全文获取类型
收费全文 | 268篇 |
免费 | 14篇 |
专业分类
化学 | 185篇 |
晶体学 | 4篇 |
力学 | 23篇 |
数学 | 21篇 |
物理学 | 49篇 |
出版年
2023年 | 6篇 |
2022年 | 14篇 |
2021年 | 20篇 |
2020年 | 10篇 |
2019年 | 13篇 |
2018年 | 11篇 |
2017年 | 6篇 |
2016年 | 12篇 |
2015年 | 11篇 |
2014年 | 14篇 |
2013年 | 19篇 |
2012年 | 27篇 |
2011年 | 15篇 |
2010年 | 11篇 |
2009年 | 5篇 |
2008年 | 10篇 |
2007年 | 8篇 |
2006年 | 7篇 |
2005年 | 6篇 |
2004年 | 11篇 |
2003年 | 4篇 |
2002年 | 9篇 |
2001年 | 7篇 |
2000年 | 2篇 |
1999年 | 3篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 4篇 |
1994年 | 7篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1983年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
排序方式: 共有282条查询结果,搜索用时 15 毫秒
121.
Adawy Ahmed I. Abbas Mohamed A. Zakaria Khaled 《Research on Chemical Intermediates》2016,42(4):3385-3411
Research on Chemical Intermediates - Two new Schiff base cationic surfactants were synthesized and their chemical structures confirmed using FTIR spectroscopy. The tensioactive and thermodynamic... 相似文献
122.
Highly sensitive and selective catalytic determination of formaldehyde and acetaldehyde 总被引:2,自引:0,他引:2
A highly sensitive, simple and selective kinetic method was developed for the determination of ultra-trace levels of formaldehyde and acetaldehyde based on their catalytic effect on the oxidation of N,N-diethyl-p-phenylenediamine (DPD) with hydrogen peroxide. The reaction was monitored spectrophotometrically by tracing the formation of the red-colored oxidized product of DPD at 510nm, within 30s of mixing the reagents. The optimum reaction conditions were: 20mmolL(-1) DPD, 250mmolL(-1) H(2)O(2), 150mmolL(-1) phosphate, 150mmolL(-1) citrate and pH 6.60+/-0.05 at 25 degrees C. Following the recommended procedure, formaldehyde and acetaldehyde could be determined with linear calibration graphs up to 0.50 and 1.4microg mL(-1) and detection limits, based on the 3S(b)-criterion, of 0.015 and 0.035microg mL(-1), respectively. In addition, analytical data for other 10 aldehydes were also presented. The high sensitivity and selectivity of the proposed method allowed its successful application to rain water, mainstream smoke (MSS) and disposed tips of smoked cigarettes (DTSC). A sample aliquot was directly analyzed for its total water-soluble aldehyde content. A second sample aliquot was heated at 80 degrees C for 10min to expel acetaldehyde and the aliquot was analyzed for its content of other water-soluble aldehydes (expressed as formaldehyde equivalent), and acetaldehyde was determined by difference. The analytical results were in excellent agreements with those obtained following the standard HPLC method based on pre-column derivatization with 2,4-dinitrophenylhydrazine. Moreover, published catalytic-spectrophotometric methods for the determination of aldehydes were reviewed. 相似文献
123.
Alam Abedini Farhad Larki Elias B. Saion Azmi Zakaria M. Zobir Hussein 《Journal of Radioanalytical and Nuclear Chemistry》2012,292(1):361-366
This work concerns the study of Al–Ni bimetallic nanoparticles synthesized by gamma-radiolysis of aqueous solution containing
aluminium chloride hexahydrate, nickel chloride hexahydrate, polyvinyl alcohol for capping colloidal nanoparticles, and isopropanol
as radical scavenger. While the Al/Ni molar ratio is kept constant, size of the nanoparticles can be well controlled by varying
the radiation dose. The products were characterized by UV–vis spectroscopy, transmission electron microscopy (TEM), energy-dispersive
X-ray spectroscopy (EDX), and X-ray diffraction analysis (XRD). Observations of UV–vis absorption spectra and TEM images showed
that as the radiation dose increases from 50 to 100 kGy the particle size decreases and the number particles distribution
increases. It may be explained due to the competition between nucleation and aggregation processes in the formation of metallic
nanoparticles under irradiation. The EDX and XRD analysis confirmed directly the formation of Al–Ni bimetallic nanoparticles
in form of alloy nanoparticles. 相似文献
124.
