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1.
Repeated exposure to a single target type (sequential priming) during visual search for multiple cryptic targets commonly improves performance on subsequent presentations of that target. It appears to be an attentional phenomenon, a component of the searching image effect. It has been argued, however, that if searching image is an attentional process, sequential priming should also interfere with performance on subsequent nonprimed targets, and such interference has never been unequivocally demonstrated. In blue jays (Cyanocitta cristata) searching in an operant apparatus for targets derived from images of cryptic moths, detection performance was strongly facilitated in the course of a sequential prime but was relatively unaffected by sequences of mixed target types. Detection accuracy in subsequent probe trials was enhanced by priming with targets of the same type, whereas accuracy on cryptic probes following priming with a more conspicuous target was significantly degraded. The results support an attentional interpretation of searching image. 相似文献
2.
Possible respondents in a 1974 survey of University of Kentucky doctoral graduates were sent either computer-prepared or offset-printed questionnaires, personalized and identical in content. No difference was found in the overall response rates to the two types of instruments. But when the responses were categorized by the academic major of each recipient according to the theories of Holland (1973) and Biglan (1973a, 1973b), differential response rates appeared. Moreover, interactions of questionnaire type and grouping category were also evident. Response rates were projected using the best type of questionnaire for each grouping category in which a significant interaction occurred. Neither grouping theory was found to be superior to the other in projected response rates. 相似文献
3.
We used a psychophysical method to examine the ability of three corvid species to discern fine-grained spatial information.
Nutcrackers, pinyon jays, and scrub-jays were required to discriminate the distance between two landmarks on a computer screen
in an operant chamber. All three species were able to discriminate between arrays that differed by 20 mm; the discrimination
gradients for scrub-jays and pinyon jays were sharper than those for nutcrackers, however. The results suggest that differences
in spatial memory among these species are not related to differences in fine-grained perception. 相似文献
4.
5.
The importance of ingestive contexts (feeding and drinking) and deprivation states to rats’ transfer of a taste aversion were examined, In Experiments 1 and 2, rats were trained with novel saccharin-treated foods while either food deprived or food and water deprived, They were then tested with a 1,0% saccharin solution while either water deprived or food and water deprived, Comparable aversions to the solution were displayed regardless of deprivation states, Two further experiments examined transfer to a .1% saccharin solution in conjunction with deprivation state change, When both stimulus properties and deprivation were widely discrepant from training to test, reduced transfer was noted. The results suggest that stimulus similarity was a stronger controlling variable than deprivation state similarity in facilitating the transfer of an aversion from a feeding context to a drinking context, The results were viewed as being consistent with the known parameters affecting generalization gradients. 相似文献
6.
Lacy E. Krueger 《Educational gerontology》2013,39(12):915-924
Although increased age is associated with greater errors in spatial memory tasks, it is unclear if there are age differences in error types. To investigate this, 334 participants (ages 22–88) completed a task in which they remembered object locations across multiple study-test trials. Far and close error types were categorized based on the spatial proximity of recalled objects to their actual location. Younger adults showed a greater difference in the proportion of close and far errors, and middle-aged adults showed this pattern to a lesser extent. However, older adults committed close and far errors at an equal rate. Results revealed that all age groups reduced their far errors across trials, and task complexity similarly affected older and younger adults' error-type rates. Study time did not appear to predict error types. Overall, these results suggest that increased age is associated with more far errors, but that a reduction in these error types can occur through repeated learning trials. 相似文献
7.
P. J. Hitchman 《Educational research; a review for teachers and all concerned with progress in education》2013,55(3):209-214
Ten boys and ten girls in a nursery class, who were matched in age and in nursery experience, were each observed for a complete school day. Every response uttered by and to them was recorded in longhand. Their activities and the time spent on each were noted. The behaviour of the staff and the entire nursery environment were scrutinized. The responses and activities were categorized and analysed in relation to their social class and intellectual and verbal ability. However, no association appeared to exist between the use of certain language forms, such as the question, and certain types of behaviour and any of these dimensions. It was suspected that this was due to the minimal interaction between children and staff, for the same children, in a more structured situation, appeared more ready to use a variety of linguistic forms to explore and to seek to understand their environment. The result would suggest a re‐orientation of aims and a more structured approach to nursery activities, if pre‐school education is to have a beneficial effect on the linguistic and cognitive development of the young child. 相似文献
8.
