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1.
Oligoribonucleotides carrying 5-ethyluridine units were prepared using solid-phase phosphoramidite chemistry. The introduction
of the tert-butyldimethylsilyl group at the 2′-OH position proceeded in good yield and very high 2′-regioselectivity. RNA duplexes carrying
5-ethyluridine either at the sense or the guide strands display RNAi activity comparable to or slightly better than that of
unmodified RNA duplexes. Gene suppression experiments using luciferase targets in SH-SY5Y cells show that the ethyl group
is generally well accepted at all positions although a small decrease in RNA interference activity is observed when one 5-ethylU
residue is incorporated in the 3′ overhangs. 相似文献
2.
Aviñó A Ocampo SM Lucas R Reina JJ Morales JC Perales JC Eritja R 《Molecular diversity》2011,15(3):751-757
Oligoribonucleotide conjugates and the corresponding siRNA duplexes against tumor necrosis factor carrying one, two, or four
glucose and galactose residues at the 5′-end have been prepared using phosphoramidite chemistry. Carbohydrate-modified siRNA
duplexes have similar inhibitory properties than unmodified RNA duplexes in HeLa cells transfected with oligofectamine. When
HeLa cells were treated with siRNA carrying one, two, or four glucose residues without oligofectamine, no inhibition was observed.
The inhibitory properties of siRNA carrying galactose residues without transfecting agent were tested on HuH-7 cells that
have abundant asialoglycoprotein receptors. In these cells siRNA carrying galactose residues have slight anti-TNF inhibitory
properties (25% in the best case) that are eliminated if the receptors are blocked with a competitor. These results demonstrate
receptor-mediated uptake of siRNA carrying galactose residues, although the efficacy of the process is not enough for efficient
RNA interference experiments. 相似文献
3.
Y. Zhang C. Y. Chen M. Huang Y. S. Wang Y. M. Zou 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,56(2):157-166
Ab initio calculations of the total dielectronic
recombination (DR) rate coefficients for thirteen ions along the NiI
isoelectronic sequence in the ground state (Kr8+, Mo14+,
Ag19+, Sn22+, Xe26+, Nd32+, Gd36+,
Yb42+, W46+, Au51+, Pb54+, At57+, and
U64+) have been performed using the flexible atomic code. The
level-by-level calculations are performed for evaluating the DR
contributions through the relevant Cu-like autoionizing inner-shell
excited 3l174l′n′′l′′ and 3l175l′n′′l′′ configuration complexes with n′′
≤15, which are associated with Δn=1 and Δn=2
core-excitations, respectively. The usual (n′′)-3 scaling
law is found to be invalid for low-Z ions. A level-by-level
extrapolation procedure is employed to obtain the contributions
through higher n′′ complexes. The decays to autoionizing
levels followed possibly by radiative cascades could enlarge the
rates at relatively high temperature by a factor up to about 23%.
For the whole isoelectronic ions the contributions from
3s23p63d9 4l′n′′l′′ dominate the total DR
rates while the contributions from the 3s23p63d9 5l′n′′l′′ configuration complexes are about 10-20% at
relatively high temperature. On the basis of the calculated results,
a general analytic formula for the total DR rate coefficients of all
the ions with 36≤Z ≤92 along the NiI isoelectronic
sequence is constructed. The comparisons of the rates obtained from
the general formula with those from the detailed calculations show
that the formula is of high precision, generally better than 3%
accuracy for electron temperatures kT≥0.1EI, where EI is
the ionization energy of the Cu-like ion. The present DR rates at
temperature above 1.0EI are larger than the previously published
data by a factor above 30%. The commonly used semiempirical formula
proposed by Burgess and modified by Merts may overestimate the rates
at high temperature by a factor of about 2 for low-Z ions. 相似文献
4.
Tuning of the emission color of organic electroluminescent devices by exciplex formation at the organic solid interface 总被引:1,自引:0,他引:1
′ ,4′′-tris(3-methylphenylphenylamino)triphenylamine, 1,3,5-tris[(4-diphenylaminophenyl)phenylamino]benzene, N, N′-bis(3-methylphenyl)-N, N′-diphenyl-[1,1′-biphenyl]-4,4′-diamine, and 4,4′,4′′-tri(N-carbazolyl)triphenylamine, emitted bright light resulting from the exciplex formed at the solid interface between TPOB
and the hole-transporting material. The exciplex formation was evidenced by the measurements of the photoluminescence spectra
and lifetimes of the mixture of an equimolar amount of TPOB and each of the hole-transporting materials. Tuning of the emission
color from greenish blue to orange was attained by varying the ionization potential of the hole-transporting material for
the fixed electron-transporting material of TPOB.
