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 562 毫秒
1.
The effect of H2S on the activity and selectivity of catalysts (Ru/Al2O3, Pd/Al2O3 and Ru and Pd promoted molydena-alumina) was different (on differnt catalysts and different conversions of cyclohexene). Ru-containing catalysts showed higher sulfur sensitivities than the Pd-containing ones. The sequence of catalysts by their H2S uptake related to mass of catalyst was PdMo/Al2O3RuMo/Al2O3Mo/Al2O3>Pd/Al2O3Ru/Al2O3.  相似文献   

2.
Triterpene glycosides from Pulsatilla chinensis   总被引:1,自引:0,他引:1  
Four triterpene glycosides were isolated from the roots of Pulsatilla chinensis (Bunge) Regel (Ranunculaceae). Two new glycosides, chinensiosides A (1a) and B (2), were identified as 3-O-[-L-rhamnopyranosyl-(12)--L-arabinopyranosyl]-28-O-[-L-rhamnopyranosyl-(14)--D-glucopyranosyl-(16)--D-glucopyranosyl]-3,23-dihydroxylup-20(29)-en-28-oic acid and 3-O-{-L-rhamnopyranosyl-(12)-[-D-glucopyranosyl-(14)]--L-arabinopyranosyl}-28-O-[-L-rhamnopyranosyl-(14)--D-glucopyranosyl-(16)--D-glucopyranosyl]-3,23-dihydroxylup-20(29)-en-28-oic acid. The other two glycosides were identified as previously known hederasaponin C (3) from Hedera helix and glycoside III (4) from Pulsatilla cernua.  相似文献   

3.
Summary Crystals of Co2(X 2O7)·2H2O,X=P/As were synthesized under hydrothermal conditions. Their crystal structures were determined by single crystal X-ray diffraction:a=6.334(1)/6.531(2),b=13.997(2)/14.206(4),c=7.637(1)/7.615(2)Å, =94.77(2)/94.74(2)°, space group P21/n,R=0.032/0.046,R w=0.028/0.034 for 2423/2042 reflections and 131/119 variables. Within the twoXO4 tetrahedra connected via a common corner to anX 2O7 group the average P-O bond lengths are approximately equal (1.540 and 1.543 Å), but As-O differs significantly (1.685 and 1.696 Å). A comparison with the isotypic Mn and Mg pyrophosphates shows a correlation between the ratio Me-O/X-O and the angle O-X-O.
Vergleich der Kristallstrukturen von Co2(X 2O7)·2H2O,X=P und As
Zusammenfassung Kristalle von Co2(X 2O7)·2H2O,X=P/As wurden unter Hydrothermalbedingungen synthetisiert. Ihre Kristallstrukturen wurden mittels Röntgenbeugung an Einkristallen bestimmt:a=6.334(1)/6.531(2),b=13.997(2)/14.206(4),c=7.637(1)/7.615(2) Å, =94.77(2)/97.74(2)°, Raumgruppe P21/n,R=0.032/0.046,R w=0.028/0.034 für 2423/2042 Reflexe und 131/119 Variable. In den beiden über eine gemeinsame Ecke zuX 2O7-Gruppen verknüpftenXO4-Tetraedern sind die mittleren P-O-Abstände ungefähr gleich (1.540 und 1.543 Å), hingegen differiert As-O signifikant (1.685 und 1.696 Å). Ein Vergleich mit den isotypen Mn- und Mg-Pyrophosphaten zeigt eine Korrelation zwischen dem Quotienten Me-O/X-O und dem WinkelX-O-X.
  相似文献   

4.
Steroid polyols from the Far-Eastern starfish Henricia sanguinolenta   总被引:2,自引:0,他引:2  
A new polyhydroxylated steroid (20R,24S)-5-cholestane-3,6,15,24-tetraol and a known glycoside, laeviuscoloside G, was isolated from the Far-Eastern starfish Henricia sanguinolenta, collected in the sea of Okhotsk, and characterized.  相似文献   

