于1。垂枝藓、塔藓有较多水分贮存于死的中轴内。4、塔藓失水最快,毛疏鲜较慢。五种苔藓都有很强的耐干燥能力,空气中短期干旱对光合能力不产生影响。这些结果表明:苔藓是一个C3植物,具有典型的阴性植物特征,有较强的环境适应能力和高度的抗逆性。

Relevância:

80.00% 80.00%

Publicador:

Resumo:

本论文由四部分组成。第一部分报道了佛手参提取物的化学成分研究,建立了活性成分含量测定的高效液相测定和指纹图谱研究,采用液质联用技术鉴定了主要色谱峰;第二部分报道了丹参及其复方制剂的特征图谱研究;第三部分探讨了两面针生物碱的电喷雾质谱裂解规律,并采用液质联用技术分离鉴定了提取物中的多种生物碱。第四部分概述了液质联用在药物代谢研究中的运用。 第一部分包括第一、第二和第三章。第一章针对佛手参(Gymnadeniaconopsea)块茎的甲醇提取物,采用大孔树脂和反相硅胶柱层析等各种分离方法,共分离鉴定出4 个化合物,通过波谱分析将它们的结构确定为dactylorhin B (1)、loroglossin (2)、dactylorhin A (3)和militarine (4)。这4 个化合物均是首次从佛手参中分离得到的琥珀酸葡萄糖苷类成分。第二章采用高效液相色谱法对西藏、四川、河北、青海和尼泊尔等不同地区产的十个佛手参样品进行腺嘌呤核苷和对羟基苯甲醇的定量分析,结果表明这2 个成份可视为佛手参的特征成分,但也注意到产地不同该2 个特征成分的含量也有所不同。第三章采用标准中药指纹图谱相似度计算软件,以10 个佛手参样品HPLC 图谱的平均值为相似性评价对照模板,对10 个样品进行了相似度评价,并经液质联用分析指认了7 个共有峰,分别为腺嘌呤核苷(1)、对羟基苯甲醇(2)、对羟基苯甲醛(3) 、dactylorhin B(4) 、loroglossin(5)、dactylorhin A(6)和militarine(7)。 第二部分包括第四、第五、第六和第七章。第四章运用电喷雾质谱检测了对照药材和五个不同产地的丹参药材中脂溶性和水溶性成分,系统地探讨了多种成分的电喷雾质谱规律,并以对照药材为标准建立了特征指纹图谱。五个产地的药II材通过与对照药材相对比,采用聚类分析的方法,得到了定性的鉴别与判断。并采用液质联用技术对丹参药材提取液中的化学成份进行分析,推测了九个特征峰,并对六样品的液相色谱图进行了聚类分析。第五章探讨了三七皂苷的电喷雾质谱电离和裂解规律,并采用电喷雾质谱法对三七标准药材,血通片中的皂苷成分进行了分析。第六章运用电喷雾质谱研究复方丹参片提取液的特征图谱,并和单味药材丹参和三七的特征图谱进行了对比研究。并运用HPLC-ESI MSn 分析鉴定了复方丹参片提取液中的化学成分,推测了12 个色谱峰。第七章总结了电喷雾质谱和液质联用技术在丹参药材,三七药材及复方丹参制剂中的运用的优势和局限性。 第三部分(第八章)研究了两面针生物碱中二氢白屈菜红碱(1)、二氢两面针碱(2)、8-酮基二氢白屈菜红碱(3)、8-丙酮基二氢两面针碱(4)、两面针碱(5)、和1,3-二(8-二氢两面针碱)丙酮(6)等六个苯并菲啶型生物碱的电喷雾质谱裂解规律,其中二氢两面针碱和二氢白屈菜红碱,8-丙酮基二氢两面针碱和8-酮基二氢白屈菜红碱是两对二个甲氧基分别在C-9 和C-10,C-10 和C-11 的同分异构体。实验结果表明,在相同的碰撞能下,这类位置异构体的ESI MS2 质谱二级碎片离子的相对峰度存在很大差异,这可以用于区分该类同分异构体,采用液-质联用可以对两面针的总生物碱提取物中的这些同分异构体加于区分。同时在本实验采用的液相色谱条件下,多种生物碱得到较好的分离,通过和对照品的保留时间,紫外吸收光谱及电喷雾质谱图对照,鉴定了11 个主要色谱峰。 第四部分(第九章)对液质联用技术在药物代谢中的运用进行了综述。 This dissertation consisted of four sections. The first two sections elaborated thephytochemical investigation of the rhizomes Gymnadenia conopsea R. Br., methoddevelopment for rapid identifying and qutifying the chemical condtituent of thistibetant medicine, and the chemical fingerprint analysis of rhizomes of G. conopsea,Salviae miltiorrhiza and P. notoginseng. The third section studied the fragmentationmechanism of six alkaloids from Zanthoxylum nitidium and method development forrapid identifying varieties of alkaloids from the extract of this herbal medicine. Thefourth section reviewed HPLC- MS method in drug metabolism studies. The first section consisted of chapters 1, 2, 3. Chapter 1 elaborated the phytochemicalinvestigation of Gymnadenia conopsea R. Br. Four succinate derivative esters wereisolated from the methanol extract of the rhizomes of G. conopsea through repeatedcolumn chromatography on normal and reversed phase silica gel, their structures weredetermined by ESI-MS, 1D and 2D NMR evidence. They were firstly discoveredfrom this species. In chapter 2, a high-performance liquid chromatography.diodearray detection (HPLC-DAD) method has been firstly developed for quantitation oftwo characteristic constituents, adenosine and 4-hydroxybenzyl alcohol, from theextract of rhizomes of G. conopsea. All 10 samples of G. conopsea contained differentamount of adenosine and 4-hydroxybenzyl alcohol. Adenosine and the4-hydroxybenzyl alcohol can be applied in identification and quality control for theroots of G. conopsea. In chapter 3, a high-performance liquid chromatography.diodearray detection.tandem