全文获取类型
收费全文 | 88篇 |
免费 | 6篇 |
专业分类
化学 | 63篇 |
力学 | 3篇 |
数学 | 1篇 |
物理学 | 27篇 |
出版年
2023年 | 2篇 |
2022年 | 2篇 |
2021年 | 1篇 |
2020年 | 6篇 |
2019年 | 3篇 |
2018年 | 3篇 |
2016年 | 5篇 |
2015年 | 2篇 |
2014年 | 5篇 |
2013年 | 9篇 |
2012年 | 4篇 |
2011年 | 11篇 |
2010年 | 4篇 |
2009年 | 2篇 |
2008年 | 3篇 |
2007年 | 5篇 |
2006年 | 7篇 |
2005年 | 4篇 |
2004年 | 1篇 |
2003年 | 2篇 |
2000年 | 1篇 |
1997年 | 1篇 |
1994年 | 1篇 |
1992年 | 3篇 |
1990年 | 3篇 |
1988年 | 1篇 |
1985年 | 1篇 |
1981年 | 1篇 |
1978年 | 1篇 |
排序方式: 共有94条查询结果,搜索用时 31 毫秒
61.
Ghasem Marandi Nourallah Hazeri Malek T. Maghsoodlou Sayyed M. Habibi‐Khorassani Niloufar Akbarzadeh Torbati Faramarz Rostami‐Charati Brian W. Skelton Mohamed Makha 《Journal of heterocyclic chemistry》2013,50(3):568-572
1,10‐Phenanthroline reacts with malonitrile and aldehydes in the presence of isocyanides as domino‐Knoevenagel‐nucleophilic cycloaddition for generation of a new class of 10‐(aryl)‐11‐(alkyl‐ or arylamino‐)pyrrolo[1,2‐a][1,10]phenanthroline‐9‐carbonitrile compounds in excellent yield. All compounds are fully characterized with one structurally authenticated by a single X‐ray diffraction study. 相似文献
62.
Hassan Yari Rahebeh A. Dehkharghani Ghasem R. Bardajee Niloufar Akbarzadeh-T 《中国化学会会志》2020,67(8):1490-1500
Mesoporous heterogeneous santa barbara amorphous (SBA)-15-supported cobalt complex, as a novel nanocatalyst containing N–O chelating Schiff-base ligand was successfully synthesized by the reaction of SBA-15 and Cobalt(II)-Schiff-base complex. The Co(II)-Schiff base complex also was prepared for the first time, by the reaction of pyridoxal 5′-phosphate or PLP (biological active form of vitamin B6), 3-(aminopropyl)-triethoxysilane in methanol that complexation with CoCl2. The subsequent grafting of entitled complex to SBA-15 afforded Co(II)-PLP-Schiff base/SBA-15 mesoporous catalyst. Characterization of the product was carried out with powder X-ray diffraction, Brunauer–Emmett–Teller nitrogen adsorption–desorption, transmission electron microscopy, scanning electron microscopy, thermogravimetric analysis, atomic absorption spectroscopy, and inductively coupled plasma, Fourier-transform infrared spectroscopy. The results revealed the retention of the textural properties and hexagonally uniform structures of SBA-15 during the grafting procedure. This nanocatalyst was applied successfully for one-pot synthesis of various benzothiazole heterocycles under green conditions. This catalyst is an active, reusable, and stable nanomaterial with no leaching of metal ions to the reaction medium. It was used for the synthesis of desired benzothiazole heterocycles by the cyclo-condensation of aryl-aldehydes with 2-aminothiophenol with good to excellent yields and under green conditions. 相似文献
63.
64.
Maryam Jamshidi Niloufar Jamshidi Cavus Falamaki 《Particle & Particle Systems Characterization》2023,40(3):2200173
This study proposes a novel and simple in-house design of a nanoparticle tracking analysis (NTA) device for the online characterization of nanoparticles in an aqueous solution. The particle size distribution of two sets of model nanoparticles, for example, transparent (SiO2) and opaque (TiO2) materials with respect to water as a dispersion medium could be successfully analyzed. Experiments are conducted using two different laser wavelengths of 632.8 (red) and 510 nm (green) and a range of concentrations. The accuracy of the green laser is larger compared to the red laser for all particle concentrations used. The measured average diameter using the presented in-house NTA setup is in the acceptable range compared to the electron microscopy data. The average diameter of the transparent (SiO2) and opaque (TiO2) samples is calculated as 36.29 and 27.26 nm using NTA, 36.44 and 27.8 nm analyzing field emission scanning electron microscopy images, and 23.97 and 19.7 nm analyzing transmission electron microscopy images. In the new viewing sample holder, nanoparticles undergo mere Brownian motion with no bulk drift velocity. The effect of solid concentration and wavelength of the laser light on the performance of the NTA sensor is investigated, and the optimal concentration range for model particles is reported. 相似文献
65.
