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以龙牙百合主要自毒物质-2,4-二叔丁基苯酚(2,4-DTBP)和抗氧化剂2246(AO 2246)为供试介质,使用含不同浓度自毒物质培养基,采用平板对峙法,探究龙牙百合枯萎病病原菌-尖孢镰刀菌LD12和茄腐镰刀菌LD21与拮抗细菌-贝莱斯芽孢杆菌株TP54和TP58的互作关系。结果表明,高浓度自毒物质2,4-DTBP介导下,拮抗菌TP54对病原菌LD12抑菌率显著降低,LD12产孢量增加;对拮抗菌TP58对病原菌LD12抑菌率影响表现为低浓度促进,高浓度抑制;拮抗菌TP54对病原菌LD21抑菌率影响不显著,但促进了LD21产孢;高浓度2,4-DTBP显著降低拮抗菌TP58对病原菌LD21抑菌率。高浓度自毒物质AO 2246介导下,拮抗菌TP54对病原菌LD12抑菌率显著降低,产孢量增加;拮抗菌TP58对病原菌LD12抑菌率影响不显著,但促进了LD12产孢;拮抗菌TP54和TP58对病原菌LD21抑菌率显著降低,但前者LD21产孢量减少,后者产孢量无明显变化规律。在龙牙百合自毒物质的介导下,拮抗菌对枯萎病病原菌的抑菌率有可能降低也可能增加,变化因不同自毒物质浓度、拮抗菌和病原菌而异,相... 相似文献
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本文以湖北光敏核不育水稻(Hubei Photoperiod Sensitive Genio Male—Sterile Rice i·e·HPGMR)农垦58A和常规品种农垦58为材料,在人工控制的长,短日照条件下,用DuPont9900型差示扫描量热计测取了不同发育时期花药的DSC谱。结果表明:可育花药的DSC谱上的低温吸热峰面积随发育呈现周期性变化;不育花药在单核中期以前与可育花药差别不大,而在单核中期以后的DSC谱上的低温吸热峰面积明显小于可育花药,且不呈现周期性变化,而逐渐减小到接近对零。 相似文献
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短光敏核不育水稻种质研究 总被引：4，自引：2，他引：4
水稻短光敏不育材料是与农垦58S等光温敏核不育水稻的光温敏育性反应特性相反的光温敏核不育水稻新类型，具有短光低温诱导不育、长光高温诱导可育的育性特性，对水稻短光敏核不育品系宜DSl的育性表现、农艺性状、利用前景进行了研究和讨论。 相似文献
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《小雪花(小学生成长指南)》2006,(12)
[生日祝福]以下是几位本月过生日的小同学,欣心姐姐在这里代表《小雪花》编辑部祝他(她)们——生日快乐!陈思旭(牡丹江市东宁县徐悲鸿远东艺校)王思宇(鹤岗市萝北县第一小学)马钰菲(哈尔滨市道里区晨光双语小学)胥芸菲(新疆伊犁农四师七十团子弟校)付凯文(省农垦总局建三江农垦 相似文献
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一、转换法在某些由多种元素组成的化合物中,当某种元素的表观化合价(氧化数)为分数时,仍按常规方法配平难度很大,此时可将化合物的分子式进行变形转换,使之成为熟悉的形式,再进行配平。[例1]配平 Na_2S_x+NaClO+NaOH—Na_2SO_4+NaCl+H_2O。分析:Na_2S_x中 S 的表观化合价为-2/x 价,这种价态学生不能接受,也不便于配平。根据上述物质组成的特点,可将 Na_2S_x 变形为 Na_2S·S_(x-1),在 Na_2S 和 S_(x-1)中 S 的化合价分别为-2价和0价,电子转移分别是: 相似文献
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以红肉脐橙[Citrus sinenisis(L.)Osbeck'Cara Cara']幼树为试材,采用4个水杨酸(SA)水平(0,0.1、0.5和2.5mmol/L)叶面喷施并结合根部灌溉后进行干旱处理,清水正常灌溉为对照.对干旱胁迫过程中幼树叶片抗氧化酶、脂质过氧化产物、脯氨酸以及叶片相对含水量进行分析测定.结果表明:与正常灌水相比,干旱胁迫下,叶片丙二醛(MDA)含量增多,脯氨酸(Pro)积累增加,超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性变化显著;另一方面,在干旱胁迫过程中,红内脐橙经SA处理后叶片抗氧化酶SOD,POD、CAT活性以及渗透调节物质Pro的积累显著高于未用SA处理的叶片,同时,SA处理能显著降低叶片MDA含量. 相似文献
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对高温不育水稻育性敏感期细胞色素氧化酶活性变化的研究 总被引：1，自引：0，他引：1
细胞色素氧化酶活性按B．N奥列霍维奇的方法测定,本文以常规品种紫壳作对照,分别测定了紫壳,高温敏感核不育材料1356S,衡农S－2在花粉母细胞形成期和花粉母细胞减数分裂期不同育性条件下的叶片和幼穗花药的细胞色素氧化酶的活性,并进行了统计学分析－－两因素方差分析（F检验）及平均数的Duncan多重比较,结果表明,在育性敏感的2个时期,1356S和衡农S－2不育株幼穗花药的细胞色素氧化酶的活性极显著低于可育株细胞色素氧化酶的活性,分别是可育株的72％,72．1％,63．2％,67．7％,必然会使不育株花药中能量供应短缺,造成物质合成等许多生命活动衰 减,最终导致不育。 相似文献
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尚连聚 《商丘师范学院学报》2003,19(5):12-16
推导了LD端面泵浦Nd：YVO4激光器的工作物质(Nd：YVO4晶体)内部的温度和热应力的理论表达式，为进一步消除高功率泵浦情况下Nd：YVO4晶体的热效应提供了新的理论依据。 相似文献
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以马铃薯大西洋(Solanum tuberosum L.cv.Atlantic)单节茎段培养为实验体系,记录了8%蔗糖处理不同时间及TD,SD,LD下对结薯情况影响的差异。TD是诱导结薯的最佳光照处理,块茎生成百分率最高,诱导强度最高,薯块白色,多无柄。诱导结薯不同处理时间后转入LD条件下,能结薯,块茎生成率低,紫红色,多保龄球状。诱导结薯不同处理时间后转入SD条件下,没有块茎生成,全部长成匍匐茎。8%蔗糖诱导结薯不是短时瞬间完成的。而存在时间上的数量累加效应。 相似文献
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This replication study examined whether 158 college students classified as learning disabled (LD) who were granted course substitutions for the foreign language (FL) requirement would display significant cognitive and academic achievement differences when grouped by levels of IQ-achievement and achievement-achievement discrepancy and by level of performance on an FL aptitude test (Modern Language Aptitude Test; MLAT), phonological/orthographic processing measures, and in FL courses. The results showed that there