全文获取类型
收费全文 | 162篇 |
免费 | 5篇 |
国内免费 | 2篇 |
专业分类
化学 | 97篇 |
晶体学 | 4篇 |
力学 | 5篇 |
数学 | 8篇 |
物理学 | 55篇 |
出版年
2024年 | 2篇 |
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 3篇 |
2020年 | 4篇 |
2019年 | 3篇 |
2018年 | 1篇 |
2017年 | 3篇 |
2016年 | 4篇 |
2015年 | 3篇 |
2014年 | 4篇 |
2013年 | 12篇 |
2012年 | 12篇 |
2011年 | 9篇 |
2010年 | 5篇 |
2009年 | 14篇 |
2008年 | 22篇 |
2007年 | 10篇 |
2006年 | 5篇 |
2005年 | 4篇 |
2004年 | 11篇 |
2003年 | 7篇 |
2002年 | 7篇 |
2001年 | 2篇 |
2000年 | 4篇 |
1999年 | 4篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1978年 | 1篇 |
排序方式: 共有169条查询结果,搜索用时 234 毫秒
141.
Jayakumar Arunkumar Sethu Sundar Pethaiah Ramos Maximiano Robertson John Al-Jumaily Ahmed 《Ionics》2015,21(1):1-18
Ionics - The operation of polymer electrolyte membrane (PEM)-based fuel cells involves numerous physicochemical processes and components actively governing its function and, among them, gas... 相似文献
142.
An efficient protocol for the synthesis of biologically active benzoheterocyclic compounds such as benzothiazoles, benzimidazoles, benzospirothiazoles, and quinoxaline scaffolds have been accomplished via solid state melt reaction (SSMR) with excellent yields. The new protocol does not require any catalyst, solvent, and workup. Two anti-tumor agents have been prepared to demonstrate the application of this new method. 相似文献
143.
144.
K.V. Rajkumar R. Rajaraman Anish Kumar G. Amarendra T. Jayakumar C.S. Sundar 《哲学杂志》2013,93(20):1597-1610
Microstructural evolution of M250 grade maraging steel subjected to various thermal-aging treatments has been investigated using positron annihilation, X-ray diffraction, hardness and electron microscopy studies. Isochronal aging treatment in the range of 600–900 K, in steps of 100 K, was carried out and positron lifetime, austenite volume fraction and hardness values have been measured. The stages corresponding to point defect dynamics and formation of intermetallics have been clearly identified. Based on these results, measurements were performed on specimens isothermally aged at 755 K from 0.1 to 100 h to elucidate the time evolution of microstructural changes, and the results are discussed. 相似文献
145.
Soil applied cobalt alters the nodulation, leg-haemoglobin content and antioxidant status of Glycine max (L.) Merr 总被引:1,自引:0,他引:1
Jayakumar K Vijayarengan P Changxing Z Gomathinayagam M Jaleel CA 《Colloids and surfaces. B, Biointerfaces》2008,67(2):272-275
The present investigation has been carried out to estimate the effect of cobalt on the nodulation leg-haemoglobin content and antioxidant enzyme activities of soybean plants. The experiments were conducted in earthen pots containing 3 kg of air dried soil. The inner surface of pots was lined with polythene sheet. Soybean plants were raised in soil amended with different concentration of cobalt (0, 50, 100, 150, 200 and 250 mg/kg). The root nodule formation, leg-haemoglobin contents and antioxidant enzyme activities were analysed at 15 days intervals, namely 15, 30, 45, 60 and 75 days after sowing (DAS). There found a significant increase in the total number of root nodules, leg-haemoglobin content and antioxidant enzyme activities at 50 mg/kg cobalt application in the soil in all the sampling days when compared to control. Further increase in the cobalt level (100–250 mg/kg) in the soil decreased root nodules formation as well as leg-haemoglobin content antioxidant enzyme activities of soybean plants in all the sampling days. 相似文献
146.
A novel effect of any oxide particle/intermetallics enhancing hydrogen generation from water as compared to water alone when subjected to ultrasonic irradiation is reported here. Addition of methanol to water or decrease in particle size also improved the hydrogen yield. Hydrogen generation from water was further enhanced by the presence of both methanol and particles in water. 相似文献
147.
Casabianca LB An D Natarajan JK Alumasa JN Roepe PD Wolf C de Dios AC 《Inorganic chemistry》2008,47(13):6077-6081
Nuclear magnetic resonance (NMR) measurements of magnetic susceptibility have been utilized to study the equilibrium between two forms (high-spin monomer vs the antiferromagnetically coupled mu-oxo dimer) of ferriprotoporphyrin(IX) as a function of pH. The pH dependence of this equilibrium is significantly altered by the addition of either chloroquine or quinine. Chloroquine promotes the mu-oxo dimer whereas quinine promotes the monomer. 相似文献
148.
Harikumar B Varghese HT Panicker CY Jayakumar G 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2008,71(2):731-738
5,6-Dihydro-6-styryl-2-pyrone (Goniothalamin), is isolated from the leaves of Goniothalamus wightii and identified by spectral analysis and X-ray diffraction studies. FT-IR spectroscopy has also been used to characterize the vibrational bands. The vibrational wavenumbers and corresponding vibrational assignments are examined theoretically using the Gaussian03 set of quantum chemistry codes. Predicted IR and Raman intensities are reported. 相似文献
149.
Padmaja L Ravikumar C James C Jayakumar VS Hubert Joe I 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2008,71(1):252-262
FT Raman and IR spectra of the crystallized biologically active molecule, L-alanylglycine (L-Ala-Gly) have been recorded and analyzed. The equilibrium geometry, bonding features and harmonic vibrational frequencies of L-Ala-Gly have been investigated with the help of B3LYP density functional theory (DFT) method. The calculated molecular geometry has been compared with the experimental data. The assignments of the vibrational spectra have been carried out with the help of normal coordinate analysis (NCA) following the scaled quantum mechanical force field methodology (SQMFF). The optimized geometry shows the non-planarity of the peptide group of the molecule. Potential energy surface (PES) scan studies has also been carried out by ab initio calculations with B3LYP/6-311+G** basis set. The red shifting of NH3+ stretching wavenumber indicates the formation of N-H...O hydrogen bonding. The change in electron density (ED) in the sigma* antibonding orbitals and E2 energies have been calculated by natural bond orbital analysis (NBO) using DFT method. The NBO analysis confirms the occurrence of strong intermolecular hydrogen bonding in the molecule. 相似文献
150.
The paper deals with a thorough investigation on the antimicrobial activity of RF oxygen plasma and Azadirachtin (neem extract) treated cotton fabric. The hydrophilicity of cotton fabric was found to improve when treated with RF oxygen plasma. The process parameters such as electrode gap, time of exposure and oxygen pressure have been varied to study their effect on improving the hydrophilicity of the cotton fabric. The static immersion test has been carried out to assess the hydrophilicity of the oxygen plasma treated samples and the process parameters were optimized based on these test results. The formation of carbonyl group during surface modification in the plasma treated sample was analysed using FTIR studies. The surface morphology has been studied using SEM micrographs.The antimicrobial activity was imparted to the RF oxygen plasma treated samples using methanolic extract of neem leaves containing Azadirachtin. The antimicrobial activity of these samples has been analysed and compared with the activity of the cotton fabric treated with neem extract alone. The investigation reveals that the surface modification due to RF oxygen plasma was found to increase the hydrophilicity and hence the antimicrobial activity of the cotton fabric when treated with Azadirachtin. 相似文献