A series of 2-(thiazol-2-yl)-4,5-dihydropyridazin-3(2H)-one derivatives were synthesized by one-pot multicomponent cyclocondensation of ketoacid, thiosemicarbazide, and phenacyl bromide using catalytical amount of KSF in EtOH under reflux. The straightforward synthesis, presence of two important class of heterocyclic rings in the individual molecule, easy workup of the products, rapid reaction, mild conditions, and good to excellent yields are notable features of this protocol.
[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.] 相似文献
66.
This paper investigates the effect of localized faults on the chaotic vibration of rolling element bearings. The presence
of chaotic behavior is demonstrated using experimental vibration data. A nonlinear mathematical model is developed that captures
bearing dynamics. The numerical simulations of the model agree with the experimental evidence and provide insight into the
bearings chaotic response in a wide range of rotational speeds. The bearing chaotic behavior is quantified using the Lyapunov
exponent and correlation dimension. It is further shown that these measures can be exploited in detecting bearing failure. 相似文献
67.
Sayyed Mostafa Habibi‐Khorassani Ali Ebrahimi Malektaher Maghsoodlou Osman Asheri Mehdi Shahraki Niloufar Akbarzadeh Younes Ghalandarzehi 《国际化学动力学杂志》2013,45(9):596-612
In this work, three speculative mechanisms of the reaction between triphenylphosphine and dimethyl acetylendicarboxylate in the presence of 3‐chloropentane‐2,4‐dione were energetically and thermodynamically developed using quantum mechanical calculations and were profoundly compared with stopped‐flow and UV spectrophotometry approaches. The third speculative mechanism that led to the five‐membered ring structure was experimentally and theoretically favorable. The five‐membered ring structure of product was characterized by X‐ray crystallographic data. Also, steps 1 and 2 of the third mechanism were determined as fast and rate‐determining steps, respectively. The experimental kinetic evidence of the formation and decay of intermediate in steps 1 and 2 (fast and rate‐determining steps, respectively) was compatible with theoretical data. Experimental kinetic data were recognized for overall reaction along with activation parameters for fast and rate‐determining steps of the reaction. Theoretical kinetic data (k and Ea) and activation parameters (ΔG≠, ΔS,≠ and ΔH≠) were calculated for each step and overall reactions. 相似文献
68.
M. Ghafari R. K. Day J. B. Dunlop W. Keune A. C. McGrath 《Hyperfine Interactions》1990,54(1-4):533-538
In order to obtain information on the nature of spin coupling in Fe-rich alloys, we performed high-precision57Fe Mössbauer effect and magnetizations measurements in a wide temperature range. These results show that with increasing temperature amorphous Fe90Sc10 alloys undergo a transition from a cluster spin-glass to superparamagnetism followed by paramagnetism. 相似文献
69.
We report results of57Fe Mössbauer measurements on the magnetically concentrated re-entrant amorphous Fe100?xZr x alloys (8≤x≤12) which give convincing evidence for a microscopic origin of the low-temperature magnetization anomaly atT f<T c. This is shown by an anomalous increase in the magnetic hyperfine field and in the relative intensities of the (?m=0)-Mössbauer lines belowT f upon cooling. No evidence was found for an antiferromagnetic phase. The shape of the hyperfine-field distribution atT=4.2 K in zero external field and in a field of 3 T is unchanged, indicating homogeneous behaviour of all Fe moments near saturation. Ferromagnetic order is not long-ranged, but determined by exchange-coupled magnetic clusters. The cluster moment nearT c is found to decrease strongly with increasing Fe content and extrapolates to zero atx≈96. 相似文献
70.
Amorphous metals (Metglass Fe80B20) have been studied by Mössbauer spectroscopy. In the analysis the radial distribution function of Bernal's liquid-structure model has been correlated with the distribution of magnetic hyperfine spectra. 相似文献