5.
The sound velocities of aqueous NaCl, Na2SO4, MgCl2, and MgSO4 solutions were measured from 25 to 95°C in 10o intervals from dilute to saturated solutions. The results were combined with our earlier data and fitted to functions of molality and temperature to within ±0.4 m-sec–1. The adiabatic compressibilities S were calculated from sound speeds and used to calculate the adiabatic apparent molal compressibilities . Isothermal compressibilities and isothermal apparent molal compressibilities were calculated from S using literature values for the expansibilities and heat capacities. The values of were extrapolated to infinite dilution using the Debye-Huckel limiting law to determine partial molal compressibilities. The apparent molal compressibilities were fitted to Pitzer's equations. The Pitzer parameters for the concentration dependence of were determined as a function of temperature. Correlations of and V at various temperatures were found for the electrolytes.  相似文献   

6.
Polarographic study of Pd(II) reveals that it reduces quasireversibly at d.m.e. in 0.2M-pyridine+0.1N-HCl medium. Kinetic parameters of Pd(II) in various concentrations of -resorcyclic acid were calculated usingGellings method and thus the effect of concentration of -resorcyclic acid on the kinetics of the reduction of Pd(II) has been explained.DeFord/Hume graphical extrapolation method and the mathematical method ofMihailov have been employed for the evaluation of overall formation constants of the complexes formed with -resorcyclic acid. The logarithmic values of overall formation constants 1, 2 and 3 obtained by the two methods are 7.47, 8.60, 9.66 (DeFord andHume Method) and 7.44, 8.64, 9.66 (Mihailov Method) at 298 K. Thermodynamic parameters of these complexes are reported.
Elektrodenkinetik und thermodynamische Untersuchungen an Pd(II)-Komplexen mittels polarographie
Zusammenfassung Pd(II) zeigt eine quasireversible Reduktion in 0,2M-Pyridin/0,1N-HCl. Kinetische Parameter wurden mittels der Methode vonGelling ermittelt und damit der Effekt verschiedener -Resorcylsäurekonzentrationen erklärt. Bildungskonstanten der entsperechenden Komplexe wurden nachDeFord/Hume und nachMihailov ermittelt. Die logarithmischen Werte der Gesamtbildungskonstanten 1, 2 und 3 bei 298 K betragen nach derDe Ford/Hume-Methode 7,47, 8,60 und 9,66, nach derMihailov-Methode 7,44. 8,64 und 9,66. Die thermodynamischen Parameter der Komplexbildung werden angegeben.
  相似文献   

7.
The effect of representing dielectric properties in terms of the complex polarizability c = – i is examined. Loss curves ( and tan ) are shifted towards higher frequencies, revealing the existence of new relaxations and allowing the clarifications of ones already known. We have calculated the shift ratios (at maximum or tan )/ (at maximum or tan ) from the more conventional empirical equations representing the dielectric behavior. Some examples are given.  相似文献   

8.
Three polyhydroxylated steroids were isolated from the Far-Eastern starfish Hippasteria phrygiana collected from the Sea of Okhotsk and were characterized as a new glycoside phrygioside A, viz., sodium (20R, 24S)-3,4,7,8,15,24-hexahydroxy-24-O-[3-O-methyl--D-xylopyranosyl-(12)--L-arabinofuranosyl]-5-cholestan-6-yl sulfate, its aglycone, and the already known marthasterone sulfate.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2526–2529, November, 2004.  相似文献   

