285 resultados para 2-9
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研究了基于SOI(silicon-on-insulator)材料的阵列波导光栅(AWG)分波器件,给出了此器件材料色散的数值拟合公式,进而利用BPM方法研究了材料色散脊型波导结构变化和器件制做中刻蚀深度误差对波导有效折射率和波分复用模块性能的影响。结果表明,刻蚀深度误差对模块性能优劣起关键作用。
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密集波分复用(DWDM)已经成为光纤通信的主要发展方向,光上下路分插复用器(OADM)作为WDM网络中的关键技术,它的优劣将直接影响通信网络的性能。侧重于从器件的角度对OADM的功能和发展现状进行介绍,并对其构成的关键器件的发展进行了概述。
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The characteristics of thickness enhancement factor and bandgap wavelength of selectively grown In-GaAsP are investigated. A high thickness enhancement factor of 2.9 is obtained. Spotsize converter integrated DFB lasers are fabricated by using the technique of SAG. The threshold current is as low as 10.8mA. The output power is 10m W at 60mA without coating and the SMSR is 35.8dB. The vertical far field angle (FWHM) is decreased from 34 °to 9 °. The tolerance of 1dBm misalignment is 3.4μm vertically.
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Resonant-cavity-enhanced (RCE) photodetectors have been demonstrated to be able to improve the bandwidth-efficiency product. We report one top-illumination and one bottom-illumination SiGe/Si multiple quantum-well (MQW) RCE photodetectors fabricated on a separation-by-implanted-oxygen (SIMOX) wafer operating near 1300nm, The buried oxide layer in SIMOX is used as a mirror to form a vertical cavity with the silicon dioxide/silicon Bragg reflector deposited on the top surface. A peak responsivity with a reverse bias of 5V is measured 10.2mA/W at 1285nm, and a full-width at half maximum of 25nm for the top-illumination RCE photodetector, and 19mA/W at 1305nm, and a full-width at half maximum of 14nm for the bottom-illumination one. The external quantum efficiency of the bottom-illumination RCE photodetector is up to 2.9% at 1305nm with a reverse bias of 25V. The responsivity of the bottom-illumination RCE photodetector is improved by two-fold compared with that of the top-illumination one.
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The size and shape Evolution of self-assembled InAs quantum dots (QDs) influenced by 2.0-ML InAs seed layer has been systematically investigated for 2.0, 2.5, and 2.9-ML deposition on GaAs(1 0 0) substrate. Based on comparisons with the evolution of InAs islands on single layer samples at late growth stage, the bimodal size distribution of InAs islands at 2.5-ML InAs coverage and the formation of larger InAs quantum dots at 2.9-ML deposition have been observed on the second InAs layer. The further cross-sectional transmission electron microscopy measurement indicates the larger InAs QDs: at 2.9-ML deposition on the second layer are free of dislocation. In addition, the interpretations for the size and shape evolution of InAs/GaAs QDs on the second layer will be presented. (C) 2001 Elsevier Science B.V. All lights reserved.