mass spectrometry (HPLC-DAD-MSn) method has been firstly developed for chemical fingerprint analysis of rhizomes of G. conopsea andrapid identification of major compounds in the fingerprints. Comparing the UV andMS spectra with those of authentic compounds, seven main peaks in the fingerprintswere identified as adenosine, 4-hydroxybenzyl alcohol, 4-hydroxybenzyl aldehyde,dactylorhin B, loroglossin, dactylorhin A and militarine. The Computer AidedSimilarity Evaluation System for Chromatographic Fingerprint of TraditionalChinese Medicine (CASES) was employed to evaluate the similarities of 10 samplesof the rhizomes of G. conopsea collected from Sichuan, Qinghai and Hebei provincesand Tibet autonomous region of China, and Nepal. These samples from differentsources had similar chemical fingerprints to each other. The second section consisted of chapters 4, 5, 6 and 7. In chapter 4,both thecharacteristic spectra of liposoluble tanshinones and aqueous-soluble salvianolic acidswere established by the electrospray ionization mass spectrometry (ESI MS)technique and the differences between standard and crude rhizomes of Salviaemiltiorrhiza Bge. from 5 sources were analyzed. The law of electrospray ion trap mass(ESI ITMS) of typical tanshinones and salvianolic acids is studied.The analysis of the chemical constituent of rhizomes of Salviae miltiorrhiza Bge. byliquid chromatography coupled with mass spectrum (LC/MS) technique wasestablished,and the distances among standard herb and crude herb from 5 sourceswere calculated by clustering analysis. According the DAD spectra and MS2 data,9tanshinones could be speculated. In chapter 5, the character spectra of total saponinsin P. notoginseng extracts were established by ESI ITMS and selective ion monitoring(SIM) technology. The law of notoginsenosides by ESI MS2 was studied. In chapter 6,the characteristic spectra of Compound Danshen Tablet established and compared byESI-MS and HPLC/DAD/MS, 6 known tanshinones and 3 saponins were speculated.In chapter 7, the advantage and disadvantage of the strategy, using the ESI ITMS andLC/MS techniques for study of characteristic spetra of danshen and Compound Danshen Tablet, were summerized. The third section (chapter 8) studied the fragmentation mechanism of six alkaloids,dihydronitidine, dihydrochelerythrine, 8-acetonyl dihydronitidine,8-acetonyldrochelerythrine, nitidine and 1,3-bis (8-dihydronitidinyl)-acetone, by ESIMSn. Tandem mass spectrometry experiments indicated that different substitutionsites of the methoxyl groups at C-9 and C-10 or at C-10 and C-11 determined thedifferent abundances of the MS2 fragmentation ions using the same collision energy.According to the different abundances of MS2 product ions, positional isomericbenzo[c] phenanthridine alkaloids can be differentiated. Moreover, ten constituents inthe crude alkaloids extract from the roots of Zanthoxylum nitidium were rapidlyidentified by high-performance liquid chromatography coupled with tandem massspectrometry (HPLC-MSn), through comparing the retention times and ESI MSn spectra with the authentic standards. The fourth section (chapter 9) is a review on HPLC-MS method development in drug metabolism studies.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

