首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 578 毫秒
1.
Plastification was in focus of research on metals and alloys in the first third of the 20th century. Wichard von Moellendorff built up a research laboratory at the “Allgemeine Elektricitätsgesellschaft” (AEG) in Berlin‐Oberschöneweide in the “Kabelwerk Oberspree” (KWO). With systematic investigations on the metallographic and mechanic properties of metals and alloys he made substantial contributions to the scientific discussion of plastification. His results were partially contrary to the current opinion in metal science, but nevertheless true. Together with Czochralski he derived first conceptions on the mechanism for such deformations considering the crystalinity of the metals. After an interruption due to the first world war, Moellendorff started investigations as director of the “Staatliches Materialprüfungsamt” and the “Kaiser‐Wilhelm‐Institut für Metallforschung” on the plastic flow conus of metallic rods during rupture. This process was explained in 1929 by “turning, distortion and shearing of crystallographic planes”. Polanyi at the Kaiser‐Wilhem‐Institut für Faserforschung, was able to explain the mechanism in 1932. Single atoms move step by step through the lattice on inclined positions and form dislocations. Together with neighbored atoms whole plains can be moved with a minimal energy through the crystal. With the dislocation mechanism, hammering, rolling and bending of metals and alloys can be explained. 1933 Polanyi left Nazi‐Germany and became Professor in Manchester, Moellendorff was brave enough to make an affront against the Nazi regime in giving up the membership of the Kaiser‐Wilhelm‐Gesellschaft stating his personal opposition in an official letter which was not widespread behaviour of the German scientific and technical elite.  相似文献   

2.
We outline the institutional history and highlight aspects of the scientific history of the Fritz Haber Institute (FHI) of the Max Planck Society, successor to the Kaiser Wilhelm Institute for Physical Chemistry and Electrochemistry, from its founding in 1911 until about the turn of the 21st century. Established as one of the first two Kaiser Wilhelm Institutes, the Institute began as a much-awaited remedy for what prominent German chemists warned was the waning of Germany's scientific and technological superiority relative to the United States and to other European nations. The history of the Institute has largely paralleled that of 20th century Germany. It spearheaded the research and development of chemical weapons during World War I, then experienced a "golden era" during the 1920s and early 1930s, in spite of financial hardships. Under the National Socialists it suffered a purge of its scientific staff and a diversion of its research into the service of the new regime, accompanied by a breakdown in its international relations. In the immediate aftermath of World War II it suffered crippling material losses, from which it recovered slowly in the postwar era. In 1952, the Institute took the name of its founding director and the following year joined the fledgling Max Planck Society, successor to the Kaiser Wilhelm Society. During the 1950s and 1960s, the Institute supported diverse research into the structure of matter and electron microscopy in its geographically isolated and politically precarious location in West Berlin. In subsequent decades, as Berlin benefited from the policies of détente and later glasnost and the Max Planck Society continued to reassess its preferred model of a research institute, the FHI reorganized around a board of coequal scientific directors and renewed its focus on the investigation of elementary processes on surfaces and interfaces, topics of research that had been central to the work of Fritz Haber and the first "golden era" of the Institute. Throughout its one-hundred-year history, the Institute's pace-setting research has been shaped by dozens of distinguished scientists, among them seven Nobel laureates. Here we highlight the contributions made at the Institute to the fields of gas-phase kinetics and dynamics, early quantum physics, colloid chemistry, electron microscopy, and surface chemistry, and we give an account of the key role the Institute played in implementing the Berlin Electron Synchrotron (BESSY I and II). Current research at the Institute in surface science and catalysis as well as molecular physics and spectroscopy is exemplified in this issue [Angew. Chem. 2011, 123, 10242; Angew. Chem. Int. Ed. 2011, 50, 10064].  相似文献   

3.
A systematic study on the synthesis of 8‐aminoquinoline derivatives with an n‐butyl group at each alternate position of the quinoline ring was carried out. Skraup Reaction and its Doebner–von Miller variation were used to obtain most of the quinoline ring except for the 2‐butyl‐8‐aminoquinolines and 4‐butyl‐8‐aminoquinolines where the commercially available methylquinoline derivatives were used as precursors. The structures of the synthesized compounds were characterized by FTIR, 1H‐NMR, COSY, 13C‐NMR and HRMS spectra.  相似文献   