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空间生态规划着重于研究城乡土地和空间资源,达到城乡土地和空间资源合理配置。辽宁本溪市南芬区属山地资源型工矿城镇,由于空间用地类型配置不合理,中心城区环境污染严重,而广阔的乡村空间资源未尽其用。为此,有必要对南芬全区城乡空间进行生态规划。本文在理论上补充空间生态规划中生态适宜性评价理论,在方法上提出了基于适宜性评价的空间生态规划方法后,就南芬主要用地类型工业用地、居住用地、作物用地和林业用地分别进行生态适宜性评价和用地配置研究,并综合适宜性评价结果和探讨了南芬空间生态分区及空间生态规划途径。 主要结果为:(1) 工业用地最适宜区、次适宜、勉强适宜和不适宜区面积分别为91.23km2、182.72km2、182.08km2和162.97km2;居住用地分别为208.08km2、169.95km2、149.51km2和91.46km2;作物用地分别为124.23km2、130.65km2、159.02km2和205.1km2;林业用地分别为201.7km2、150.43km2、130.21km2和136.66km2。(2) 工业用地现状位于最适宜区、次适宜区、勉强适宜区、不适宜区的面积分别为9.81km2、10.66km2、6.54km2和11.73km2;居住用地分别为9.05 km2、12.57km2、15.7km2和11.53km2;作物用地分别为16.61km2、7.88km2、22.25km2和24.15km2;林业用地分别为193.91km2、104.88km2、81.74km2和67.27km2。(3)综合评价表明,工业用地、居住用地、作物用地、林业用地适宜区面积分别为46.75km2;71.32km2;94.46km2;406.47km2。南芬生态空间区划为生态保护区、生态居住区(2个)和生态工业区(3个)。(4) 最后详细阐述了南芬城乡空间生态规划途径及其内涵,即:生态优先、整体优化、经济优效和社会持续。
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目前在包膜控释肥料方面的研究热点是采用树脂型包膜材料制备包膜肥料,并且取得了一定的成绩,控释效果比较良好,但由于树脂材料需用大量有机溶剂,给生产成本和工艺都带来了新的问题。本试验针对此问题,选用水性聚氨酯(PU)和水性丙烯酸(PA)作为包膜材料,应用旋转包膜工艺和流化床包膜工艺制备包膜肥料,采用水培法、淋溶法、土培法、电镜观察等方法对其进行释放性能评价,最终确定水性聚氨酯和水性丙烯酸在肥料中应用的效果。结果表明: 以旋转包膜工艺、用水性聚氨酯(PU)为膜材料制备的9种包膜肥料,并做了封闭处理,通过扫描电镜观察都形成了致密连续的控释膜,经评价都具有一定的控释效果,其中CRF-6(水性聚氨酯用量6%,封闭剂用量3%)、CRF-9(水性聚氨酯用量9%,封闭剂用量3%)两种包膜肥料控释性能较优,水培条件下其氮素初期溶出率分别为29.11%和19.48%,钾素初期溶出率分别为33.15%和24.93%。各种评价方法结果表明:同一材料不同包膜量控释效果比较:6%用量优于9%用量,优于3%用量。封闭剂用量在2%时效果相对较好。 以流化床包膜工艺、用水性聚氨酯(PU)和水性丙烯酸(PA)为膜材料制备的15种包膜肥料,经检测FCRF-9(PA:PU=1:2,9%)、FCRF-11(PA:PU=1:1,6%)和FCRF-12(PA:PU=1:1,9%)这3种肥料控释效果最为突出,在水培条件下其氮素初期溶出率分别为12.58%、15.62%和16.02%。材料组合以水性聚氨酯(PU)和水性丙烯酸(PA)以1:2复合包膜最理想。对于同一包膜材料不同用量控释效果顺序:9%用量优于6%用量,优于3%用量。与普通肥料肥料相比,包膜肥料吸湿率大幅下降。 旋转包膜工艺与流化床包膜工艺比较表明:在低用量时,水性包膜材料在流化床包膜工艺与旋转包膜工艺制备肥料控释性能没有差异;在高用量时,流化床包膜工艺比旋转包膜工艺更适合应用于水性高分子材料肥料包膜。
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近几年,松果采摘对红松林的健康构成了极大的威胁。本文在野外调查研究的基础上,结合史料分析研究了松果采摘对红松地面种源贮藏量分布状况、红松林主要乔木树种组成和幼苗幼树更新等的影响,通过与20世纪70年代相应数据对比,结合红松更新过程与动物的关系,分析了松果采摘对红松林生态系统健康的影响。研究结果表明:(1)松果采摘后,红松林地面红松种子数量少,大部分是废种子,且主要呈单粒状分布,地面红松种子贮藏量1582-2640粒/hm2,仅为70年代的0.3-0.5%,废种子比值大于67.8%,单粒状占总簇数的46.8-77.1%。(2)“采摘掠青”对种子质量具有显著影响,9月15日与8月20日采摘的松果相比,种子千粒重增加了69%,种仁重增加了30.3%,出仁率增加了2.7%,球果鲜重减少了20.0%,种子重增加了21.3%,出种率增加了51.7%。(3)与红松林中其他主要更新树种相比,采摘使红松更新不良,红松幼苗数量大大减少,减少幅度达49.5-95.0%。(4)破坏了红松天然更新规律,2000年是结实年,但2002年并没有出现更新年。(5)林分中红松小径级植株占比值很小,而大径级比值大,呈生长下降性种群;而其它主要伴生树种与此相反,呈生长增长性种群。(6)以松籽为主要食物来源的动物食物链遭到破坏,红松林生物群落结构发生变化。在此分析基础上,提出了以松果采摘为例的长白山自然保护区健康管理策略,以期为保护区管理提供科学依据。
