全文获取类型
收费全文 | 277篇 |
免费 | 11篇 |
专业分类
化学 | 179篇 |
晶体学 | 5篇 |
力学 | 7篇 |
综合类 | 1篇 |
数学 | 13篇 |
物理学 | 83篇 |
出版年
2024年 | 1篇 |
2023年 | 5篇 |
2022年 | 31篇 |
2021年 | 31篇 |
2020年 | 13篇 |
2019年 | 4篇 |
2018年 | 12篇 |
2017年 | 12篇 |
2016年 | 19篇 |
2015年 | 6篇 |
2014年 | 12篇 |
2013年 | 22篇 |
2012年 | 28篇 |
2011年 | 13篇 |
2010年 | 13篇 |
2009年 | 4篇 |
2008年 | 9篇 |
2007年 | 3篇 |
2006年 | 4篇 |
2005年 | 6篇 |
2004年 | 1篇 |
2003年 | 1篇 |
2002年 | 1篇 |
1999年 | 1篇 |
1998年 | 2篇 |
1997年 | 3篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 4篇 |
1992年 | 2篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 4篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
排序方式: 共有288条查询结果,搜索用时 15 毫秒
31.
32.
W.T. Sulaiman 《Applied Mathematics Letters》2010,23(4):361-365
New kinds of Hardy–Hilbert’s integral inequalities are presented. 相似文献
33.
W.T. Sulaiman 《Journal of Mathematical Analysis and Applications》2006,322(2):1224-1230
Extension and improvement has been made on a recent result proved by Mazhar [S.M. Mazhar, Absolute summability factors of infinite series, Kyungpook Math. J. 39 (1999) 67-73] concerning absolute summability factors of infinite series. 相似文献
34.
Ahmed M. Abd-Eldayem Sulaiman Mohammed Alnasser Hanan H. Abd-Elhafeez Soha A. Soliman Rania A. Abdel-Emam 《Molecules (Basel, Switzerland)》2022,27(17)
The main bioactive constituents in the standardized Ginkgo biloba leaf extract (EGb 761) are the terpene lactones and flavonoid glycosides. EGb 761’s antioxidant and anti-inflammatory properties have previously been demonstrated. Indomethacin-induced gastric ulcers have a multifactorial etiology and represent a major restriction to its therapeutic utility. The underlying ulcerogenic process involves oxidative and inflammatory biomolecular insults. This study was performed to explore the curative and preventative benefits of EGb 761 in experimentally-induced ulcers. To develop gastric ulcers in mice, indomethacin (40 mg/kg) was administered orally. EGb 761 (200 mg/kg) was given by gavage for 7 days before (preventative) and after (therapeutic) indomethacin administration. The histological alterations and macroscopic mucosal lesions were assessed. In gastric tissue homogenates, malondialdehyde (MDA), reduced glutathione (GSH), nitric oxide (NO), and inflammatory cytokines were measured. The expressions of cyclooxygenase-2 (COX-2), cytokines, and proliferating cell nuclear antigen (PCNA) in the stomach mucosa were also investigated. The ulcer index, histological alterations, gastric oxidants, and inflammatory biomarkers were all significantly increased by indomethacin. In stomach specimens, it increased COX-2 and PCNA expression. EGb 761 treatments, both prophylactic and therapeutic, resulted in significant reductions in ulcer lesions, nitrosative and oxidative damage, and inflammatory markers, along with the lowering of COX-2 and PCNA expressions. Furthermore, in the fight against stomach ulcers, EGb 761 treatment was found to be more efficient than prevention. 相似文献
35.
Aik Sian Tan Jaymeer Singh Nurul Syafiqah Rezali Musthahimah Muhamad Nik Nur Syazni Nik Mohamed Kamal Yvan Six Mohamad Nurul Azmi 《Molecules (Basel, Switzerland)》2022,27(17)
The Heck cross-coupling reaction is a well-established chemical tool for the synthesis of unsaturated compounds by formation of a new C-C bond. In this study, 1,3-diarylpropene derivatives, designed as structural analogues of stilbenoids and dihydrostilbenoids, were synthesised by the palladium-catalysed reactions of 2-amidoiodobenzene derivatives with either estragole or eugenol. The products were obtained with high (E) stereoselectivity but as two regioisomers. The ratios of isomers were found to be dependent on the nature of the allylbenzene partner and were rationalised by electronic effects exercising a determining influence in the β-hydride elimination step. In addition, the cytotoxic effects of all the Heck reaction products were evaluated against MCF-7 and MDA-MB-231 human breast cancer cells, with unpromising results. Among all, compound 7d exhibited weak cytotoxic activity towards MCF-7 cell lines with IC50 values of 47.92 µM in comparison with tamoxifen and was considered to have general toxicity (SI value < 2). 相似文献
36.