近年来,随着对作物重茬障碍原因的深入研究,植物的化感作用越来越受到国内外众多学者的重视。花椒(Zanthoxy piperitum.)为芸香科植物,是一种收益早、用途广、价值高的经济树种,是川西干旱河谷地区的重要经济作物,其连作障碍也倍受关注,系统研究花椒化感作用将有助于理解和最终解决花椒连作障碍问题。本文首先通过萃取、层析等方法分离花椒主效化感成分;通过外加不同浓度的花椒叶水浸液研究了对土壤氮素养分循环的影响;研究了花椒叶水浸液对苜蓿生理生化、光合作用、氮素养分吸收的影响,并对外施氮肥对这种化感影响的缓解作用做了研究;研究了花椒化感潜力对全球变化——UV-B增强辐射的响应。主要研究结果如下: 1.用不同极性的有机溶剂对花椒叶水浸液浓缩浸膏萃取、柱层析,结合生物活性检测,分离得到主效化感作用组分的一种化感物质——对甲氧基苯酚。采用该物质纯品进行生物活性检测,证明其具有化感作用。 2.花椒叶水浸液处理土壤30天后,土壤硝态氮、铵态氮、无机氮(硝态氮+铵态氮)与对照相比,随着花椒叶水浸液浓度的增加呈现降低的趋势,其中土壤铵态氮含量显著降低,而硝态氮含量的变化则不显著,无机氮含量也显著降低。土壤脲酶和蛋白酶的活性与无机氮含量的变化趋势相同。随着花椒叶水浸液浓度的增加,氨化细菌数量显著降低,固氮菌的数量变化不显著,硝化细菌和反硝化细菌数量有减少的趋势。60天后,硝态氮含量、铵态氮含量、无机氮随水浸液浓度增加的变化趋势与30天时相似;随着花椒叶水浸液浓度的增加,氨化细菌、固氮菌的数量显著减少,硝化细菌数量、反硝化细菌数量仍呈减少趋势;土壤脲酶、蛋白酶活性与第30天的变化趋势相同。第60天与第30天的结果相比,相同水浸液浓度处理的硝态氮、铵态氮、无机氮均有下降的趋势,但除了25g.L-1水浸液处理的外,其它相同浓度的处理间差异均不显著;除了12.5 g.L的处理外土壤脲酶活性均呈增强的趋势;蛋白酶活性都有不同程度的增加;花椒叶水浸液处理的土壤硝化细菌和反硝化细菌数量呈增加趋势。 3.随着花椒叶水浸液浓度的增加,显著抑制了苜蓿根长、地上地下生物量、叶绿素含量、叶片中可溶性蛋白的含量,净光合速率。苜蓿体内四种抗氧化酶(POD、SOD、CAT、APX) 活性随着水浸液浓度的增加而降低,而丙二醛含量则增加。苜蓿氮初级同化相关酶硝酸还原酶(NR)、谷氨酰合成酶(GS)、谷氨酸脱氢酶(GDH)的活性随着水浸液浓度的增加受到不同程度的影响。总的来说,苜蓿硝酸还原酶、谷氨酰合成酶的活性受到抑制,而谷氨酸脱氢酶活性的变化则比较复杂,根呈先降低后增加的趋势,叶片则无显著变化。外施两种不同浓度的硝酸铵氮肥后,对12.5、25 g.L-1花椒叶水浸液处理的苜蓿化感作用有显著的缓解作用,表现在株高、生物量、光合作用等方面,大多达到与对照(0 g.L-1)未施氮肥无显著差异的水平,而对50 g.L-1水浸液处理的苜蓿幼苗,虽有一定的缓解作用,但这种作用均未达到与对照(0 g.L-1)未施氮肥时无显著差异的水平。 4. UV-B增强辐射处理花椒后,花椒的化感潜力显著增强。花椒叶片内UV-B吸收物质的含量和总酚含量均显著增加。 In recent years, with profound research on the reasons of continuous cropping obstacles, allelopathy received increasing attention to many scholars at home and abroad. Zanthoxy bungeanum as a Rutaceae plant is a high economic value species which gains early and uses widely. Zanthoxylum is an important economic crop in the arid valley of western Sichuan region, and its not even has received much concern for the continuous cropping obstacles. The systematic study of allelopathy of Zanthoxylum will contribute to the understanding and final settlement of this issue. The major allelopathic composition was separated through the extraction, chromatography combined with other methods. The impact on soil nutrient cycling was also studied through the addition of different concentrations of water extracts of Zanthoxylum. Furthermore, the effects of water extracts of Zanthoxylum leaves on alfalfa leaf physiological and biochemical indexes, photosynthesis, soil enzymes and nutrient uptake of nitrogen and the mitigation of allelopathy through using external fertilizer were studied to put forward scientific resolvent for Zanthoxylum continuous cropping obstacles .The response of allelopathic potential of Zanthoxylum to global change - UV-B enhanced radiation was studied . The main findings are as follows: 1. Through extraction with different polar organic solvents on concentrated water extract of Zanthoxylum leaf and then using column chromatography combined with detection of biological activity, one of the main allelopathic components- methoxy-phenol was isolated. The biological activity testing of the pure material of methoxy-phenol proved that it does have allelopathic potential. 