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森林生态系统是陆地最大的碳储存库,森林土壤呼吸是陆地生态系统土壤呼吸的重要组成部分,其动态变化将刘全球碳平衡产生深远的影响。精确测定土壤呼吸及其各组分的贡献,是目前全球变化研究中最基础和最迫切需要解决的问题。本文对长白山典型森林生态系统土壤碳通量及其过程机理进行了研究,结果表明:(1)阔叶红松林、红松云冷衫林、岳桦云冷杉林和岳桦林有不同的凋落节律;随海拔高度的上升,年凋落物量逐渐减少,分别为4.90、4.51、3.08和2.65thm-2;凋落物分解残留率与时间均呈指数关系,不同类型森林凋落物年分解常数的变化范围是25-47%之间。(2)阔叶红松林土壤总呼吸和断根土壤呼吸速率都存在明显的昼夜变化,为单峰型曲线,与土壤温度的昼夜变化趋势一致;不同森林类型土壤总呼吸和断根土壤呼吸的季节变化都比较明显,阔叶红松林、红松云冷杉林和岳桦云冷杉林变化趋势基本相似,都呈双峰型,岳桦林呈单峰型;土壤呼吸与土壤温度、大气温度之间都呈极显著(P<0.01)指数相关关系,且与土壤温度的相关性要好于与大气温度的相关性;长白山四种类型森林土壤和根系呼吸的Q10值变化范围是1.8-2.9,根系呼吸的Q10值均大于土壤总呼吸和断根土壤呼吸的Q10值;土壤含水量对呼吸速率影响较为复杂,与土壤呼吸之间没有明显的相关关系;根系对土壤总呼吸贡献的季节变化与根系呼吸的季节变化相似,生长季内测定的阔叶红松林、红松云冷杉林、岳桦云冷杉林和岳桦杉林根系呼吸对土壤总呼吸贡献平均值分别为43.6%、44.1%、45.5%和44.4%。(3)长白山典型森林生态系统土壤碳的年释放量有随海拔高度上升而减小的趋势,且阔价卜林大于针叶林。阔叶红松林、红松云冷杉林、岳桦云冷杉林和岳桦林土壤碳的年释放量分别为7392.43、7181.83、6507.29和6841.09kghm-2a-1;根系的年碳释放量分别为3332.93、2965.68、2708.84和3015.48kghm-2a-1。
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进行了来流Mach数2.9,24°压缩折角激波-湍流边界层干扰的直接数值模拟,在上游的平板添加扰动以激发边界层转捩到湍流.计算得到的统计结果与实验吻合,验证了结果的可靠性.分析了角部分离区附近湍能的生成,耗散及分配机制.结果显示角部区域激波与湍流边界层相互作用造成大量湍动能产生,而湍动能的主要耗散区仍在近壁.湍流输运项起到了主要的平衡机制,把湍动能由外层输运到近壁区.通过对激波后及壁面瞬时压力的分析,认为激波低频振荡并非上游扰动引起,而是由于分离泡本身不稳定振荡产生的
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A direct numerical simulation of the shock/turbulent boundary layer interaction flow in a supersonic 24-degree compression ramp is conducted with the free stream Mach number 2.9. The blow-and-suction disturbance in the upstream wall boundary is used to trigger the transition. Both the mean wall pressure and the velocity profiles agree with those of the experimental data, which validates the simulation. The turbulent kinetic energy budget in the separation region is analyzed. Results show that the turbulent production term increases fast in the separation region, while the turbulent dissipation term reaches its peak in the near-wall region. The turbulent transport term contributes to the balance of the turbulent conduction and turbulent dissipation. Based on the analysis of instantaneous pressure in the downstream region of the mean shock and that in the separation bubble, the authors suggest that the low frequency oscillation of the shock is not caused by the upstream turbulent disturbance, but rather the instability of separation bubble.
