共查询到19条相似文献，搜索用时 234 毫秒
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Xu Jianming 《大连大学学报》1992,(1)
本研究对238名(男110女128)年令在18～43周岁,国人辽宁地区青、中年的上颌磨牙1070颗,其中第一磨牙(M_1)476颗.第二磨牙(M_2)476颗,第三磨牙(M_3)118颗进行了观测。测出了上颌磨牙的牙尖型在各类磨牙的分布状态及牙冠的二种退化形式各自表现的特征,取得了各项有关数据;测出了上颌磨牙中各类磨牙的卡氏征阳性率及卡氏征出现各形的频率。讨论中以国人活体牙各项数值与国内、外各有关数值进行了比较,得出活体牙与尸牙的异同及人种间的差异,并对磨牙形态及卡氏征的形态学进行了扼要地探讨。 相似文献
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在磨牙、双尖牙的牙面上有牙尖、窝沟、点隙等是正常的解剖标志,但在不该形成牙尖的部位出现牙尖就称为畸形牙尖。最易出现这种畸形牙尖的牙齿是下颌第二双尖牙。这种畸形牙尖虽然薄小,但在薄薄的外壳内有一个与牙髓相通的空隙,当咀嚼时很容易磨损或折断,使牙髓与外界相通,并发感染,出现疼痛。这种畸形牙尖一般常为家长所忽视,待发展成为严重的慢性根尖周炎时才被医生发现,以致于影响了该牙正常的生理性牙根的继续形成。在此提醒家长,应定期带孩子去做口腔检查,及早发现畸形牙尖。医生对尚未磨损的畸形牙尖进行多次缓慢的调磨、涂药以刺激小… 相似文献
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下颌第一磨牙远舌根已经被广泛报道,它的存在使牙周炎的治疗更为复杂。本研究旨在评估中国东部地区人群中下颌第一磨牙远舌根的发生率,并探讨远舌根的形态学特征与骨破坏及牙周状况的关联性。本研究通过对中国东部地区836例患者共1497颗下颌第一磨牙的锥形射束电脑断层扫描（CBCT）进行流行病学分析。其中,69例患者的103颗下颌第一磨牙有完整的牙周检查表。随后采用相关分析和回归分析评估下颌第一磨牙远舌根的形态学特征与骨缺损及牙周临床参数间的关系,包括临床附着缺失、探诊深度、牙龈退缩和根分叉病变情况。研究结果发现,中国东部地区人群中下颌第一磨牙远舌根在患者和牙位水平的患病率分别为29.4%和26.3%。多元线性回归分析表明,第一磨牙舌侧的骨缺损及临床附着丧失水平与位于横截面的远舌根与近中根的分离角呈负相关,而与年龄和位于冠状面上的远颊根与近中根的分离角呈正相关。综上,中国东部地区人群下颌第一磨牙远舌根患病率较高,而且下颌第一磨牙远舌根的形态特征与牙周状况具有相关性。本研究旨在提高下颌第一磨牙远舌根的早期诊断率,并对存在远舌根的第一磨牙的治疗决策提供重要的信息。 相似文献
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目的:探讨牙(牙合)面偏颊或偏舌腭侧1/3至正中1/2完全性纵折磨牙(以下简称完全性纵折磨牙)的保存治疗。方法:采取裂隙冲洗、清创、牙冠结扎、调(牙合)、牙周牙髓联合治疗、分层充填裂隙及冠缺损处,临时冠修复、过渡至金属全冠或烤瓷全冠修复的综合系列治疗,保存上述类型完全性纵折的磨牙。结果:34例患者的39颗完全性纵折磨牙,成功保存35颗,保留时间最长的达16年。结论:牙(牙合)面偏颊或偏舌腭侧1/3至正中1/2完全性纵折的磨牙是折裂牙中比较严重和特殊的一种类型折裂牙,尤其折裂时间长、髓底穿通合并牙龈瘘管,慢性根尖周炎的患牙,经恰当的综合系列治疗和全冠修复后,仍可保存并恢复其咀嚼功能。 相似文献
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采用自编中小学教师工作-家庭冲突（WFC）问卷考察中小学教师工作家庭冲突现状。研究发现：WIF显著高于FIW,报告WIF严重的人数的百分比远高于FIW严重的百分比。工作-家庭冲突存在显著的性别、年龄差异;在学校因素中,学校类型、是否是班主任、周工作时间和工作规律性与WFC显著相关。在家庭因素中,是否与父母、孩子同住,是否有人帮做家务与WFC显著相关。并根据研究结果对学校提出了相应的管理建议。 相似文献
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Development of cortical circuitry and cognitive function 总被引：14，自引：0，他引：14
P S Goldman-Rakic 《Child development》1987,58(3):601-622
Recent functional and anatomical studies in nonhuman primates have elucidated the basic neural circuitry underlying delayed-response function in adult nonhuman primates. Thus circuitry includes connections of the principal sulcus with other areas of parietal association and limbic cortex and projections to the caudate nucleus, superior colliculus, and other premotor centers. Anatomical tracing in primate fetuses and in monkeys at various stages of postnatal development indicates that these various classes of cortical connections begin to form by the second trimester of pregnancy. Electromicroscopic studies of the principal sulcus and other areas of cerebral cortex show that the number and density of synapses in the cortex increase rapidly, reaching and maintaining higher than normal adult values between 2 and 4 months postnatally, before slowly declining over a period of years to stable adult levels. The capacity to perform delayed-response and/or AB at short delays emerges around 4 months of age, coinciding with the end of the period of highest synaptic density in the principal sulcus. These findings suggest that a critical mass of cortical synapses is important for the emergence of this cognitive function, and that fully mature capacity may depend upon the elimination of excess synapses that occurs during adolescence and young adulthood. Knowledge of the neural basis of normal cognitive development may prove useful both to social and educational purposes as well as to understanding developmental disorders of cognition. 相似文献