Yue ZHANG Hai-peng LV Cheng-ying MA Li GUO Jun-feng TAN Qun-hua PENG Zhi LIN 《Journal of Zhejiang University. Science. B》2015,16(2):103-112
目的:从茶树中克隆一种可以催化表没食子儿茶素没食子酸酯(EGCG)生成甲基化EGCG的酶——咖啡酰辅酶A氧甲基转移酶(CCo AOMT),实现甲基化EGCG的酶学合成,为甲基化EGCG的进一步开发利用提供理论依据和技术指导。创新点:本研究首次从茶树中克隆了一条CCo AOMT基因组序列;分析了CCo AOMT基因在不同茶树品种和不同成熟度茶鲜叶中的基因表达规律;证明了CCo AOMT具有催化合成甲基化EGCG的生物活性。方法:采用聚合酶链式反应(PCR)和序列分析获得CCo AOMT的编码序列和基因组序列;采用高效液相色谱-四级杆-飞行时间串联质谱技术(HPLC-QTOF-MS)分析酶促反应生成的甲基化EGCG产物(图4);采用实时荧光定量PCR分析CCo AOMT基因的表达差异(图5)。结论:本研究从茶树中克隆了CCo AOMT基因的编码序列(738 bp)和基因组序列(2678 bp),明确了该基因具有4个内含子和5个外显子;揭示了CCo AOMT可以催化EGCG生成EGCG4"Me、EGCG3"Me和EGCG3’Me等多种甲基化产物;证明了CCo AOMT具有催化生成甲基化EGCG的活性;并发现该基因的表达量高低与茶鲜叶的成熟度呈正相关关系。 相似文献
9.
Individual ducklings received electrical shock in the presence of an imprinting stimulus whenever they pecked at food. Other ducklings received an identical series of shocks in the presence of an imprinting stimulus, but for them shock delivery was independent of their pecking behavior. In a subsequent session, the use of shock was discontinued and all birds were afforded the opportunity to approach either the imprinting stimulus (i.e., the stimulus previously present during shock) or a novel imprinting stimulus that was simultaneously presented. Ducklings that were shocked when they pecked at food either exhibited no preference or they preferred the original imprinting stimulus. In contrast, birds for whom shock was independent of their feeding behavior preferred the novel stimulus. These findings imply that the delivery of shock in the presence of an imprinting stimulus can endow the stimulus with conditioned aversive properties. They also imply that the stimulus will acquire little or no aversiveness if shock delivery is contingent upon a specific response such as pecking. 相似文献
10.
Ines Ben Chobba Amine Elleuch Imen Ayadi Lamia Khannous Ahmed Namsi Frederique Cerqueira Noureddine Drira Néji Gharsallah Tatiana Vallaeys 《Journal of Zhejiang University. Science. B》2013,14(12):1084-1099
Endophytic flora plays a vital role in the colonization and survival of host plants, especially in harsh environments, such as arid regions. This flora may, however, contain pathogenic species responsible for various troublesome host diseases. The present study is aimed at investigating the diversity of both cultivable and non-cultivable endophytic fungal floras in the internal tissues (roots and leaves) of Tunisian date palm trees (Phoenix dactylifera). Accordingly, 13 isolates from both root and leaf samples, exhibiting distinct colony morphology, were selected from potato dextrose agar (PDA) medium and identified by a sequence match search wherein their 18S–28S internal transcribed spacer (ITS) sequences were compared to those available in public databases. These findings revealed that the cultivable root and leaf isolates fell into two groups, namely Nectriaceae and Pleosporaceae. Additionally, total DNA from palm roots and leaves was further extracted and ITS fragments were amplified. Restriction fragment length polymorphism (RFLP) analysis of the ITS from 200 fungal clones (leaves: 100; roots: 100) using HaeIII restriction enzyme revealed 13 distinct patterns that were further sequenced and led to the identification of Alternaria, Cladosporium, Davidiella (Cladosporium teleomorph), Pythium, Curvularia, and uncharacterized fungal endophytes. Both approaches confirmed that while the roots were predominantly colonized by Fusaria (members of the Nectriaceae family), the leaves were essentially colonized by Alternaria (members of the Pleosporaceae family). Overall, the findings of the present study constitute, to the authors’ knowledge, the first extensive report on the diversity of endophytic fungal flora associated with date palm trees (P. dactylifera). 相似文献
11.
