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21.
and
provided a variety of
and
alkaloids as well as novel ring-opened indole alkaloids including leuconolam (6), rhazinilam (8) and 5,21-dihydrorhazinilam (9). Facile acid and base reactions of leuconolam lead to ring reclosure products. Physical and spectral data of norfluorocurarine (
), norfluorocurarine-Nb-oxide (
), eburnamine (2), kopsinine (5) and epileuconolam (7) as well as some derivatives of leuconolam are also provided. 相似文献
22.
23.
R. A. Brown Razak Abd. Samad Bin Yahya 《Journal of Polymer Science.Polymer Physics》1985,23(3):451-459
Measurements of thermal diffusivities of peroxide-cured and sulfur-cured rubbers, over the range 0–100°C and 0–75 phr of carbon, are described. They are based on the asymptotic time dependences of heating and cooling curves, recorded following quenching of the samples into baths at various temperatures. The diffusivities are shown to depend linearly on both temperature and carbon content, to reasonable accuracies over the ranges studied. Some theory bearing on measurement techniques is presented. 相似文献
24.
I. M. Gella Razak Yaya Amadu G. V. Cherkaev S. V. Fialkova V. D. Orlov 《Chemistry of Heterocyclic Compounds》1997,33(12):1425-1429
In the interaction of N-thiocarbamoylhexahydroindazoles with -bromoacetophenones, the corresponding N-thiazolylpyrazolines are formed. In some cases, the heterocyclization is accompanied by a shift of the double bond and cis-trans isomerization in the pyrazoline ring. A study has been made of the influence of the stereochemistry of these compounds on their spectral and luminescence properties.Khar'kov State University, Khar'kov 310077. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1650–1654, December, 1997. 相似文献
25.
Muhammad Umar Aslam Khan Iqra Iqbal Mohamed Nainar Mohamed Ansari Saiful Izwan Abd Razak Mohsin Ali Raza Amna Sajjad Faiza Jabeen Mohd Riduan Mohamad Norhana Jusoh 《Molecules (Basel, Switzerland)》2021,26(19)
The present research is based on the fabrication preparation of CS/PVA/GG blended hydrogel with nontoxic tetra orthosilicate (TEOS) for sustained paracetamol release. Different TEOS percentages were used because of their nontoxic behavior to study newly designed hydrogels’ crosslinking and physicochemical properties. These hydrogels were characterized using Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and wetting to determine the functional, surface morphology, hydrophilic, or hydrophobic properties. The swelling analysis in different media, degradation in PBS, and drug release kinetics were conducted to observe their response against corresponding media. The FTIR analysis confirmed the components added and crosslinking between them, and surface morphology confirmed different surface and wetting behavior due to different crosslinking. In various solvents, including water, buffer, and electrolyte solutions, the swelling behaviour of hydrogel was investigated and observed that TEOS amount caused less hydrogel swelling. In acidic pH, hydrogels swell the most, while they swell the least at pH 7 or higher. These hydrogels are pH-sensitive and appropriate for controlled drug release. These hydrogels demonstrated that, as the ionic concentration was increased, swelling decreased due to decreased osmotic pressure in various electrolyte solutions. The antimicrobial analysis revealed that these hydrogels are highly antibacterial against Gram-positive (Staphylococcus aureus and Bacillus cereus) and Gram negative (Pseudomonas aeruginosa and Escherichia coli) bacterial strains. The drug release mechanism was 98% in phosphate buffer saline (PBS) media at pH 7.4 in 140 min. To analyze drug release behaviour, the drug release kinetics was assessed against different mathematical models (such as zero and first order, Higuchi, Baker–Lonsdale, Hixson, and Peppas). It was found that hydrogel (CPG2) follows the Peppas model with the highest value of regression (R2 = 0.98509). Hence, from the results, these hydrogels could be a potential biomaterial for wound dressing in biomedical applications. 相似文献
26.
