全文获取类型
收费全文 | 88篇 |
免费 | 0篇 |
专业分类
化学 | 80篇 |
物理学 | 8篇 |
出版年
2022年 | 5篇 |
2021年 | 13篇 |
2020年 | 11篇 |
2019年 | 6篇 |
2018年 | 1篇 |
2017年 | 2篇 |
2016年 | 2篇 |
2015年 | 2篇 |
2013年 | 6篇 |
2012年 | 2篇 |
2011年 | 3篇 |
2009年 | 2篇 |
2008年 | 2篇 |
2007年 | 5篇 |
2006年 | 2篇 |
2005年 | 3篇 |
2003年 | 4篇 |
2002年 | 1篇 |
2000年 | 1篇 |
1998年 | 3篇 |
1997年 | 1篇 |
1995年 | 1篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1984年 | 1篇 |
1976年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有88条查询结果,搜索用时 31 毫秒
51.
This review describes the chemistry of 2,3-dihydroxynaphthalene and the related analogues. The synthetic routes reported to obtain the investigated structures are discussed. In addition, the reactivity and the synthesis of fused heterocyclic systems containing one or two heteroatoms are discussed. The compounds derived from 2,3-dihydroxynaphthalene are located in the basic skeleton of several natural drugs. The products were applied in the fields of polymer chemistry, physical chemistry, and medicinal chemistry. The different sections cover: methods of preparation, reactions, heterocyclic systems, macrocycles, organosilicon derivatives, coordination chemistry, and biological importance. The assessment relates to the recent reports and contains a short, targeted survey of the title compound for the past 15 years. 相似文献
52.
Fouda A. S. Abdel-Latif E. Helal H. M. El-Hossiany A. 《Russian Journal of Electrochemistry》2021,57(2):159-171
Russian Journal of Electrochemistry - The influence of corrosion inhibition of some thiazole derivatives, namely: 2-(3,5-dimethyl-4-(p-tolyldiazenyl)-1H-pyrazole-1-yl)thiazol-5(4H)-one,... 相似文献
53.
IR, NMR, TG, DTA, DTG and molar conductance studies have been carried out on complexes of La(III) with some hydroxy nitrosocoumarins and those of trivalent Y, Ce, Pr, Nd, Sm, Gd, Dy, Er, Yb; tetravalent Th and hexavalent uranium complexes with 7-hydroxy-4-methyl-8-nitrosocoumarins. The solid complexes were prepared, separated, analysed and their structures elucidated by elemental analysis, IR, NMR, TG, DTA, DTG and molar conductance. 相似文献
54.
Liposomal FRET Assay Identifies Potent Drug-Like Inhibitors of the Ceramide Transport Protein (CERT)
Doaa Samaha Dr. Housam H. Hamdo Dr. Xiaojing Cong Dr. Fabian Schumacher Dr. Sebastian Banhart Öznur Aglar Prof. Dr. Heiko M. Möller Dr. Dagmar Heuer Prof. Dr. Burkhard Kleuser Dr. Essa M. Saied Prof. Dr. Christoph Arenz 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(70):16616-16621
Ceramide transfer protein (CERT) mediates non-vesicular transfer of ceramide from endoplasmic reticulum to Golgi apparatus and thus catalyzes the rate-limiting step of sphingomyelin biosynthesis. Usually, CERT ligands are evaluated in tedious binding assays or non-homogenous transfer assays using radiolabeled ceramides. Herein, a facile and sensitive assay for CERT, based on Förster resonance energy transfer (FRET), is presented. To this end, we mixed donor and acceptor vesicles, each containing a different fluorescent ceramide species. By CERT-mediated transfer of fluorescent ceramide, a FRET system was established, which allows readout in 96-well plate format, despite the high hydrophobicity of the components. Screening of a 2 000 compound library resulted in two new potent CERT inhibitors. One is approved for use in humans and one is approved for use in animals. Evaluation of cellular activity by quantitative mass spectrometry and confocal microscopy showed inhibition of ceramide trafficking and sphingomyelin biosynthesis. 相似文献
55.
AbstractThe reaction of benzohydrazonamides with cyclic 1,3-diketones affords β-enaminones in good to excellent yields (14 examples, 69???89%). This transformation proceeds under mild reaction conditions (ethyl acetate, 25?°C, 12???24?h) in the absence of any catalyst and gives access to novel nitrogen-rich organic scaffolds. 相似文献
56.
The theory of nuclear fission process is considered. The effective mass parameters are calculated as a function of the following collective coordinates: the separation between the centres of harmonic oscillators, the mass asymmetry parameter and the necking parameter. Numerical calculations are carried out for the fission of236U and238U nuclei. Symmetric and asymmetric cases are considered. From the present calculation we see the importance of taking into account the necking parameter as a dynamical collective coordinate. 相似文献
57.
The theory of nuclear fission is reconsidered by introducing the charge asymmetry in the asymmetric two center shell model as a dynamical collective coordinate. The quantum mechanical fluctuations, which are accompanied with the collective motion as a function of the mass asymmetry, are responsible for the mass distributions in nuclear fission. Numerical calculations are carried out for the mass distributions and charge dispersions for the nuclear fission of the 236U and 238U nuclei. The present obtained theoretical calculations are in good agreement with the experimental measurements. 相似文献
58.