Received: 27 July 1998/Accepted: 28 July 1998 相似文献
5.
《The European Physical Journal C - Particles and Fields》2006,48(2):329-341
We report a new measurement of J/ψ, ψ′ and Drell–Yan cross-sections, in the kinematical domain -0.425<ycm<0.575 and -0.5<cosθCS<0.5, performed at the CERN-SPS using 400 GeV/c incident protons on Be, Al, Cu, Ag, W and Pb targets. The dependence of the charmonia production cross-sections on the size of the target nucleus allows to quantify the so-called normal nuclear absorption. In the framework of the Glauber model, this new measurement is combined with results previously obtained with the same apparatus, under different experimental conditions, and leads to a precise determination of the J/ψ and ψ′ absorption cross-sections in the surrounding nuclear matter. 相似文献
6.
Syntheses and mesomorphic properties of di-, tri- and tetrafluorosubstituted 4′-(4-alkylphenyl)-4-isothiocyanatotolanes are
described. Four fluorine substituted compounds in the position 2′, 3′, 3, and 5 show stronger nematic character than difluorosubstituted
ones in the position 3, 5 or 2′, 3′. Example of high birefringence nematic mixture and its properties are given. 相似文献
7.
The Pictet–Spengler reaction is known as a useful tool for the synthesis of constrained analogs of tryptophan. Herein, we
present the further cyclization of 1,2,3,4-tetrahydro-β-carboline-3-carboxylic acid methyl esters with 1-(1′-aminoalkyl) side chain. These transformations lead to heterocyclic structures
which can find useful applications in medicinal chemistry as peptide mimetics. 相似文献
8.
H. Koibuchi 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,66(1):85-90
A compartmentalized surface model of Nambu and Goto is studied on triangulated spherical surfaces by using the canonical Monte
Carlo simulation technique. One-dimensional bending energy is defined on the skeletons and at the junctions, and the mechanical
strength of the surface is supplied by the one-dimensional bending energy defined on the skeletons and junctions. The compartment
size is characterized by the total number L′ of bonds between the two-neighboring junctions and is assumed to have values in the range from L′ = 2 to L′ = 8 in the simulations, while that of the previously reported model is characterized by L′ = 1, where all vertices of the triangulated surface are the junctions. Therefore, the model in this paper is considered to
be an extension of the previous model in the sense that the previous model is obtained from the model in this paper in the
limit of L′↦1. The model in this paper is identical to the Nambu-Goto surface model without curvature energies in the limit of L′↦∞ and hence is expected to be ill-defined at sufficiently large L′. One remarkable result obtained in this paper is that the model has a well-defined smooth phase even at relatively large
L′ just as the previous model of L′↦ 1. It is also remarkable that the fluctuations of surface in the smooth phase are crucially dependent on L′; we can see no surface fluctuation when L′≤ 2, while relatively large fluctuations are seen when L′≥ 3. 相似文献
9.
J. P. Wesley 《Foundations of Physics Letters》1997,10(2):189-204
The electrodynamics that predicts all known relevant observations is based upon the force F=(qq ′R/R3) [1 − 2v·v′/c2 + 3(v·R) (v′·R)/c2R2 + (a — a′)·R/c2] on charge q at r with the absolute velocity v and acceleration a due to charge q′ at r′ with absolute velocity v′ and acceleration
a′, where R=r − r′. This force yields Ampere’s original empirical law for the force between current elements, which predicts
the many effects due to Ampere tension between colinear current elements. It yields Faraday induction as well as Müller’s
localized unipolar induction. The force on an accelerating charge due to a stationary charge yields Lenz’s law for the induced
back emf; and, when applied to gravitation, qq′ being replaced by — Gmm′, it yields the inertial force ma, confirming Mach’s
priniciple. For charge velocities approaching the velocity of light c it predicts the results of the Kaufmann-Bucherer experiments
and the Bertozzi experiment, assuming neomechanics, or mass change with velocity. It is readily written as a field theory.
Introducing time retardation, it yields waves and radiation. It predicts the observed zero self-torque on the Pappas-Vaughan
Z-shaped antenna. Energy is conserved. The Weber electrodynamic theory is shown to fail. 相似文献
10.
