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1.
粘膜是动物有机体与外界环境相隔的最大屏障 ,是病原体入侵的最大门户。粘膜免疫近几年来倍受人们的关注。粘膜免疫为免疫学提出了新的内容 ,并成为发展最迅速的领域。本文就粘膜免疫的机理、粘膜免疫系统的组成与功能、粘膜免疫应答细胞、粘膜免疫的解剖组织学结构特征、分泌型免疫球蛋白A的结构与功能等方面的内容作一简述。 相似文献
2.
INTRODUCTION Helicobacter pylori (H.pylori) was grouped as a class I carcinogen by the International Agency for Research on Cancer in 1994. A direct relation be-tween H.pylori infection and gastric carcinogenesis was demonstrated in 1998 in an experimental animal model (Watanabe et al., 1998). However, the role of H.pylori in human gastric carcinogenesis is sup-ported almost exclusively by epidemiological data and prospective histopathological studies. So far the mechanism of H.pylor… 相似文献
3.
Objective: To investigate the distribution of H. pylori antigens in the gastric mucosa in patients with H. pylori infection, and the relationship between the distribution and gastric cancer. Methods: Of 112 patients confirmed by pathological study to have chronic superficial gastritis, precancerous changes (chronic atrophic gastritis, intestinal metaplasia or atypical hyperplasia) and gastric cancer, 28 were H. pylori negative and 84 were H. pylori positive. H. pylori antigens in the gastric mucosa were detected by immunohistochemistry. Results: The H. pylori positive group, comprised 12 of 22 (50.0%) in the chronic superficial gastritis group, 22 of 25 (88.0%) in the precancerous changes group and 13 of 35 (37.1%) in the gastric cancer group. The positive rates of H. pylori antigens in the cytoplasm progressively increased, respectively at 0.0% (0/12),63.6% (14/22) and 84.6% (11/13) for the same groups (χ2=19.76, P=0.000); H.pylori antigens were located in the mucus layer and above the neck of the mucosal gland in 9 of 12 (75.0%) cases with chronic superficial gastritis, at the neck of the mucosal gland and the isthmus in 12 of 22 (54.5%) cases with precancerous changes, below the isthmus in 9 of 13 (69.2%) cases with gastric cancer (x2=25.30, P=0.000). In the H. pylori negative group, no H.pylori antigen was observed. Conclusion: With the progression of chronic superficial gastritis→precancerous changes→gastric cancer, H. pylori antigens progressively migrated from the outer part to the inner part of the cell, and from the superficial to the deep gastric mucosa. 相似文献
4.
巴夫金藻耐受Cu~(2+)、Cd~(2+)毒害作用的研究 总被引：5，自引：0，他引：5
[目的]研究单胞藻对重金属离子毒害的耐受性,为生物去污提供依据。[方法]分别用不同浓度(c=1～150mg/L)Cu~(2+)、Cd~(2+)处理巴夫金藻(Monochrysis lutheri),观察了重金属离子对其生长的影响;用微量减压法研究毒害抑制呼吸作用;用ICP法研究毒害抑制下重金属离子的富集。[结果]①2种离子的毒性强度的顺序为Cu~(2+)>Cd~(2+);②Cu~(2+)对生长的抑制较强,其EC_(50)(72h)为15.0mg/L;Cd~(2+)对生长的抑制较弱,其EC_(50)(72h)为75mg/L;③在EC_(50)毒害浓度下,毒害组均提前进入生长静止期,缩短了种群生长周期;呼吸作用先增强后降低;④在EC_(50)毒害浓度下,单胞藻对Cu~(2+)的富集量为6866.1mg·kg~(-1),对Cd~(2+)的富集量678.25mg·kg~(-1)。[结论]巴夫金藻具有较强的耐受重金属离子毒害能力,耐受顺序为Cd~(2+)相似文献
5.
低尘低毒碱性焊条的试制 总被引：1，自引：0，他引：1
谢清莲 《天津职业院校联合学报》2010,12(2):27-31
为了解决低氢型焊条焊接时产生大量有毒烟尘问题,试制一种既能满足原有工艺性能条件,又能降尘降毒的卫生指标先进的新型低尘低毒碱性焊条,试制两种焊条配方方案对比其优劣,进而寻求一种全新配方的降光降毒。 相似文献
6.