were few differences among groups with differing levels of IQ-achievement or achievement-achievement discrepancy (i.e., < 1.0 SD, 1.0-1.49 SD, and > 1.50 SD) on MLAT and American College Testing (ACT) scores, graduating grade point average (GPA), or college FL GPA. The results also showed that between groups who scored at or above versus below the 15th percentile (i.e., < 1.0 SD) on the MLAT, there were no differences on measures of graduating GPA, college FL GPA, native language skill, ACT score, and Verbal IQ. Demographic findings showed that 44% of these petition students met a minimum IQ-achievement discrepancy criterion (> or = 1.0 SD) for classification as LD. These findings suggest that many traditional assumptions about LD and FL learning are likely to be false. 相似文献
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Sandra Smith 《Annals of dyslexia》1992,42(1):141-158
Extended families of 12 young adults (9 LD, 3 non-LD) were given a battery of tests and questionnaires, and 131 persons, ranging
in age from 6 to 85, were classified as LD or non-LD on the basis of subtest scores 1 SD below the mean or less on subtests
of the PIAT and WRAT achievement tests. Pedigree analysis indicated that LD was strongly familial, with the most probable
mode involving a major gene effect, but the type of disability (reading/ math) was not directly inherited. Autoimmune disorders
were significantly correlated (P<.005) with LD, especially in families in which LD remained a major handicap into adulthood,
a trait that also varied between families. In two of the LD families, adults showed little evidence of the reading/spelling
deficits they had shown when tested as children, while adults in other families failed to make gains in reading and spelling. 相似文献
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四种药用蕨类DNA提取的比较研究 总被引：3，自引：0，他引：3
以四种药用蕨类的叶片为材料,采用改进的CTAB法、SDS法分别对四种蕨类进行了总DNA提取效果的比较分析,结果表明,通过实验获得最佳的DNA提取方法,为PCR扩增,引物设计,为筛选四种药用蕨类中的活性成份的相关基因奠定理论和实践基础。两种方法均能有效的提取较高质量的DNA,其中CTAB法效果最好,获得的DNA纯度较高、产量较大;SDS法提取的量次之且多糖等杂质含量更多。 相似文献
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光敏感核不育水稻,在长日诱导的不育花药中,可溶性蛋白质含量,比短日诱导的可育花药为低;在花粉母细胞发育期和单核早期,不育花药中吲哚乙酸氧化酶总活性和比活性,均较可育花药高得多;单核晚期以后,酶活性仍以不育花药较高。 相似文献
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Susan Dickerson Mayes Daniel A. Waschbusch Susan L. Calhoun Richard E. Mattison 《Exceptionality》2020,28(1):60-75
ABSTRACTLittle is known about the characteristics of academic overachievers, children whose achievement significantly exceeds IQ. Correlates of overachievement (achievement test scores ≥ 1 SD above IQ), nondiscrepant achievement, and learning disability (LD; achievement ≥ 1 SD below IQ) were analyzed in 1,543 children (739 ADHD, 285 autism, and 519 general population), 6–16 years of age. Significant correlates of the reading and math achievement groups were diagnosis (autism greatest overachievement, ADHD greatest LD), IQ (lowest in overachievers and highest in LD), and Working Memory scores relative to the child’s IQ (close to or exceeding IQ in overachievers and lower than IQ in LD). Demographics (age, sex, race, and parent occupation) and parent and teacher ratings of psychopathology (e.g., behavior problems, anxiety, and depression) and personality characteristics (e.g., motivation and self-confidence) did not contribute significantly more to predicting overachievement and LD beyond that explained by IQ, diagnosis, and working memory. These findings suggest an underlying neurobiological etiology for both overachievement and LD. 相似文献
