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891.
林路 《邵阳学院学报(社会科学版)》1998,(5)
给出拟Fisher信息达到其上界的充要条件,此条件为真得分函数是线性无偏的,即观测数据来自指数族分布,当拟Fisher信息太小时,提出了一种线性有偏拟得分方法,该方法能增加拟Fisher信息,从而改进了参数估计。 相似文献
892.
893.
田振夫 《商丘师范学院学报》1998,(Z4)
基于Kreiss[1]所建立的紧致差分逼近公式,提出一种数值求解二维泊极方程的高精度紧致差分方法.该方法是矩形网络下九结点差分近似,其推导过程简单,且具有四阶精度.最后给出了误差估计和数值结果. 相似文献
894.
肖黎明 《广东技术师范学院学报》1998,(4)
本文用连续延拓法(压缩映射原理结合解的一致先验估计)研究了非线性SobolevGalpem方程的初边值问题,得到了该问题整体强解的存在唯一性结果。 相似文献
895.
896.
程友良 《上海大学学报(英文版)》1999,3(1):84-86
The study of solitary waves has been a subject highly popular and full of interest sinec Russell[1]first observed the solitary waves in a channel and the research on the internal solitary waves in stratified fluids is one of the branches of this subject.There are extensively internal solitary waves in the atmosphere,oceans.fjords and lakes.To study them is of academic and practical significance[2].Numerous investigators have made contributions since the theoretical work on internal solitary waves was initiated by Keulegan[3].Nevertheless,some problems remain still to be discussed,for example,the higher-order theories for one-dimensional internal solitary waves in stratified fluids of small depth,the two-dimensional internal solitary waves,the explanation of the experimental and the practical phenomena by means of theoretical analysis.In this thesis,we hope to gain an insight into the above three items by combining of theoretical analysis and symbolic computation.The following work has been completed. 相似文献
897.
大连与日本成年人皮褶厚度的比较 总被引:8,自引:0,他引:8
通过测试大连男女背部、上臂、腹部、大腿四个部位的皮招厚度,观察不同年龄体脂肪分布的规律与特征,并与日本人体脂肪分布资料进行比较研究 相似文献
898.
Long xiao han 《昌潍师专学报》1999,(5)
本文将文[1]中的锥K加以修改,在更一般的条件下,证明了双时滞微分方程缓振动解的存在性。 相似文献
899.
While there is a growing body of work that examines disciplinary identity development, unlike qualitative work in this area, quantitative research has not fully incorporated the importance of different contexts, nor has it uniquely focused on underrepresented groups (in this case, women in physics). This study examines how the constructs posited by prior work as important for physics identity, as well as an additional theorized construct, may interrelate and affect female students' physics identity differently depending on the context. Context in this study refers to two different experiential levels in college. The constructs examined include performance/competence, recognition, and interest, as well as sense of belonging. In particular, we used structural equation modeling to examine the effect that these constructs have on the physics identity of two groups of female physics undergraduates: first year students and senior year students. The results reveal that the relationship of the theorized constructs with physics identity vary between the two groups as well as compared to prior research with broad college student populations (not just physics majors). Unlike broad college student populations, for our sample of female physics undergraduates, interest did not have a direct effect on physics identity while sense of belonging was significant only for senior year students. These results exemplify the importance of examining context or different types of student experiences when studying disciplinary identity development rather than generalizing previous frameworks to all contexts. 相似文献
900.
The study evaluated the relationship among teaching, leadership, teacher certification, student and teacher number related factors, and index of economic, social and cultural status (ESCS), and science literacy from an international comparative perspective. 2015 dataset of the Programme for International Student Assessment for Turkey, Singapore, the United States, Korea, Italy, and Brazil was used. Two-level hierarchical linear models were established for analysis. Results revealed that school ESCS was the best predictor of science literacy across six countries and additionally teacher-related factors came to the forefront of science literacy performance. The study underlined policymakers should focus primarily on policies that increase equity in education. Furthermore, the effectiveness of investments made in factors related to leadership, teacher certification, the number of students and teachers, which contribute very little to science literacy performance, need to be more questioned. Inferences about the findings were discussed in detail, and recommendations for further research were made. 相似文献