Picomolar Detection of Melamine Using Molecularly Imprinted Polymer‐Based Electrochemical Sensors Prepared by UV‐Graft Photopolymerization 下载免费PDF全文
Idriss Bakas Zakaria Salmi Mohamed Jouini Florence Geneste Isabelle Mazerie Didier Floner Benjamin Carbonnier Yusuf Yagci Mohamed M. Chehimi 《Electroanalysis》2015,27(2):429-439
Molecularly imprinted polymer (MIP) films of melamine were prepared by photopolymerization of vinylic monomers on diazonium‐modified gold electrodes. The gold‐grafted MIPs are specific and selective for melamine in either organic or aqueous media. The interferent molecules cyromazine and cyanuric acid were not recognized by the MIPs. The limit of detection was as low as 1.75×10?12 mol L?1 at S/N=3. Efficiency of melamine rebinding is related to the solubility parameter of the organic solvent or pH and ionic strength of the aqueous medium. It is concluded that diazonium salts permit to design robust electrochemical MIP sensors. 相似文献
125.
Hassanain M. A. Alshrani H. F. A. Ibraheem Awad A. Anwar M. Behairy Kassem O. Mahmoud Zakaria M. M. Darwish Eed M. 《Physics of Atomic Nuclei》2019,82(6):615-622
Physics of Atomic Nuclei - The elastic scattering of 16O+40Ca system at the incident energy 214 MeV has been analyzed within the optical model (OM) potential using the phenomenological Woods-Saxon... 相似文献
126.
We apply the Wigner function formalism from quantum optics via two approaches, Wootters' discrete Wigner function and the generalized Wigner function, to detect quantum phase transitions in critical spin- systems. We develop a general formula relating the phase space techniques and the thermodynamical quantities of spin models, which we apply to single, bipartite and multi-partite systems governed by the XY and the XXZ models. Our approach allows us to introduce a novel way to represent, detect, and distinguish first-, second- and infinite-order quantum phase transitions. Furthermore, we show that the factorization phenomenon of the XY model is only directly detectable by quantities based on the square root of the bipartite reduced density matrix. We establish that phase space techniques provide a simple, experimentally promising tool in the study of many-body systems and we discuss their relation with measures of quantum correlations and quantum coherence. 相似文献
127.
Zakaria Salmi Sarra Gam-Derouich Samia Mahouche-Chergui Mireille Turmine Mohamed M. Chehimi 《Chemical Papers》2012,66(5):369-391
This review emphasises the role of aryl diazonium compounds as a new class of coupling agents for grafting polymer thin layers
onto carbon, diamond, metals, metal oxides, alloys, semi-conductors, ceramics, and polymers. Physical and chemical methods
are first reported for anchoring aryl layers to the surfaces, then the review concentrates on the modification of the above
substrates by thin polymer films via a range of the “grafting from” and “grafting onto” strategies. Some applications are
described which highlight the important role that diazonium salts will continue to play in the near future in the polymer
and surface sciences. 相似文献
128.
Alam Abedini Farhad Larki Elias Saion Azmi Zakaria M. Zobir Hussein 《Radiation Physics and Chemistry》2012,81(10):1653-1658
Colloidal Al–Ni nanoclusters were prepared in an aqueous polyvinyl alcohol solution containing aluminum chloride and nickel chloride as metal precursors, polyvinyl alcohol as a capping agent, isopropanol as a scavenger of hydroxyl radicals, and distilled water as a solvent. Gamma irradiations were carried out in a 60Co gamma source chamber at doses up to 100 kGy. The nanocluster properties were characterized by transmission electron microscopy (TEM), UV–visible spectrophotometry, and X-ray diffraction (XRD). By controlling the dose and precursor concentration, nanoclusters with different particle sizes were obtained. The average particle diameter increased with increase of precursor concentration and decreased with increase of dose. This is owing to the competition between nucleation, growth, and aggregation processes in the formation of nanoclusters during irradiation. 相似文献
129.
Shideh Ahmadi Chin-Hua Chia Sarani Zakaria Kasra Saeedfar Nilofar Asim 《Journal of magnetism and magnetic materials》2012
Magnetite (Fe3O4) nanocrystals were synthesized using a facile hydrothermal method. FeCl2, FeCl3 and NaOH with a molar ratio of 1:2:8 were added into an autoclave and this was followed by heat treatment at elevated temperature (100, 150 and 200 °C). The produced results show that the average crystallite and the physical size of the resulting Fe3O4 nanocrystals increased with the hydrothermal temperature. The Fe3O4 nanocrystals exhibited superparamagnetic behavior. The saturation magnetization and coercivity of the produced nanocrystals also increased with the hydrothermal temperature. 相似文献
130.
New picket porphyrins delivering at least one carboxylic group around the coordination site of the macrocycle were synthesized for bismuth coordination. The influence of the number, the length, and the pre-organization of the carboxylic acid pickets on the stability of the bismuth complexes was explored. Their stabilities in acidic medium were compared with those of their precursors bearing ester pickets. The molecular structure of one of the bismuth complexes, which is the only monomeric bismuth porphyrin reported up to now, is discussed. At the opposite of what we initially reported, and in agreement with the theoretical calculations, the distortion of the macrocycle in this structure is mainly due to the number of water molecules in the first sphere of coordination of the bismuth. 相似文献