9.
Polymers having phosphoric acid groups were prepared as a model binder for magnetic coatings, and the correlation among the adsorption behavior of the polymers onto-Fe2O3 particles and the dispersibility, the orientation, and the packing density of-Fe2O3 particles in the magnetic coatings was investigated.PMMA homopolymer molecules hardly adsorbed on-Fe2O3, and the interfacial tension at a water/polymer solution (toluene) interface ( W/T) was scarcely changed compared with a water/toluene interface. Increasing with the content of polymeric phosphoric acid group, the adsorbance of polymer increased and the interfacial tension ( W/T) decreased. When the content of polymeric phosphoric acid groups was over 0.4 mol%, the adsorbance of polymer and interfacial tension ( W/T ) remained constant. When these polymers were used as a binder for magnetic tapes, the dispersibility of-Fe2O3 in the magnetic coatings was improved, increasing with the content of polymeric phosphoric acid group; however, when the content of phosphoric acid group was over 0.2 mol%, its dispersibility decreased abruptly.Studies on Recording Magnetic Materials and Magnetic Composite. XVIII.  相似文献   

10.
The thermodynamic parameters for the interaction of Cu2+, Ni2+, Co2+, Cd2+, andAg+ with the new title ligand have been determined by titration calorimetry in 50% THF–methanol (V/V) at 25 °C.Ag+ exhibited remarkably higher complexation selectivity.Ag+ and several transition metal ions have been transportedusing this ligand as carrier in a bulk liquid membrane. CompetitiveAg+–M2+ transport studies have also beencarried out for the same system. In this membrane transport study, high transport of Ag+ was observed in both single and competitiveAg+–M2+ transport studies. The complexformation of N,N-bis[o-(diphenylphosphino)benzylidene]ethylenediamine (P2N2) with silver,[Ag(P2N2)] (NO3), (1) is reported. Complex 1 has been characterized by X-ray crystallography. 1 ismonoclinic, space group P21/n (No. 14), with cell dimensionsa = 13.398(4) , b=12.577(5) , c = 21.521(4) , =100.14(2) , V = 3570(2) 3 and Z = 4.  相似文献   

11.
Zusammenfassung Es werden diecis,cis- undtrans,trans-Isomeren der primären Alkohole Octadien-(3,5)-ol-(1) (I), 15-Acetoxy-nonadeca-dien-(10,12)-ol-(1) (IV), 17-Acetoxy-heneikosa-dien-(10,12)-ol-(1) (V), 12-Acetoxy-pentadeca-dien-(8,10)-ol-(1) (VII) und 13-Acetoxy-heptadeca-dien-(8,10)-ol-(1) (VI) synthetisiert und zusammen mit einigen Zwischenprodukten und Analogen unter Verwendung des Seidenspinners (Bombyx mori L.) und des Schwammspinners (Lymantria dispar L.) auf Attraktivität getestet. DieL. E.-Werte der synthetisierten cis,cis-VI-Präparate liegen in der Größenordnung von 10–9 g/ml.
Thecis, cis- andtrans, trans-isomere of the primary alcohols octadien-(3,5)-ol-(1) (I), 15-acetoxy-nonadecadien-(10,12)-ol-(1) (IV), 17-acetoxy-heneicosadien-(10,12)-ol-(1) (V), 12-acetoxypentadecadien-(8,10)-ol-(1) (VI) have been synthesized and tested for effectiveness as attractant together with several intermediates and analogues using the Silk Moth (Bombyx mori L.) and the Gipsy Moth (Lymantria dispar L.) The values of the attractant units of the cis, cis-VI-compounds synthesized are of the order 10–9 g/ml.


4. Mitt. der Reihe Synthese und Wirksamkeit von Sexualduftstoff-Analogen; 3. Mitt.:R. Riemschneider, A. Kühnl undK. Brockmeyer, unveröffentlichte Versuche; 2. Mitt.:R. Riemschneider undG. Kasang, Z. Naturforschg.18 b, 646 (1963); 1. Mitt.:R. Riemschneider, Vortrag vom 1. 9. 1962 in S. Paolo.  相似文献   

12.
Seeds of Fatsia japonica (Araliaceae) yielded the new glycosides of gypsogenin: 3-O--D-glucopyranosyl-(12)-O--D-glucopyranoside and 3-O--D-galactopyranosyl-(12)-O--D-glucopyranoside. The structures of these compounds were established by chemical methods and NMR spectroscopy.  相似文献   

