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1.
欧阳修自幼与园林结缘,仕宦四十年,所到之处植花造园,笔耕不辍,留下数座园林景观、二十多篇园亭记及百余首园林诗词,撰写了现存最早的牡丹专著《洛阳牡丹记》,为后人研究园林提供了珍贵的史料。欧阳修的园林活 动和园林书写与其宦海沉浮、文学创作紧密相关。欧阳修热爱但不耽溺于园林,其崇尚自然、开放自适,不拘于形,不役于物的园林观,拓宽了园林审美的视域,启发了后人对“物”的审美思考,为园林理论注入了新鲜血液。欧阳修进一步打开了园林的大门,推动了园林的开放,为园林的繁荣与普及做出贡献。 相似文献
2.
人为影响下古尔班通古特沙漠小尺度生态环境变化 总被引:1,自引:1,他引:1
随着沙漠中油气资源勘探开发、公路建设和重大工程相继实施 ,对生态环境的人为影响日益加深。本文以重大工程实验点为例 ,通过研究对比工程影响区内人工沙垄和自然沙垄的砂质新成土理化性状和植被群落特征 ,指出了沙漠生态环境在人为干扰下发生的一系列变化 ,以及受损生态环境在人们采取积极补救措施的情况下所具有的自然修复能力 相似文献
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Xiao-Peng Lu Yong-Zhong Liu Gao-Feng Zhou Qing-Jiang Wei Hong-Ju Hu Shu-Ang Peng 《Scientia Horticulturae》2011
‘Yandangxueli’ is a pear cultivar with predominant citric acid in the ripe fruit, different from most of pear cultivars such as ‘Gengtouqing’ in which malic acid is the predominant acid type. It was found that ‘Yandangxueli’ accumulated citric acid for three times against that in ‘Gengtouqing’ at fruit ripening stage. To investigate the mechanism of citric acid accumulation in ‘Yandangxueli’, organic acids content, gene expression and enzyme activity were studied in both cultivars. Five genes, Pp:mtCs, Pp:cyAco, Pp:cyIdh, Pp:mtMdh and Pp:cyMe which encoded citric synthase (CS), cytosolic aconitase (cyACO), NADP-dependent isocitrate dehydrogenase (NADP-IDH), NAD-dependent malate dehydrogenase (NAD-MDH) and NADP-dependent malic enzyme (NADP-ME) respectively, were identified from pear fruit. Their expression profiles and the corresponding enzyme activities were determined throughout fruit development in both cultivars. Results from these enzymes indicated that there were no strict relationship between gene expression, enzyme activity and citric acid accumulation. Expression analysis for two Py:vVAtp genes encoding vacuolar H+-ATPase A subunit and one Py:vVpp gene encoding Vacuolar H+-pyrophosphatase showed that they were all with up-regulated expression at the later development stage of ‘Yandangxueli’ but with down-regulated expression in ‘Gengtouqing’. Therefore, it is concluded that the different ability in citric acid transportation and storage might be involved in the high citric acid content in ‘Yandangxueli’. 相似文献
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以热带柱花草和黑籽雀稗为材料,通过盆栽试验,研究不同磷水平对其根际酸性磷酸酶、微生物数量及根系活力的影响。结果表明:2种牧草根际酸性磷酸酶(ACP)活性随着磷浓度的增加而降低,在低磷(P0)处理时达最高,柱花草的ACP活性为603.24 mg/(kg·h),黑籽雀稗为367.21 mg/(kg·h)。当高磷浓度处理时,柱花草根际ACP活性较黑籽雀稗低。各处理中,柱花草的根际微生物总量较黑籽雀稗高,柱花草根际真菌的数量随磷浓度的增加而减少,处理间差异达极显著水平,低磷处理时土壤真菌数量较多,这有利于根瘤菌的形成。2种牧草的根系活力随着施磷浓度的增加而递减。黑籽雀稗根系活力P0处理极显著高于P3和P4处理,显著高于P2处理。黑籽雀稗根系活力受供磷水平的影响大于柱花草。 相似文献
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L. N. Rønnow Kjærulff N. J. Dorch Lauritsen C. Thorn Ekstrøm S. Østergaard E. Olsen S. Hyldahl Laursen C. Lindegaard 《Equine Veterinary Education》2021,33(7):360-367
Caudal epidural analgesia is a well-established therapeutic modality for pain alleviation in horses. Additionally, epidural analgesia could potentially be a complementary diagnostic tool for confirmation of pain-related conditions in horses presenting with nonspecific signs of poor performance or rideability issues. To use the epidural as a diagnostic tool, the administered medications should provide efficient analgesia without accompanying adverse effects. Therefore, the objectives of the current study were to evaluate the analgesic properties and effects on locomotor function, mentation and physical examination parameters of caudal epidural co-administration of methadone and morphine in horses. Five mares received a