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61.
Liquid accelerating agents have the advantages of simple operation and fast construction, and have become indispensable admixtures in shotcrete. However, most liquid accelerating agents in the market at present contain alkali or fluorine, which adversely affect concrete and seriously threaten the physical and mental health of workers. Therefore, in view of the above deficiencies, it is necessary to develop a new type of alkali-free fluorine-free liquid accelerating agent. In this paper, the polyaluminum sulfate early strength alkali-free liquid accelerator is prepared using polymeric aluminum sulfate, diethanolamine, magnesium sulfate heptahydrate and nano-silica. The influence of this agent on the setting time of fresh cement paste and compressive strength of the corresponding cement mortar is determined. Thermogravimetric analysis curves, X-ray diffraction and scanning electron microscopy images are obtained to investigate the mechanism. Findings show that the initial setting time and the final setting time of cement paste are 2 min 30 s and 7 min 25 s. The compressive strengths of cement mortar cured for 1 d, 28 d and 90 d are 2.4 MPa, 52.2 MPa and 54.3 MPa respectively. Additionally, the corresponding flexural strengths are 3.4 MPa, 9.8 MPa, 11.8 MPa. When the mass rate of accelerator is 7%, the mechanical strengths of cement mortar are the highest. The additions of fly ash and blast furnace slag can affect the mechanical of cement mortar mixed with accelerator. When the mass ratio of the fly ash and blast furnace slag is 15%, the mechanical strengths of cement mortar reach the highest. Moreover, the hydration heat release rate of cement is increased by the accelerator and the corresponding time of hydration heat peak is decreased by the accelerator. The accelerator can decrease the amount of needle-like hydration products and improve the compactness. The mechanical strengths are improved by consuming a large amount of Ca(OH)2 and forming more compact hydration products. It is recommended that the optimum dosage range of the polyaluminum sulfate early strength alkali-free liquid accelerator is 7%.  相似文献   
62.
ObjectivesMenstrual hygiene management (MHM) in developing countries is linked to human rights, social justice, and the education and empowerment of young girls. The objective of this study was to assess menstrual hygiene practices and their determinants among adolescent girls, including school dropouts, and the effects of pad distribution programs in urban resettlement areas of Delhi, India.Methods A cross-sectional study was conducted from March 2019 to February 2020 in urban resettlement colonies and 2 villages of Delhi among 1,130 adolescent girls aged 10 to 19 years, who were interviewed face to face.Results In total, 954 participants (84.4%) used only disposable sanitary pads, 150 (13.3%) used both sanitary pads and cloths, and 26 (2.3%) used only cloths (n=1,130). Most school-going girls utilized the scheme for pad distribution, but only two-thirds of the girls who were out of school utilized the scheme. In the adjusted analysis, girls with lower educational status, those who had dropped out of school, and those from the Muslim religious community were more likely to use cloths for MHM.Conclusion More than 4 out of 5 adolescent girls in Delhi in low-income neighborhoods preferred sanitary pads for MHM. The government free pad scheme reached near-universal utilization among school-going girls (97%), but the subsidized pad scheme for girls who did not attend school was insufficiently utilized (75%).  相似文献   
63.
Reducing the alcoholic strength in beverages as a strategy to reduce harmful alcohol use has been proposed by multilateral institutions such as the World Health Organization and governments worldwide. Different industrial and artisanal techniques are used to achieve low-alcohol content beverages. Therefore, regulations regarding the content of alcohol in beverages and strategies to monitor compliance are important, because they are the main reason for classification of the beverages and are central to their categorization and market labelling. Furthermore, analytical techniques with adequate sensitivity as low as 0.04% vol are necessary to determine the alcohol ranges necessary for classification. In this narrative review, the definitions of no and low (NoLo) alcohol products are described and the differences in the legal definitions of these products in several regions of the world are highlighted. Currently, there is clearly confusion regarding the terminology of “no”, “free”, “zero”, “low”, “light”, or “reduced” alcohol products. There is an urgent need for global harmonization (e.g., at the Codex Alimentarius level) of the definitions from a commercial perspective and also to have common nomenclature for science and for consumer information.  相似文献   
64.