2. Thirty days after treating soil with water extract of Zanthoxylum leaf, as compared with the control, the contents of soil nitrate, ammonium, nitrate plus ammonium nitrogen showed a trend of decrease with the increase of the concentration of water extract whereas the content of ammonium nitrogen showed a significant reduction, and the content of nitrate did not change significantly, the content of nitrate plus ammonium nitrogen also showed a significant (P <0.05) redction. The activity of soil urease and protease showed the same trend as the content of nitrate nitrogen plus ammonium nitrogen. With the increase in the concentration of water extract, the number of ammonification bacteria significantly reduced but nitrogen-fixing bacteria did not change significantly and there was a decreasing trend in the number of nitrifying bacteria and denitrifying bacteria. Sixty days after the treatment, with the increase in solution concentration of water extract of Zanthoxylum leaf, the content of nitrate、 ammonium nitrogen, nitrate plus ammonium nitrogen showed a similar change trend to 30 days’; the number of ammonification bacteria, nitrogen-fixing bacteria significantly reduced ; the number of nitrifying bacteria, denitrifying bacteria was still an downward trend; the activity of soil urease and protease showed the same trend as the 30th days’. Compared to the results of the 30th days’, the content of nitrate, ammonium, nitrate plus ammonium nitrogen showed a decrease trend between the treatment of same concentration, but there was no significant difference except the treatment of 25g.L-1 between the same concentration; the activity of soil urease showed enhanced trend except the treatment of 12.5 g.L-1; the activity of protease increased to varying degrees; the number of ammonification bacteria、 nitrifying bacteria and denitrifying bacteria were growing while nitrogen-fixing bacteria reduced.. 3. With the increase of the concentration of water extract of Zanthoxylum leaf, the water extract significantly inhibited the root length, aboveground biomass, content of chlorophyll and soluble protein in leaf and net photosynthetic rate. The activity of four antioxidant enzymes (POD, SOD, CAT, APX) reduced with the increase in concentration of the water extract but the content of MDA increased. The activity of enzymes related to primary nitrogen assimilation such nitrate reductase (NR), glutamyl synthetase (GS), glutamate dehydrogenase (GDH) were subject to different degrees with an increase in the concentration of water extracts. In general, the activity of nitrate reductase, glutamyl synthetase were inhibited, while change in the activity of glutamate dehydrogenase was more complex. The activity of glutamate dehydrogenase in leaf was first reduced and then increase,but did not change significantly in root. After using two external different concentrations of nitrogen fertilizer, there was a significant mitigation in inhibiton in plant height, biomass, photosynthesis, etc. in the treatment of 12.5,25 gL-1 of water extract of Zanthoxylum leaf, and most of these indexes showed no significant difference with the control (0 g.L-1, no external fertilizer was added) .Although there showed a certain degree of ease in the treatment of 50 g.L-1 , there was still a significant difference compared with the control (0 gL-1) in which no external fertilizer was used. 4.The allelopathic potential of Zanthoxylum positively responded to enhanced UV-B significantly. The content of UV-B absorbing compounds and the total phenol also significant increased.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