Badriah Saad Al-Farhan Maram T. Basha Laila H. Abdel Rahman Ahmed M. M. El-Saghier Doaa Abou El-Ezz Adel A. Marzouk Mohamed R. Shehata Ehab M. Abdalla 《Molecules (Basel, Switzerland)》2021,26(16)
Despite the common use of salens and hydroxyquinolines as therapeutic and bioactive agents, their metal complexes are still under development. Here, we report the synthesis of novel mixed-ligand metal complexes (MSQ) comprising salen (S), derived from (2,2′-{1,2-ethanediylbis[nitrilo(E) methylylidene]}diphenol, and 8-hydroxyquinoline (Q) with Co(II), Ni(II), Cd(II), Al(III), and La(III). The structures and properties of these MSQ metal complexes were investigated using molar conductivity, melting point, FTIR, 1H NMR, 13C NMR, UV–VIS, mass spectra, and thermal analysis. Quantum calculation, analytical, and experimental measurements seem to suggest the proposed structure of the compounds and its uncommon monobasic tridentate binding mode of salen via phenolic oxygen, azomethine group, and the NH group. The general molecular formula of MSQ metal complexes is [M(S)(Q)(H2O)] for M (II) = Co, Ni, and Cd or [M(S)(Q)(Cl)] and [M(S)(Q)(H2O)]Cl for M(III) = La and Al, respectively. Importantly, all prepared metal complexes were evaluated for their antimicrobial and anticancer activities. The metal complexes exhibited high cytotoxic potency against human breast cancer (MDA-MB231) and liver cancer (Hep-G2) cell lines. Among all MSQ metal complexes, CoSQ and LaSQ produced IC50 values (1.49 and 1.95 µM, respectively) that were comparable to that of cisplatin (1.55 µM) against Hep-G2 cells, whereas CdSQ and LaSQ had best potency against MDA-MB231 with IC50 values of 1.95 and 1.43 µM, respectively. Furthermore, the metal complexes exhibited significant antimicrobial activities against a wide spectrum of both Gram-positive and -negative bacterial and fungal strains. The antibacterial and antifungal efficacies for the MSQ metal complexes, the free S and Q ligands, and the standard drugs gentamycin and ketoconazole decreased in the order AlSQ > LaSQ > CdSQ > gentamycin > NiSQ > CoSQ > Q > S for antibacterial activity, and for antifungal activity followed the trend of LaSQ > AlSQ > CdSQ > ketoconazole > NiSQ > CoSQ > Q > S. Molecular docking studies were performed to investigate the binding of the synthesized compounds with breast cancer oxidoreductase (PDB ID: 3HB5). According to the data obtained, the most probable coordination geometry is octahedral for all the metal complexes. The molecular and electronic structures of the metal complexes were optimized theoretically, and their quantum chemical parameters were calculated. PXRD results for the Cd(II) and La(III) metal complexes indicated that they were crystalline in nature. 相似文献
59.
Mohamed Monier Doaa Abdel‐Latif Ahmed El‐Mekabaty Khaled M. Elattar 《Journal of heterocyclic chemistry》2019,56(12):3172-3196
The present study demonstrates a synopsis of the scientific researches reported on the different reactions of oxazolo[3,2‐a]pyridines, besides the preparation of significant fused heterocycles up till now. The different main sections that described the reactivity of the inspected analogues include stereoselective alkylation, reactions involved oxazolidine ring, synthesis of polycyclic systems, indole alkaloids, and alkyl amines. The stereochemical selectivity of oxazolopiperidone lactams is studied, in which the configuration of the stereocenter C8a and substituents at the C8 and C8a effect on the stereoselectivity. On the other hand, the synthetic consequence of the alkylation products provides diverse routes for the synthesis of substituted enantiopure piperidines that are used for the synthesis of natural products, for example, (?)‐rhazinilam, (+)‐eburnamonine, (+)‐aspidospermidine, indole alkaloids such as dihydrocleavamine, nor‐20‐epiuleine, (+)‐dasycarpidone, (+)‐uleine, indoloquinolizidine, (+)‐dihydrocorynantheine, (?)‐dihydrocorynantheol, and indolizines, eg, octahydroindolizines, monomorine I, (?)‐S‐coniceine, and (?)‐R‐coniceine. 相似文献
60.
Mahmoud-Ghoneim D Toussaint G Constans JM de Certaines JD 《Magnetic resonance imaging》2003,21(9):983-987
The discrimination of tumor boundaries from normal tissue, as well as the evaluation of tissue heterogeneity and tumor grading often continue to pose a challenge in MRI. Although yielding promising results in various fields of medical imaging, two- dimensional (2D) texture analysis in MRI has, until now, demonstrated a lack of specificity in brain tumor classification. A new three-dimensional (3D) approach using Cooccurrence Matrix analysis is proposed to increase the sensitivity and specificity of brain tumor characterization. A preliminary comparative evaluation of 2D and 3D texture analysis was performed on T(1)-weighted MRI of seven gliomas for characterization of solid tumor, necrosis, edema and surrounding white matter. With 3D compared to 2D method, a better discrimination is obtained between necrosis and solid tumor as well as between edema and solid tumor. Using both methods, peritumoral white matter overlaps with edema, but is completely separated from far homo-lateral matter. This latter shows a complete overlapping with contra-lateral matter. The 3D texture analysis approach could provide a new tool for tumor grading and treatment follow-up, as well as for surgery or radiation therapy planning. 相似文献