4.
Yttrium triflate or triflic acid catalysed Povarov reaction of methyl anthranilate with ethyl vinyl ether, both as aldehyde surrogate and as alkene, gave the desired 2-methyl-4-ethoxytetrahydroquinoline diastereoisomers as the major products along with four component coupling von Miller adducts. A proton NMR-study, using yttrium triflate as catalyst, revealed that the cis-diastereoisomers were the initial major products in both the Povarov and von Miller reactions but that these isomerised to the trans-diastereoisomers under the reaction conditions. Two distinct pathways for forming von Miller adducts were uncovered with the initial Povarov products being converted to von Miller adducts under the reaction conditions. Replacement of the 4-ethoxy with a 4-methoxy group under acidic conditions gave predominantly the trans-diastereoisomer, which was subsequently converted to a cis/trans mixture of the tetrahydroquinoline antibiotic helquinoline. It was also possible to convert the von Miller products to Povarov products under acidic conditions.  相似文献   

5.
Following his seminal work in 1953, Stanley Miller conducted an experiment in 1958 to study the polymerization of amino acids under simulated early Earth conditions. In the experiment, Miller sparked a gas mixture of CH4, NH3, and H2O, while intermittently adding the plausible prebiotic condensing reagent cyanamide. For unknown reasons, an analysis of the samples was not reported. We analyzed the archived samples for amino acids, dipeptides, and diketopiperazines by liquid chromatography, ion mobility spectrometry, and mass spectrometry. A dozen amino acids, 10 glycine‐containing dipeptides, and 3 glycine‐containing diketopiperazines were detected. Miller’s experiment was repeated and similar polymerization products were observed. Aqueous heating experiments indicate that Strecker synthesis intermediates play a key role in facilitating polymerization. These results highlight the potential importance of condensing reagents in generating diversity within the prebiotic chemical inventory.  相似文献   

6.
The Time: May 7, 1999. The Place: The auditorium (Döbereiner-Hörsaal) (Figure 1) of the Chemical Institute of the Friedrich-Schiller-Universität Jena, the famous German university founded in 1558, which numbered among its faculty the illustrious philosophers Johann Gottlieb Fichte, Georg Wilhelm Friedrich Hegel, and Friedrich Wilhelm Joseph von Schelling; the writer and critic Friedrich von Schlegel; and the dramatist and poet (Johann Christoph) Friedrich Schiller, whose name the university now bears [1].  相似文献   

7.
8.
The chemist Dr. Arthur von Weinberg was a member of the Cassella – Gans – Weinberg families of traders and industrialists. In close cooperation with his uncle, Dr. Leo Gans, and his brother, Carl von Weinberg, he developped the small dyestuff factory of his uncle into the world's largest azodyestuff fabrication site of the end of the 19th century. This was achieved by scientifically exploring the chemistry of naphthalene and its derivatives and exploiting their commercial potential as dyestuff precursors. Furthermore, Dr. Arthur von Weinberg realized the market opportunities of sulfur dyes, which could be manufactured in large volumes at low cost. Most important, he very early recognized the great importance of synthetic pharmaceuticals. In 1908 he and his brother Carl were ennobled for their scientific and economic achievements; his hometown Frankfurt/Main made Arthur von Weinberg a “Honorary Citizen” in 1930. Imprisoned based on his jewish background by the Nazi‐government he died in the concentration camp of Theresienstadt in 1943.  相似文献   

9.
none 《Ambix》2013,60(3):203-233
Abstract

Just five British students of chemistry studied with Robert Wilhelm Bunsen (1811–1899) at Marburg in the 1840s, and over a hundred with him at Heidelberg between 1852 and 1888. These pupils were largely responsible for transmitting knowledge of Bunsen's instrumental innovations such as gasometry and spectroscopy to Britain. They also voiced Bunsen's merits as an outstanding teacher. The paper traces (where possible) their careers as researchers, teachers, and industrialists. A list of Bunsen's students is included in the form of a Biographical Register.  相似文献   

10.
This Essay is an account of the institutional and scientific development of the Max‐Planck‐Institut für Kohlenforschung in Mülheim an der Ruhr (Germany), which is the successor to the Kaiser‐Wilhelm‐Institut für Kohlenforschung founded in 1914. The Essay is divided into four main parts, corresponding to the four major periods which are closely associated with the respective Directors of the Institute from 1914 to 2014: 1) Franz Fischer; 2) Karl Ziegler; 3) Günther Wilke; and 4) the period beginning with Manfred T. Reetz, who established a directorate comprising five Directors of equal status, each heading a different research department under the banner of catalysis. Along with key historical events associated with the Institute, research highlights of the four periods are featured.  相似文献   

11.
Gauss's law or Poisson's equation is conventionally used to calculate solvation free energy. However, the near‐solute dielectric polarization from Gauss's law or Poisson's equation differs from that obtained from molecular dynamics (MD) simulations. To mimic the near‐solute dielectric polarization from MD simulations, the first‐shell water was treated as two layers of surface charges, the densities of which are proportional to the electric field at the solvent molecule that is modeled as a hard sphere. The intermediate water was treated as a bulk solvent. An equation describing the solvation free energy of ions using this solvent scheme was derived using the TIP3P water model. © 2013 Wiley Periodicals, Inc.  相似文献   

