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排序方式: 共有242条查询结果,搜索用时 15 毫秒
1.
I. A. Ronova L. V. Dubrovina A. Yu. Kovalevskii C. Hamciuc M. Bruma 《Russian Chemical Bulletin》1998,47(7):1248-1256
Hindered rotation was considered in calculations of the conformational parameters of a series of polyheteroarylenes with bulky
side substituents by the Monte-Carlo method. Within the range of experimental errors, the results of calculations for several
polyarylates coincide with the values of conformational rigidity, determined from hydrodynamic experimental data. The proposed
procedure was used to estimate the rigidities of a number of polymers with bulky side substuents for which experimental determination
is difficult.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1287–1296, July, 1998. 相似文献
2.
Preparation and characterization of individual peptide-wrapped single-walled carbon nanotubes 总被引:3,自引:0,他引:3
Zorbas V Ortiz-Acevedo A Dalton AB Yoshida MM Dieckmann GR Draper RK Baughman RH Jose-Yacaman M Musselman IH 《Journal of the American Chemical Society》2004,126(23):7222-7227
Two challenges for effectively exploiting the remarkable properties of single-walled carbon nanotubes (SWNTs) are the isolation of intact individual nanotubes from the raw material and the assembly of these isolated SWNTs into useful structures. In this study, we present atomic force microscopy (AFM) evidence that we can isolate individual peptide-wrapped SWNTs, possibly connected end-to-end into long fibrillar structures, using an amphiphilic alpha-helical peptide, termed nano-1. Transmission electron microscopy (TEM) and well-resolved absorption spectral features further corroborate nano-1's ability to debundle SWNTs in aqueous solution. Peptide-assisted assembly of SWNT structures, specifically in the form of Y-, X-, and intraloop junctions, was observed in the AFM and TEM images. 相似文献
3.
Michael Woolman Jimmy Qiu Claudia M. Kuzan-Fischer Isabelle Ferry Delaram Dara Lauren Katz Fowad Daud Megan Wu Manuela Ventura Nicholas Bernards Harley Chan Inga Fricke Mark Zaidi Brad G. Wouters James T. Rutka Sunit Das Jonathan Irish Robert Weersink Howard J. Ginsberg David A. Jaffray Arash Zarrine-Afsar 《Chemical science》2020,11(33):8723
Integration between a hand-held mass spectrometry desorption probe based on picosecond infrared laser technology (PIRL-MS) and an optical surgical tracking system demonstrates in situ tissue pathology from point-sampled mass spectrometry data. Spatially encoded pathology classifications are displayed at the site of laser sampling as color-coded pixels in an augmented reality video feed of the surgical field of view. This is enabled by two-way communication between surgical navigation and mass spectrometry data analysis platforms through a custom-built interface. Performance of the system was evaluated using murine models of human cancers sampled in situ in the presence of body fluids with a technical pixel error of 1.0 ± 0.2 mm, suggesting a 84% or 92% (excluding one outlier) cancer type classification rate across different molecular models that distinguish cell-lines of each class of breast, brain, head and neck murine models. Further, through end-point immunohistochemical staining for DNA damage, cell death and neuronal viability, spatially encoded PIRL-MS sampling is shown to produce classifiable mass spectral data from living murine brain tissue, with levels of neuronal damage that are comparable to those induced by a surgical scalpel. This highlights the potential of spatially encoded PIRL-MS analysis for in vivo use during neurosurgical applications of cancer type determination or point-sampling in vivo tissue during tumor bed examination to assess cancer removal. The interface developed herein for the analysis and the display of spatially encoded PIRL-MS data can be adapted to other hand-held mass spectrometry analysis probes currently available.Integration between a hand-held mass spectrometry desorption probe based on picosecond infrared laser technology (PIRL-MS) and an optical surgical tracking system demonstrates in situ tissue pathology from point-sampled mass spectrometry data. 相似文献
4.
