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81.
Subhajit Laha Nimish Dwarkanath Abhishek Sharma Darsi Rambabu Sundaram Balasubramanian Tapas Kumar Maji 《Chemical science》2022,13(24):7172
Light hydrocarbon separation is considered one of the most industrially challenging and desired chemical separation processes and is highly essential in polymer and chemical industries. Among them, separating ethylene (C2H4) from C2 hydrocarbon mixtures such as ethane (C2H6), acetylene (C2H2), and other natural gas elements (CO2, CH4) is of paramount importance and poses significant difficulty. We demonstrate such separations using an Al-MOF synthesised earlier as a non-porous material, but herein endowed with hierarchical porosity created under microwave conditions in an equimolar water/ethanol solution. The material possessing a large surface area (793 m2 g−1) exhibits an excellent uptake capacity for major industrial hydrocarbons in the order of C2H2 > C2H6 > CO2 > C2H4 > CH4 under ambient conditions. It shows an outstanding dynamic breakthrough separation of ethylene (C2H4) not only for a binary mixture (C2H6/C2H4) but also for a quaternary combination (C2H4/C2H6/C2H2/CO2 and C2H4/C2H6/C2H2/CH4) of varying concentrations. The detailed separation/purification mechanism was unveiled by gas adsorption isotherms, mixed-gas adsorption calculations, selectivity estimations, advanced computer simulations such as density functional theory (DFT), grand canonical Monte Carlo (GCMC) and ab initio molecular dynamics (AIMD), and stepwise multicomponent dynamic breakthrough experiments.Industrially important C2H4 purification from multi-component hydrocarbon mixtures. 相似文献
82.
Dr. Venkata Suresh Mothika Dr. Papri Sutar Parul Verma Dr. Shubhajit Das Prof. Dr. Swapan K. Pati Prof. Dr. Tapas Kumar Maji 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(15):3867-3874
Bandgap engineering in donor–acceptor conjugated microporous polymers (CMPs) is a potential way to increase the solar-energy harvesting towards photochemical water splitting. Here, the design and synthesis of a series of donor–acceptor CMPs [tetraphenylethylene (TPE) and 9-fluorenone (F) as the donor and the acceptor, respectively], F0.1CMP , F0.5CMP , and F2.0CMP , are reported. These CMPs exhibited tunable bandgaps and photocatalytic hydrogen evolution from water. The donor–acceptor CMPs exhibited also intramolecular charge-transfer (ICT) absorption in the visible region (λmax=480 nm) and their bandgap was finely tuned from 2.8 to 2.1 eV by increasing the 9-fluorenone content. Interestingly, they also showed emissions in the 540–580 nm range assisted by the energy transfer from the other TPE segments (not involved in charge-transfer interactions), as evidenced from fluorescence lifetime decay analysis. By increasing the 9-fluorenone content the emission color of the polymer was also tuned from green to red. Photocatalytic activities of the donor–acceptor CMPs ( F0.1CMP , F0.5CMP , and F2.0CMP ) are greatly enhanced compared to the 9-fluorenone free polymer ( F0.0CMP ), which is essentially due to improved visible-light absorption and low bandgap of donor–acceptor CMPs. Among all the polymers F0.5CMP with an optimum bandgap (2.3 eV) showed the highest H2 evolution under visible-light irradiation. Moreover, all polymers showed excellent dispersibility in organic solvents and easy coated on the solid substrates. 相似文献
83.
We propose a variant of the time-dependent multi-configuration Hartree method within the framework of Fourier grid Hamiltonian
method. The workability of the method proposed is demonstrated with a well-known coupled two-mode problem. 相似文献
84.
Saayak Halder Narendra Nath Jha Soumik Ray Surabhi Mehra Vipin Agarwal Samir K. Maji 《Angewandte Chemie (International ed. in English)》2018,57(19):5262-5266
α‐Synuclein (α‐Syn) aggregation is associated with Parkinson's disease (PD) pathogenesis. In PD, the role of oligomers versus fibrils in neuronal cell death is debatable, but recent studies suggest oligomers are a proximate neurotoxin. Herein, we show that soluble α‐Syn monomers undergo a transformation from a solution to a gel state on incubation at high concentration. Detailed characterization of the gel showed the coexistence of monomers, oligomers, and short fibrils. In vitro, the gel was highly cytotoxic to human neuroblastoma cells. The individual constituents of the gel are short‐lived species but toxic to the cells. They comprise a structurally heterogeneous population of α‐helical and β‐sheet‐rich oligomers and short fibrils with the cross‐β motif. Given the recent evidence of the gel‐like state of the protein associated with neurodegenerative diseases, the gel state of α‐Syn in this study represents a mechanistic and structural model for the in vivo toxicity of α‐Syn in PD. 相似文献
85.