12.
200 years ago, in 1806, began Napoleon's continental blockade of Great Britain. Especially in Germany and France this triggered an intensive search for substitutes for a variety of British colonial goods and manufactured wares which had become rare and expensive. For the first time, chemists and pharmacists developed substitutes for coffee, china‐bark, indigo, cochenille, cane‐sugar and other products. Napoleon's economic pressure particularly affected the development of chemistry and chemical industry in France and Germany. The paper shows the clear and close relationship of chemical research and the political situation of the Napoleonic Era.  相似文献   

13.
Suzuki's scaling theory for transient phenomena is applied to the calculation of the kinetics of phase separation in the early-to-intermediate stage based on a nonlinear theory proposed by Langer, Bar-on, and Miller (LBM). Calculated results are compared with experimental data on light scattering from a polymer blend system. Deviations from predictions of Cahn's linearized theory in the early time range of phase separation can be explained well by the proposed method of calculation. Nonlinear effects are found to play an essential role in characterizing the light scattering behavior of phase separation in the intermediate stage. Time evolutions of the single-point distribution function of composition are calculated, and the results are in good agreement with those reported in digital imaging analysis experiments and computer simulations of the time-dependent Ginzburg-Landau equation. The influence of asymmetry of free-energy on the single-point distribution function is also investigated in this study. © 1993 John Wiley & Sons, Inc.  相似文献   

14.
An iridium‐catalyzed asymmetric hydrogenation of unfunctionalized exocyclic C=C bonds was performed by using an axially flexible chiral phosphine–oxazoline ligand, providing the desired chiral 1‐benzyl‐2,3‐dihydro‐1H‐indene products with up to 98 % ee (enantiomeric excess). This represents the first general hydrogenation of unfunctionalized exocyclic olefins with high selectivity reported thus far. The additive acetate ion plays an important role in the reaction's high enantioselectivity. The chiral product can be further transformed into key intermediates required for the synthesis of an important insecticide and a drug compound.  相似文献   

15.
The possibility of detecting extraneous milk in singles species cheese‐milk has been explored. A mass spectrometry (MS)‐based procedure has been developed to detect 'signature peptides', corresponding to the predefined subset of 'proteotypic peptides', as matchless analytical surrogates of the parent caseins. Tryptic digests of skimmed milk samples from four species were analyzed by matrix‐assisted laser desorption/ionization time‐of‐flight (MALDI‐TOF) MS. Amongst the candidate signature peptides that are able to differentiate milks from the four species, the αs1‐casein (CN) f8‐22 peptide was selected as a convenient marker for bovine, ovine and water buffalo milk while the f4‐22 peptide was selected as a marker for the two caprine αs1‐CN A and B variants, which differ by a Pro16 (B)‐>Leu16 (A) substitution. MALDI analysis of the digest allowed the detection of αs1‐CN f8‐22 and caprine αs1‐CN f4‐22. The accurate evaluation of caprine milk in a quaternary mixture required the development of a liquid chromatography/electrospray ionization (LC/ESI)‐MS procedure. Five synthetic signature peptide analogues, which differed from their natural counterparts by a single amino acid substitution, were used as internal standards to quantify the αs1‐CN, which was chosen as a reference milk protein, from the different species. The limits of detection were 0.5% (1% for caprine) for either the MALDI or the LC/ESI‐MS method. The isotopic‐label‐free quantification of isoform‐ or variant‐specific signature peptides has disclosed a convenient approach for targeting proteins in complex mixtures. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

16.
The mole and Avogadro’s number are two important concepts of science that provide a link between the properties of individual atoms or molecules and the properties of bulk matter. It is clear that an early theorist of the idea of these two concepts was Avogadro. However, the research literature shows that there is a controversy about the subjects of when and by whom the mole concept was first introduced into science and when and by whom Avogadro’s number was first calculated. Based on this point, the following five matters are taken into consideration in this paper. First, in order to base the subject matter on a strong ground, the historical development of understanding the particulate nature of matter is presented. Second, in 1811, Amedeo Avogadro built the theoretical foundations of the mole concept and the number 6.022 × 1023 mol?1. Third, in 1865, Johann Josef Loschmidt first estimated the number of molecules in a cubic centimetre of a gas under normal conditions as 1.83 × 1018. Fourth, in 1881, August Horstmann first introduced the concept of gram-molecular weight in the sense of today’s mole concept into chemistry and, in 1900, Wilhelm Ostwald first used the term mole instead of the term ‘gram-molecular weight’. Lastly, in 1889, Károly Than first determined the gram-molecular volume of gases under normal conditions as 22,330 cm3. Accordingly, the first value for Avogadro’s number in science history should be 4.09 × 1022 molecules/gram-molecular weight, which is calculated by multiplying Loschmidt’s 1.83 × 1018 molecules/cm3 by Than’s 22,330 cm3/gram-molecular weight. Hence, Avogadro is the originator of the ideas of the mole and the number 6.022 × 1023 mol?1, Horstmann first introduced the mole concept into science/chemistry, and Loschmidt and Than are the scientists who first calculated Avogadro’s number. However, in the science research literature, it is widely expressed that the mole concept was first introduced into chemistry by Ostwald in 1900 and that Avogadro’s number was first calculated by Jean Baptiste Perrin in 1908. As a result, in this study, it is particularly emphasised that Horstmann first introduced the mole concept into science/chemistry and the first value of Avogadro’s number in the history of science was 4.09 × 1022 molecules/gram-molecular weight and Loschmidt and Than together first calculated this number.  相似文献   