Ronova I. A. Eylshina L. B. Vasilyuk A. N. Rusanov A. L. Bulycheva E. G. 《Russian Chemical Bulletin》2002,51(5):820-824
The dependence of the glass transition and initial decomposition temperatures of polyperyleneimide and polynaphthylimide on the conformational rigidity was studied by the Monte Carlo, Kuhn segment, and quantum chemical AM1 methods. The corresponding linear plots can be used for estimation of the glass transition and initial decomposition temperatures when experimental determination is difficult. 相似文献
5.
M. N. Vidyakin Yu. N. Lazareva Yu. P. Yampol’skii A. Yu. Alentiev I. A. Ronova M. Bruma E. Hamciuc R. Lungu 《Polymer Science Series A》2007,49(9):1045-1052
The gas permeabilities of a number of new structurally related polyimides containing phenylquinoxaline moieties were studied for the first time. The test polymers had different dianhydride units, whereas their diamine components differed in the presence of flexible ether bonds-O-in the main chain, a structure that is reflected in the effective packing of chains and, as a result, in transport parameters. The permeability, diffusion, and solubility coefficients for the gases H2, He, O2, N2, CO, CO2, and CH4, as well as the ideal separation factors for gas pairs, were determined. The transport characteristics of polymers were compared within the given polymer series and with published data for other polymer series. 相似文献
6.
Saulius Armalis Inga Krikŝĉiuniene Erika Kubiliene Nii-Kotey Djane Kuria Ndungu Lennart Mathiasson 《International journal of environmental analytical chemistry》2013,93(1-4):233-242
Abstract The performance of a flow-through mercury coated reticulated vitreous carbon (RVC) electrode in the potentiometric stripping analysis (PSA) of trace metals has been examined. A wall-jet glassy carbon cell was used for the comparative experiments. Experimental parameters influencing the stripping signals have been optimised in order to use the stripping analysis after the preconcentration and matrix isolation by supported liquid membrane (SLM) technique. The SLM with di-2-ethylhexyl-phosphoric acid (DEHPA) as the extractant in the membrane liquid for proton driven transport of trace metals across the membrane has been chosen. Results presented for lead determination in river water demonstrate the analytical advantages of coupled technique SLM-PSA. 相似文献
7.
Ionela-Daniela Carja Corneliu Hamciuc Tachita Vlad-Bubulac Maria Bruma Inga A. Ronova 《Structural chemistry》2013,24(5):1693-1703
Heteroaromatic polymers are considered to be high performance organic materials due to their unique and highly attractive properties, including outstanding thermal and mechanical resistance, that arise from their aromatic structure and strong interactions between macromolecular chains. Modification or designing new molecular architectures with tailored physico-chemical characteristics allows expanding the applications of these materials in various advanced technologies. Herein, a series of polymers containing bulky phenoxyphthalonitrile pendant units was synthesized and their physical properties were studied and correlated with their conformational parameters, as well as free and van der Waals volumes. For comparison, the related polymers without lateral moieties were also investigated to highlight the effect of bulky substituent on the polymer rigidity. Thus, it is shown that conformational rigidity determines the packing of macromolecules in solid state, and, therefore, the free volume, glass transition, and decomposition temperatures. The values found experimentally for T g correlate well with those obtained using the conformational rigidity parameters. The dependence of T g of these polymers on Kuhn segment is described by linear equations, with very good factors of convergence. The correlations established by Monte Carlo method allow obtaining the T g values for related polymers where the experimental measurement of this parameter is difficult. 相似文献
8.
Structural Chemistry - The effect of structural inhomogeneities on the equilibrium flexibility of rigid-chain aromatic polymers containing complex condensed cycles in the main chain has been... 相似文献
9.
10.
Cover Picture: Monitoring Conformational Changes in the NDM‐1 Metallo‐β‐lactamase by 19F NMR Spectroscopy (Angew. Chem. Int. Ed. 12/2014) 下载免费PDF全文