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The petroleum ether and ethyl acetate fractions of dried ground seeds of Piper nigrum Linn. afforded sixteen compounds (1-16) including one new insecticidal amide, pipwaqarine (1) and six constituents (3,4,6,7,11,15) previously unreported from this plant. The structure of (1) has been elucidated through extensive 1D-, 2D-NMR spectral studies as, 1-[13-(3',4'-methylenedioxyphenyl)-2E,4E,12E-tridecatrienoyl]-N-isopentylamide, while those of known constituents through comparison of spectral data. 1 exhibited toxicity of 30ppm against fourth instar larvae of Aedes aegypti Liston determined by WHO method. A portion of petroleum ether fraction was also subjected to GC and GC-MS analysis resulting in the identification of three compounds (17-19) using the NIST Mass spectral search program 1998 and Kovat's retention indices. Two of these compounds, 17 and 18, are reported for the first time from this plant. 相似文献
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魏琴 吴丹 杜斌 张慧 欧庆瑜Lanzhou Institute of Chemical Physics Chinese Academy of Sciences Lanzhou Gansu China 《中国化学》2004,(7)
Introduction Microemulsion, which consists of surfactant, consurfactant, water and oil at appropriate ratios, is colorless, transparent or subtransparent, low viscosity and thermodynamically stable system. Compared with micellar system, microemulsion has lower surface tension and strong soluble power to organic and inorganic substances.1 Microemulsion, as the media, is not only applied to the determination of many metal ions by different methods2-5 in our previous research, but also firstly in… 相似文献
44.
Sobia Mastoor Shaheen Faizi Rubeena Saleem Bina Shaheen Siddiqui 《Magnetic resonance in chemistry : MRC》2014,52(3):115-121
The 1H and 13C NMR spectral study of several biologically active derivatives of 8‐quinolinol have been made through extensive NMR studies including homodecoupling and 2D‐NMR experiments such as COSY‐45°, NOESY, and HeteroCOSY. Electron donating resonance and electron withdrawing inductive effect of several groups showed marked changes in chemical shifts of nuclei at the seventh positions of O‐substituted quinolinols (2–15). Although in N‐alkyl, 8‐alkoxyquinolinium halides (16–21), ring A rightly showed low frequency chemical shift values. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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Lehman JH Dempsey LP Lester MI Fu B Kamarchik E Bowman JM 《The Journal of chemical physics》2010,133(16):164307
We report joint experimental and theoretical studies of outcomes resulting from the nonreactive quenching of electronically excited OD?A (2)Σ(+) by H(2). The experiments utilize a pump-probe technique to detect the OD?X (2)Π product state distribution under single collision conditions. The OD?X (2)Π products are observed primarily in their lowest vibrational state (v(") = 0) with substantially less population in v(") = 1. The OD?X (2)Π products are generated with a high degree of rotational excitation, peaking at N(") = 21 with an average rotational energy of 4600 cm(-1), and a strong propensity for populating the Π(A(')) Λ-doublet component indicative of alignment of the half-filled pπ orbital in the plane of OD rotation. Branching fraction measurements show that the nonreactive channel accounts for less than 20% of quenching outcomes. Complementary classical trajectory calculations of the postquenching dynamics are initiated from representative points along seams of conical intersections between the ground and excited-state potentials of OD(A (2)Σ(+),X (2)Π) + H(2). Diabatic modeling of the initial momenta in the dynamical calculations captures the key experimental trends: OD?X (2)Π products released primarily in their ground vibrational state with extensive rotational excitation and a branching ratio that strongly favors reactive quenching. The OD?A (2)Σ(+) + H(2) results are also compared with previous studies on the quenching of OH?A (2)Σ(+) + H(2); the two experimental studies show remarkably similar rotational energy distributions for the OH and OD?X (2)Π radical products. 相似文献
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We address entanglement transfer from a three-mode bosonic system to a tripartite systems of spatially separated flying or fixed qubits through the interaction with their local environments. We focus on the robustness of entanglement transfer against several effects, including off-resonant interactions for both qubit-local environment and local environment-bosonic mode subsystems, and also exploring the effect of changing the coupling constants, with the possibility to have different values for each qubit-local environment interaction. For the entangled bosonic modes we consider both Gaussian states and qubit-like states, comparing three different Generalized Schmidt Decompositions forms widely used in the literature and analyzing how the deviation from qubit-like approximation influences entanglement transfer. Finally, we investigate the multimode coupling between bosonic modes and each local environment showing a comparison between various qubit-like initial states and discussing how to improve the efficiency of entanglement transfer. 相似文献
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We present the exact solution of the dynamics of N two-level atoms strongly driven by an external coherent field and equally coupled on resonance to a cavity mode, in the presence
of both cavity dissipation and atomic decay. Analytical results are presented for system and subsystem dynamics, showing how
environment-induced decoherence leads the system from pure to mixed states. In the limit of negligible atomic decay, where
the system is known to exhibit decoherence-free subspaces, we present a detailed discussion of the decoherence function that
can be monitored by atomic population measurements. 相似文献
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In the present study, the reaction of thiols with alkyl sulfonyl halides was carried out in a nitrogenous base to compare the reactivity of ‐SH with that of ‐OH, which, however, led to the formation of disulfides. The reaction achieved as a result offers the use of an inexpensive reagent, quantitative yields of the product, and simplicity for the formation of the S‐S bond. 相似文献
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N. Supriya Korah Bina Catherine R. Rajeev 《Journal of Thermal Analysis and Calorimetry》2013,112(1):201-208
The cure behavior of diglycidyl ether of bisphenol A with a simple ether amine (4,7,10, trioxa -1,13, tridecane diamine), system I and a polyether amine (polypropylene glycol block polyethylene glycol block polypropylene glycol bis 2 amino propyl ether), system II was compared by Differential Scanning Calorimetry. The exothermicity of the curing reaction of system I is higher than that of system II (316 ± 15 J g?1 for System I and 230 ± 15 J g?1 for system II). Kinetic parameters viz., activation energy, pre-exponential factor, and rate constant for curing were evaluated by Kissinger method and Kissinger–Akahira–Sunose isoconversion method. Both systems showed low glass transition temperatures and System II shows a much lower T g (?38 °C) than system I (26 °C). The thermogravimetric analysis of the two cured epoxy amine systems showed comparable thermal stability. 相似文献
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Novel unsymmetrical bissalicylaldimine bis-Schiff bases with a benzo-10-aza-15-crown-5 pendant and their cobalt complexes have been synthesized via condensation of 3 or 5-[(benzo-10-aza-15-crown-5)-10-ylmethyl] salicylaldehyde with the half unit Schiff bases and characterized by ^1H NMR, IR, mass spectroscopy, elemental analysis, molar conductances and molar magnetic susceptibility. 相似文献