全文获取类型
收费全文 | 513篇 |
免费 | 36篇 |
国内免费 | 11篇 |
专业分类
化学 | 372篇 |
晶体学 | 2篇 |
力学 | 25篇 |
数学 | 59篇 |
物理学 | 102篇 |
出版年
2023年 | 3篇 |
2022年 | 7篇 |
2021年 | 33篇 |
2020年 | 35篇 |
2019年 | 24篇 |
2018年 | 36篇 |
2017年 | 28篇 |
2016年 | 39篇 |
2015年 | 23篇 |
2014年 | 37篇 |
2013年 | 52篇 |
2012年 | 46篇 |
2011年 | 55篇 |
2010年 | 33篇 |
2009年 | 31篇 |
2008年 | 23篇 |
2007年 | 19篇 |
2006年 | 8篇 |
2005年 | 6篇 |
2004年 | 5篇 |
2003年 | 1篇 |
2002年 | 3篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1998年 | 1篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1978年 | 1篇 |
1966年 | 1篇 |
1932年 | 1篇 |
排序方式: 共有560条查询结果,搜索用时 156 毫秒
481.
Rezaei H. Choiset Y. Debey P. Grosclaude J. Haertl T. 《Journal of Thermal Analysis and Calorimetry》2003,71(1):237-247
Well-defined set of sheep PrP polymorphisms at positions 136, 154 and 171 define susceptibility to scrapie, ranging from very high susceptibility observed for V136-R154-Q171 (VRQ) variant to resistance for A136-R154-R171 (ARR).To gain insight into the mechanisms of scrapie susceptibility/resistance, the unfolding pathways of the sheep prion protein variants were analysed by differential scanning calorimetry over a wide range of pH. Thermal unfolding occurs, in the 5.0 to 6.0 pH range, through a reversible one-step process while at pH<4.5 and >6.0 unfolding intermediates are formed, which are stable in the 65–80°C range. The observed differences correlate with ovine susceptibility to scrapie.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
482.
Hypercyclicity on the Algebra of Hilbert-Schmidt Operators 总被引:1,自引:0,他引:1
We prove that the Hypercyclicity Criterion for any operator T on a Hilbert space is equivalent to the hypercyclicity of the left multiplication operator induced by T on the algebra of Hilbert-Schmidt operators. 相似文献
483.
Seagle BL Rezai KA Gasyna EM Kobori Y Rezaei KA Norris JR 《Journal of the American Chemical Society》2005,127(32):11220-11221
Melanin, a ubiquitous, heterogeneous biological polymer composed of many different monomers, contains a population of stationary, intrinsic semiquinone-like radicals. Additional extrinsic semiquinone-like radicals are reversibly photogenerated with visible or UV irradiation. The free radical chemistry of melanin is complex and not well characterized, especially the photochemistry of melanin in the presence of oxygen. To determine directly how melanin reacts in the presence of oxygen, time-resolved electron paramagnetic resonance (TREPR) spectroscopy was used to examine melanin free radical chemistry in human retinal pigment epithelium (RPE) cells under aerobic and anaerobic conditions. A TREPR difference spectrum was used to explore the nature of melanin chemistry in the presence of oxygen. The position and symmetrical line shape of the TREPR three-dimensional difference spectrum shows that when reactive oxygen species (ROS) are scavenged, only one of the two or more chemically different melanin free radical species participates in ROS scavenging. This protective melanin radical species exists in both the extrinsic and intrinsic populations of melanin free radicals, allowing melanin to protect the RPE from toxic species in both the light and dark. 相似文献
484.
Kinetic-spectrophotometric determination of ascorbic acid by inhibition of the hydrochloric acid-bromate reaction 总被引:2,自引:0,他引:2
Ensafi AA Rezaei B Movahedinia H 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2002,58(12):2589-2594
A new analytical method was developed for the determination of ascorbic acid in fruit juice and pharmaceuticals. The method is based on its inhibition effect on the reaction between hydrochloric acid and bromate. The decolourisation of Methyl Orange by the reaction products was used to monitor the reaction spectrophotometrically at 510 nm. The linearity range of the calibration graph depends on bromate concentration. The variable affecting the rate of the reaction was investigated. The method is simple, rapid, relatively sensitive and precise. The limit of detection is 7.6 x 10(-6) M and calibration rang is 8 x 10(-6)-1.2 x 10(-3) M ascorbic acid. The relative standard deviation of seven replication determinations of 8 x 10(-6) and 2 x 10(-5) M ascorbic acid was 2.8 and 1.7%, respectively. The influence of potential interfering substance was studied. The method was successfully applied for the determination of ascorbic acid in pharmaceuticals. 相似文献
485.