远志不同炮制品皂苷类成分含量的比较   总被引:1,自引:0,他引:1  
目的:研究生远志、制远志、蜜远志中皂苷类成分含量的差异。方法:以远志酸和远志皂苷元含量为指标对3种炮制品进行HPLC测定。色谱柱为Agilent ZORBAX SB-C18(4.6 mm×250 mm5,μm),流动相为乙腈-0.1%磷酸(41∶59);检测波长210 nm;流速1.0 mL·min-1,柱温25℃。结果:远志酸含量和远志皂苷元含量,均为制远志>生远志>蜜远志。结论:不同炮制方法能改变远志皂苷类成分的含量,蜜远志的远志酸含量与远志皂苷元含量均低于生远志与制远志。  相似文献   
65.
阴火的概念首见于李东垣的《内外伤辨惑论》,详实于《脾胃论》,但其中并没有对阴火的本质做出详细解释,因此后世医家对其有很多不同见解。主要包括:气虚发热、阴虚发热、相火离位、阴火非火四种观点,但是以上观点仍不能较全面解释阴火。现通过复习李东垣对于阴火的论述,并结合个人对气机循环的理解,同时应用以方测证的方法,得出阴火的本质是脾胃之气在受劳倦,饥饱失宜或七情内伤的情况下,脾胃的运化和受纳腐熟的功能受损,产生的一种病理产物。补中益气汤治疗阴火的原理为健运中焦,恢复脾胃运化谷食的正常功能,使阴火所生乏源,再以风药泻之,则元气复,阴火散。  相似文献   
66.
内生真菌与天然产物研究进展   总被引:9,自引:0,他引:9  
王兴红 《中草药》2007,38(1):140-143
内生真菌生境独特,分布广泛,是发现新颖结构化合物的理想资源。植物是药用植物的主要材料,药用植物体内有大量内生真菌分布,内生真菌对药用植物的生长及活性成分的形成都有影响,如名贵中药血竭的形成需要内生真菌的参与,中药材的道地性可能也与内生真菌有密切关系。从内生真菌中发现活性成分所面临的一个重要问题是:随着野生中药资源及其生境遭到破坏,伴生的内生真菌也会随着大量消失,由此可能对中药长远发展产生重大影响,但这一现象尚未引起人们足够的重视。  相似文献   
67.
中药活性成分生物转化的研究思路与方法   总被引:13,自引:0,他引:13  
结合本课题组近几年来的研究结果,对中药活性成分的生物转化方法进行总结,并对今后生物转化的研究思路进行了展望。目前,生物转化在有机合成领域的应用比较广泛,而该技术用于中药活性成分的结构修饰还处于初级阶段,尤其缺乏对某类中药活性成分系统的生物转化研究,因此有很多方面的研究值得关注,尤其是生物催化酶的研究将是生物转化的重要发展方向。此外,生物转化在中药活性化合物合成中的应用以及利用“微生物模型”研究中药活性的体内代谢,也将成为今后生物转化研究中不可忽视的领域。  相似文献   
68.