Farook Ahmad Ahmad Pauzi Mohd Yusof Martina Bainbridge Sulaiman Ab Ghani 《Electroanalysis》2007,19(5):541-548
Hydrogen peroxide (H2O2) was the main types of many peroxides produced in living mammalian cells that consumed oxygen. In the brain, the main source of H2O2 was the superoxide dismutase (SOD)‐catalyzed reaction in mitochondria. However, the level of H2O2 would be elevated through administration of control drugs and alcohol by dopamine metabolism of monoamine oxidase. In this study, a H2O2 microsensor was used to investigate the level of H2O2 in the brain striatum after administration of methamphetamine (MAP), morphine (MrP) or ethanol (Eth). The placement of microsensor in the brain was done at coordinates A/P 1.1 from bregma, M/L+2.6 and D/V‐1.5. A working potential of +0.05 V vs. Ag/AgCl was applied. The H2O2 concentration was measured direct from the current generated by its catalytic reaction at the electro active surface of the electrode. A significant increase of H2O2 level was observed after 7 successive injections of the controlled drugs or alcohol. The initial measurement of H2O2 is essential as excess dosage of H2O2 during treatment will contribute to the formation of neurotoxin oxygenated radicals. The H2O2 was the precursor of O2? and OH radicals. Thus, this study provided a mean to monitor H2O2 level in the brain. 相似文献
37.
Spermidine, 1,3-diaminopropane, and p-phenylenediamine form molecular complexes with chloranil at pH 9. The composition and stability of these complexes have been studied spectrophotometrically. The results indicate that complexes were of 1:1 type and their stability increases with the basicities. The method of complexation was used to determine spectrophotometrically a ppm amount of SD, DAP, and PhDA in solution. The accuracy and precision of the method were found to be very high. 相似文献
38.
Szekeres obtained some exact solutions of Einstein's equations for dust which have applications in cosmology, in the theory of collapse, and in the study of gravitational radiation. It is shown that in their most general form these space-times have no Killing vectors.Dedicated to Achille Papapetrou on the occasion of his retirement.On leave from the Department of Mathematics, University of Malaya, Kuala Lumpur, Malaysia.Supported by the Public Services Department, Government of Malaysia.On leave from Centro Brasileiro de Pesquisas Fisicas. 相似文献
39.
Conductivity studies of plasticized anhydrous PEO-KOH alkaline solid polymer electrolyte 总被引:1,自引:0,他引:1
Polyethylene oxide (PEO)–potassium hydroxide (KOH)-based alkaline solid polymer electrolyte films have been prepared by using
methanol as solvent. The highest room temperature ionic conductivity of (2.1 ± 0.5) × 10−8 S cm−1 was achieved for the composition of 70 wt% PEO:30 wt% KOH. The addition of plasticizer, ethylene carbonate, propylene carbonate,
or polyethylene glycol to the highest conductivity of PEO–KOH system helps to increase the ambient ionic conductivity to the
order of 10−6–10−4 S cm−1. The log σ vs 1/T plot of PEO–KOH showed a small conductivity decrease at 50–60 °C range. The small decrease and the hysteresis that occur
during the heating–cooling cycle was overcome by the presence of the plasticizer. X-ray diffraction observation supports the
conductivity results. 相似文献
40.
Muhammad Fawad Khan Muhammad Sulaiman Carlos Andrs Tavera Romero Ali Alkhathlan 《Entropy (Basel, Switzerland)》2021,23(11)
In this work, an important model in fluid dynamics is analyzed by a new hybrid neurocomputing algorithm. We have considered the Falkner–Skan (FS) with the stream-wise pressure gradient transfer of mass over a dynamic wall. To analyze the boundary flow of the FS model, we have utilized the global search characteristic of a recently developed heuristic, the Sine Cosine Algorithm (SCA), and the local search characteristic of Sequential Quadratic Programming (SQP). Artificial neural network (ANN) architecture is utilized to construct a series solution of the mathematical model. We have called our technique the ANN-SCA-SQP algorithm. The dynamic of the FS system is observed by varying stream-wise pressure gradient mass transfer and dynamic wall. To validate the effectiveness of ANN-SCA-SQP algorithm, our solutions are compared with state-of-the-art reference solutions. We have repeated a hundred experiments to establish the robustness of our approach. Our experimental outcome validates the superiority of the ANN-SCA-SQP algorithm. 相似文献