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This study was conducted to determine whether students classified as learning disabled (LD) who were permitted to substitute courses for the college foreign language (FL) requirement at one university would display significant cognitive and academic achievement differences when grouped by level of discrepancy between IQ and achievement, by discrepancy between achievement according to different measures, and by level of performance on phonological-orthographic processing measures, on the Modern Language Aptitude Test (MLAT), and in FL courses. Results showed that there were no differences among students with different levels of discrepancy (i.e., < 1.0 SD, 1.0-1.49 SD, and > 1.50 SD) on MLAT and American College Testing (ACT) scores, graduating grade point average (GPA) or college FL GPA. Results also showed that among students who scored below versus at or above the 25th percentile on phonological-orthographic processing measures, there were no differences on measures of IQ, ACT, MLAT, and GPA, as well as most measures of academic achievement. Implications for the use of the LD label to grant FL course substitutions or waivers, use of the MLAT in the diagnostic and course substitution/waiver process, and the validity and reliability of traditional criteria for the classification as LD are discussed. 相似文献
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With the passage of the Americans with Disabilities Act in the United States and the Canadian Chartre of Rights and Freedoms, there is a new work environment for individuals with learning disabilities (LD) in North America. This qualitative study sought to compare the employment experiences of 25 U.S. adults with LD and 24 Canadian adults with LD. Areas of comparison were job getting, experiences on the job, and job advancement. Remarkably, the U.S. and Canadian adults with LD had nearly the same employment experiences. In essence, each set of data mirrored the other despite marked differences in U.S. and Canadian federal disability legislation. 相似文献
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This empirical study focused on high school students with a learning disability (LD), particularly adolescents undergoing training in secondary vocational study programmes. A total of 417 1st-year high school students were included in the survey, 105 of whom were LD students. Data on social anxiety and perceived social self-efficacy were collected at the beginning and end of the school year using the Social Self-Efficacy Scale and the LSAA Social Anxiety Scale. The results mostly relate to male students because the sample included 359 boys and 58 girls. In both the initial and final measurements, a significantly lower level of perceived social self-efficacy and a higher level of social anxiety were found in students with special needs compared to their peers. Perceived self-efficacy in LD students decreased significantly during the school year, while changes in social anxiety were not statistically significant. Results could indicate some difficulties in social integration of LD youths in vocational school classes. Thus, it would be desirable for schools to provide a more supportive and efficient learning environment for strengthening social integration of LD students in secondary vocational education. 相似文献