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本论文由三章组成。第一章阐述了藏药水菖蒲的化学成分研究,共分离鉴定了39个化学成分,其中6个为新化合物。第二章报道了几种忍冬属植物的HPLC、HPLC-MS、GC分析以及抑菌活性、重金属含量测定结果。第三章概述了菖蒲属植物的研究进展。 第一章报道了水菖蒲(Acorus calamus L.)化学成分的分离纯化与结构鉴定。采用正、反相硅胶柱层析等分离方法,从水菖蒲的根中共分离出41个化合物,通过红外、质谱、核磁共振及X-ray单晶衍射等波谱方法和模拟计算方法鉴定了其中39个化合物的结构,主要为倍半萜、苯丙素、甾体类化合物。其中含有5个新的倍半萜类化合物和1系列新的甾体皂苷衍生物。经波谱分析将它们的结构鉴定为 1b, 7a(H)-cadinane-4a, 6a, 10a-triol (1), (2R,6R,7S,9S)-1(10), 4-cadinadiene-2, 9-diol (2), 1a, 5b-guaiane-10a-O-ethyl-4b, 6b-diol (7), 6b, 7b(H)-cadinane-1a, 4a, 10a-triol (13),(1R,4R,6S,10R)-1-hydroxy-7(11)-cadinen-5, 8-dione (14), 4′-O-正n碳酰基-3-O- β-D-葡萄糖基谷甾醇(n=14, 16, 18, 22) (15)。 第二章包括四个部分。第一部分报道了忍冬属三种植物40个样品的HPLC测定和对主要活性成分绿原酸的定量分析结果,以及运用HPLC-MS技术对色谱图中8个峰进行指认。在此基础上,考察了种植和采收多个因素对绿原酸含量的影响。第二部分报道了忍冬属三种植物27个样品的GC分析,根据样品的挥发性成分的保留时间对不同样品进行了定性比较,并考察了花期及海拔高度对植物挥发性成分的影响。第三、四部分分别阐述了灰毡毛忍冬和红腺忍冬的体外抑菌活性研究和重金属含量测定结果。 第三章全面系统地概述了菖蒲属植物的化学成分和药理活性研究进展。 This dissertation is composed by three chapters. The first chapter elaborates the phytochemical investigation of Acorus calamus L. Thirty-nine compounds including six new compounds were isolated and identified. The second chapter reports the research on genus Lonicera by HPLC, HPLC-MS and GC. Antifungal activity and heavy metals measurement of genus Lonicera were reported. The third chapter is a review about the research progress on the plant family of Acorus. The first chapter focuses on the isolation and identification of chemical constituents from Acorus calamus L.. Forty-one compounds were isolated from the root of Acorus calamus L. by repeat column chromatography over normal and reversed phase silica gel, the structure of thirty-nine compounds was identified by spectroscopic methods and computational methods, including IR, MS, NMR and X-ray. Those compounds mainly belonged to sesquiterpene, phenylpropanoid and steroid. Among them, five are new sesquiterpenes and one series are new steroid glycoside derivatives. Their structure were suggested as 1b, 7a(H)-cadinane-4a, 6a, 10a-triol (1), (2R,6R,7S,9S)-1(10), 4-cadinadiene-2, 9-diol (2), 1a, 5b-guaiane-10a-O-ethyl-4b, 6b- diol (7), 6b, 7b(H)-cadinane-1a, 4a, 10a-triol (13), (1R,4R,6S,10R)-1-hydroxy-7(11)- cadinen-5, 8-dione (14), 4′-O-carbonyl-3-O-β-D-glucosyl-sitosterol (carbonyl = tetradecanoyl, hexadecanoyl, octadecyl, docosanoyl) (15). The second chapter consists of four parts. The first part reports the HPLC analysis of forty samples of the genus Lonicera, and the quantitative investigation of chlorogenic acid in these samples by HPLC analysis. Relationship between the content of chlorogenic acid in different samples and their planting conditions and harvesting time were discussed. Furthermore, eight compounds were identified or tentatively characterized based on their mass spectra and UV spectra profiles. The second part is about qualitative analysis of the volatile constituent in twenty-seven samples of genus Lonicera by GC. The effect of planting altitude and harvesting time on the volatile constituent was also investigated. The third and fourth parts describe the antifungal activity and content of some kinds of heavy metals of L. macranthoides Hand.-Mazz. and L. hypoglauca Miq.. The third chaspter is a review about the research progress of the plant family of Acorus.