RAJPUT Zahid Iqbal HU Song-hua XIAO Chen-wen ARIJO Abdullah G. 《Journal of Zhejiang University. Science. B》2007,8(3)
Vaccines require optimal adjuvants including immunopotentiator and delivery systems to offer long term protection from infectious diseases in animals and man. Initially it was believed that adjuvants are responsible for promoting strong and sustainable antibody responses. Now it has been shown that adjuvants influence the isotype and avidity of antibody and also affect the properties of cell-mediated immunity. Mostly oil emulsions, lipopolysaccharides, polymers, saponins, liposomes, cytokines,ISCOMs (immunostimulating complexes), Freund's complete adjuvant, Freund's incomplete adjuvant, alums, bacterial toxins etc.,are common adjuvants under investigation. Saponin based adjuvants have the ability to stimulate the cell mediated immune system as well as to enhance antibody production and have the advantage that only a low dose is needed for adjuvant activity. In the present study the importance of adjuvants, their role and the effect of saponin in immune system is reviewed. 相似文献
7.
Adjuvant effects of saponins on animal immune responses 总被引：2，自引：0，他引：2
Vaccines require optimal adjuvants including immunopotentiator and delivery systems to offer long term protection from infectious diseases in animals and man. Initially it was believed that adjuvants are responsible for promoting strong and sustainable antibody responses. Now it has been shown that adjuvants influence the isotype and avidity of antibody and also affect the properties of cell-mediated immunity. Mostly oil emulsions, lipopolysaccharides, polymers, saponins, liposomes, cytokines, ISCOMs (immunostimulating complexes), Freund’s complete adjuvant, Freund’s incomplete adjuvant, alums, bacterial toxins etc., are common adjuvants under investigation. Saponin based adjuvants have the ability to stimulate the cell mediated immune system as well as to enhance antibody production and have the advantage that only a low dose is needed for adjuvant activity. In the present study the importance of adjuvants, their role and the effect of saponin in immune system is reviewed. 相似文献
8.
职教师资的匮乏,极大影响了美国生涯和技术教育(CTE)的质量,美国各州纷纷出台相应政策,设立和完善CTE教师资格证项目,改革CTE教师资格证体系,为社会人员开辟获得CTE教师资格证书的"备选"途径,以吸引职业技术人才进入CTE师资队伍。以南卡罗来纳州的CTWCP项目为例,美国各州职教教师资格证备选途径具有以下特征:强调知识整合,注重课程平衡;强调课程标准,注重培养质量;强调以人为本,注重学生自主;强调市场需求,注重与行业合作。 相似文献
9.
10.
Objective: To investigate the distribution ofH. pylori antigens in the gastric mucosa in patients withH. pylori infection, and the relationship between the distribution and gastric cancer. Methods: Of 112 patients confirmed by pathological
study to have chronic superficial gastritis, precancerous changes (chronic atrophic gastritis, intestinal metaplasia or atypical
hyperplasia) and gastric cancer, 28 wereH. pylori negative and 84 wereH. pylori positive.H. pylori antigens in the gastric mucosa were detected by immunohistochemistry. Results: TheH. pylori positive group, comprised 12 of 22 (50.0%) in the chronic superficial gastritis group, 22 of 25 (88.0%) in the precancerous
changes group and 13 of 35 (37.1%) in the gastric cancer group. The positive rates ofH. pylori antigens in the cytoplasm progressively increased, respectively at 0.0% (0/12), 63.6% (14/22) and 84.6% (11/13) for the same
groups (χ
2=19.76,P=0.000);H. pylori antigens were located in the mucus layer and above the neck of the mucosal gland in 9 of 12 (75.0%) cases with chronic superficial
gastritis, at the neck of the mucosal gland and the isthmus in 12 of 22 (54.5%) cases with precancerous changes, below the
isthmus in 9 of 13 (69.2%) cases with gastric cancer (χ
2=25.30,P=0.000). In theH. pylori negative group, noH. pylori antigen was observed. Conclusion: With the progression of chronic superficial gastritis→precancerous changes→gastric cancer,H. pylori antigens progressively migrated from the outer part to the inner part of the cell, and from the superficial to the deep gastric
mucosa. 相似文献
11.
Frankie Santos Laanan Jonathan I. Compton Janice Nahra Friedel 《Community College Journal of Research & Practice》2013,37(4):293-310
ABSTRACT This scholarly paper describes and analyzes the role of career and technical education (CTE) in Iowa community colleges. Iowa's community colleges are doing a good job of responding to the changing workforce needs of the state and providing smooth career pathways. However, changes in the population and economy of the state will call for further changes in CTE programs. The distinctive characteristics of CTE in Iowa community colleges, the impact of community college CTE programs on the state's economy, the role of accountability, and the future implications for CTE in the state are discussed. Recommendations based on the results of the study include improving articulation agreements, increasing retention among at-risk students, and increasing collaboration among Iowa's 15 community colleges. 相似文献
12.