目前,随着全球气候变化的加剧,水分短缺更加明显。在干旱与半干旱地区,水分胁迫是影响植物存活和生长的主要限制因子。同时,随着大气平流层中臭氧浓度的减少,过量的紫外辐射(UV-B)到达地球表面,一些地区的植物不可避免地受到增强UV-B 和水分胁迫的共同作用。文献表明在UV-B 增强的情况下,干旱表现为减弱或增强UV-B 对植物的影响,这与种、品种有一定的相关性。另外,脱落酸(ABA)是近年来研究报道最多的信息调控物质,与植物抗旱性途径有较大的关系,但其对植株抗UV-B 的影响还有待于研究。本论文以滇杨(Populus yunnanensis)为模式植物,从形态和生理方面研究了增强UV-B、干旱和脱落酸对它的影响,并探讨了UV-B 与干旱的互作效应以及喷施脱落酸对植株抗旱性和抗UV-B 能力的影响。主要研究结果如下:1. 增强的UV-B 和干旱胁迫都影响了滇杨的形态生长和生理生化反应。它们都导致了滇杨植株的株高、基茎、整株叶面积、平均叶面积、总生物量和净光合速率的显著降低,使得叶片增厚,过氧化物酶(GPX)活性升高,脯氨酸和花色素苷含量增加,膜脂过氧化程度增大。不同的是干旱显著降低了植株叶片数目,增大了根/冠比(Rs)、细根/总根比(Ft)、提高了内源ABA 含量、碳同位素(δ13C)以及紫外吸收物质含量和超氧化物歧化酶(SOD)的活性,而UV-B 对它们没有影响。干旱与UV-B 的复合作用加剧了任一单独胁迫对植株的抑制,表现为更小的株高、基茎、整株叶面积、平均叶面积、总生物量,更低的光合作用和更高的MDA 含量。而且UV-B 辐射降低了干旱胁迫下生物量分配的可塑性,表现为降低了干旱情况下的Rs 和Ft,ABA 的含量也显著下降,复合胁迫下脯氨酸含量和过氧化氢酶(CAT)的活性比任一单独胁迫时都要低。这些实验结果表明,增强的UV-B 与干旱的复合胁迫加剧了对植株的抑制作用。II2. 干旱情况下同时施加外源ABA 提高了植株的根/冠比、细根/总根比和单位面积叶重,即提高了干旱胁迫下植株对生物量分配的可塑性。而且外源ABA 使干旱胁迫下的长期用水效率、ABA 含量、脯氨酸含量、GPX 活性进一步增加,并有效调节了活性氧代谢的平衡,抑制了受旱植株MDA 的增加。结果表明,外源ABA 的喷施提高了滇杨植株的抗旱性。3. 在增强的UV-B 情况下,外源ABA 加剧了UV-B 对滇杨形态生长的抑制效果,表现为进一步降低了滇杨植株的整株叶面积、平均叶面积、单位面积叶重和总生物量,而且ABA 还降低了UV-B 胁迫下的净光合速率和脯氨酸的含量,增大了MDA 的含量。通过以上的数据我们可以看出,外源ABA 虽然提高了滇杨植株的抗旱性,但却加剧了UV-B 胁迫对植株的抑制作用。Currently, drought is one of the most serious environmental stresses. In arid and semi-aridregions, drought is a major constraint imposed on tree survival and growth. The decrease ofozone layer leads to a significant increase in ultraviolet-B (UV-B, 280-320 nm) radiationreaching the earth surface. In some places, plants suffer both UV-B and water stresssimultaneously. Their combination will increase or decrease the sensitivity of plants to UV-Bstress which lies on the species. On the other hand, abscisic acid (ABA), as a plant homoneand growth regulator, is better for plants resistant to drought stress, but it is uncleared aboutthe relationship between exogenous ABA and supplemental UV-B. In the present study, weemployed Populus yunnanensis Dode as a model species to characterize the growth andecophysiological responses of woody plants to supplemental UV-B, drought and exogenous ABA. The results are as follows:1. Both supplemental UV-B and drought affected the morphological, physiological andbiochemical responses of P. yunnanensis. They decreased the plant height, basal diameter,total leaf area, average leaf area, biomass and photosynthesis, and increased specific leaf mass,the activity of guaiacol peroxidase (GPX), the content of proline, anthocyanins andmalondialdehyde (MDA). However, drought decreased the leaf number and increasedroot/shoot ratio, fine root/total ratio, the activity of superoxide dimutase (SOD) and thecontents of ABA, carbon isotope composition (δ13C), UV-absorbing compounds. Whilesupplemental UV-B had no effects on them. The combination of drought and UV-Baugmented the growth inhibtion acting as further lower plant height and smaller basaldiameter, leaf area, biomass and higher MDA content. And compared with drought stress,root/shoot ratio and fine root/total root ratio decreased under the combination stresses. The photosynthesis, proline content and Catalase (CAT) activity became lower under combinationstresses than that of either stress lonely. According to these results, we suggested that,compared with the effect of stress lonely, the combination of supplemental UV-B and droughtdid not mitigate the harmful effect, but augmented it.2. Under drought conditions, exogenous ABA increased root/shoot ratio, fine root/total rootratio and the specific leaf mass. That was to say exogenous ABA increased plant plasticityunder drought conditions. Also ABA content, proline content, activity of GPX and δ13C wereenhanced further. In addition the enhancement of MDA was restrained. So the resultssuggested that exogenous ABA increased the seedling capacity of resistance to drought.3. Under supplemental UV-B conditions, exogenous ABA augmented the growth restrain ofUV-B to seedlings, which acted as further decreased leaf area, specific leaf mass and biomass.Compared with UV-B stress alone, proline content and photosynthesis were decreased andMDA content was increased under the combination of UV-B and ABA. These resultssuggested that although exogenous ABA increased the seedling capacity of resistance todrought, it augmented the growth restrain of supplemental UV-B to P. yunnanensis.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