13.
Using the Fokker-Planck version of an approximate Boltzmann equation for the ion (translational) energy distribution function fI we have calculated the deviation, k, of the non-equilibrium ion-(polar)molecule reaction rate coefficient k (based) on fI from its equilibrium value k(0). The D (dipole moment)-dependence of the reaction cross section applied leads to a corresponding dependence of k on D.
- , k - ( fI) k(0). k D.
  相似文献   

14.
The catalysts prepared sequentiallyvia the interaction of C3H5PdC5H5 with the surface of evacuated Pr4O7/C and reduction with H2 at 573 K, contain 20–30 Pd particles and Pr4O7 particles<20 . The catalysts obtained have two-order of magnitude higher specific activity in the CH3OH synthesis than Pd/C.  相似文献   

15.
Differential scanning calorimetry is undoubtedly one of the most powerful techniques for investigating the reactions leading to thermoplastic or thermosetting materials. The conditions for the obtaining of reliable experimental results are summarized. A mechanism for the curing of epoxyamine systems is suggested, which is capable of describing the behaviour of stoichiometric and nonstoichiometric mixtures up to high reaction degrees. The advantage of coupling a DSC instrument with a device for the photochemical activation of polymerizations is demonstrated by some examples.
Zusammenfassung Die Differential-Scanning-Kalorimetrie (DSC) gehört ohne Zweifel zu den leistungsfähigsten Methoden der Untersuchung von Bildungsreaktionen thermoplastischer und thermisch härtbarer Substanzen. Die Bedingungen zur Gewinnung zuverlässiger experimenteller Ergebnisse werden zusammengestellt. Für die Härtung von Epoxid-Amin-Systemen wird ein Mechanismus vorgeschlagen, der das Verhalten stöchiometrischer und nichtstöchiometrischer Mischungen bis zu hohen Umsätzen beschreiben kann. Die Vorzüge der Kopplung eines DSC-Instruments mit einer Einrichtung für die photochemische Aktivierung von Polymerisationen wird an einigen Beispielen demonstriert.

. . - , . .
  相似文献   

16.
The stability of the inclusion complex of -CD with cinnamic aldehyde was investigated by means of TG and DSC. The mass loss takes place in three stages: dehydration occurs at 50–120°C; dissociation of -CD·C9H8O proceeds in the range 200–260°C; and decomposition of -CD begins at 280°C. The kinetics of the dissociation of -CD·C9H8O was studied by means of thermogravimetry both at constant temperature and with linearly increasing temperature. The results demonstrate that the dissociation of -CD·C9H8O is dominated by a one-dimensional diffusion process. The activation energyE is 160 kJ mol–1, and the pre-exponential factorA is 5.8×1014 min–1. Scanning electron microscope observations and the results of crystal structure analysis are in good agreement with those of thermogravimetry.  相似文献   

17.
Starting from optically active 5,5-dimethyl, diethyl, and 5-ethyl-5-methyl-2,2-spirobiindane as well as from 5-ethyl-spirobiindane-5-carboxylic ester of known enantiomeric purity and configuration 75 mono to polysubstituted 2,2-spirobiindanes have been prepared. Amongst these are several compounds with rings anellated in the 6,7 (and 6, 7) positions, especially a spirohydrocarbon4 x with orthogonal naphthalene units the circular dichroism of which is reported and discussed.Several mono and disubstituted 5-methyl and ethylindanes (1,2) have been prepared as models for synthetic transformations in the spirobiindane series.From the molar rotations of symmetrically diacylated 5,5-dimethyl and diethyl spirobiindanes (4a, 7b, 7c) empirical ligand parameters for acetyl and methoxycarbonyl were determined which gave much better results in the calculation of the rotations of appropriate spirobiindanes (with the shortened polynomal Ansatz) than the -values deduced previously from 5,5-disubstituted spirobiindanes. The significance of these results is briefly discussed.
10. Mitt.:Neudeck, H., Schlögl, K., Angew. Chem.92, 318 (1980), Intern. Ed. Engl.19, 308 (1980).  相似文献   