Somnath Roy Tarak Nath Mandal Anil Kumar Barik Sachindranath Pal Samik Gupta Arijit Hazra Ray J. Butcher Allen D. Hunter Matthias Zeller Susanta Kumar Kar 《Polyhedron》2007
Two new pyrimidine based NNS tridentate Schiff base ligands S-methyl-3-((2-S-methyl-6-methyl-4-pyrimidyl)methyl)dithiocarbazate [HL1] and S-benzyl-3-((2-S-methyl-6-methyl-4-pyrimidyl)methyl)dithiocarbazate [HL2] have been synthesised by the 1:1 condensation of 2-S-methylmercapto-6-methylpyrimidine-4-carbaldehyde and S-methyl/S-benzyl dithiocarbazate. A Ni(II) complex of HL1 and Co(III) and Fe(III) complexes of HL2 have been prepared and characterized by elemental analyses, molar conductivities, magnetic susceptibilities and spectroscopic studies. All the bis-chelate complexes have a distorted octahedral arrangement with an N4S2 chromophore around the central metal ion. Each ligand molecule binds the metal ion using the pyrimidyl and azomethine nitrogen and thiolato sulfur atoms (except in the nickel complex, one ligand molecule uses the thione sulfur in lieu of thiolato sulfur atom). In the Ni(II) complex, one of the ligand molecules behaves as a neutral tridentate and the other molecule functions as a uninegative tridentate, whereas in the Co(III) and Fe(III) complexes, the ligand molecules behave as monoanionic tridentate. All the complexes were analyzed by single crystal X-ray diffraction and significant differences concerning the distortion from an octahedral geometry of the coordination environment were observed. 相似文献
86.
Maji T. K. Das D. Sain S. Ray Chaudhuri N. 《Journal of Thermal Analysis and Calorimetry》2002,68(1):319-328
CuL2C4O4 [L=ethane-1,2-diamine (en)], CuL2C4O4⋅2H2O [L=N-methylethane-1,2-diamine (meen), N-ethylethane-1,2-diamine (eten),N-propylethane-1,2-diamine (pren), N-methyl-N’-ethylethane-
1,2-diamine (meeten) andpropane-1,2-diamine (pn)], CuL2C4O4⋅0.5H2O [L=N,N’-dimethylethane- 1,2-diamine (dmeen)], CuL2C4O4⋅4H2O [L=propane-1,2-diamine (pn)]and CuL2C4O4⋅H2O[L=2-methylpropane-1,2-diamine (ibn)] have been synthesized by the addition of respective diamine to finely powdered CuC4O4⋅2H2O and their thermal studies have been carried out in the solid state. Cu(en)2C4O4 upon heating loses one molecule of diamine with shar pcolour change yielding Cu(en)C4O4 which upon further heating transforms to unidentified products. All aquated-bis-diamine species [CuL2C4O4⋅2H2O, CuL2C4O4⋅0.5H2O and CuL2C4O4⋅H2O] upon heating undergo deaquation–anation reaction in the solid state showing thermochromism and transform to CuL2C4O4, which revert on exposure to humid atmosphere (RH ∼90%). All the squarato bis-diamine species, CuL2C4O4, on further heating transform to unidentified products through the formation of CuLC4O4 as intermediates. The mono diamine species, have been isolated pyrolytically in the solid state and can be stored in a desiccator
as well as in open atmosphere. They are proposed to be polymeric.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
87.
A multiconfiguration time‐dependent Hartree method based recipe is used to study the role of mass and electrical asymmetry in controlling the quantum dynamics of relaxation of a locally excited O? H bond in a water molecule, modeled by a pair of interacting Morse oscillators. The fast periodic energy transfer between the two equivalent O? H bonds in H? O? H is replaced by a rather slow process when one of the H atom is replaced by a deuterium atom. Application of static electric field along the O? D bond in HOD molecule is seen to either enhance or damp the relaxation rate, depending on the strength of the applied field. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005 相似文献
88.
In the 3.33–4.95 pH range, buffered with an excess of phenanthroline (phen), [Mn
3
IV
(-O)4(phen)4(H2O)2]4+
(1) quantitatively oxidises H2O2 to O2; the only manganese product is [Mn
2
III,IV
(-O)2(phen)4]3+
(2), provided a large excess of H2O2 is avoided; an excess of H2O2 [ > 7 × (1)] reduces (1) to Mn2+. When (1) and H2O2 were mixed in the stoichiometric molar proportion (1:0.75), the measured second-order rate constant for the reduction of (1) to (2) increased with increasing [H+], tending to saturate at lower pH. Added phenanthroline did not affect the rate constant. The results suggest an inner-sphere mechanism, ca. 10 times higher kinetic activity for (1) than for its hydroxo derivative [Mn
3
IV
(-O)4(phen)4(OH)(H2O)]3+
(1h), and a hydrolysis constant K
a = (2.9 ± 1) × 10–4 mol dm–3 for (1) (1h) + H+. 相似文献
89.
Prof. Dr. Sunney I. Chan Yu‐Jhang Lu Dr. Penumaka Nagababu Dr. Suman Maji Mu‐Cheng Hung Marianne M. Lee Prof. Dr. I‐Jui Hsu Pham Dinh Minh Jeff C.‐H. Lai Kok Yoah Ng Sridevi Ramalingam Prof. Dr. Steve S.‐F. Yu Prof. Dr. Michael K. Chan 《Angewandte Chemie (International ed. in English)》2013,52(13):3731-3735
90.