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Klaus Dumpert 《International Journal of Science Education》2013,35(3):339-346
Summaries English An investigation was conducted, for the entire Federal Republic of Germany, on the use of living organisms in biological instruction. Besides the scope and manner in which living organisms are used, the expenditure of time and material by teachers was examined and teachers’ views of the value of including living organisms in biology instruction were ascertained. In addition, it was determined whether there are verifiable differences among the various types of schools, among schools located in differently sized communities, and also among schools of different size. The results are compared with statements from professional educators. 相似文献
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在中华蜜蜂(中蜂)和意利蜜蜂(意蜂)种间生存竞争中,而中峰成为失势者,数量锐减、密度下降、生栖范围缩小,在意蜂占绝对优势的情况下,中蜂处女王交尾受到意蜂雄蜂严重干扰的结果,交尾成功率极低或交尾不成。这种干扰是生存竞争中的特殊表现形式,成为中蜂在平原丘陵地区繁衍困难,而又不被人们注意的重要原因。 相似文献
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目的研究骨性Ⅱ类与骨性Ⅰ类错[牙合]畸形患者第二恒磨牙的萌出位置和钙化时间上的差异。方法对平均年龄为11．2岁的220例患者的治疗前病历资料进行分析,其中19％为骨性Ⅰ类错[牙合]畸形,32％为上颌骨骨性Ⅱ类错[牙合]畸形,49％为下颌骨骨性Ⅱ类错[牙合]畸形。结果各错牙[牙合]形组中第二恒磨牙钙化阶段的分布相近,骨性错[牙合]形类型与第二恒磨牙的发育阶段没有明显相关性。在骨性Ⅱ类错[牙合]畸形组最大年龄组（12岁以上）,上颌第二恒磨牙的萌出位置更偏将向。结论上颌骨骨性Ⅱ类错[牙合]畸形中,上颌第二恒磨牙萌出较早,但钙化时间没有差异。 相似文献
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Odd Nordhaug Paul Gooderham Xian Zhang Yali Liu Gunn Elisabeth Birkelund 《Scandinavian Journal of Educational Research》2013,57(2):109-123
The focus of this paper is on the work‐related values, preferences, and future expectations among female students at two elite business schools in China and Norway. The paper argues that while gender theory predicts no significant differences between these two groups, both cultural and economic development theory imply fundamental differences. The overall picture we get from this study is mixed, in that while both cultural dimensions and economic development dimensions generally have a significant impact on the variations in job‐related values between the selected Chinese and Norwegian female business students, there are also commonalities that are ascribable to gender. That is, while there clearly are differences between the two groups there are also a number of significant similarities. 相似文献
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In this study we examined Chinese physical educators' attitudes toward teaching physical activity and fitness. We then compared the Chinese teacher attitudes to their American counterparts. Participants were 330 Chinese elementary, middle and high school physical educators. The Teachers' Attitudes Toward Curriculum in Physical Education (TATCPE) instrument was used to gather data. One‐way repeated measures ANOVA and Bonferroni post hoc tests indicated that the Chinese teachers scored significantly higher on the self‐actualization and physical activity/fitness than the motor skill development and social development outcome goals. The MANOVA on motor skill development, physical activity/fitness, self‐actualization and social development outcome goals showed no significant differences for gender, teaching level, or years of teaching experience among the Chinese teachers. Teachers from both countries, however, considered all four domain areas to be important outcome goals. Despite cultural differences, Chinese and American teachers share key core attitudinal values about their respective programs. 相似文献