排序方式： 共有11条查询结果，搜索用时 15 毫秒
1.
本文根据我国薯蓣属(Dioscorea L．)根状茎组(Sect. Stenophora Uline)的外部形态特征、细胞染色体数、花粉形态、植物化学成分、地理分布等的规律，证明根状茎组是该属中的一个比较原始的自然类群：1．具横走的多年生地下根状茎，其它组是一年生或多年生的块茎；2．大部分是2倍体，其它组是多倍体；3．花粉粒单沟型，外壁纹饰网纹或颗粒条纹，其它组为双沟型，外壁纹饰网纹；4．含甾体皂甙元(steroidal sapogenin)，其它组不含。
我们的研究观察证明，N．N．TepaCNMeHKO根据R.Knuth系统(1924)提出的薯蓣皂甙元在该属中无分布规律的说法是无充分依据的。
本文讨论了某些组或种的划分及系统位置：取消sect.Illigerestrum Prain et Burk.；将马 肠薯蓣(D．simulans Prain et Burk．)改属根状茎组；触丝薯蓣(D．tentaculigera Prain et Burk.)应列入顶生翅组 (Sect．shannicorea Prain et Burk．)， 并提出了盾叶薯蓣 (D. zingiberensis Wright)和穿龙薯蓣(D．nipponica Makino)种的划分和定名的意见。 相似文献
2.
伞形科植物染色体数目报告 总被引：3，自引：0，他引：3
In the present paper, chromosome numbers are reported for 33 species
and varieties of Chinese Umbelliferae which belong to 17 genera in the subfamily Api-
oideae. Chromosome number of each species is shown in Table I. Eighteen countings
are newly reported. Chromatin bridges and fragments were observed at anaphase I in
some materials. It is suggested that the fertility reduction in some species is due to
the chromosome aberrations. 相似文献
3.
Pai-Lin Lee Hui-Hsiang Chang Chih Kun Huang Wen-Chen Cheng Pi-Yu Lee Hui-Chen Chao 《Educational gerontology》2013,39(10):614-626
ABSTRACTObjective: Memory loss affects a large proportion of older adults. Research indicates a positive association between memory training and better memory performance as people age. However, studies on specific memory training using an experimental design are limited. This study explored whether memory training has improved memory performance in a group of older adults.Method: A convenience sample of 48 participants was recruited from two communities. Disregarding dropouts, this left 23 experimental (mean age = 65.4 ± 6.0, range = 56–80) and 19 control participants (mean age = 64.5 ± 4.9, range: 57–72). The intervention consisted of 60-min classes held on a weekly basis continuing for 8 weeks. The class session was held after a 1-h exercise class and before a 1-h session of cognitive games. The pre–post objective memory performances, including associative, list, text, place, grocery learning, and transfer-effect of daily event memory (ecology validity), were examined to determine whether the intervention was effective.Results: Intragroup: With Wilcoxon test, the findings showed that the intervention of both the list and place learning had significant differences for the experimental group, but not for the control group. Intergroup: The main effects were found for the associative and text learning. The mixed design ANOVA indicated that there is an interaction (time x group) on the dependent variable of the place learning test. Daily events memory: We found within group that the pre–post differences were significant for the experimental group but not for the control group.Conclusion: The study showed that memory training can help older adults to ameliorate memory loss problems and these findings deserve more attention. 相似文献
4.
The present paper deals mainly with the karyotype analysis of five
materials in Angelica dahurica collected in Yanbian of Jilin, Anguo of Hebei, Yuxian of
Henan, Hangzhou of Zhejiang and Suining of Sichuan. They are under the names
“Dongbeidahuo”, “Qibaizhi”, “Yubaizhi”, ”Hangbaizhi” and “Chuanbaizhi” respe-
ctively. Among then “Dongbeidahuo” is a wild plant, which occurs in northeastern
China, and the others are cultivated as important crude drugs in some provinces. “Qi-
Baizhi” and “Yubaizhi” have been identified as conspecific with the wild Baizhi-“Do-
Ngbeidahuo” (A. dahurica) according to the external morphological features, whereas the
other cultivated ones, “Hangbaizhi” and “Chuanbaizhi”, treated as a variety (A. dahu-
rica var. formosana).
The results of karyotype analysis are shown in Plate 1, 2, with the formula 2n=22
=12 m+2 mSAT+4sm+4st. The karyotypes described here are constantly characterized by
satellites attached to the fourth pair of metacentric chromosomes and differ from the pu-
blished reports on the other species of the genus. It is reasonable to say that the five
materials collectively named “Baizhi” are taxonomically closely related to each other
and could be regarded as conspecific. Since the second chromosome pair is submetacen-
tric in “Dongbeidahuo”, it may be justifiable to separate the wild plant from the cul-
tivated ones and treat them as two separate varieties. 相似文献
5.
