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排序方式: 共有298条查询结果,搜索用时 15 毫秒
101.
Shiripoure Ganjineh Ketab Roghayeh Tafvizi Farzaneh Khodarahmi Parvin 《Journal of Cluster Science》2021,32(5):1389-1399
Journal of Cluster Science - Since green synthesis of silver nanoparticles (AgNPs) is a simple, safe, cost-effective and eco-friendly method, AgNPs appear to be promising anti-cancer agents in the... 相似文献
102.
Dr. Zhaowen Dong J. Terence Blaskovits Dr. Farzaneh Fadaei-Tirani Dr. Rosario Scopelliti Dr. Andrzej Sienkiewicz Prof. Clémence Corminboeuf Prof. Kay Severin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(46):11983-11988
Mesoionic imidazolylidenes are recognized as excellent electron-donating ligands in organometallic and main group chemistry. However, these carbene ligands typically show poor π-accepting properties. A computational analysis of 71 mesoionic imidazolylidenes that bear different aryl or heteroaryl substituents in C2 position was performed. The study has revealed that a diphenyltriazinyl (Dpt) substituent renders the corresponding carbene particularly π-acidic. The computational results could be corroborated experimentally. A mesoionic imidazolylidene with a Dpt substituent was found to be a better σ-donor and a better π-acceptor compared to an Arduengo-type N-heterocyclic carbene. To demonstrate the utility of the new carbene, the ligand was used to stabilize a low-valent paramagnetic tin compound. 相似文献
103.
Periodica Mathematica Hungarica - Let $$\mathcal {A}$$ be a von Neumann algebra acting on the complex Hilbert space $$\mathcal {H}$$ and $$\Phi {:}\,\mathcal {A} \longrightarrow \mathcal {A}$$ be a... 相似文献
104.
The authors describe the synthesis of a multifunctional nanocomposite with an architecture of type Fe3O4@SiO2@graphene quantum dots with an average diameter of about 22 nm. The graphene quantum dots (GQDs) were covalently immobilized on the surface of silica-coated magnetite nanospheres via covalent linkage to surface amino groups. The nanocomposite displays a strong fluorescence (with excitation/emission peaks at 330/420 nm) that is fairly selectively quenched by Hg2+ ions, presumably due to nonradiative electron/hole recombination annihilation. Under the optimized experimental conditions, the linear response to Hg2+ covers the 0.1 to 70 μM concentration range, with a 30 nM lower detection limit. The high specific surface area and abundant binding sites of the GQDs result in a good adsorption capacity for Hg2+ (68 mg?g?1). The material, due to its superparamagnetism, can be separated by using a magnet and also is recyclable with EDTA so that it can be repeatedly used for simultaneous detection and removal of Hg2+ from contaminated water. 相似文献
105.
Faezeh Farzaneh Mahtab Kashani Maleki Elnaz Rashtizadeh 《Journal of Cluster Science》2017,28(6):3253-3263
Sr3Al2O6 nanocomposite was prepared by sol gel method using aluminum isopropoxide, strontium nitrate, acetylacetone and polyethylene glycol as template, followed by calcination at 900 °C. This nanocomposite was characterized by various techniques including X-ray powder diffraction, infrared spectroscopy, elemental analysis, scanning transmission microscope and transmission electron microscope. It was found that Sr3Al2O6 nanocomposite successfully catalyzes the Knöevenagel condensation of aromatic aldehydes with malononitrile in room temperature in ethanol. Expedient access to the corresponding Knöevenagel adducts in moderate to high yields within 6 min is promising. The recovered catalyst was reused for three times without significant loss of activity. 相似文献
106.
Li Hong Dr. Jovana V. Milić Paramvir Ahlawat Dr. Marko Mladenović Dr. Dominik J. Kubicki Farzaneh Jahanabkhshi Dr. Dan Ren María C. Gélvez-Rueda Dr. Marco A. Ruiz-Preciado Dr. Amita Ummadisingu Dr. Yuhang Liu Chengbo Tian Linfeng Pan Dr. Shaik M. Zakeeruddin Prof. Anders Hagfeldt Prof. Ferdinand C. Grozema Prof. Ursula Rothlisberger Prof. Lyndon Emsley Prof. Hongwei Han Prof. Michael Graetzel 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(12):4721-4727
Formamidinium (FA) lead iodide perovskite materials feature promising photovoltaic performances and superior thermal stabilities. However, conversion of the perovskite α-FAPbI3 phase to the thermodynamically stable yet photovoltaically inactive δ-FAPbI3 phase compromises the photovoltaic performance. A strategy is presented to address this challenge by using low-dimensional hybrid perovskite materials comprising guaninium (G) organic spacer layers that act as stabilizers of the three-dimensional α-FAPbI3 phase. The underlying mode of interaction at the atomic level is unraveled by means of solid-state nuclear magnetic resonance spectroscopy, X-ray crystallography, transmission electron microscopy, molecular dynamics simulations, and DFT calculations. Low-dimensional-phase-containing hybrid FAPbI3 perovskite solar cells are obtained with improved performance and enhanced long-term stability. 相似文献
107.