The fluorescence excitation spectra and polarization of the fluorescence of a bichromophore cooled in a supersonic jet are
measured. The bichromophore consists of 2,5-diphenyloxazole (PPO) and 1-(5′-phenyl-1′, 3′-oxazole-2′-yl)-4-(5′-phenyl-1′,3′,4′-oxadiazole-2′-yl)-benzene
(POPDP) connected by the methylene bridge -(CH2)-. Based on the analysis of these components and theoretical calculations, it has been proven that the total intramolecular
singlet-singlet transfer of the energy of electronic excitation from the energy donor PPO to the acceptor POPDP occurs in
a time of 10−12 sec.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 4, pp. 460–463, July–August, 2005. 相似文献
11.
M. K. Srivastava 《Pramana》2004,63(5):1053-1062
An approximate simple scaling law is obtained for asymmetric (e, 3e) process on helium-like ions for double ionization by fast electrons. It is based on the equation (Z
′3π) exp[-Z(r1 + r2)],Z′ = Z – (5/16) for ground state wave function of helium-like ions and Z′2 scaling of energies. The scaling law is found to work very well if the lower energy electron is ejected along the momentum
transfer direction and the other one is ejected in the opposite direction. It also works quite well if this electron is ejected
within about 90° of the momentum transfer direction with the other electron going in the opposite direction. The scaling law
becomes increasingly accurate as the target nuclear charge and the energy increase. 相似文献
12.
Hongfei Jiang Guilan Wang Wenzhu Zhang Xiaoyu Liu Zhiqiang Ye Dayong Jin Jingli Yuan Zhiguang Liu 《Journal of fluorescence》2010,20(1):321-328
Because highly luminescent lanthanide compounds are limited to Eu3+ and Tb3+ compounds with red (Eu, ~615 nm) and green (Tb, ~545 nm) emission colors, the development and application of time-resolved
luminescence bioassay technique using lanthanide-based multicolor luminescent biolabels have rarely been investigated. In
this work, a series of lanthanide complexes covalently bound silica nanoparticles with an excitation maximum wavelength at
335 nm and red, orange, yellow and green emission colors has been prepared by co-binding different molar ratios of luminescent
Eu3+–Tb3+ complexes with a ligand N,N,N1,N1-(4′-phenyl-2,2′:6′,2′′-terpyridine-6,6′′-diyl)bis(methylenenitrilo) tetrakis (acetic acid) inside the silica nanoparticles.
The nanoparticles characterized by transmission electron microscopy and luminescence spectroscopy methods were used for streptavidin
labeling, and time-resolved fluoroimmunoassay (TR-FIA) of human prostate-specific antigen (PSA) as well as time-resolved luminescence
imaging detection of an environmental pathogen, Giardia lamblia. The results demonstrated the utility of the new multicolor luminescent lanthanide nanoparticles for time-resolved luminescence
bioassays. 相似文献
13.
Jalilzadeh M Noroozi Pesyan N Rezaee F Rastgar S Hosseini Y Sahin E 《Molecular diversity》2011,15(3):721-731
Reaction of barbituric acid (BA), 1,3-dimethyl barbituric acid (DMBA) and 2-thiobarbituric acid (TBA) with cyanogen bromide
and various aldehydes in presence of triethylamine afforded a new class of heterocyclic stable 5-alkyl and/or 5-aryl-1H, 1′H-spiro[furo[2,3-d]pyrimidine-6,5′-pyrimidine]2,2′,4,4′,6′(3H,3′H,5H)-pentaones which are dimeric forms of barbiturate (uracil and thiouracil derivatives) at 0 °C to ambient temperatures. Structure
elucidation is proved by X-ray crystallography, 1H NMR, 13C NMR, FT-IR, CHN and mass analyses techniques. Mechanisms of the formations are discussed. 相似文献
14.
N. G. Bryantseva I. V. Sokolova R. M. Gadirov V. P. Khilya Ya. L. Garazd 《Journal of Applied Spectroscopy》2009,76(6):813-818
Fluorescence spectra at 298 and 77 K and phosphorescence spectra at 77 K have been measured for five new compounds. Fluorescence
and phosphorescence quantum yields have been measured by comparison with a standard (8-methoxypsoralen). Phosphorescence lifetimes
at 77 K have been found for 2-hydrazyl-3,4-cyclopentyl-14,14-dimethylpryanocoumarin (1.60 msec); 2-hydrazyl-3,4-cyclohexyl-7-methoxycoumarin
(1.35); 3,4-phenyl-4′,5′-cyclohexylpsoralen (2.50); 4′-methyl-3,4-cycloheptylpsoralen (1.10); and 4′,5′-dimethyl-3,4-cyclohexylpsoralen
(1.25). The basic channel of energy deactivation for 3,4-phenyl-4′,5′-cyclohexylpsoralen; 4′-methyl-3,4-cycloheptylpsoralen;
and 4′,5′-dimethyl-3,4-cyclohexylpsoralen is radiative transfer. Energies of the lowest excited triplet states have been calculated
using an INDO/S quantum-chemical method. 相似文献
15.
