排序方式: 共有66条查询结果,搜索用时 15 毫秒
1.
Multicomponent Ni-base alloys exhibit good mechanical properties even at elevated temperatures and they are widely used for
industrial production of exertion-resistive parts of engines. These properties are mainly determined by the coexistence of
a disordered γ matrix with a face centred cubic lattice and cuboidal domains of its ordered γ′ structure. Therefore it is
useful to study phase equilibria in Ni-base systems, namely in the regions involving both mentioned phases. One of the conclusions
of our recent work on Ni–Al–Cr–W system was a necessity of modification of selected thermodynamic parameters of the ternary
Ni–Al–W subsystem in order to achieve a better agreement of our experimental observations with theoretical modelling. This
involves new measurements of the microstructure of selected samples of the Ni–Al–W system at 900°C and the comparison of the
results with existing literature data in order to confirm our conclusions on higher order system investigated before. It is
a first step on the way to an assessment of the Ni–Al–W system, which has not been done before. 相似文献
2.
Jan Turek Zdeňka Růžičková Eva Tloušťová Helena Mertlíková‐Kaiserová Jana Günterová Lubomír Rulíšek Aleš Růžička 《应用有机金属化学》2016,30(5):318-322
Two gold(I) complexes of the (NHC)AuX type bearing a triazole‐based N‐heterocyclic carbene (NHC) ligand (1‐tert‐butyl‐4‐(4‐methylphenyl)‐3‐phenyl‐1H‐1,2,4‐triazol‐4‐ium‐5‐ylidene) and various halide ligands (X = Br, I) were synthesized and characterized in solution using NMR spectroscopy as well as in the solid state using X‐ray diffraction techniques. The cytotoxic properties of both compounds and the precursor, (NHC)AuCl, were screened against a panel of human tumour cell lines including liver cancer (HepG2), cervical cancer (HeLa S3) and leukaemia (CCRF‐CEM, HL‐60) and compared to cisplatin and auranofin. It was found that the activities of the chloro and bromo derivatives were generally superior to that of cisplatin and slightly less effective compared to auranofin, except for HepG2 cells where auranofin was not as effective. In addition, the ability to induce membrane phosphatidyl serine externalization as a hallmark of apoptosis in CCRF‐CEM leukaemic cells was investigated. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
3.
Reaction of the neutral tricarbaborane nido-7,8,9-C3B8H12 (1) with triethylamine in CH2Cl2 led to quantitative deprotonation and isolation of the corresponding Et3NH+ salt of the [nido-7,8,9-C3B8H11]− anion (2). This was converted into PSH+ and Me4N+ salts via metathetic cation exchange. Heating of the solid Me4N+[7,8,9-C3B8H11]− in mineral oil at 350 °C for 2 h resulted in thermal rearrangement and isolation of the cage isomeric compound Me4N+[7,8,10-C3B8H11]−. Finally, compound 1 was directly complexed via reaction with [CpFe(CO)2]2 (Cp = η5-C5H5) to generate the ferratricarbollide sandwich [1-Cp-closo-1,2,4,10-FeC3B8H11] (4) in 60% yield. The structures of all the generic compounds of tricarbollide chemistry, 1 (PSH+ salt), 2 (MePPh3+salt), and 4, were established unambiguously by an X-ray diffraction analysis. 相似文献
4.
Dr. Shantanu Ganesh Kulkarni Kristýna Jelínková Dr. Marek Nečas Dr. Zdeňka Prucková Dr. Michal Rouchal Dr. Lenka Dastychová Dr. Petr Kulhánek Dr. Robert Vícha 《Chemphyschem》2020,21(18):2084-2095
Stilbene derivatives are well-recognised substructures of molecular switches based on photochemically and/or thermally induced (E)/(Z) isomerisation. We combined a stilbene motif with two benzimidazolium arms to prepare new sorts of supramolecular building blocks and examined their binding properties towards cucurbit[n]urils (n=7, 8) and cyclodextrins (β-CD, γ-CD) in water. Based on the 1H NMR data and molecular dynamics simulations, we found that two distinct complexes with different stoichiometry, i. e., guest@β-CD and guest@β-CD2, coexist in equilibrium in a water solution of the (Z)-stilbene-based guests. We also demonstrated that the bis(benzimidazolio)stilbene guests can be transformed from the (E) into the (Z) form via UV irradiation and back via thermal treatment in DMSO. 相似文献
5.
Galina Karabanovich Jaroslav Roh Zdeňka Padělková Zdeněk Novák Kateřina Vávrová Alexandr Hrabálek 《Tetrahedron》2013
1-Substituted-5-alkylsulfanyl-1H-tetrazoles are well known class of organic substances with various applications in medicinal chemistry or photographic industry. Their selenium analogues, 1-substituted-5-alkylselanyl-1H-tetrazoles are, however, much less explored because of the lack of suitable methods for their preparation. In this work we investigated the synthesis of 1-alkyl/aryl-5-alkylselanyl-1H-tetrazoles from synthetically available alkyl/arylisoselenocyanates. One-pot reactions of arylisoselenocyanates with sodium azide and alkylating agent led to the target 5-alkylselanyl-1-aryl-1H-tetrazoles but also to interesting side products, namely N-alkyl-N-arylcyanamides and (Z)-Se-alkyl-N-cyano-N,N′-diarylisoselenoureas. Nevertheless, when alkylisoselenocyanates were utilized as the substrates, the reactions led exclusively to the formation of 1-alkyl-5-alkylselanyl-1H-tetrazoles in good yields. This simple one-pot procedure brings new possibilities for the preparation of variously substituted selenium compounds. It also opens the way to further investigations of selenium isosteres of the widely utilized 5-thiotetrazole moiety in biomedical applications. 相似文献
6.
