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排序方式: 共有405条查询结果,搜索用时 17 毫秒
1.
2.
Analysis of dye degradation products and assessment of the dye purity in dye‐sensitized solar cells 下载免费PDF全文
3.
Ratios for target Ar K-shell ionization associated with single and double electron capture, as well as the ratios corresponding to total capture and the projectile K x rays, were determined for 1.8- to 2.2-MeV/u F7 + ,8 + ,9+ projectiles. This work was performed at Western Michigan University with the tandem Van de Graaff accelerator. Coincidences between emitted K-shell X-rays (both target and projectile) and the corresponding charge-changed particles were observed. The F9+ Ar K X-ray coincidence ratios for double to single capture are found to well exceed unity over the limited energy range of the measurements. Possible explanations for this anomalous behavior are discussed. 相似文献
4.
Umar Asghar Mehvish Iram Zile Huma Rubina Nelofer Muhammad Nadeem 《Natural product research》2015,29(2):125-131
This study was conducted to analyse structural changes through scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) after alkaline pretreatment of wheat straw for optimum steaming period. During the study, 2 mm size of substrate was soaked in 2.5% NaOH for 1 h at room temperature and then autoclaved at 121°C for various steaming time (30, 60, 90 and 120 min). Results revealed that residence time of 90 min at 121°C has strong effect on substrate, achieving a maximum cellulose content of 83%, delignification of 81% and hemicellulose content of 10.5%. Further SEM and FTIR spectroscopy confirmed structural modification caused by alkaline pretreatment in substrate. Maximum saccharification yield of 52.93% was achieved with 0.5% enzyme concentration using 2.5% substrate concentration for 8 h of incubation at 50°C. This result indicates that the above-mentioned pretreatment conditions create accessible areas for enzymatic hydrolysis. 相似文献
5.
The present paper deals with the study of semilinear and non-homogeneous Schrödinger equations on a manifold with conical singularity. We provide a suitable constant by Sobolev embedding constant and for p ∈ (2, 2?) with respect to non-homogeneous term g(x) ∈ L 2 n/2 (B), which helps to find multiple solutions of our problem. More precisely, we prove the existence of two solutions to the problem 1.1 with negative and positive energy in cone Sobolev space H 2,0 1,n/2 (B). Finally, we consider p = 2 and we prove the existence and uniqueness of Fuchsian-Poisson problem. 相似文献
6.
Amino alcohols typically react with aldehydes to produce oxazolidines. It was hypothesized that the condensation of several commercially available amino alcohols with dialdehydes would produce a series of bicyclic oxazolidines containing two secondary amines. However, there were remarkable differences in the type of products formed depending on the structure of the dicarbonyl compounds and the reaction conditions. When linear aliphatic dialdehydes such as glyoxal were used, the expected bis‐oxazolidines were not produced; instead, polycyclic structures or oxazines were formed. However, when cyclic dialdehydes such as 1,3/1,4 cyclohexane dicarboxaldehyde were used, they resulted in products bearing the desired oxazolidine moieties. 相似文献
7.
Majid Ramezani Ali Asghar Azarmehr Ali Mohammadzadeh 《Russian Journal of Applied Chemistry》2015,88(12):2021-2028
A sensitive, simple, and rapid method is developed for ion-pair-based surfactant-assisted dispersive liquid–liquid microextraction (IPSA-DLLME) and flame atomic absorption spectrometric determination of cadmium in water samples. In this procedure, trace amounts of Cd2+ were converted to CdI 4 2– , and after addition of a tetrabutylammonium bromide (TBAB) solution as cationic surfactant the analyte was transformed to the ion-pair state. This cadmium species was extracted by fast injection of a solution containing 200 μL of chloroform and 800 μL of methanol as extraction and disperser solvents, respectively. The pH of the sample solution, concentration of iodide, TBAB amount, and the extractant volume were optimized using a 27-run Box–Behnken design with a triplicate central point. Under the optimized conditions, the calibration curve was linear in the range 1–200 μg L–1 (R 2 = 0.9959); with the detection limit (signal/noise = 3) of 0.28 μg L–1. The relative standard deviations (RSD) for eight runs (Cd2+ = 10 μg L–1) and enrichment factor were found to be 3.04 % and 50, respectively. 相似文献
8.
This study investigates the rotating magnetohydrodynamic (MHD) flow of a third-grade fluid in a porous space. Modified Darcy's
law has been utilized for the flow modeling. The Hall effects are taken into consideration. The basic equations governing
the flow are reduced to a highly nonlinear ordinary differential equation. This equation has been solved analytically by employing
the homotopy analysis method (HAM). The effects of the various interesting parameters on the velocity distribution have been
discussed. 相似文献
9.
Arash Bahrami Asghar Nosier 《International Journal of Solids and Structures》2007,44(25-26):8119-8142
Within the elasticity formulation the most general displacement field for hygrothermal problems of long laminated composite plates is presented. The equivalent single-layer theories are then employed to determine the global deformation parameters appearing in the displacement fields of general cross-ply, symmetric, and antisymmetric angle-ply laminates under thermal and hygroscopic loadings. Reddy’s layerwise theory is subsequently used to determine the local deformation parameters of various displacement fields. An elasticity solution is also developed in order to validate the efficiency and accuracy of the layerwise theory in predicting the interlaminar normal and shear stress distributions. Finally, various numerical results are presented for edge-effect problems of several cross-ply, symmetric, and antisymmetric angle-ply laminates subjected to uniform hygrothermal loads. All results indicate high stress gradients of interlaminar normal and shear stresses near the edges of laminates. 相似文献
10.
On Solutions of Some Non-Linear Differential Equations Arising in Newtonian and Non-Newtonian Fluids
Mohyuddin M. R. Hayat T. Mahomed F. M. Asghar S. Siddiqui A. M. 《Nonlinear dynamics》2004,35(3):229-248
Some steady as well as unsteady solutions of the equations of motion for an incompressible Newtonian and non-Newtonian (second-grade)
fluids are obtained by applying different methods including the Lie symmetry group method. The flows considered are axially
symmetric with the swirling motion, and the governing equations for second-grade fluid flow have been modeled. Expressions
for streamlines, velocity and vorticity components are constructed explicitly in each case. Exact analytical solutions in
second-grade fluid are obtained and compared with the corresponding viscous solutions. 相似文献