论文包括两部分内容:利用强子动力学模型和相对论平均场近似方法研究了强子的有效质量;扩展了夸克质量密度相关的模型,讨论了核子的基本性质。 从非线性σ-ω-ρ模型拉氏量出发,给出了核物质标量密度和矢量密度的关系,利用其修正了K介子有效质量;在不变耦合系数和密度相关耦合系数下,研究了Θ+的有效质量,并发现在密度相关的耦合系数下,标量介子与重子的相互作用在高密度区域被削弱。 在改进的夸克质量密度相关(IQMDD)模型的基础上,引入了ω介子来描述夸克间排斥作用,给出了夸克和σ,ω场函数满足的方程, 通过自洽求解,分B^(1/4)=145MeV和c2=0两种情况,研究了在不同条件下夸克波函数和夸克密度的变化情况,给出了σ,ω场函数的分布。计算了rp,磁矩μp,以及核子的轴矢量与矢量的β衰变耦合系数之比gA/gv,发现与实验值有较好的吻合

Relevância:

80.00% 80.00%

Publicador:

Resumo:

重离子束治癌是当今放射治疗中最科学、最先进、最有效的方法,是有代表性的高技术。目前仅有美、日、德实现了该技术,并已取得常规疗法难以实现的疗效。我国近年来开展了“重离子束治癌技术的基础研究”,其中,放射生物学及机理研究是重要内容。本论文从细胞、DNA分子、以及动物个体的三个不同层次上分别研究了重离子束治癌相关的生物学问题。在细胞研究方面。采用HeLa、B 16两种细胞分别研究了X一射线和重离子在水介质中入射的深度与相应细胞的存活率(1一失活率),结果表明:X一射线对细胞的损伤随深度而逐渐衰减(或细胞存活随深度逐渐增加),而重离子对细胞的损伤则为Bragg曲线(或细胞存活为倒Bragg曲线)。研究了25MeV/u ~(40)Ar~(14+)辐照人肝癌细胞SMMC一7721的微核及存活的动态变化,结果表明: 单次照射与分次照射的微核率随时间的变化规律在96h内没有明显区别,受照(单次、分次) 肝癌细胞的存活数随时间表现出衰减趋势,微核率与细胞存活数关系的动态变化为负相关性。研究了6MV X-射线和125.5keV/μm的重离子辐照B 1 6、V79细胞的2Gy存活率(SF2),结果表明:B16和V79细胞的存活率(P<0.01)依赖于不同的辐射性质(X-射线、~(12)C离子),其X-射线与~(12)C离子辐射这两种细胞的存活率之比分别为5.4和1.43,即~(12)C离子辐射增强了X-射线抗性细胞系的敏感性,从而显示了重离子治疗癌症的优势。研究了125.5keV/um的碳离子辐照小鼠黑色素瘤B16、人的宫颈癌HeLa、中国仓鼠肺V79、人的肝癌SMMC-7721四种细胞的相对生物学效率(RBE),得.到了RBE依赖于细胞种类的关系、RBE随细胞存活水平的升高而增加的关系、以及当LET≥125.5keV/μm时,RBE随着LET的增大而变小的关系。在DNA分子研究方面。研究了125.5keV/μm~(12)C~(6+)辐照小鼠黑色素瘤B 16、中国仓鼠肺V79、人的宫颈癌HeLa、人的肝癌SMMC一7721细胞的灵敏度(由D50表示)、DNA双链断裂(DSB)和DNA双链断裂片段分布,结果表明:细胞敏感性与DNA双链断裂之间没有一致的关系,提出了细胞辐射敏感性的一种可能的分子机理,即DNA序列敏感性位点协同DNA双链断裂互补性机理。由此解释了四种细胞系的不同敏感性问题。在动物个体研究方面。研究了57.28MeV/u氧离子50Gy一次性局部照射对B16黑色素瘤小鼠肿瘤生长的抑制作用,并观测了受照小鼠的死亡情况,结果表明:照射B16黑色素瘤后第10天观察,肿瘤生长延迟为6天、肿瘤抑制率为66%,耐受剂量小于50Gy。研究了50MeV/u ~(12)C~(6+)离子辐照对小鼠移植性肿瘤S180的抑制作用、控制率、治愈率和病理组织学变化,结果表明:各剂量组对S180肉瘤的抑制作用均大于90%,高剂量组抑瘤作用明显强于低、中剂量组(P