田清华  张亚  徐聪  陈燕  陈塞特  王维  颜继忠  张慧 《中草药》2019,50(20):4925-4931
目的建立舒筋活血制剂(舒筋活血胶囊、舒筋活血片)HPLC指纹图谱的方法,为其整体质量评价提供参考。方法色谱柱为Agilent Poroshell 120 SB-C18(150 mm×4.6 mm,2.7μm),以乙腈-0.2%甲酸水溶液为流动相,进行梯度洗脱;体积流量0.5mL/min,检测波长277nm,柱温30℃。采用"中药色谱指纹图谱相似度评价系统"(2012版)考察23批舒筋活血制剂的相似度,结合主成分分析(principal component analysis,PCA)、聚类分析(cluster analysis,CA)以及正交偏最小二乘判别分析(orthogonal partial least squares discriminant analysis,OPLS-DA)对舒筋活血制剂进行整体质量评价。结果舒筋活血制剂的HPLC指纹图谱中18批样品(S1~S17和S23)的相似度0.900,通过PCA、CA和OPLS-DA,23批样品聚成3类,S1~S16来自同一厂家为一类;S23和S17为一类;S18~S22为一类,并从10个共有峰中确定差异较大的4个共有峰,分别为1、3(5-羟甲基糠醛)、6(苯乙酸)和10(4-甲氧基水杨醛)号峰。结论所建立的指纹图谱结合化学模式识别方法稳定、简单,可用于评价舒筋活血制剂质量。  相似文献   
69.
It has previously been reported that magnolol, a phenolic compound isolated from Magnolia obovata, inhibited tumour cell invasion in vitro. The purpose of this study was to investigate the antimetastatic effect of magnolol on tumour metastasis in vivo with experimental and spontaneous metastasis models and to clarify the mechanism. The antimetastatic effects of magnolol were evaluated by an experimental liver and spleen metastasis model using L5178Y-ML25 lymphoma, or an experimental and spontaneous lung metastasis model using B16-BL6 melanoma. Intraperitoneal (i.p.) administration of 2 or 10 mg/kg of magnolol significantly suppressed liver and spleen metastasis or lung metastasis. As for the spontaneous lung metastasis model using B16-BL6 melanoma, multiple i.p. administrations of 10 mg/kg of magnolol after and before tumour inoculation significantly suppressed lung metastasis and primary tumour growth. In addition, magnolol significantly inhibited B16-BL6 cell invasion of the reconstituted basement membrane (Matrigel, MG) without affecting cell growth. These data from the in vivo experiments suggest that magnolol possesses strong antimetastatic ability and that it may be a lead compound for drug development. The antimetastatic action of magnolol is considered to be due to its ability to inhibit tumour cell invasion.  相似文献   
70.
目的:比较枳壳不同炮制品的燥性,考察其对功能性消化不良(FD)大鼠胃肠功能的影响。方法:以大鼠饮水量、排尿量、肾水通道蛋白3(AQP3)含量、血清环磷酸腺苷(c AMP)与血清环磷酸鸟苷(c GMP)比值为评价指标,观察不同剂量的枳壳生品、麸炒枳壳、蜜麸枳壳对健康大鼠水液代谢的影响;以胃黏膜损伤指数,血清肿瘤坏死因子-α(TNF-α),白细胞介素6(IL-6),IL-8含量为评价指标,观察不同剂量枳壳生品、麸炒枳壳、蜜麸枳壳对健康大鼠胃黏膜损伤的影响;以大鼠胃残留率和小肠推进率,血清胃动素(MTL),血管活性肠肽(VIP),降钙素基因相关肽(CGRP)含量为评价指标,观察不同剂量枳壳生品、麸炒枳壳、蜜麸枳壳对FD大鼠胃肠功能的影响。结果:在水液代谢方面,同等剂量给药组与空白组相比,差异性排序为枳壳生品麸炒枳壳蜜麸枳壳,且高剂量组低剂量组;在胃黏膜损伤方面,不同剂量枳壳生品、麸炒枳壳、蜜麸枳壳组各项指标与空白组比较均无显著性差异;在促胃肠动力方面,同等剂量给药组与模型组相比,差异性为麸炒枳壳枳壳生品蜜麸枳壳,且低剂量组高剂量组。结论:枳壳生品的燥性主要表现为对机体津液的损伤,且强度与剂量有关,对健康大鼠胃黏膜未见明显直接刺激。炮制后可在一定程度上缓和伤津之弊,且以蜜麸枳壳缓和作用最佳;枳壳生品和炮制品均可促进FD大鼠胃肠功能的恢复,麸炒枳壳治疗作用优于生品与蜜麸制品。  相似文献   
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