Angela D. Benson Scott D. Johnson John Duncan Olga N. Shinkareva Gail D. Taylor Tod Treat 《Community College Journal of Research & Practice》2013,37(9):665-687
This article presents the results of a national study of distance learning in postsecondary career and technical education (CTE). The main purpose of this study was to identify the current status and future trends associated with distance learning in postsecondary CTE. The results show that community colleges are (a) actively involved in the delivery of CTE via distance learning for the purpose of meeting the needs of their diverse student body, (b) more likely to provide credit courses via distance than noncredit courses, and (c) offering few CTE programs fully at a distance. 相似文献
13.
美国社区学院远程生涯技术教育研究 总被引：1，自引：0，他引：1
随着信息通信技术(ICT)的迅猛发展,美国社区学院生涯技术教育中应用远程教育的比重不断增加。本文分析认为,远程教育广泛用于生涯技术教育是基于美国文化中崇尚"技术"和"平等"的特性,分析了生涯技术教育自身所强调的"从学校到工作"和"能力为本位"的功能定位,以及现代远程教育灵活学习方式的适切性。此外,本文还介绍了远程生涯技术教育中的技术传输、资源开发和课程教学模式,最后指出了其面临的挑战。 相似文献
14.
Jaime Lester Aoi Yamanaka Brice Struthers 《Community College Journal of Research & Practice》2016,40(11):909-926
Career and technical education (CTE) programs account for a large proportion of student enrollments in community colleges each year. While women tend to dominate CTE enrollments overall, they remain concentrated in historically feminized fields contrary to nontraditional occupations in which less than 25% of workers are females. Drawing on the emerging research on microaggressions and classroom learning environments, this classroom observation research project of more than 80 hours of observations with supplemental student interviews sought to further an understanding of why women are underrepresented in specific CTE fields. The findings of this study indicated two distinct aspects of the classroom environment that helped stew a culture of gender microaggressions: the instructor pedagogy and communication style, and the impact of physical space. Physical structure, instructor pedagogy, and communication create an environment that often emphasizes and perpetuates social norms connecting men and masculinity to CTE and science, technology, engineering, and math education (STEM), which historically have been male-dominated environments. Results from this study extend the research on microaggressions and learning environments and fill a significant gap on gender and CTE. 相似文献
15.
属间远缘杂交水稻耐铁毒性研究 总被引：4，自引：0，他引：4
以吉田昌—培养液为对照，添加不同浓度ＦｅＳＯ４作为铁毒胁迫处理，对二个属间远缘杂交水稻“远诱１号”和“遗传工程水稻１号”及三系杂交组合“汕优６３”二叶龄幼苗进行耐铁毒性比较鉴定．试验结果表明，３个试验材料的耐铁毒性以高粱稻远诱１号及三系稻汕优６３较强，遗传工程水稻１号耐铁毒性相对较弱．根据溶液中Ｆｅ２＋／Ｆｅ３＋的变化规律，稻体内持铁量的差异，稻株根系氧化力的区别，拒斥可能是汕优６３的耐铁毒性生理基础，遗传工程水稻１号的耐性机制为容耐，而远诱１号的耐铁生理基础兼具拒斥与氧化双重机制而偏倚于主动氧化机制．体内钾、硅、镁、钙含量与铁离子含量密切相关，丰富的钾、硅、镁可以改善水稻的耐铁毒性 相似文献
16.
本实验初步研究万年油对红眼果蝇的7天急性毒性效应及对红眼雌性处女蝇的22天慢性毒性效应。采用野生型黑腹红眼果蝇,在其培养基中加入浓度分别为2%、20%的万年油,以2%的未加热食用油作为阴性对照组,计算平均寿命,最高平均寿命和死亡率,作为3个毒性指标。结果显示通过急性毒性试验计算出万年油的半数致死剂量为2.86%。慢性实验结果显示,与对照组相比,2%组3个毒性指标有显著性差异;20%万年油组3个毒性指标存在极显著性差异。结果说明万年油对红眼果蝇有较强毒性,且含油量越高,其毒性效应越大。 相似文献
17.
Marisa Castellano Kirsten Ewart Sundell George B. Richardson 《Peabody Journal of Education》2017,92(2):254-274
This study investigated the relationships between completing the high school portion of a college- and career-preparatory program of study and high school achievement outcomes in a large urban district in the West. Programs of study are secondary-to-postsecondary educational programs mandated by the federal legislation (Perkins IV) governing career and technical education (CTE) in the United States. At graduation, 49.5% of students in the sample who began a program of study had completed their programs. Using multiple regression models, we compared graduates who completed a program of study (hereafter POS completers) to graduates who completed a number of CTE courses in a specific occupational area (CTE concentrators), and to graduates who may have taken a CTE course or two during high school but were neither POS completers nor CTE concentrators (All Others). POS completers were more likely to (a) have a higher overall GPA, (b) have a higher CTE GPA, and (c) earn more STEM (science, technology, engineering, and mathematics) credits than All Other students. Compared with CTE concentrators, POS completers were more likely to (a) have a higher overall GPA and (b) earn more STEM credits. Qualitative data describe contextual elements of programs of study as offered in West District that could explain these results. Study results suggest that districts should consider implementing career-themed programs such as programs of study that enhance their existing college- and career-readiness initiatives. We also call for further study of the postsecondary and labor market outcomes associated with programs of study in order to generate a clearer picture of their potential to increase academic and technical achievement and promote successful student transitions to higher education and the workplace. 相似文献
18.
