首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   17篇
  免费   0篇
化学   9篇
数学   4篇
物理学   4篇
  2023年   1篇
  2018年   1篇
  2017年   1篇
  2014年   2篇
  2013年   4篇
  2012年   1篇
  2008年   1篇
  2007年   2篇
  2006年   1篇
  1987年   1篇
  1979年   1篇
  1978年   1篇
排序方式: 共有17条查询结果,搜索用时 25 毫秒
1.
The heavy liquid bubble chamber, Gargamelle, has been used to investigate the gross features of the annihilation of antineutrons in light nuclei (mainly Carbon). Results are presented on the distributions of multiplicity, momentum and emission angle for charged pions and protons together with a simple model to describe them.  相似文献   
2.
In this research, two new series of N-arylsulfonyl hydrazone compounds ( 14 – 25 ) possessing a sulfonate moiety were synthesized and characterized by elemental analysis and various spectroscopic techniques including fourier transform infrared (FT-IR), 1H-, and 13C nuclear magnetic resonance (NMR). These compounds synthesized as target molecules ( 14 – 25 ) were tested for their in vitro acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibition activities and antioxidant potential. The antioxidant capacities of the tested molecules were determined by four different assays. The IC50 values of the screened molecules were determined in the range of 60.14 ± 0.25–84.81 ± 1.09 μM against AChE and in the range of 70.11 ± 0.67–93.60 ± 0.47 μM against BChE. In the AChE assay, 4-hydroxybenzaldehyde-based compound 25 (60.14 ± 0.25 μM) showed the highest activity in comparison to rivastigmine (501 ± 3.08 μM). This compound (71.42 ± 0.19 μM) is also one of the compounds with the highest activity against BChE. In the BChE assay, 2-hydroxybenzaldehyde-based compound 19 (70.11 ± 0.67 μM) indicated the highest activity in comparison to rivastigmine (19.95 ± 0.20 μM). In antioxidant activity studies, the tested molecules showed lower activities than the standard compounds (butylated hydroxytoluene and α-tocopherol). Consequently, some novel compounds can be used as potential inhibitor candidates in future studies.  相似文献   
3.
Acoustic predictions of the recently developed traceo ray model, which accounts for bottom shear properties, are benchmarked against tank experimental data from the EPEE-1 and EPEE-2 (Elastic Parabolic Equation Experiment) experiments. Both experiments are representative of signal propagation in a Pekeris-like shallow-water waveguide over a non-flat isotropic elastic bottom, where significant interaction of the signal with the bottom can be expected. The benchmarks show, in particular, that the ray model can be as accurate as a parabolic approximation model benchmarked in similar conditions. The results of benchmarking are important, on one side, as a preliminary experimental validation of the model and, on the other side, demonstrates the reliability of the ray approach for seismo-acoustic applications.  相似文献   
4.
We present a microscopic evaluation of nuclear momentum distributions for the ground states of 4He and 16O. The momentum distribution is the sum of a single particle part and a correlation part. Beyond a momentum of 2 fm?1 the correlation part becomes dominating and exceeds the single particle part by arbitrary orders of magnitude for sufficiently high momenta. Even a quite crude experimental determination of momentum distributions would yield extremely useful information on nuclear correlations.  相似文献   
5.
Schiff base ligands HL1–HL6 have been prepared from the reaction of 2,6-diformyl-4-t-butylphenol and 2,6-di-formyl-4-methylphenol with various aromatic amines in ethanolic solution. The Schiff base ligands 2,2′-dipyridine (dp) mixed-ligand CuII complexes have been obtained. Mixed-ligand CuII complexes containing the dp ligand have ionic nature and they conduct the electricity in solution media. The complexes have been obtained in two different forms: one of them is [Cu2(Ln)Cl3] (n: 1, 2, 3, 4, 5 and 6) and other complexes have the general formula [Cu2(Ln)(dp)2]3Cl. Ligands and their complexes have been characterized by elemental analyses, FT-IR, electronic spectra, molar conductance, 1H(13C)-n.m.r. and mass spectral data. Their stoichiometric protonation constants have been determined potentiometrically in dioxan using a combined pH electrode at 25 °C, under a nitrogen atmosphere. For the calculation of the protonation constants, PKAS computer programme has been used. The effects of the substituents on the protonation constants and the additivities of these effects are discussed. The antimicrobial activity studies of the ligands and their complexes have been studied against the Bacillus megaterium, Micrococcus luteus, Corynebavterium xenosis, Enterococcuc faecalis, bacteria and Saccoramyces cerevisia, yeast. The catalytic properties of the complexes have been studied on the ascorbic acid, catechol and 2,6-di-t-butylphenol substrates. Thermal behaviour of the complexes has been studied by thermal techniques.  相似文献   
6.