18.
Zusammenfassung Die manganreiche Seite der Systeme Mn–V und Mn–Cr wurde hochtemperatur-röntgenographisch untersucht. Im System Mn–V treten bei 90 At% Mn zwei bisher nicht beobachtete Phasen, und , mit -bzw. -Manganstruktur auf. Diese gehören möglicherweise der Klasse der -bzw. -Phasen an. Die -Mischphase besitzt einen größeren Existenzbereich als in der Literatur angegeben. Die Existenz der -Phase Mn3V, sowie die Phasenzustände bis 80 At% Mn und bei manganreicheren Legierungen unterhalb 700°C werden bestätigt. Das lineare thermische Ausdehnungsverhalten der Phasen , und sowie des -und -Mischkristalls werden angegeben. Für den manganreichen Teil wird ein vorläufiges Zustandsdiagramm entworfen. Im System Mn–Cr konnte in großen Zügen Über-einstimmung mit Literaturangaben gefunden werden. Es wird das lineare thermische Ausdehnungsverhalten der -Phase Mn3Cr angegeben.
High temperature X-ray investigation of Mn—rich Mn—V and Mn—Cr alloys
The manganese rich portions of the phase diagrams Mn–V and Mn–Cr have been investigated by means of a high temperature X-ray technique. In the system Mn–V two new phases, and , have been observed with -manganese and -manganese type structure, resp. These phases are probably to be classified as -and -phase. The -manganese solid solution with vanadium has a wider range of homogeneity as compared with previous work. The existence of a -phase Mn3V and phase equilibria below 700°C reported previously could be confirmed. The linear thermal expansion of the intermetallic compounds , , , the -and -manganese solid solutions with vanadium has been evaluated. A tentative phase diagram for the manganese rich portion is given. The main features of the system Mn–Cr according to previous investigations could be confirmed. The linear thermal expansion of the -phase Mn3Cr is reported.