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本学位论文报道了西藏产三种藏族传统植物药材的化学成分研究。论文由四章组成,前三章是实验部分,分别报道了尼泊尔黄堇(Corydalis hendersonii Hemsl.)、藏波罗花(Incarvillea younghusbandii Sprague)和全缘叶绿绒蒿(Meconopsis interifolia Franch.)的化学成分研究结果。从这三种青藏高原药用植物中共分离鉴定出33 个化合物,其中1 个是新化合物。第四章概述了罂粟科紫堇属植物的化学和药理研究进展。 第一章为尼泊尔黄堇的化学成分研究。通过正、反相硅胶柱色谱等分离方法从药用植物尼泊尔黄堇的地上部分共分离纯化得到12 个化合物。运用MS、1H-NMR、13C-NMR、DEPT、HMBC、NOESY 等现代波谱学方法将它们的结构鉴定为:刺罂粟碱(1) , 普托品(2) , 新那亭(3) , 斯可任(4) , tetrahydrothalifendine (5) ,9-methyl-decumbenine C (6),tetrahydroberberrubine (7),隐品碱(8),α-别隐品碱(9),6,7-methylenedioxy-1(2H)-oxoisoquinolinone (10),6-丙酮基-5,6 -二氢血根碱(11)和β-谷甾醇(12)。其中化合物6 为新化合物,为首次发现的分子骨架上C-9 位连有甲基的苯肽异喹啉类型生物碱。另外,除化合物1 和2 外,其它9 个生物碱(3~11)均为首次从该种植物中分离得到。同时,我们还对对尼泊尔黄堇中的总生物碱进行了串联质谱分析。 第二章为藏波罗花的化学成分研究。从该药用植物的地上部分共分离得到16个化合物,通过理化常数和波谱数据鉴定为:异佛手柑内酯(1),6-甲氧基当归素(2),欧前胡素(3),花椒毒内酯(4),珊瑚菜素(5),水合氧化前胡素(6),rivulobirin A (7),齐墩果酸甲酯(8),咖啡酸甲酯(9),银桦酸(10),(D)-boschniakinic acid (11),对羟基苯甲酸(12) , tert-O-β-D-glucopyranosyl-(R)-heraclenol (13) , 5-methoxy-8-O-β-D-glucopyranosyloxypsoralen (14),前胡苷V(15)和苯乙醇-O-β-D-吡喃葡萄糖-(1→2)-O-β-D-吡喃葡萄糖苷(16)。所有以上化合物均为首次从该种植物中分离得到。另外我们还首次对藏波罗花挥发油的化学成分进行了气相色谱-质谱(GC-MS)联用分析,共鉴定出39 个挥发性成分。 第三章为全缘叶绿绒蒿化学成分的分离鉴定。从传统藏药材全缘叶绿绒蒿地上部分共分离纯化出8 个化合物。通过理化常数和波谱数据将他们的结构分别鉴定为:去甲血根碱(1),β-谷甾醇(2),3-羟基-齐墩果烷-12(13)-烯-30-酸(3),6-丙酮基-5,6-二氢血根碱(4),木犀草素(5),胡萝卜苷(6),quercetin 3-O-β-D-glucopyranosyl-(1→6)-β-D-glucopyranoside (7)和普托品(8)。其中化合物1,4 和7 为首次从该种药用植物中分离得到。 第四章为综述,总结和归纳了近年来罂粟科紫堇属植物的化学和药理研究进展。 This dissertation consists of four parts. The first, second and third parts report the studies on the chemical constituents from the medicinal plants of Corydalis hendersonii, Incarvillea younghusbandii and Meconopsis interifolia. The forth part reviews the progress of the studies on Corydalis species. The first chapter is about the isolations and identifications of alkalids from the aerial parts of C. hendersonii which is a traditional Tibetan medicine to treat febrifuge, high blood pressure and hepatitis. A new isoquinoline alkaloid, 9-methyl-decumbenine