We investigate a class of second-order linear difference equations by applying results of harmonic analysis on polynomial hypergroups. For the scalar case we show that the solutions are either bounded by the modulus of the initial value or are unbounded. For the Hilbert space-valued case we establish a concrete representation of the solutions whenever they are bounded and stationary. Among various examples we discuss those corresponding to Jacobi polynomials.  相似文献   
7.
In this study, we have proposed a novel organophosphate mimic surface molecular imprinted polymer for selective binding of the nerve agent by chitosan–Cd(II) as a new metal-chelating monomer via metal coordination–chelation interactions and dimethoate templates. We have improved a method for the selective binding behavior of dimethoate compounds on the surface of molecular imprinted polymer, which was prepared using ligand-exchange (chitosan–Cd(II)) monomers. The influence of ligand exchange imprinting on the creation of recognition sites toward dimethoate has determined application of adsorption isotherms. The effect of initial concentration of dimethoate, adsorption time, and imprinting efficiency on the adsorption selectivity for molecular imprinted polymer-ligand exchange has been investigated. The number of accessible sites (Qmax), relative selectivity coefficients (k′), and binding abilities have also been evaluated. Then, molecular imprinted polymer-ligand exchange was treated with formaldehyde to remove dimethoate templates.  相似文献   
8.
In this study, Schiff bases containing azomethine (–HC=N–) compounds were synthesized from the condensation reaction of 4-aminophenol and 2-aminophenol and 5-methyl-2-furaldehyde. Orange-colored Schiff bases, 4-[(5-methyl- 2-furyl) methyleneamino] phenol (4MFMAP) and 2-[(5-methyl-2-furyl) methyleneamino] phenol (2MFMAP) turned to poly-4-[(5-methyl-2-furyl) methyleneamino] phenol (P-4MFMAP) and poly-2-[(5-methyl-2-furyl) methyleneamino] phenol (P-2MFMAP) polyazomethine derivatives by NaOCl oxidant in alkaline aqueous medium. In addition, poly-2-[(5-methyl-2-furyl) methyleneamino] phenol cobalt (II) and copper (II) complexes were synthesized. FTIR and NMR measurements for structural analysis of the synthesized compounds, UV–Vis analysis for optical properties, electrical conductivity measurements, and thermal analysis with the TG–DTA techniques were determined. The yield of P-4MFMAP and P-2MFMAP was found to be 84.6% and 78.6 as follows [4MFMAP] = 0.066, [KOH] = 0.198 [NaOCl] = 0.066 mol L?1 at 60 °C for 3 h and [2MFMAP] = 0.066, [KOH] = 0.132 [NaOCl] = 0.066 mol L?1 at 70 °C for 3 h, respectively.  相似文献   
9.
Abstract

The molecule (?)-(S)-1-[2-(benzenesulfonamido)-3-phenylpropanoyl]-4-[(4-methyl)phenyl] thiosemicarbazide was synthesized and its structure analyzed by X-ray diffraction to understand its geometry, and inter/intra-molecular interactions. Theoretical calculations were carried out using DFT and TD-DFT methods with B3LYP/6-31G(d, p) and B3LYP/6-31G?+?(d, p) basis sets. Theoretical bond parameters, harmonic vibration frequencies, and chemical shifts are in good agreement with the experimental results. Electronic properties of the molecule derived from frontier orbitals, molecular electrostatic potential, and theoretical UV-Visible spectrum are validated experimentally.  相似文献   
10.
We apply method of separation of the variables to q-analogs of several equations of mathematical physics. Dedicated to Dick Askey on his 70th birthday. 2000 Mathematics Subject Classification Primary—33D45, 42C10; Secondary—33D15.  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