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121.
为了解西藏色季拉山暗针叶林苔藓多样性及林窗干扰的影响,在过去工作积累的基础上研究了色季拉山西坡5块样地内不同林内环境(林窗、林缘和林下)地面、腐木和树附生苔藓生物量特征。结果表明, 地面生单位面积苔藓植物生物量储量最高,平均910.10 g/m2,其次为腐木生(221.90 g/m2),树附生的最低(53.59 g/m2)。林窗地面生苔藓单位面积生物量最高,均值为360.47 g/m2,其次为林下(305.51 g/m2),最小为林缘(244.11 g/m2);林窗、林缘和林下间的地面生苔藓单位面积生物量差异显著(P<0.05)。沿海拔梯度,林窗苔藓单位面积生物量表现出先增加后减少的趋势。因此,在西藏色季拉山暗针叶林内,林窗对地面生苔藓单位面积生物量有显著影响。 相似文献
122.
摘要 目的:探讨参苓白术散联合针刺对溃疡性结肠炎大鼠内质网应激、炎症反应的作用机制。方法:采用三硝基苯磺酸的方法构建溃疡性结肠炎大鼠模型。给予大鼠参苓白术散联合针刺干预。采用ELISA法检测大鼠病变结肠的炎症反应和氧化应激水平;采用肉眼观察各组结肠组织形态学评分;采用Western blot 检测大鼠内质网应激相关蛋白的表达。结果:与空白组相比,模型组、针刺组、参苓白术散、参苓白术散组联合针刺组大鼠体质量更低(P<0.05);与模型组相比,针刺组、参苓白术散、参苓白术散组联合针刺组溃疡指数评分和大鼠体质量更低(P<0.05),且参苓白术散组联合针刺组明显低于针刺组和参苓白术散组;与空白组相比,模型组、针刺组、参苓白术散、参苓白术散组联合针刺组ROS、GSH-Px、MDA更高(P<0.05);与模型组相比,针刺组、参苓白术散、参苓白术散组联合针刺组ROS、GSH-Px、MDA更低(P<0.05),且参苓白术散组联合针刺组明显低于针刺组和参苓白术散组;与空白组相比,模型组、针刺组、参苓白术散、参苓白术散组联合针刺组TNF-α、IL-1β、IL-18更高(P<0.05);与模型组相比,针刺组、参苓白术散、参苓白术散组联合针刺组TNF-α、IL-1β、IL-18更低(P<0.05),且参苓白术散组联合针刺组低于针刺组和参苓白术散组;与空白组相比,模型组、针刺组、参苓白术散、参苓白术散组联合针刺组GRP78、p-PERK、p-eIF2α更高(P<0.05);与模型组相比,针刺组、参苓白术散、参苓白术散组联合针刺组GRP78、p-PERK、p-eIF2α更低(P<0.05),且参苓白术散组联合针刺组明显低于针刺组和参苓白术散组。结论:参苓白术散组联合针刺可有效抑制溃疡性结肠炎大鼠内质网应激,进而抑制炎症反应和氧化应激反应,并促进溃疡性结肠炎大鼠病变病情转归。 相似文献
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124.
圈养林麝母幼关系的初步研究 总被引:8,自引:2,他引:6
本文研究圈养林麝(Moschusmoshiferusberezovskii)的母幼关系。林麝的母幼关系属于典型的隐蔽者(hider)类型。母幼分开躺卧,相距20.37±11.06m。吮乳时间、母幼联系时间、母幼联系时间/幼麝活动总时间随周龄的增加均呈明显的下降。4周龄前,幼麝躺卧居多,母麝以叫声主动联系幼麝,5周龄开始幼麝独立程度逐渐提高。听觉和视觉通讯是母幼远距离通讯的主要方式。 相似文献
125.