以菘蓝离体叶片为外植体,研究了激素种类和浓度、接种方式、光照条件等因素对叶片再生的影响,建立了菘蓝离体叶片高频再生体系.结果表明:以MS+6-BA2.0 mg/L+NAA0.2 mg/L+3%蔗糖为培养基,接种后暗培养5天转到光下培养,叶片远轴面向下接触培养基对不定芽的再生最为有效,不定芽不经过愈伤组织阶段直接从叶片上分化产生,再生率高达93.10%.以1/2MS为培养基附加0.1 mg/LNAA可使不定芽生根率达到100%. 相似文献
12.
采用TAS-ELISA,DAS-ELISA和ID-ELISA 3种检测方法,选用11种病毒病原血清对禄劝烟区烟草成熟期受害典型样本进行检测.结果表明,禄劝烟区烟草成熟期的病毒病具有从单一侵染向复合侵染演变趋势,且病原危害种类以TMV为主,CMV次之,除此之外尚存在TEV,TVBMV等病毒.烟草成熟期受害叶片症状呈现＂复杂化与多样化＂特征,借助先进检测手段、扩大病原血清种类是探索清楚当地烟草成熟期主要病毒病种类的必要措施. 相似文献
13.
Bo Sun Fen Zhang Guo-jun Zhou Guo-hai Chu Fang-fang Huang Qiao-mei Wang Li-feng Jin Fu-cheng Lin Jun Yang 《Journal of Zhejiang University. Science. B》2013,14(12):1100-1109
Alkaloids are plant secondary metabolites that are widely distributed in Nicotiana species and contribute greatly to the quality of tobacco leaves. Some alkaloids, such as nornicotine and myosmine, have adverse effects on human health. To reduce the content of harmful alkaloids in tobacco leaves through conventional breeding, a genetic study of the alkaloid variation among different genotypes is required. In this study, alkaloid profiles in leaves of five Nicotiana tabacum cultivars and Nicotiana tomentosiformis were investigated. Six alkaloids were identified from all six genotypes via gas chromatograph-mass spectrometry (GC-MS). Significant differences in alkaloid content were observed both among different leaf positions and among cultivars. The contents of nornicotine and myosmine were positively and significantly correlated (R 2=0.881), and were also separated from those of other alkaloids by clustering. Thus, the genotype plays a major role in alkaloid accumulation, indicating a high potential for manipulation of alkaloid content through traditional breeding. 相似文献
14.
Sarah P. McGeown Rhona S. Johnston Emma Medford 《Learning and individual differences》2012,22(3):360-364
This study examined the cognitive skills associated with early reading development when children were taught by different types of instruction. Seventy-nine children (mean age at pre-test 4;10 (.22 S.D.) and post-test 5;03 (.21 S.D.)) were taught to read either by an eclectic approach which included sight-word learning, guessing from context and analytic phonics, or by a synthetic phonics approach, where children were taught solely to sound and blend letters to read unfamiliar words. The results illustrated differences in the skills supporting children's word reading based on their method of reading instruction. For the eclectic group, pre-test letter knowledge, vocabulary and rhyming skills predicted later reading ability, whereas for the synthetic phonics group, letter knowledge, phonemic awareness and memory span predicted later reading skill. The results suggest that children will draw upon different cognitive skills when reading if they are taught to use different word recognition strategies. 相似文献
15.
Copper accumulation and intracellular distribution in Elsholtzia splendens, a native Chinese Cu-tolerant and accumulating plant species, was investigated by transmission electron microscope (TEM) and gradient centrifugation techniques.Copper concentrations in roots, stems and leaves of E. splendens increased with increasing Cu levels in solution. After exposure to 500 μmol/L Cu for 8 d, about 1000 mg/kg Cu were accumulated in the stem and 250 mg/kg Cu in the leaf of E. splendens. At 50μmol/L Cu, no significant toxicity was observed in the chloroplast and mitochondrion within its leaf cells, but separation appeared at the cytoplasm and the cell wall within the root cells. At ＞250 μmol/L Cu, both root and leaf organelles in E. splendens were damaged heavily by excessive Cu in vivo. Copper subcellular localization in the plant leaf after 8 days' exposure to 500 μmol/L Cu using gradient centrifugation techniques was found to be decreased in the order: chloroplast＞cell wall＞soluble fraction＞other organelles. The plant root cell wall was found to be the site of highest Cu localization. Increase of Cu exposure time from 8 d to 16d, increased slightly Cu concentration in cell wall fraction in roots and leaves, while that in the chloroplast fraction decreased in leaves of the plants grown in both 0.25 μmol/L and 500 μmol/L Cu. TEM confirmed that much more Cu localized in cell walls of E. splendens roots and leaves, but also more Cu localized in E. splendens' chloroplast when the plant is exposed to Cu levels＞250μmol/L, as compared to those in the plant grown in 0.25 μmol/L Cu. Copper treatment at levels＞250 μmol/L caused pronounced damage in the leaf chloroplast and root organelles. Copper localization in cell walls and chloroplasts could mainly account for the high detoxification of Cu in E. splendens. 相似文献
16.