伞形科植物染色体数目报告 总被引：1，自引：0，他引：1
本文报道了伞形科15属24种和交种的染色体数，其中18个种和变种是首次报道。研
究表明， 我国天胡荽属 (Hydrocotyle L．)是伞形科多倍体比较普遍的类群。柴胡属(Bupleu-
rum L.)分别有4、6、7、8等基数，茴芹属(Pimpinella L.)的毛果组(Sect. Tragium)和光
果组(Sect．Tragoselinum)的代表种类的基数分别为9和10，因此，染色体基数可作为深入
研究某些属内种类演化的细胞学资料之一。思茅独活(Heracleum henryi Wolff)的花粉母细 胞在终变期时出现了4体环，说明结构杂合体可能是伞形科种类分化的一个因素。 相似文献
6.
伞形科植物染色体数目报告 总被引：2，自引：0，他引：2
Chromosome numbers are reported for 26 species and varieties of Umbelliferae
which belong to 3 subfamilies and 19 genera in this paper. Of these, 13 counts are
new records and some problems about chromosome numbers of Umbelliferae are simplydiscussed. 相似文献
7.
本文继续报道了薯蓣属(Dioscorea L.)块茎类5个组(sect． Combilium Pr．et Burk.，Sect. Lasiophyton Pr． et Burk.， Sect. Opsophyton Uline， Sect． Shannicorea Pr. et Burk.， Sect. Enantiophyllum Uline)23个种和变种的染色体数，并对一些分类群进行了讨论。它们都是基数为10的多倍体，是本属进化的类型。 根据染色体数的演化和二倍体种类的地理分布，我们推论我国横断山脉地区可能是薯蓣属的起源中心。 相似文献
8.
Hui-Chen Lin 《Interactive Learning Environments》2019,27(8):1011-1027
ABSTRACTMedical education is a domain with fast-changing knowledge and attention to knowledge application and higher order thinking; therefore, how to implement effective teaching is a crucial issue. Based on the technology-based learning model, this study provides a multi-dimensional analysis of published papers on the flipped classroom in medical education from the SCOPUS database, including the form of the learning materials, learning system or player, learning strategies, educational technology, application domains, research issues, participants, and research methods. Based on the results, the application of flipped classrooms in medical education has grown rapidly over the past decade, with the number growing dramatically from 7 papers in 2014, to 16 papers in 2015, and 22 papers in 2016. It was found that a great number of studies adopted instructional videos uploaded on online learning systems or used existing online videos to conduct before-class teaching in the before-class stage of the flipped classroom; moreover, most studies involved no online discussion in the before-class stage. As for learning strategies in the in-class stage, the most frequently adopted strategies were issue discussion, practicing or doing exercises, and problem-based learning. This implies that most studies mainly emphasized basic knowledge understanding and skills training, while little attention was paid to developing learners’ higher order thinking skills. In addition, the majority of studies explored students’ learning interest/satisfaction, learning experience, and performance on the cognitive aspect, while little research was found to investigate their preparation degree or cognitive loading. Based on the review results, this study provides the research trends and potential research issues of flipped medical education to serve as a reference for researchers, instructors, and decision makers. 相似文献
9.
This study uses bibliographic coupling to identify missing relevant patent links, in order to construct a comprehensive citation network. Missing citation links can be added by taking the missing relevant patent links into account. The Pareto principle is used to determine the threshold of bibliographic coupling strength, in order to identify the missing relevant patent links. Comparisons between the original patent citation network and the comprehensive patent citation network with the missing relevant patent links are illustrated at both the patent and assignee levels. Light emitting diode (LED) illuminating technology is chosen as the case study. The relationships between the patents and the assignees are obviously enhanced after adding the missing relevant patent links. The results show that the growth rates on both the total number and the average number of links have apparently improved at the patent level. At the assignee level, the number of linked assignees and the average number of links between two assignees are increased. The differences between the two citation networks are further examined by means of the Freeman vertex betweenness centrality and Johnson's hierarchical clustering. The patents with more new links to other patents have distinct results in terms of the Freeman vertex betweenness centrality. The enhancement of links among patents also results in different clustering. 相似文献
10.
Chang Ching-Yi Panjaburee Patcharin Lin Hui-Chen Lai Chiu-Lin Hwang Gwo-Haur 《Educational technology research and development : ETR & D》2022,70(1):185-204
Educational technology research and development - Fostering students’ abilities to deal with practical problems is an important objective of professional training. To enable students to have... 相似文献