Phenylalanine‐Derived Imidazolines Bearing Heteroaromatic Pendants: Synthesis,Characterization, and Application in the Asymmetric Henry Reaction 下载免费PDF全文
Starting from L ‐phenylalanine, (2S)‐3‐phenylpropane‐1,2‐diamine has been prepared and used as building block for the construction of the imidazoline ring. Four new optically pure NH‐imidazolines bearing different six‐membered heteroaromatic substituents on the C(2) position have been prepared and subsequently N‐modified. N‐Substitution afforded two regioisomers that were separated. Some of them proved to be instable and hydrolyzed to diamides. The molecular structures of NH‐imidazolines, both N‐substituted regioisomers, as well as diamides, were unambiguously confirmed by X‐ray‐analysis and NMR spectra. The successfully prepared imidazolines, as well as diamides, were applied as catalysts in a Cu(II)‐catalyzed Henry reaction achieving 26–98% chemical yields and enantiomeric excesses of 3–42%. 相似文献
7.
Jiří Čmelík Zdeňka Nainarová Petr Ryšánek 《International journal of environmental analytical chemistry》2015,95(12):1090-1098
The developed and tested method is based on the acid volatile sulphur (AVS) releasing from a sample of sediment by acidification with hydrochloric acid and sequential absorption of released hydrogen sulphide into the absorption solution of sodium hydroxide. Total sulphur absorbed in the absorption solution is subsequently determined by inductively coupled plasma optical emission spectrometry (ICP-OES) technique. The method was tested using both model and real samples of the river sediment. Obtained results were compared with the results of iodometric determination as the method routinely used for the AVS determination. In case of using ICP-OES with purge and trap, there is no spectral interference of calcium; therefore for the determination of sulphur, it is possible to use atomic emission line of sulphur S I 180.7 nm. The tested method provides the results comparable with the iodometric method within the range of tested concentrations. The detection limit (LOD) of this method is 0.09 mg· S2? ? L?1 in the absorption solution which corresponds to 0.23 mg S2?·kg?1 in a sediment. Value of LOD is comparable with the iodometric determination. 相似文献
8.
Dr. Maria Korabik Zuzana Repická Ladislav Martiška Jan Moncol Jozef Švorec Zdeňka Padělková Tadeusz Lis Milan Mazúr Prof. Dr. Dušan Valigura 《无机化学与普通化学杂志》2011,637(2):224-231
Polymeric salicylatocopper(II) complexes of unusual composition [C u(X‐ sal)2( μ‐denia)(H2O)]n [denia = diethylnicotinamide, and X‐sal = 5‐methylsalicylate ( 1 ), 3‐methylsalicylate ( 2 ), 4‐methoxysalicylate ( 3 ), 3,5‐dichlorosalicylate ( 4 ) and 3,5‐dibromosalicylate ( 5 )] were synthesized and characterized. Magnetic measurements were performed in the temperature range 1.8–300 K. The structural unit of all complexes consists of a CuII atom, which is monodentately coordinated by the pair of X‐salicylate anions in trans positions. Water and the diethylnicotinamide ligand occupy the other two basal plane positions of the tetragonal pyramid. The axial positions are occupied by a diethylnicotinamide oxygen atom of neighboring structural units, thus forming a spiral polymeric structure parallel to b axis. Magnetic measurements showed that all complexes 1 – 5 exhibit a susceptibility maximum at about 6–8 K. The obtained data fit to Bleaney–Bowers equation gave singlet‐triplet energy gaps 2J = –8.60 cm–1 for 1 , 2J = –6.57 cm–1 for 2 , 2J = –8.57 cm–1 for 3 , 2J = –6.82 cm–1 for 4 , and 2J = –6.45 cm–1 for 5 . The supramolecular structure based on hydrogen bonds [described by supramolecular synthons R22(10) and R22(12)] is the pathway for antiferromagnetic interactions of the magnetically coupled pairs of copper atoms of neighboring chains within the 2D supramolecular layers. The results of the magnetic measurements suggest involvement of the COO groups in the magnetic interaction pathway for all five complexes. 相似文献
9.
Miroslav Holub Miloš Buděšínský Zdeňka Smítalovǎ David Šaman Urszula Rychlewska 《Tetrahedron letters》1984,25(34):3755-3758
The newly established structures of sesquiterpene lactones from Laser trilobum showed that these lactones belong among the stereostructural types of germacranolides, guaianolides, eudesmanolides and elemanolides. 相似文献
10.
Pavel?Bro?Email author Jir?í?Bur?ík Zdeňka?Stará 《Monatshefte für Chemie / Chemical Monthly》2005,136(11):1915-1920
Summary. Multicomponent Ni-base alloys exhibit good mechanical properties even at elevated temperatures and they are widely used for
industrial production of exertion-resistive parts of engines. These properties are mainly determined by the coexistence of
a disordered γ matrix with a face centred cubic lattice and cuboidal domains of its ordered γ′ structure. Therefore it is
useful to study phase equilibria in Ni-base systems, namely in the regions involving both mentioned phases. One of the conclusions
of our recent work on Ni–Al–Cr–W system was a necessity of modification of selected thermodynamic parameters of the ternary
Ni–Al–W subsystem in order to achieve a better agreement of our experimental observations with theoretical modelling. This
involves new measurements of the microstructure of selected samples of the Ni–Al–W system at 900°C and the comparison of the
results with existing literature data in order to confirm our conclusions on higher order system investigated before. It is
a first step on the way to an assessment of the Ni–Al–W system, which has not been done before. 相似文献