Yojiro Ishino Naoki Hayashi Ili Fatimah Bt Abd Razak Takahiro Kato Yudai Kurimoto Yu Saiki 《Flow, Turbulence and Combustion》2016,96(3):819-835
In order to provide a suitable technique for 3D observation of high speed turbulent flames, non-scanning 3D-CT(Computer Tomography) technique using a multi-directional quantitative schlieren system with flash light source, is proposed for instantaneous density distribution of unsteady premixed flames. This “schlieren 3D-CT” is based on (i)simultaneous acquisition of flash-light schlieren images taken from numerous directions, and (ii) 3D-CT reconstruction of the images by an appropriate CT algorithm. In this paper, first, as a preliminary research, 3D-CT reconstruction of non-axisymmetric steady flame is made with a single-directional quantitative schlieren system. Next, with custom-made 20 directional schlieren camera, instantaneous density distributions of a high-speed turbulent flames of nozzle exit velocities of 8.0 and 10.0 m/s has been CT-reconstructed. The 3D-views of the reconstructed flame front shape clearly give the information of the flame structure with fine scale corrugations. Based on the distributions, area-enlargement rates of the flame front area are derived, and investigated. 相似文献
27.
Shyamaprosad Goswami Reshmi Mukherjee Kumaresh Ghosh Ibrahim Abdul Razak S. Shanmuga Sundara Raj Hoong‐Kun Fun 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(4):477-478
In the title cocrystal, 2‐aminopyrimidine–(+)‐camphoric acid (1/1), C4H5N3·C10H16O4, the 2‐aminopyrimidine forms two eight‐membered hydrogen‐bonded rings with two different camphoric acid molecules. This results in infinite wave‐like chains of molecules in which neighbouring chains are connected by weak C—H?O contacts. The five‐membered ring in the acid molecule adopts a half‐chair conformation. 相似文献
28.
Ibrahim Abdul Razak S. Shanmuga Sundara Raj Hoong‐Kun Fun Zhen‐Feng Chen Jing Zhang Ren‐Geng Xiong Xiao‐Zeng You 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(8):e341-e342
In the title compound, C18H16N2O4, the piperidine ring adopts a chair conformation, lying on an inversion centre. The 4‐hydroxybenzyl groups are in quasi‐axial positions. A two‐dimensional network is formed through N—H?O and O—H?O intermolecular hydrogen bonds and C—H?O interactions. 相似文献
29.
Shusheng Zhang Zhongwei Wang Ming Li Kui Jiao Ibrahim Abdul Razak S. Shanmuga Sundara Raj Hoong‐Kun Fun 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(5):566-568
In both the title structures, O‐ethyl N‐(2,3,4,6‐tetra‐O‐acetyl‐β‐d ‐glucopyranosyl)thiocarbamate, C17H25NO10S, and O‐methyl N‐(2,3,4,6‐tetra‐O‐acetyl‐β‐d ‐glucopyranosyl)thiocarbamate, C16H23NO10S, the hexopyranosyl ring adopts the 4C1 conformation. All the ring substituents are in equatorial positions. The acetoxymethyl group is in a gauche–gauche conformation. The S atom is in a synperiplanar conformation, while the C—N—C—O linkage is antiperiplanar. N—H?O intermolecular hydrogen bonds link the molecules into infinite chains and these are connected by C—H?O interactions. 相似文献
30.
Qingli Hao Hoong‐Kun Fun Suchada Chantrapromma Ibrahim Abdul Razak Fangfang Jian Xujie Yang Lude Lu Xin Wang 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(6):717-718
The title coordination complex, [Ni(C14H14O2PS2)2(C12H8N2)] or [Ni(pMePh‐dtp)2(phen)] (phen is 1,10‐phenanthroline; dtp is diaryldithiophosphate), has a non‐crystallographic twofold axis of symmetry through the Ni atom and the phen moiety. Two O,O‐di‐p‐tolyldithiophosphate (dtp) ions act as bidentate ligands. The central metal atom is coordinated by four S atoms from two dtp groups and two N atoms from the phen ligand. The title compound displays distorted octahedral geometry around the central Ni atom. 相似文献