C (6), together with ten known alkaloids, stylopine (1), protopine (2), canadine (3), scoulerine (4), tetrahydrothalifendine (5), tetrahydroberberrubine (7), cryptopine (8), α-allocryptopine (9), 6,7-methylenedioxy-1(2H)-isoquinolinone (10) and 6-acetonyl-5,6-dihydrosanguinarine (11), and β-sitosterol (12) were isolated. Their structures were elucidated by spectroscopic methods. Furthermore, the total alkaloids were analyzed by ESI-MSn. The second chapter is about the isolations and identifications of chemical constituents from the aerial parts of I. younghusbandii. Sixteen compounds were isolated and purified by normal and reversed phase silica gel column chromatography. By spectral analysis, there structures were identified as isobergapten (1), sphondin (2), imperatorin (3), xanthotoxin (4), phellopterin (5), heraclenol (6), rivulobirin A (7), methyl oleanolate (8), methyl caffeate (9), grevillic acid (10), (D)-boschniakinic acid (11), 4-hydroxybenzoic acid (12), tert-O-β-D-glucopyranosyl-(R)-heraclenol (13), 5-methoxy-8-O-β-D-glucopyranosyloxypsoralen (14), decuroside Ⅴ(15), and phenylethyl-O-β-Dglucopyranosyl-(1→2)-β-D-glucopyranoside (16). All of these compounds were isolated from this plant for the first time.By the way, the chemical components of the essential oil from I. younghusbandii were analyzed by GC-MS for the first time. The third chapter is about the the isolations and identifications of the chemical constituents of M. interifolia. Eight compounds were isolated and identified as norsanguinarine (1), β-sitosterol (2), 3-hydroxyolean-12(13)-en-30-oic acid (3), 6-acetonyl-5,6-dihydrosanguinarine (4), luteolin (5), daucosterol (6), quercetin 3-O-β-D-glucopyranosyl-(1→6)-β-D-glucopyranoside (7) and protopine (8). The compounds 1, 4 and 7 were isolated from this herb for the first time. The last chapter is a review of the research progress of the studies on Corydalis species, which includes the chemical constituents in this genus and their pharmacology.
