105,799 research outputs found
Lepidoptera, rhopaloceres and heteroceres, indigenous and exotic : with descriptions and colored illustrations /
No full textParts issue: Each pt. (no.) in buff, yellow, green, pink or blue paper covers. Publisher's advertisements and notices on p. [2-4] of covers.Illustrations: 15 prints : lithograph, hand col. ; full-page. Drawn on the stone by Strecker.Originally issued in 15 pts.Mode of access: Internet.Arents copy: Author's presentation copy, inscribed: "To Rev. Dr. Schmucker, with compliments, Herman Strecker" (cover of pt. 1).Arents copy: Parts issue.Copy in QKK+: Bound from parts. Original covers bound in at end
Hilfsbuch für die Elektrotechnik
No full textvon C. Grawinkel und K. Strecker ; Unter Mitwirkung von Borchers, Eulenberg, Fink, Goppelsroeder, Pirani, Seyffert und H. Strecker ; bearbeitet und herausgegeben von Dr. K. Strecke
Dissertatio Jvris Pvblici Inavgvralis De Splendore Familiarvm Illvstrivm Conservando
No full textErfurt, Univ., Jur. Diss., 1747Qvam Ex Decreto Et Avctoritate Amplissimi Jctorvm Ordinis, In Illvstri Et Perantiqva Vniversitate Erfordiensi Svb Præsidio Altissimi, Pro Gradv Doctorali ... Pvblico Ervditorvm Examini Svbjicit Avctor Ernest. Wilhelmvs Strecker, Erfordiensis In Avditorio Jctorvm Majori Horis Consvetis Die VI. Martii. MDCCXLVII.Enth. Widmung an Anselm Franz Ernst von Warsberg und 7 Gedichte der BeiträgerVorlageform des Erscheinungsvermerks: Erfordiæ Typis Joh. Christoph. Heringii, Acad. Typogr.Text teilw. in dt. Sprach
Catalytic enantioselective Strecker reactions and analogous syntheses
No full textGröger H. Catalytic enantioselective Strecker reactions and analogous syntheses. Chemical Reviews. 2003;103(8):2795-2828
Small Molecule as a Chiral Organocatalyst for Asymmetric Strecker Reaction
No full textA simple and novel chiral amide-based
organocatalyst 6 was synthesized from readily available
starting materials for the
asymmetric Strecker reaction. A variety of N-benzhydryl-
and N-tosyl-substituted imines were found to be suitable
substrates with i-PrOH as an additive in the presence
of chiral organocatalyst 6 at 0 °C with ethylcyanoformate
as a source of cyanide for the synthesis of chiral α-amino nitriles.
High yield (up to 91%) with excellent enantioselectivity (ee up to
99% of product) were achieved in 24–30 h in the case of both N-benzhydryl- and N-tosyl-substituted imines.
To understand the mechanism of the catalytic Strecker reaction, NMR
studies and kinetic investigations were carried out with different
concentrations of the catalyst 6, ethylcyanoformate,
and substrate. It was found that the asymmetric Strecker reaction
was first-order with respect to the concentration of the catalyst,
EtOCOCN, and saturation kinetics in substrate. An appropriate stereochemical
model for the enantioselective Strecker reaction is proposed. We further
extend our study, using chiral α-amino nitriles [2-(benzhydrylamino)-2-(pyridin-3-yl)acetonitrile]
for the synthesis of chiral amino amide and hydantoin in high yield
with high enantioselectivity
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
Studien zur lateinischen Dichtung des Mittelalters. Ehrengabe für Karl Strecker, hgg. von W. STACH und H. Walther. Dresde, 1931. (Heft der Schriften-Reihe zur Historischen Vierteljahrschrift.)
No full textSamaran Charles. Studien zur lateinischen Dichtung des Mittelalters. Ehrengabe für Karl Strecker, hgg. von W. STACH und H. Walther. Dresde, 1931. (Heft der Schriften-Reihe zur Historischen Vierteljahrschrift.). In: Bibliothèque de l'école des chartes. 1933, tome 94. pp. 163-164
Realizing the right to health through the use of health print materials in the Western Cape, South Africa
No full textIncludes bibliographical references.This qualitative study was conducted in Cape Town, South Africa in 2010. It examines the effectiveness of promotional educational pamphlets on the awareness, understandings and practice of the right to health among eight civil society organizations and their constituents
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe 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
Highly Active Chiral Dilithium(I) Binaphthyldisulfonate Catalysts for Enantio- and Chemoselective Strecker-Type Reactions
No full textAn enantioselective Strecker-type
reaction of aldimines and ketimines was developed by using a chiral
dilithium(I) binaphthyldisulfonate as a chiral acid–base cooperative
catalyst. The present catalytic system features an extremely short
reaction time (10 min to 4 h), unlike conventional catalytic systems.
Along with the design of stronger chiral Li(I) Lewis acid catalysts,
a highly reactive pentacoordinate silicate generated in situ could
promote the reactions. In particular, instead of unstable N-Bn Strecker products, more stable N-CH2(9-anthryl) and N-CH2(1-naphthyl)
Strecker products could be obtained in high yields with high enantioselectivities.
By a switch of the present and previous catalyst systems, chemoselective
cyanation to a ketoaldimine could be performed, respectively. Moreover,
mechanistic investigations provided useful information regarding the
active catalysts, catalytic cycles, and possible transition states
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