caudal epidural injection of 0.1 mg/kg bwt methadone and 0.1 mg/kg bwt morphine diluted to a total volume of 4.4 mL/100 kg. Before and several times thereafter, horses were subjected to mechanical nociceptive threshold evaluation, physical examination, assessment of mentation and locomotor function examination. Horses were assigned ataxia scores (0–4) by a group of inexperienced raters (three senior-year veterinary students) and a group of experienced raters (two board-certified internal medicine specialists) that assessed the locomotor examinations either live or video-based. The epidural co-administration of methadone and morphine resulted in clinically relevant and statistically significant increases of horses’ tolerance to mechanical noxious stimuli at the coccygeal, perineal, sacral, lumbar and thoracic regions. Analgesia was evident after 4.4 h and lasted at least 5 h. Regional differences in the onset of analgesia reflected a cranial spread of the analgesic solution. No horses showed signs of gait disturbances; the overall median ataxia score was 0 at all times; and the average difference in scores between two randomly selected raters for a random horse at a random time point was 0.377 indicating high inter-rater agreement. There were no adverse changes of mentation and physical examination parameters. Observed side effects included signs of decreased frequency of defaecation, generalised sweating, and pruritus. 相似文献
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为探明东北地区常见野生葱属植物耐旱能力,筛选野生葱属植物耐旱种质资源,本研究以野韭(Allium ramosum L.)、山韭(Allium senescens L.)和蒙古韭(Allium mongolicum Regel)3种葱属植物为材料,采用不同浓度的PEG-6000模拟干旱胁迫,分析其种子萌发期渗透调节物质及酶活性的影响,并结合主成分分析和隶属函数分析比较抗旱性。结果表明:干旱胁迫下,3种葱属植物种子萌发期相对电导率显著升高(P<0.05),丙二醛、脯氨酸、可溶性糖、可溶性蛋白含量及超氧化物歧化酶、过氧化氢酶、过氧化物酶、多酚氧化酶活性均呈现先上升后下降的趋势。3种植物相比,山韭相对电导率最低,渗透调节物质积累量最高,酶活性变化明显。主成分分析表明,4种酶活性之间显示出强相关性。隶属函数分析得出3种植物种子的抗旱性由高到低依次为:山韭 > 野韭 > 蒙古韭。 相似文献
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《The Journal of Applied Poultry Research》2016,25(3):422-427
Xinyang green-shell laying hens (n = 720), 32 wk of age were allocated to 5 dietary treatments groups, each of which included 6 replicates of 24 hens. The control group was given a basal corn-peanut-soybean meal diet containing 0.47% L-threonine (L-Thr). L-Thr levels of the experimental groups were 0.57, 0.67, 0.77, and 0.87%, respectively. The trial lasted 10 wk. Serum concentrations of total superoxide dismutases (T-SOD) and superoxide dismutases (SOD) were maximized at 0.67% L-Thr group. The 0.57% L-Thr group had the highest serum total antioxidative capacity (T-AOC), while the 0.67% L-Thr group had the lowest serum malondialdehyde (MDA) concentration. Hens fed 0.67% L-Thr of the diet resulted in the highest SOD and T-AOC levels in the liver. The activity of amylase and lipase in the jejunum was maximized at 0.77% L-Thr level. Hens fed 0.77% L-Thr in the diet resulted in the highest IgM and IgG levels in the jejunum. In conclusion, we suggest that a L-Thr level above 0.67% may have had an antioxidant capacity and positive effect on digestive enzyme activities and antibody production in the jejunum of Xinyang green-shell laying hens. 相似文献
10.
以款冬叶片为试材,采用微波辅助法提取总黄酮,在单因素试验的基础上,采用正交实验法优化款冬叶片总黄酮提取工艺,同时以分光光度法测定提取物对1,1-二苯基-2-三硝基苯肼自由基(1,1-diphenyl-2-picrylhydrazyl,DPPH·)、羟基自由基(·OH)和超氧阴离子自由基(O-·2)的清除作用。结果表明:款冬叶片总黄酮最佳提取条件为乙醇体积分数70%,微波提取时间3 min,微波功率500 W,料液比1∶15 g·mL^-1,在该条件下,总黄酮的提取率为0.91%。款冬叶片总黄酮的质量浓度与抗氧化活性呈一定的线性关系,当总黄酮质量浓度为0.069 8 mg·mL^-1时,对DPPH·、·OH和O-·2的清除率分别达84.21%、84.10%和68.32%,表明款冬叶片具有良好的抗氧化能力,可作为天然的抗氧化剂进一步的开发和利用。 相似文献