Rezaei F Joh LD Kashima H Reddy AP VanderGheynst JS 《Applied biochemistry and biotechnology》2011,164(6):793-803
Solid-state fermentation has been widely used for enzyme production. However, secreted enzymes often bind to the solid substrate
preventing their detection and recovery. A series of screening studies was performed to examine the role of extraction buffer
composition including NaCl, ethylene glycol, sodium acetate buffer, and Tween 80, on xylanase and cellulase recovery from
switchgrass. Our results indicated that the selection of an extraction buffer is highly dependent on the nature and source
of the enzyme being extracted. While a buffer containing 50 mM sodium acetate at pH 5 was found to have a positive effect
on the recovery of commercial fungal-derived cellulase and xylanase amended to switchgrass, the same buffer had a significant
negative effect on enzyme extraction from solid fermentation samples colonized by the bacterium Acidothermus cellulolyticus. Xylanase activity was more affected by components in the extraction buffers compared to cellulase. This study demonstrated
that extraction followed by diafiltration is important for assessing enzyme recovery from solid fermentation samples. Reduction
in activity due to compounds present in the switchgrass extracts is reversible when the compounds are removed via diafiltration. 相似文献
108.
Heidar Raissi Farzaneh Farzad Emad Saleh Nadim Mehdi Yoosefian Hossein Farsi Alireza Nowroozi Danial Loghmaninejad 《International journal of quantum chemistry》2012,112(5):1273-1284
We report an investigation on intermolecular interactions in R? CN ··· H? OCH3 (R = H, CH3, F, Cl, NO2, OH, SH, SCH3, CHO, COCH3, CH2Cl, CH2F, CH2OH, CH2COOH, CF3, SCOCH3, SCF3, OCHF2, CH2CF3, CH2OCH3, and CH2CH2OH) complexes using density functional theory. The calculations were conducted on B3LYP/6‐311++G** level of theory for optimization of geometries of complexes and monomers. An improper hydrogen bonding (HB) in the H3CO? H ··· NC? R complexes was observed in that N atom of the nitriles functions acts as a proton acceptor. Furthermore, quantum theory of “Atoms in Molecules” (AIM) and natural bond orbital (NBO) method were applied to analyze H‐bond interactions in respective complexes. The electron density (ρ) and Laplacian (?2ρ) properties, estimated by atoms in molecules calculations, indicate that H ··· N bond possesses low ρ and positive ?2ρ values, which are in agreement with partially covalent character of the HBs, whereas O? H bonds have negative ?2ρ values. In addition, the weak intermolecular force due to dipole–dipole interaction (U) is also considered for analysis. The examination of HB in these complexes by quantum theory of NBO method fairly supports the ab initio results. Natural population analysis data, the electron density, and Laplacian properties, as well as, the ν(O? H) and γ(O? H) frequencies of complexes, calculated at the B3LYP/6‐311++G** level of theory, are used to evaluate the HB interactions. The calculated geometrical parameters and conformational analysis in water phase solution show that the H3CO? H ··· NC? R complexes in water are more stable than that in gas phase. The obtained results demonstrated a strong influence of the R substituent on the properties of complexes. Numerous correlations between topological, geometrical, thermodynamic properties, and energetic parameters were also found. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012 相似文献
109.
AbstractWe introduce a representative benchmark database of 20 cycloreversion reaction energies obtained by means of the high-level W1 thermochemical protocol. We use these benchmark values to assess the performance of a variety of contemporary DFT, double-hybrid DFT (DHDFT), standard ab initio, and compound thermochemistry methods. We show that this set of reaction energies provides an extremely challenging test for nearly all of the considered DFT and DHDFT methods. For example, about 80% of the considered functionals result in root-mean-square deviations (RMSDs) above 10 kJ mol?1. The best DFT and DHDFT procedures are ωB97X and DSD-PBEP86-D3, with RMSDs of 4.7 and 7.9 kJ mol?1, respectively. Coupled with the fact that the barrier heights for these reactions also pose a significant challenge for many DFT methods, this work shows that only a handful of functionals can quantitatively describe all aspects of the potential energy surface of this important class of reactions. In addition, this work shows that London dispersion effects are particularly large for this class of reactions. For example, empirical D3 dispersion corrections reduce the RMSDs for the DFT and DHDFT procedures by amounts ranging from 3.5 (PBE and B2K-PLYP) to 22.0 (BLYP) kJ mol?1. 相似文献
110.
Yahya Sefidbakht Khodadad Nazari Farzaneh Farivar Zainab Moosavi-Movahedi Nader Sheibani Ali Akbar Moosavi-Movahedi 《Journal of the Iranian Chemical Society》2012,9(2):121-128
The catalytic activity of heme peptides is an area of intense investigation. They are utilized for exploring the fine details of structural and functional properties of an active site, and to create minimized and industrial catalysts. The peroxidase activity and kinetics of suicide-inactivation of microperoxidase-11/FSM16 as a heterogeneous nanobiocatalyst in oxidation reaction of guaiacol were studied in the presence of high concentration of hydrogen peroxide (2?mM), as its natural suicide-substrate. The substrate concentration was first-order in relation to aromatic substrate (AH), and the ratio of suicide-substrate (H2O2) was kept much higher than the benign substrate (guaiacol). The results of kinetic analysis confirmed a similar mechanism for suicide-peroxide inactivation of horseradish peroxidase (HRP), microperoxidase (MP-11) and MP-11/NH2-FSM16. Inactivation kinetic parameters, including intact activity of MP-11/NH2-FSM16, ??i, and the apparent inactivation rate constant (k i) were obtained as 0.229?±?0.009?min?1 and 0.651?±?0.041?min?1 at [H2O2]?=?2.0?mM, respectively, in 5.0?mM phosphate buffer solution (PBS; pH 7.0) at 27?°C. Our results indicated that covalent immobilization of microperoxidase onto NH2-FSM16 protected the heme group against peroxide inactivation resulting in generation of an efficient peroxide-resistant heterogeneous nanobiocatalyst. 相似文献