Relevância:

80.00% 80.00%

Publicador:

Resumo:

本工作用120Kev的He~+离子对非晶态Ni_(60)Nb_(40)、Fe_(40)Ni_(38)Mo_4B_(18)、Fe-Ni-B合金样品进行了辐照,辐照剂量为1.6、2.0、2.5,3.0 * 10~(18)/cm~2四种。借助X射线衍射扫描电子显微镜(SEM),内转换电子穆斯堡文谱(CEMS)等方法对辐照前后的样品进行了分析。X射线衍射结果表明在冷却靶的辐照条件下,样品辐照前后的非晶状态来改变,但辐照产生了原子的重排。SEM研究发现:表面发论的形成须一定的临界剂量对于Ni_(60)N_(240),所需临界剂量最高;随剂量的增加,在所研究的剂量范围内,发论大小增大且来观察到表面发论的破裂与剥学;对不同组织的非晶合金,其发论程度稍有不同;辗压减药不影响材料的发论性质;表面结构的粗糙有助于降低发论程度;晶化样品,发论程度的显加剂。CEMS分析指出;辐照使结构的天度增加,有效的平均原子间距减小;因辐照导致原子的重新溶合使CSRO降低;随辐照首先的缺陷周围自旋取向及急进的应力源的变化。磁各向异性发生了变化

Relevância:

80.00% 80.00%

Publicador:

Resumo:

考虑动量相关作用和介质效应,在入射能量E_L/Nucl. = 100,200,400和800 Mev及碰撞参数b = 1.0,3.0和5.0 fm时,对系统~(40)Ca + ~(40)Ca用数值方法求解BUU方程。发现状态方程的动量相关性增加了集体流,即硬化状态方程;而且增强了核物质的阻止本领。能量小于700 Mev时,动量相关作用和介质效应对集体流和状态方程的影响正好相反,二者竞争的总效果使状态方程变软,能量较高时,两者均使状态方程变硬。它们的影响密切依赖于入射能量和碰撞参数

Relevância:

80.00% 80.00%

Publicador:

Resumo:

The power-time curves of growth of three strains of petroleum bacteria at different NaCl concentrations at 40.0 and 50.0 degreesC have been determined by using a 2277 Thermometric Thermal Activity Analyser. An equation of a power-time curve, ln[alphaP(K)/P(t) - 1] = ln[(alphaK - N-0)/N-0] - alphakt, was established based on the generalized logistic equation, where P(t) is the thermal power at time t, K the carrying capacity, P-K = P0K, P-0 the thermal power of one cell, N-0 the bacterial population at time zero, alpha = (k - D)/k. The method of four observed points with the same time interval was used to calculate the value of P-K. The growth rate constant k and the death rate constant D were calculated. The NaCl concentration of optimum growth rate of petroleum bacteria at 40.0 and 50.0 degreesC, respectively, have been obtained according to the curves k - D versus NaCl concentration, which are 0.26, 0.54 and 0.57 mol l(-1) for B-1, B-2 and B-3, respectively, at 50.0 degreesC, 0.26, 0.55 and 0.56 mol l(-1) for B-1, B-2 and B-3, respectively, at 40.0 degreesC. The results indicated that the effect of temperature on NaCl concentration of optimum growth rate was small. (C) 2002 Elsevier Science B.V. All rights reserved.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

