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排序方式: 共有818条查询结果,搜索用时 31 毫秒
51.
S. H. Al-Harthi M. Al-Barwani M. Elzain Ashraf T. Al-Hinai N. Al-Naamani Issa Al-Amri T. Hysen 《Applied Physics A: Materials Science & Processing》2011,105(2):469-477
When a colloidal suspension is allowed to wet a suitable substrate, various patterns emerge that can be varied from isolated
island-like structures to fractal patterns. In this work we investigate the patterns arising from the interplay of colloidal
copper sulfate suspensions containing carbon nanotubes with few-layer graphene substrates. The compositions of the thin film
samples were investigated using X-ray photoelectron spectroscopy, surface topography and the nanostructure of the thin films
were probed with atomic force microscope and transmission electron microscope respectively. The colloidal suspensions were
characterized using contact angle and viscosity measurements. The colloidal suspensions when dip coated on few-layer graphene
substrates exhibited fractal like morphology with the aggregation of copper sulfate crystallites to hexagonal platelets. This
aggregation is explained invoking the depletion attraction theory. The various patterns observed experimentally were reproduced
using a Monte Carlo simulation. 相似文献
52.
53.
Carbon ionic liquid electrode (CILE) has been modified with a new synthesized mediator i.e. N,N′‐dimethyl‐4,4′‐azopyridinium hexafluorophosphate (MAZPHP) via sol process and the electron transfer mediating characteristics of this mediator has been evaluated. 4,4′‐Azopyridine (AZP) did not show any electrocatalytic activity toward the selected probe, NADH, while its synthesized methylated derivative, MAZPHP, is a very efficient mediator for the electrocatalytic NADH oxidation. Cyclic voltammetry of MAZPHP/Sol/CILE exhibited a pair of reversible peaks corresponding to incorporated mediator with a formal potential of about 221 mV vs. Ag/AgCl. MAZPHP/Sol/CILE is free from fouling effects by the oxidation products of NADH which generally give hindrance to amperometric detection of NADH. Using amperometric technique, NADH can be determined in the range of 1.0×10?5 M to 1.4×10?3 M with a detection limit of 2.0×10?6 M. 相似文献
54.
Ya‐Ching Shen Yu‐Hui Chen Tsong‐Long Hwang Jih‐Hwa Guh Ashraf Taha Khalil 《Helvetica chimica acta》2007,90(7):1391-1398
Chemical investigation of the gorgonian coral Junceella fragilis, collected by scuba diving in Taiwan, resulted in the isolation of four new briarane‐type diterpenoids, frajunolides A–D ( 1 – 4 ), along with three known briaranes. Their structures were elucidated on the basis of spectroscopic studies, especially 1‐ and 2D‐NMR as well as HR‐MS experiments. The inhibitory effect of all isolated metabolites towards superoxide‐anion generation and elastase release by human neutrophils in response to formylmethionyl‐leucyl‐phenylalanine/dihydrocytochalasin B (FMLP/CB) was evaluated. 相似文献
55.
Ayed Salman Andries P. Engelbrecht Mahamed G.H. Omran 《European Journal of Operational Research》2007
Differential evolution (DE) is generally considered as a reliable, accurate, robust and fast optimization technique. DE has been successfully applied to solve a wide range of numerical optimization problems. However, the user is required to set the values of the control parameters of DE for each problem. Such parameter tuning is a time consuming task. In this paper, a self-adaptive DE (SDE) algorithm which eliminates the need for manual tuning of control parameters is empirically analyzed. The performance of SDE is investigated and compared with other well-known approaches. The experiments conducted show that SDE generally outperform other DE algorithms in all the benchmark functions. Moreover, the performance of SDE using the ring neighborhood topology is investigated. 相似文献
56.
Alan R. Morgan Dimitris Skalkos George Maguire Ashraf Rampersaud Greta Garbo Rick Keck Steven H. Selman 《Photochemistry and photobiology》1992,55(1):133-136
An improved synthesis of benzochlorins is reported. Demetallation of the meso-hydroxymethylvinyl derivative of octaethylporphyrin, followed by treatment with sulfuric acid results in cyclization to generate the corresponding octaethylbenzochlorin in high yield. Prolonged treatment with acid generates the sulfonated derivative. These sensitizers were shown to be efficient photodynamic agents in vivo. Animals bearing a transplanted N-[4-(5-nitro-2-furyl)-2-thiazoly]formamide induced urothelial tumor were treated with either the benzochlorin or its sulfonated derivative. Irradiation of tumors 24 h later resulted in a significant tumoricidal effect in a short term assay. We conclude that benzochlorins warrant further examination as potential agents for use in photodynamic therapy. 相似文献
57.
Ya‐Ching Shen Yuan‐Bin Cheng Yu‐Hui Chen Ashraf Taha Khalil Chin‐Lien Ko 《中国化学会会志》2005,52(6):1263-1268
Three new clerodane diterpene derivatives were isolated from the leaves of Casearia membranacea Hance collected in Taiwan. The isolated metabolites were identified as caseamembrins P (1), Q (2), and R (3). Identification of the structures was based on detailed analysis of the spectral data, especially 2D NMR. 相似文献
58.
59.
Nadia Morcos Manar Omran Hala Ghanem Mahmoud Elahdal Nashwa Kamel Elbatoul Attia 《Photochemistry and photobiology》2015,91(4):942-951
One inescapable feature of life on the earth is exposure to ionizing radiation. The thyroid gland is one of the most sensitive organs to gamma‐radiation and endocrine disrupters. Low‐level laser therapy (LLLT) has been used to stimulate tissue repair, and reduce inflammation. The aim of this study was to gauge the value of using Helium–Neon laser to repair the damaged tissues of thyroid gland after gamma‐irradiation. Albino rats were used in this study (144 rats), divided into control, gamma, laser, and gamma plus laser‐irradiated groups, each group was divided into six subgroups according to time of treatment (total six sessions). Rats were irradiated once with gamma radiation (6 Gy), and an external dose of laser (Wavelength 632.8 nm, 12 mW, CW, Illuminated area 5.73 cm2, 2.1 mW cm?2, 120 s, 1.4 J, 0.252 J cm?2) twice weekly localized on thyroid region of the neck, for a total of six sessions. Animals were sacrificed after each session. Analysis included thyroid function, oxidative stress markers, liver function and blood picture. Results revealed improvement in thyroid function, liver function and antioxidant levels, and the blood cells count after LLLT. 相似文献
60.
1,4‐Dioxo‐1,4‐dihydronaphthalene‐2,3‐dicarbonitrile and 1,1,2,2‐Tetracyanoethene in Heterocyclization 下载免费PDF全文
Ashraf A. Aly 《Journal of heterocyclic chemistry》2015,52(4):974-989
This survey is mainly concerned with selected reactions of 1,4‐dioxo‐1,4‐dihydronaphthalene‐2,3‐dicarbonitrile and 1,1,2,2‐tetracyanoethene, which have use or potential use in heterocyclic synthesis. 相似文献