1,720,956 research outputs found
New Protocol in Rotaxane Synthesis – the “Threading-Followed-by-Swelling” Approach
No full text在內鎖分子的合成中，模板導引法（template-directed synthesis） 可將內鎖分子中的個別組成部份藉由分子間的非共價作用力引導至適當位置，以利合成各種形式的內鎖分子。由於其產率遠較傳統的機率統計法（statistical approach）為佳，現已成為合成內鎖分子的主流方法。
目前利用模板導引法合成車輪烷又可分為三種策略，分別是（1）穿透後末端封鎖法（threading-followed-by-stoppering）利用大環分子與桿狀分子間的非共價作用力來形成準車輪烷（pseudorotaxane）並在準車輪烷的末端加入巨大官能基以封鎖大環於啞鈴形分子中，進而得到車輪烷。（2）滑套法（slippage）利用加熱使大環得到越過末端封鎖基團所需要的活化能並和啞鈴形分子上的辨識中心結合，降溫後，由於大環分子缺乏跨越末端的封鎖基團所需的能量，將會形成穩定的車輪烷。（3）夾鎖法（clipping）大環分子的合成前驅物可利用非共價作用力圍繞在桿狀分子的辨識中心周圍，之後進行的環化反應將使新合成之環狀分子圍繞在辨識中心並內鎖於啞鈴形分子中。在此論文中我們將發展一種有異於上述三種合成策略的方法來合成車輪烷分子。目錄
壹、緒論………………………………………………………1
1.1 內鎖分子…………………………………………………1
1.1.1 內鎖分子定義…………………………………………1
1.1.2 內鎖分子的潛力與應用………………………………1
1.2 冠醚和二級銨離子之分子辨識系統……………………2
1.2.1 冠醚……………………………………………………2
1.2.2 冠醚與二級銨離子……………………………………4
1.3 車輪烷之合成策略………………………………………6
1.3.1 以機率統計法合成內鎖分子…………………………7
1.3.3 穿透後末端封鎖法……………………………………8
1.3.4 滑套法…………………………………………………11
1.3.5 夾鎖法…………………………………………………13
貳、結果與討論………………………………………………15
2.1 研究動機…………………………………………………15
2.1.1 車輪烷之合成策略……………………………………15
2.1.2 利用Cope rearrangement作為穿透後末端膨脹法(threading-followedby-swelling)之末端封鎖基………………………16
2.2 桿狀分子的設計與合成…………………………………18
2.3 以穿透後末端膨脹法合成車輪烷………………………21
2.3.1 大環分子為2…………………………………………21
2.3.1 大環分子為DB24C8……………………………………25
參、結論………………………………………………………28
肆、實驗部份…………………………………………………29
伍、參考文獻…………………………………………………4
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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