通过调节B5培养基中的组分,研究了金钩南瓜组培根在五种营养元素(P、Mg、Fe、Cu、B)四个浓度梯度(1/2 B5、B5、3/2 B52、B5)培养下化感作用的响应模式以及对黑籽和金钩南瓜两种受体幼苗生长的影响。结果表明:不同营养元素对受体植物幼苗生长的影响不一致,与元素含量显著相关,而且依赖于受体选择。五种营养元素在亏缺(1/2 B5)和正常(B5)条件下南瓜组培根过滤液对受体植物幼苗生长均表现为抑制作用;而适量增加营养元素的条件下(3/2 B5和2 B5),一般表现为促进作用,但2 B5含量下,B元素导致金钩南瓜的自毒作用,而Fe能引发金钩南瓜组培根过滤液对黑籽南瓜的抑制作用。因此理论上初步得出P和Mg元素可以降低南瓜根系的毒害作用,而Fe、Cu和B元素对南瓜根系的化感调控作用与品种选择有关,这对调控施肥、降低设施农业中葫芦科作物的连作障碍具有一定的参考意义。

Relevância:

80.00% 80.00%

Publicador:

Resumo:

穿透雨量是林内有效雨量的主要组成部分 ,其量能占 90 %以上。由于林冠空间分布的不均匀性 ,难以对林内穿透雨量进行精确地测量。从林冠截留降雨的作用机理出发 ,在做出几个假设的基础上 ,用数学方法建立了林内穿透雨量模型 ,即 :当 P0 ,U>0 )当 P≥ U时 ,R=P- W其中 U=W( b+ 1 ) ,式中 b,W,U为模型参数 ,R为林内穿透雨量 ,P为大气降雨量 ,α为林分郁闭度。结合两个有实测资料的针叶树林分 ,又进一步介绍了模型参数的确定方法。同时将模型的计算结果与实测数据进行了对比 ,两者吻合性很好 ,验证效果是比较理想的。模型概念清晰 ,参数物理意义明确。在风速和雨强不太大的情况下 ,本模型适用于任何林分的穿透雨量的计算。然而 ,为了应用于无实测资料地区 ,尚须进一步研究模型参数与林分特征的关系。

Relevância:

80.00% 80.00%

Publicador:

Resumo:

由Bi(Hcydta).5H2O和Nd(NO3).6H2O按1︰1的物质的量比,在水溶液中合成了含Bi(III)-Nd(III)的异核配位聚合物{[(NO3)Nd(H2O)4(μ3-cydta)Bi(μ-ONO2)].2.5H2O}n.用元素分析、红外光谱、热重-差热和X射线单晶衍射等手段对标题配合物的组成和结构进行了表征.该配合物属三斜晶系,空间群P1,晶胞参数:a=0.9235(3)nm,b=1.0902(4)nm,c=1.4253(5)nm,α=71.840(4)°,β=86.877(4)°,γ=76.991(4)°,Z=2,Mr=936.65,V=1.3284(8)nm3,Dc=2.342g.cm-3,μ=8.646mm-1,F(000)=900,最终偏离因子R1=0.0406,wR2=0.1124.在该配合物中,铋(III)与配体cydta4-的4O2N和1个硝酸根中1个O原子以及邻位分子的硝酸根形成8配位的畸变双帽三棱柱.钕(III)与4个水分子的O,1个硝酸根中2个O以及来自3个不同配体cydta4-的桥联羧基O结合,形成9配位的三帽三棱柱构型.羧酸根在Bi—Nd和硝酸根在Bi—Bi间的桥联作用...

Relevância:

80.00% 80.00%

Publicador:

Resumo:

为了研究羟酸类和氨基酸类手性化合物的构效关系,本实验引进了手性乘积算法:P=(1-b/a)(1-c/b)(1-a/c)(1-a/d),其中a、b、c和d分别为与分子中手性中心碳原子4个不同连接片断手性eAm指数和分子连接性指数mx的计算值,并考察了所得参数与羟酸类和氨基酸类化合物手性薄层色谱保留指数的相关性。为了评定所得预测模型的稳定性,文中运用了交叉验证法。结果表明,由人工神经网络方法(BP法)所得数学模型比较稳定,且明显优于多元回归分析结果。