Mit 8 Abbildungen

Herrn Prof. Dr.Hans Nowotny in Dankbarkeit gewidmet.  相似文献   

19.
The three copper(II)-arsenates were synthesized under hydrothermal conditions; their crystal structures were determined by single-crystal X-ray diffraction methods:Cu3(AsO4)2-III:a=5.046(2) Å,b=5.417(2) Å,c=6.354(2) Å, =70.61(2)°, =86.52(2)°, =68.43(2)°,Z=1, space group ,R=0.035 for 1674 reflections with sin / 0.90 Å–1.Na4Cu(AsO4)2:a=4.882(2) Å,b=5.870(2) Å,c=6.958(3) Å, =98.51(2)°, =90.76(2)°, =105.97(2)°,Z=1, space group ,R=0.028 for 2157 reflections with sin / 0.90 Å–1.KCu4(AsO4)3:a=12.234(5) Å,b=12.438(5) Å,c=7.307(3) Å, =118.17(2)°,Z=4, space group C2/c,R=0.029 for 1896 reflections with sin / 0.80 Å–1.Within these three compounds the Cu atoms are square planar [4], tetragonal pyramidal [4+1], and tetragonal bipyramidal [4+2] coordinated by O atoms; an exception is the Cu(2)[4+1] atom in Cu3(AsO4)2-III: the coordination polyhedron is a representative for the transition from a tetragonal pyramid towards a trigonal bipyramid. In KCu4(AsO4)3 the Cu(1)[4]O4 square and the As(1)O4 tetrahedron share a common O—O edge of 2.428(5) Å, resulting in distortions of both the CuO4 square and the AsO4 tetrahedron. The two Na atoms in Na4Cu(AsO4)2 are [6] coordinated, the K atom in KCu4(AsO4)3 is [8] coordinated by O atoms.Die drei Kupfer(II)-Arsenate wurden unter Hydrothermalbedingungen gezüchtet und ihre Kristallstrukturen mittels Einkristall-Röntgenbeugungsmethoden ermittelt:Cu3(AsO4)2-III:a = 5.046(2) Å,b = 5.417(2) Å,c = 6.354(2) Å, = 70.61 (2)°, = 86.52(2)°, = 68.43(2)°,Z = 1, Raumgruppe ,R = 0.035 für 1674 Reflexe mit sin / 0.90 Å–1.Na4Cu(AsO4)2:a = 4.882(2) Å,b = 5.870(2) Å,c = 6.958(3) Å, = 98.51(2)°, = 90.76(2)°, = 105.97(2)°,Z = 1, Raumgruppe ,R = 0.028 für 2157 Reflexe mit sin / 0.90 Å–1.KCu4(AsO4)3:a = 12.234(5) Å,b = 12.438(5) Å,c = 7.307(3) Å, = 118.17(2)°,Z = 4, Raumgruppe C2/c,R = 0.029 für 1896 Reflexe mit sin / 0.80 Å–1.Die Cu-Atome in diesen drei Verbindungen sind durch O-Atome quadratisch planar [4], tetragonal pyramidal [4 + 1] und tetragonal dipyramidal [4 + 2]-koordiniert; eine Ausnahme ist das Cu(2)[4 + 1]-Atom in Cu3(AsO4)2-III: Das Koordinationspolyeder stellt einen Vertreter des Übergangs von einer tetragonalen Pyramide zu einer trigonalen Dipyramide dar. In KCu4(AsO4)3 haben das Cu(1)[4]O4-Quadrat und das As(1)O4-Tetraeder eine gemeinsame O—O-Kante von 2.428(5) Å, was eine Verzerrung der beiden Koordinationsfiguren CuO4-Quadrat und AsO4-Tetraeder bedingt. Die zwei Na-Atome in Na4Cu(AsO4)3 sind durch O-Atome [6]-koordiniert, das K-Atom in KCu4(AsO4)3 ist [8]-koordiniert.
Zur Kristallchemie dreier Kupfer (II)-Arsenate: Cu3(AsO4)2-III, Na4Cu(AsO4)2 und KCu4(AsO4)3
  相似文献   

20.
The thermal ignition behaviour of various mixtures of organic fuels, magnesium and ammonium nitrate (AN) has been examined by differential thermal analysis technique. It has been observed that the thermal decomposition/ignition of organic fuel-AN mixtures is modified significantly in the presence of magnesium metal. The decomposition characteristics of the binary mixtures of AN with various metals indicate the specific action of magnesium and zinc in lowering the decomposition temperature. A possible explanation for the low temperature decomposition is given in terms of the solid state reaction causing the fusion of AN which further reacts with the metal resulting in a highly exothermic reaction.
Zusammenfassung Mittels DTA wurde das thermische Initiierungsverhalten verschiedener Gemische aus organischen Brennstoffen, Magnesium und Ammoniumnitrat (AN) untersucht. Es wurde festgestellt, daß die thermische Zersetzung/Initiierung von Gemischen aus organischen Brennstoffen und AN durch die Gegenwart von metallischem Magnesium bedeutsam beeinflußt wird. Die Zersetzungscharakteristiken binären Gemische aus AN und verschiedener Metalle zeigen eine spezielle Wirkung von Magnesium und Zink bei der Herabsetzung der Zersetzungstemperatur. Eine mögliche Erklärung für die Zersetzung bei niedrigerer Temperatur kann in Bezug auf die Festkörperreaktion gesehen werden, die das Schmelzen von AN verursacht, welches dann mit dem Metall stark exotherm reagiert.

, (). , / — . . , , .
  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