17.
As a compliment to several other publications that present and honor Rolf Huisgen's research achievements, the first part of this paper reveals the human side of this eminent chemist. From excerpts from many of his personal and professional writings, Huisgen's personality and philosophies of life are revealed. Also revealed is Huisgen functioning as a historian of chemistry. The second part of this paper examines the scientometrics of Huisgen's publication history. In the late 1950s and early 1960s, Huisgen's career experienced a major transition in terms of publication metrics and the influence these papers had on the organic chemistry community. This was the result of his research into 1,3‐dipolar cycloadditions. Citations to his scientific contributions are well spread over many of his papers, demonstrating his constant work and the building up of a research topic, which continued after his official retirement in 1988. In fact, 17 % of his more than 600 publications appeared after 1988. The majority of Huisgen's papers were co‐authored with his many graduate and postdoctoral students. Consistent with the trend of that era, Huisgen was the sole author of most of his Review articles, and not just those of his many plenary lectures, and it is those Review articles that proved to be his most cited publications. This demonstrates the power and influence of Review articles—secondary sources, in the vocabulary of historians and sociologists of science. In those Review articles, Huisgen principally described the state of the art of 1,3‐dipolar cycloadditions—his golden offspring.  相似文献   

18.
This paper is dedicated to the 300th anniversary of Michail Vasil'evič Lomonosov, Russiás first world‐renowned scholar. He was educated in Russia and Germany and founded the first chemical laboratory in the Academy of St. Petersburg. There he carried out many quantitative experiments especially in the field of melting glasses. He argued in favor of a corpuscular structure of matter and explained physical and chemical phenomena on the basis of his theory. He also contributed to the humanities by writing numerous papers about the history of the Russian nation and the grammar and the poetics of the Russian language. In his personal life he also wrote himself poems and odes.  相似文献   

19.
Poly(p‐nitrophenyl acrylate)s (PNPAs) with different molecular mass and narrow polydispersity were successfully synthesized for the first time by reversible addition–fragmentation transfer (RAFT) polymerization with azobisisobutyronitrile (AIBN) as an initiator and [1‐(ethoxy carbonyl) prop‐1‐yl dithiobenzoate] as the chain‐transfer agent. Although the molecular mass of PNPAs can be controlled by the molar ratio of NPA to RAFT agent and the conversion, a trace of homo‐PNPA was found, especially at the early stage of polymerization. The dithiobenzoyl‐terminated PNPA obtained was used as a macro chain‐transfer agent in the successive RAFT block copolymerization of styrene (St) with AIBN as the initiator. After purification by two washings with cyclohexane and nitromethane to remove homo‐PSt and homo‐PNPA, the pure diblock copolymers, PNPA‐b‐PSt's, with narrow molecular weight distribution were obtained. The structural analysis of polymerization products by 1H NMR and GPC verified the formation of diblock copolymers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4862–4872, 2004  相似文献   

20.
《Ambix》2013,60(1):29-36
Abstract

This reinterpretation of Carl Wilhelm Scheele's (1742–86) early life and career analyses the social interplay between Scheele and other chemists who were active in eighteenth-century Sweden. It is argued that Scheele, a rather lowly journeyman working in peripheral pharmacies, had to work hard and traverse several geographical and social boundaries to gain a foothold in the scientific community. Eventually, Scheele's skilful analysis of the mineral magnesia nigra would establish him as one of the pivotal Swedish chemists. However, this happened only after Scheele had managed to prove himself as a knowledgeable chemist who did not threaten the authority of certain socially superior colleagues. When Scheele had gained a place in the scientific community, the exchange logic of the eighteenth-century republic of letters permitted him to trade experimental results for other kinds of resources. Hence, he gained in both social status, economic prosperity and scientific prominence in a relatively short time.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号