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花椒(Zanthoxylum piperitum)是川西干旱河谷地区的重要经济作物,化感作用是花椒连作障碍的原因之一。系统研究花椒化感作用有助于深入理解并最终解决花椒连作障碍。本文通过研究花椒叶、林下土壤浸提液及单一纯化感物质对花椒幼苗生长、苜蓿种子萌发及幼苗生长的影响作用,从生理生化角度揭示浸提液及纯化感物质的作用方式。通过室外和室内模拟实验,对浸提液及纯化感物质的化感效应进行比较,为花椒连作障碍的解决和化感作用机制的深入理解提供依据。主要结果如下: 1.花椒叶及林下土壤浸提液对地下生物量影响作用强与对地上生物量的化感效应,两种浸提液的化感效应强度不同,叶浸提液作用表现更显著。其中在Y6、Y8 、T6和T8处理时,花椒幼苗地下生物量分别降低了31.2%、32.1%、31.6%和31.7%。 2.两种浸提液均能显著影响花椒幼苗体内的保护性酶活性,总体说来,在高浓度下抑制各种抗氧化物酶活性,幼苗体内丙二醛含量增加,幼苗受害严重;在较低浓度下,各种保护性酶活性有所增加,丙二醛含量减少,幼苗伤害减轻。同时,不同月份里,各种酶的活性高低显著不同,9月份的活性显著低于7月份的酶活性。对于养分含量的影响,Y8、T8的影响强度最大,分别使碳元素含量降低了27.8%和30.8%,使钾元素含量降低了34.7%和25.6%。 3.花椒叶及林下土壤浸提液对苜蓿种子萌发及幼苗生长有化感作用,表现在最终萌发率、不同物质代谢及保护性酶活性的差异上。两种浸提液对苜蓿种子萌发过程中蛋白质的含量均无显著性影响,对淀粉和可溶性糖的影响作用类似,高浓度处理无明显化感效应,较低浓度处理显著降低二者在萌发苜蓿种子中的含量。Y2、Y4与T4处理分别使可溶性糖含量减少了32.3%、29.1%和18.8%,Y2与T2处理分别使淀粉含量降低了29.3%和26.8%。 4.苜蓿种子在4种单一化感物质最高浓度即10-3 mol•L-1处理下,萌发率显著降低,半数萌发时间推迟,随着处理浓度降低,抑制作用逐渐减弱,当降低到10-6 mol•L-1时,又能够表现出对苜蓿种子萌发的促进作用。 5.纯化感物质在10-6 mol•L-1时使苜蓿幼苗叶片的保护性酶活性显著升高,丙二醛含量显著降低;在10-3 mol•L-1时使苜蓿叶片中保护性酶活性显著降低,丙二醛含量增加,膜脂过氧化程度加重。 Zanthoxylum piperitum is one of the most important cash crops and has been extensively cultivated in Eastern Tibetan Plateau, especially in the fragile dry valley areas. Allelopathic effects could be a reason for Z. piperitum’s continuous cropping impediment. Systemmatically research of the effect of Z. piperitum allelopathy could help to comprehend the continuous cropping impediment. The allelopathic effects on seedlings growth and seed germination of aqueous extracts of Zanthoxylum piperitum and phenolic allelochemicals were studied, and the action mechanism of the two substances was also discussed from physiology. Indoor and outdoor experiments were set to compare the difference between aqueous extracts and pure allelochemicals. The main results showed that: 1. The aqueous extracts of leaf and soil had significant allelopathic effects on aboveground and underground biomass, but the effect on underground biomass was stronger than the effect on underground evidently. Treated with Y6、Y8 、T6 and T8, the underground biomass was reduced 31.2%、32.1%、31.6% and 31.7% respectively. 2. The activity of activities of superoxide dismutase, catalase, peroxidase and ascorbate peroxidase were significantly reduced, while the content of MDA was increased and the seedlings were suffered stronger, when treated by the high concentration; but at the low concentration, these were reversed. And then, at the different month, the activities of antioxidant enzyme were significantly distinct. As for the contents of nutrient element, Y8、T8 had the more intensive effects than other treatments. 3. The results showed that the two types of aqueous extracts had significant allelopathic effects on seed germination, substances metabolize and the activity of antioxidant enzyme. But the aqueous extracts had no effects on the content of protein, while had the similar effects on the content of starch and soluble sugar. At Y2、Y4 and T4, the content of soluble sugar decreased 32.3%、29.1% and 18.8% respectively. 4. Treated with 10-3 mol•L-1 of the four allelochemicals, the seed germination of alfalfa was significantly inhibited. Ferulic acid, coumarin and vanillic acid at 10-3 mol•L-1 significantly reduced the activities of antioxidant enzyme, while the content of MDA in alfalfa seedling was significantly increased. The restrain effects became weakened with the treat concentration falled. However, ferulic acid, coumarin and vanillic acid could increase the activities of antioxidant enzyme at 10-6mol•L-1.