1,720,959 research outputs found
Synthesis and Characterization of Photo-induced Cross-linkable Poly(fluorene-co-triphenylamine) and Applications on Polymer Light-emitting Diodes
No full text在本研究中，利用Suzuki-Miyamura反應合成一系列三苯胺和芴的共聚高分子，並利用凝膠滲透層析儀、熱重分析儀、示差掃描卡計、循環伏安儀、吸收光譜與螢光光譜儀來研究其性質。
當三苯胺衍生物及光酸加入高分子，經由UV照光後可使其進行Friedel-Crafts的反應，交聯形成網路狀的結構，對溶劑具有抵抗的能力。應用於高分子發光二極體的多層元件中，作為電洞傳導層，ITO/光交聯的HTL/PVK-Ir(ppy)3-PBD/Mg-Ag，其驅動電壓為9.4 V，最大亮度為7630 cd/m2，效率可達15.8 cd/A。
利用Friedel-Crafts反應將高分子修飾上二茂鐵的單元，當三苯胺衍生物加入，經由UV照光進行交聯，這部分應用於高分子發光二極體中，來幫助電洞的注入，此外在循環伏安法測量下，可觀察到電聚現象發生。In this studies, a series of copolymers were synthesized by triphenylamine and fluorene via Suzuki-Miyamura reaction, which were characterized by gel permeation chromatography (GPC), thermal gravimetric analyzer (TGA), differential scanning calorimeter (DSC), cyclic voltammetry (CV), absorption and photoluminescence spectroscopy (PL).
The polymers were cross-linked by adding the triphenylamine derivative and the photo acid generator which catalyzed Friedel-Crafts reaction under UV irradiation. This approach can be implemented to PLED applications as hole-transporting layer. Under the optimized conditions, the polymeric light-emitting device (PLED) of ITO/photo-cross-linkable HTL/PVK-Ir(ppy)3-PBD/Mg-Ag, with a turn-on voltage of 9.4 V (100 cd/m2), a maximum brightness of 7630 cd/m2, and a current efficiency of 15.8 cd/A was achieved.
The polymer which modified with ferrocene units by Friedel-Crafts reaction could be cross-linked by triphenylamine derivative under UV irradiation. This moiety is introduced into the polymer light-emitting diodes to help the hole injection. In addition, the polymer could undergo electropolymerization by cyclic voltammetry
The determinants of target price forecasting errors
No full text以往關於分析師的研究都局限於盈餘預測與投資建議，近幾年，國外開始有研究指出，分析師的目標價預測的確提供了投資評等與盈餘預測以外的資訊，顯示目標價有其重要性。然而，受限於樣本缺乏，所以國內很少有目標價預測誤差的研究。本文利用鉅亨網所提供的券商目標價預測與原始分析報告，並參考Bonini et al.(2006)，利用兩種策略：買進並持有策略、理想世界完美策略，以及兩種目標價預測誤差的衡量方法：過度預測程度、預測的絕對誤差，對兩份樣本進行迴歸檢定。
根據第一部份樣本的結果，發現外資券商的預測誤差的確顯著的小於本國券商，但是在控制了其他因素之後，顯著性降低。而在投資評等方面，強力買進與強力賣出等級的投資建議的預測誤差最大，在投資評等修正方面，降級的預測誤差最小。而從第二部份的結果，發現分析師的經驗越多，預測誤差越小；報告字數越多，則越容易過度自信，因而預測誤差越大，然而，在控制了其他因素之後，顯著性都降低了。而在評價方法則並沒有顯著且ㄧ致的差異。不論在什麼策略下，目標價所隱含的報酬率越高、市場報酬越低，則目標價預測誤差也越大，而且越有過度預測的傾向，這兩個因素是最顯著而且一致的。
為了避免樣本選擇偏誤，或是檢驗結果受到極端值的干擾，本文中也進行的穩健性測試，發現結果並無太大的不同。Abstract
Previous research on analyst reports primarily examines revisions in stock recommendations and earnings forecasts. Recently some foreign studies have found that target price contains information even in the presence of earnings forecasts and stock recommendations. However, domestic research rarely focuses on target price for lack of database. For this paper, I use two strategies and two measures considered by Bonini et al.(2006), and run regressions on two samples from cnYES.com.
According to the results of the first sample, foreign brokerages’ errors are significantly smaller than those of domestic brokerages’. However, after controlling for other variables, the errors become significantly lower. The forecasting errors are the largest in strong buy and strong sell and the smallest in downgrade. The results of the second sample show that the forecasting errors made by the analysts are smaller when the analysts have more experiences and when the reports contain fewer words. Similar to the first sample, the errors are significantly lower after controlling for other variables. The different valuation methods do not change the magnitude of the forecasting errors. When the implied returns are higher or the market returns are lower, the forecasting errors are significantly and consistently larger.
To avoid sample selection bias or the effect of outliers, this thesis also examines the robustness of the regressions. The results are quite similar to the ones obtained by running simple regressions.目錄
第壹章、緒論 - 1 -
第一節、研究動機 - 1 -
第二節、研究目的 - 3 -
第貳章、文獻回顧 - 4 -
第参章、樣本描述 - 7 -
第一節、樣本選擇 - 7 -
第二節、券商投資評等 - 9 -
第三節、樣本分布 - 10 -
第肆章、研究方法 - 16 -
第一節、變數設定 - 16 -
第二節、研究假說 - 24 -
第三節、實証模型 - 25 -
第伍章、實證結果 - 27 -
第一節、敘述性統計 - 27 -
第二節、實證結果 - 30 -
第三節、穩健測試 - 36 -
第陸章、結論與建議 - 55
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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