Alexander Christmann Jacqueline Christmann Petra Schiller Burkhard Frenzel 《Trees - Structure and Function》1996,10(5):331-338
Levels of indole-3-acetic acid (IAA) were determined in needles from silver fir (Abies alba Mill.) trees in the northern Black Forest. IAA was quantified by gas chromatography (GC) as 1-heptafluorobutyryl-IAA-methylester
(HFB-IAA-ME) using electron capture detection. Prior to GC analysis, extensive purification of needle extracts was performed
employing two HPLC steps. Peak identity of HFB-IAA-ME was confirmed by combined gas chromatography-mass spectrometry in selected
samples. Levels of IAA in needles belonging to different needle age-classes exhibited a cyclic seasonal pattern with highest
concentrations in winter and lowest levels in spring when bud-break occurred. Such a cyclic seasonal pattern of IAA levels
was also observed in needles from declining fir trees or fir trees suffering from a strong sulfur impact (S-impact) in the
field due to a local SO2 source. Levels of IAA increased with increasing needle age. This age dependency of IAA concentrations was most pronounced
in late autumn when IAA levels were high and nearly disappeared in spring when IAA levels reached their minimum. In needles
from declining fir trees or fir trees suffering from a strong S-impact in the field, IAA levels hardly increased with increasing
needle age. It is suggested that in healthy trees high levels of IAA protect older needles from abscission and that the considerable
losses of older needles of declining fir trees or of fir trees under S-impact are a consequence of the low levels of IAA found
in older needles of such trees.
Received: 4 May 1995 / Accepted: 29 August 1995 相似文献
126.
Sandrine Sagan Hubert Josien Philippe Karoyan Alié Brunissen Gérard Chassaing Solange Lavielle 《Bioorganic & medicinal chemistry》1996,4(12):2167-2178
The action of rotameric probes introduced either in position 7 or 8 in the sequence of substance P (SP) was investigated, i.e.
-tetrahydroisoquinoleic acid (Tic),
-fluorenylglycine (Flg),
-diphenylalanine (Dip), the diastereoisomers of
-1-indanylglycine (Ing) and
-benz[ƒ]indanylglycine (Bfi), the Z- and E-isomers of dehydrophenylalanine and dehydronaphthylalanine (ΔZPhe, ΔEPhe, ΔZNal, ΔENal) and
(Dmp). The aim of this study was the topographical characterization of the binding subsites of human NK-1 receptor expressed in CHO cells, especially the S7 and S8 subsites, corresponding to residues Phe7 and Phe8 of substance P. According to the binding potencies of these substituted-SP analogues, the S7 binding subsite is smaller than the S8 subsite: the S7 subsite accepts only one aromatic nucleus, while the S8 can accommodate three coplanar nuclei altogether. These findings are compatible with the idea that the S8 binding subsite may reside in the extracellular loops of the hNK-1 receptor. NK-1 agonists bind to human NK-1 receptor and activate the production of both inositol phosphates and cyclic AMP. As already quoted for septide, [pGlu6, Pro9]SP(6–11), discrepancies are observed between affinity (Ki) and activity (EC50) values for IPs production. While a weak correlation between Ki and EC50 values for IPs production could be found (r = 0.70), an excellent correlation could be demonstrated between their affinities (Ki) and their potencies (EC50) for cAMP production (r = 0.97). The high potency (EC50) observed for ‘septide-like’ molecules on PI hydrolysis, compared to their affinity is not an artefact related to the high level of NK-1 receptors expressed on CHO cells since a good correlation was found between EC50 values obtained for PI hydrolysis and those measured for spasmogenic activity in guinea pig ileum bioassay (r = 0.94).
According to the binding potencies of constrained analogues of phenylalanine, the S7 binding subsite of human NK-1 receptor is small, whereas the S8, which can accommodate three coplanar nuclei, might probably reside in the extracellular loop. The discrepancies observed between affinity (Ki) and activity (EC50) values for IPs production are not an artefact of CHO cells since a good correlation was found between EC50 for PI hydrolysis and those measured in guinea pig ileum bioassay. 相似文献
127.
128.
129.
生态因子对森林生态系统稳定性影响的数学分析 总被引:1,自引:0,他引:1
本文在对河南省森林生态类型划分的基础上,应用主成分分析、模糊聚类和遂步判别分析的方法,对森林生态系统的稳定性进行了研究,结果表明:影响森林生态系统稳定性的因子主要有6个,即:森林覆被率、人口密度、土壤侵蚀模数、大风日数、降水集中率和地形;河南省森林生态系统按其稳定程度可分为5个等级;应用逐步判别分析是建立稳定性判别模式的较好方法。 相似文献
130.
旱地玉米农田棵间蒸发研究 总被引:3,自引:0,他引:3
采用中子微区模拟装置测量旱地玉农田棵间蒸发,实验表明,本实验装置实用可行。晋西棵间蒸发量占降水量(510nm)的55%以上,棵间蒸发与蒸散的比值同时叶面积指数呈反相关,玉米产量与作物蒸腾呈正相关。 相似文献