William J. Kermis 《科学教学研究杂志》1984,21(6):609-621
Everyone experiences some anxiety while taking an examination. High-test-anxious (HTA) and low-test-anxious (LTA) students are described by two characteristic differences: frequency and intensity of anxious responses and attentional direction to testing cues. The purposes of this study were threefold: (1) to report “potent” testing cues (i.e., 90% response agreement for both intensity and frequency) that were identified by HTA and LTA students; (2) to report differences between HTA and LTA students for frequencies and intensities of responses to testing cues; and (3) to report differences between HTA and LTA students of attentional direction to testing cues. A pool of 396 males and females who were enrolled in physical geology completed the State-Trait Anxiety Inventory. A random sample consisting of 93 HTA and 40 LTA subjects completed the Test Cues Identification Questionnaire (TCIQ). The TCIQ consists of 28 disruptive items and 27 helpful items. Subjects responded with both frequency and intensity ratings for all of the 55 items in the TCIQ. Results revealed that 22 items were viewed by subjects as “potent” testing cues. Empirical evidence obtained did not support previous theoretical reports of differences between HTA and LTA students for either frequency and intensity of anxious responses or attentional direction to the set of disruptive and helpful testing cues. Although test anxiousness did not appear to be associated with those two characteristics differences, a discriminant analysis revealed 24 items in the TCIQ which significantly, χ2 (24) = 47.59, p < 0.004, separated HTA and LTA subjects responses. Apparently, HTA and LTA students differ in their responses to specific disruptive and helpful cues but not in their responses to the set of testing cues as was previously postulated. 相似文献
19.
Jenni Donohoo 《Journal of Educational Change》2018,19(3):323-345
Collective teacher efficacy (CTE) beliefs serve to encourage certain behaviours and constrain others. Bandura (Educ Psychol 28(2):117–148, 1993) was the first to generate interest in this area by demonstrating that the effect of perceived CTE on student achievement was stronger than the link between socio-economic status and student achievement. The purpose of this study was to gain a better understanding of the productive patterns of behaviour and other consequences resulting from educators’ shared sense of efficacy. Studies showed that CTE was associated with a number of productive behaviours including implementation of school improvement strategies, increased teacher leadership, communication of high expectations, and a strong focus on academic pursuits. In addition, CTE was associated with other positive factors including greater job satisfaction, commitment to students and the teaching profession, and positive attitudes toward teaching students with special education needs and professional development. Collective efficacy was negatively related to performance goal orientations and positively related to students’ emotional engagement. Finally, there were a number of studies that established the relationship between CTE and individual teacher efficacy. It is important to acknowledge that the relationship between CTE and other variables included in the studies contained within this review are most likely bidirectional. Policy makers, system and school leaders, and staff developers’ efforts toward successful education reforms might be better served by strategically and intentionally considering how to foster collective efficacy throughout the conceptualization, design, delivery, and assessment of change initiatives. Suggestions for future research and limitations including potential measurement problems of included studies are shared. 相似文献
20.
目的观察决明山楂燕麦胶囊的急性及长期毒性反应,以确保用药安全性。方法急性毒性反应以10 g/kg（小鼠最大耐受量）的决明山楂燕麦给小鼠一次性灌胃,连续观察14 d,逐日记录毒性反应、死亡数,并作病理学检查。长期毒性反应以低剂量组1.6 g/kg、高剂量组2 g/kg给大鼠连续灌服8周,对大鼠进行一般状况、血液学指标、血液生化指标、主要脏器指数和组织病理学观察和检查。结果急性毒性实验未见小鼠出现毒性反应及死亡。长期毒性结果显示,低、高剂量组大鼠的一般状况、体质量、血液学指标、血液生化学指标及主要脏器系数与对照组比较无显著性差异;肉眼观察服药组心、肝、脾、肺、肾外观形态、颜色均无异常改变,光镜检查也未见各脏器组织结构和细胞形态异常。结论决明山楂燕麦对实验动物安全无毒,这可为临床应用提供有用信息。 相似文献