杂交水稻叶片衰老与膜脂过氧化作用的关系 总被引：9，自引：0，他引：9
杂交水稻汕优63主茎在抽穗后10d，其叶片自上而下表现出叶绿素和蛋白质含量下降．光合作用速率降低．丙二醇和脂质红过氧化物含量明显增加．SOD活性则为倒三叶＞倒四叶＞倒二叶＞旗叶．实验结果表明：叶片自下而上顺序衰老．叶片衰老与膜脂过氧化作用密切相关． 相似文献
17.
用 50mg .kg-1 和 10 0mg .kg-1 S - 330 7处理二叶一心期的高粱幼苗 ,可不同程度地提高植株根冠比 ,提高叶片叶绿素含量和光合作用强度 ,降低呼吸速率 ,减轻膜伤害程度 ,从而提高植物的抗旱性 相似文献
18.
Frederik J. A. Ranzijn 《Instructional Science》1991,20(5-6):405-418
Two experiments were carried out to study the effect of the sequencing of the information in an instructional program. In both experiments, two different ordering principles were used. These principles were based on the relation between the to be learned concepts. The ordering of the information could be successive or simultaneous. The relationship between concepts is categorized either successive or coordinate. It was hypothesized that a simultaneous presentation would show better learning results than a successive presentation if between the to-be-learned concepts exists a co-ordinate relationship. A successive presentation would lead to better results in case of a successive relationship. Results suggest that the definition of both types of relationships needs refinement. Further the results show that for coordinate related concepts a simultaneous presentation is preferable.This study was supported by a grant from the Institute for Educational Research in the Netherlands (SVO), Grant No. 6620. I wish to thank S. Dijkstra for his stimulating ideas, and M. C. Reisinger for his assistance during this project. I also wish to thank the students, the biology teacher and the management of the Willem van Oranje Mavo (Hengelo, the Netherlands) and Streekcentrum voor Tuinbouwonderwijs (Enschede, The Netherlands) for their friendly co-operation. The author is now with Boertien and Partners Educational Technology, Gooimeer 5, 1411 DD Naarden, The Netherlands. 相似文献
19.
The Role of Gender-related Information and Self-Endorsement of Traits in Preadolescents' Inferences and Judgments 总被引：1，自引：0，他引：1
Thalma E. Lobel Janine Bempechat Jonathan C. Gewirtz Tamar Shoken-Topaz Elinor Bashe 《Child development》1993,64(4):1285-1294
The major purpose of this study was to examine the effects of a target child's gender typicality on different aspects of preadolescents' inferences and judgments. The secondary purpose of the study was to investigate the relation between children's self-endorsement of traits and their inferences and judgments. Fifth and sixth graders were shown a video film, portraying a child playing either a gender-appropriate game with members of the same sex or a gender-inappropriate game with members of the other sex. In addition, subjects completed an adapted version of the BSRI and were categorized into sex-typed, androgynous, and undifferentiated subjects. Subjects made a number of different types of judgments and inferences about the target, including inferences about traits, popularity, choice of gift and name, and willingness to engage in activities with the target. All types of inferences and judgments were affected by the variations in the targets' gender-related behaviors, whereas self-endorsement of traits was not related to the inferences and judgments. The results suggest that the gender typicality of the target behavior is salient to preadolescents, regardless of their sex-role orientation. 相似文献
20.
麻胜兰刘昱昊张铮吴琛 《福建工程学院学报》2020,(1):40-45
考虑到基于2范数的正则化算法存在对结构识别结果过度光滑的效果,提出了基于模态振与L1正则化的损伤识别方法。以—2D简支梁有限元模型为数值算例,比较了使用不同振型数不同损伤程度对损伤识别效果的影响。数值模拟结果表明,对于多损伤工况,当损伤结构的振型数和无损结构的振型数乘积数大于6时,能较好地进行损伤定位,并能对损伤程度给出定性的描述。 相似文献