T.-M. Shen C.-Y. Chen Y.-S. Wang Y.-M. Zou 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,53(2):179-188
A detailed and large-scaled calculation is performed on the total electron impact excitation rate coefficients from the ground
state to the 106 fine-structure levels in 3l-14l′ of Ni-like Gd36+ employing the relativistic configuration-interaction distorted-wave approximation. The resonance contributions from 3l174l′n′′l′′ and 3l175l′n′′l′′ doubly-excited states of Cu-like Gd35+ are taken into account using the isolated process and isolated resonances approximation. The effects of the radiative decays
from the resonances are investigated carefully and are found to be significant. The present rate coefficients, as well as
the collision strength, are compared extensively with the previously published results. We believe our results should be more
accurate and reliable. 相似文献
16.
M. Versluis N. Georgiev L. Martinsson M. Aldén S. Kröll 《Applied physics. B, Lasers and optics》1997,65(3):411-417
1 (6) rotational line in the A2Σ+(v′=0)←X2Π(v′′=0) band of OH at 309 nm. The requirements for obtaining a good signal-to-noise ratio for the technique are discussed and
the possibilities of single-shot measurements are investigated.
Received: 31 October 1996/Revised version: 3 December 1996 相似文献
17.
The luminescence properties of Re(I) complexes incorporating the dcbpy ligand (dcbpy = n,n′-dicarboxylic acid-2,2′-bipyridine; n = 3, 4) were investigated as well as their utility as Pb2+ sensors. An unusual binuclear complex of the 3,3′- species was isolated. The emission intensity and lifetime for all complexes
were found to be highly temperature-dependent, with quantum yields and lifetimes dramatically greater at 77 K than at room
temperature. The monomeric 3,3′-dcbpy Re(I) complex demonstrates nearly 1:1 binding with Pb2+. The effect of this lead binding on the emission intensity is great, but the low quantum yields allow only for detection
of the metal at the micromolar level. The binding of Pb2+ to the 4,4′-dcbpy complex is modeled and the interaction is demonstrated to involve two binding sites. 相似文献
18.
W. Huang R. Richert 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,66(2):217-221
We investigate the nonlinear dielectric effects in a polar viscous liquid, propylene carbonate, by analyzing the voltage and
current traces obtained for a sinusoidal electric field at a frequency of 1 kHz and field amplitudes as high as 162 kV/cm.
The main source of non-linear behavior results from the energy absorbed from the field and is understood quantitatively. However,
there is a qualitative difference in the behavior of the field induced change, Δε′′(E), and the third harmonic amplitude of the current, I3ω. Although both Δε′′(E) and I3ω are considered reliable measures of non-linear behavior, we show here that the third harmonic signal reflects only those
non-linear responses that are instantaneous on the time scale of the test frequency. 相似文献
19.
A new polymeric material for optical switching 总被引:1,自引:0,他引:1
′ -(2′′,4′′,6′′-trichlorophenazoamino)-phenazo-4-nitrobenzene, was studied. Large nonresonant optical nonlinearity (χ(3)≥10-28 C4m/J3 or
10-9 esu) and fast response time (t<20 ps) were measured by forward degenerate four-wave mixing experiment. Optical bistable behavior
in a quasi-waveguide interferometer with the thin film of the material was observed. The potential of the material for optical
switching was evaluated.
Received: 20 July 1998/Revised version: 11 September 1998 相似文献
20.
O. Cozar I. Bratu L. David C. Crăciun A. Hernanz R. Navarro M. de la Fuente C. Bălan 《Applied magnetic resonance》2001,21(1):71-78
Electron paramagnetic resonance investigation of the Cu(II) complexes with guanosine-5′-monophosphate (5′-GMP) and cytidine-5′-monophosphate (5′-CMP) shows the affinity of the Cu(II) ion to interact with the base and the phosphate group. The different modes of the coordination of the metal ion at the nucleotide and the water molecules lead to octahedral species, distorted by dynamical Jahn-Teller effect (g0 = 2.106) for the Cu(II)-5′-CMP complex and rhombically distorted (g1 = 2.358, g2 = 2.126, g3 = 2.068) or tetragonally distorted (g∥′ = 2.299, g⊥′ = 2.126) for the Cu(II)-5′ -GMP complex. The compound with 5′-CMP presents also a more stable in time square-planar species (g∥ = 2.265, A∥ = 162 G, g⊥ = 2.076). The local symmetry changes in aqueous solution by coordination of water molecules. 相似文献