Syngas Production by Methane Reforming with Carbon Dioxide on Noble Metal Catalysts 总被引:2,自引:2,他引:2
下载免费PDF全文
![点击此处可从《天然气化学杂志》网站下载免费的PDF全文](/ch/ext_images/free.gif)
M. Rezaei S. M. Alavi S. Sahebdelfar Zi-Feng Yan 《天然气化学杂志》2006,15(4):327-334
A series of noble metal catalysts (Ru, Rh, Ir, Pt, and Pd) supported on alumina-stabilized magnesia (Spinel) were used to produce syngas by methane reforming with carbon dioxide. The synthesized catalysts were characterized using BET, TPR, TPO, TPH, and H2S chemisorption techniques. The activity results showed high activity and stability for the Ru and Rh catalysts. The TPO and TPH analyses indicated that the main reason for lower activity and stability of the Pd catalyst was the formation of the less reactive deposited carbon and sintering of the catalyst. 相似文献
486.
[reaction: see text] Substituted vinylidene zinc carbenoids undergo a Fritsch-Buttenberg-Wiechell rearrangement. The migratory aptitude of the two groups R/R1 was studied by 13C labeling experiments and depends on the degree of substitution in R and R1 groups and on the presence of an oxygen atom in the allylic position. 相似文献
487.
Ensafi AA Rezaei B Nouroozi S 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2004,60(8-9):2053-2057
A new flow-injection method is reported for the determination of bromide. The method is based on catalytic effect of bromide on the oxidation of m-cresolsulfonephthalein by periodate in acidic media. The reaction was followed spectrophotometrically by measuring the decrease in absorbance at 528 nm. The influence of pH, reagent concentration and manifold variables on the sensitivity was studied. Under optimum conditions, a calibration graph was obtained in the range of 0.160-20.00 microg ml(-1) bromides with a limit of detection of 0.150 microg ml(-1) bromide. The relative standard deviation for ten replicate measurement of 1.0 microg ml(-1) bromide was 2.1%. The influence of potential interfering ions on the selectivity was studied. The method successes to measure bromide in the presence of other halide ions. The method was used to measure bromide in river water and tap water. 相似文献
488.
B. Rezaei 《Journal of Analytical Chemistry》2006,61(11):1074-1078
A simple and selective spectrophotometric method is proposed for the determination of trace amounts of manganese. The method
is based on the extraction of manganese as a MnO2-benzyltriphenylphosphoniumchloride ion pair with chloroform. An artificial neural network (ANN) has been applied to the handling
of the spectrophotometric data of this complex in the organic phase to extend the dynamic range of manganese determination
(0.020–6.0 μg/mL). A three-layer back-propagation network (50:75:1) was used with root-mean-square error (rmse) 0.001 and
momentum (m) 0.8 overall. The application of BP-ANN makes it possible to extend the dynamic range of the determination of
manganese from its narrow linear range of 0.020–2.5 μg/mL to the dynamic range 0.020–6.0 μg/mL.
The text was submitted by the author in English. 相似文献
489.
G. Rezaei Behbehani A. Divsalar A. A. Saboury F. Faridbod M. R. Ganjali 《Journal of Thermal Analysis and Calorimetry》2009,96(2):663-668
Thermodynamics of the interaction between erbium(III) chloride, Er3+, with human serum albumin (HSA), was investigated at pH 7.0 and in phosphate buffer by isothermal titration calorimetry.
Our recently, solvation model was used to reproduce the enthalpies of HSA interaction by Er3+ over a broad range of metal ion concentration. The solvation parameters recovered from our new model, attributed to the structural
change of HSA and its biological activity. The binding parameters for the interaction of Er3+ and HSA indicate that the concentrations of Er3+ have no significant effects on the structure of HSA. 相似文献
490.
G. Rezaei Behbehani A. A. Saboury A. Fallah Baghery A. Abedini 《Journal of Thermal Analysis and Calorimetry》2008,93(2):479-483
Binding properties of myelin basic protein (MBP) from bovine central nervous system due to the interaction by divalent magnesium
ion (Mg2+) was investigated at 27°C in aqueous solution using isothermal titration calorimetry (ITC) technique. An extended solvation
model was used to reproduce the enthalpies of Mg2+-MBP interaction over the whole Mg2+ concentrations. It was found that there is a set of two identical and noninteracting binding sites for Mg2+ ions. The dissociation equilibrium constant is K
d=45.5 μM. The molar enthalpy of binding site is identical for both sites; ΔH=−15.24 kJ mol−1. The solvation parameters recovered from the solvation model were attributed to the structural change of MBP due to the metal
ion interaction. 相似文献