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81.
Two copper/cobalt metal complexes, [Cu(l-cys)(2,2′-bpy)(H2O)] (1) and {[Co(l-cys)(4,4′-bpy)(H2O)]·H2O}n (2), with the N-donor ligands 2,2′-bipyridyl/4,4′-bipyridyl and the l-cysteate dianion (l-cys) have been synthesized by different reaction methods and structurally characterized. Compound 1 exists as a discrete monomeric unit in which the metal ions possess a distorted square-pyramidal coordination environment provided by nitrogen atoms from the 2,2′-bpy ligand and the amino-carboxylate group of l-cys in a chelated coordination, constituting the square base, and with a water molecule occupying the axial coordination site to complete the penta coordination. Packing and hydrogen bonding interactions of 1 reveal that the screw related monomeric units are involved in intermolecular hydrogen bonding with the formation of helical bilayers via O–H?O and N–H?O interactions. These hydrogen bonded bilayered helical nets are involved in stacking and C–H?O interactions which generate a two dimensional hydrogen bonded network in the bc-plane. Complex 2 is a two dimensional coordination polymer which is insoluble in common polar and non-polar solvents. The coordination around the metal center possesses a distorted octahedral geometry. The adjacent metal centers are bridged via the carboxylate group of the l-cys moiety in a syn–anti fashion, generating a one dimensional helical network along the b-axis. Adjacent helical chains are further pillared by the 4,4′-bpy ligand through the terminal nitrogen atoms, generating a two dimensional square grid type coordination network. Both the complexes are characterized well by various physico-chemical techniques such as CHN analysis, IR spectroscopy, PXRD and CD analysis. 相似文献
82.
Amal Al-Kahlout Diogo Vieira César O. Avellaneda Edson R. Leite Michel A. Aegerter Agnieszka Pawlicka 《Ionics》2010,16(1):13-19
Proton-conducting gel polymer electrolytes based on gelatin plasticized with glycerol and containing acetic acid were investigated,
characterized, and applied to electrochromic window. For glycerol contents varying from 7% to 48%, the conductivity of the
uniform and predominantly amorphous gel electrolyte was found to follow a Vogel–Tamman–Fulcher behavior with the temperature.
Typically, for the electrolyte chosen to make 7 × 2 cm2 electrochromic smart window with the configuration: glass/fluor-doped tin oxide (FTO)/WO3/gelatin electrolyte/CeO2–TiO2/FTO/glass and containing 28% of glycerol, the conductivities were found to be of the order of 5 × 10−5 S/cm at room temperature and 3.6 × 10−4 S/cm at 80 °C. The device was characterized by spectroelectrochemical techniques and was tested up to 10,000 cycles showing
a fast coloring/bleaching behavior, where the coloring process was achieved in 10 s and the bleaching in 2 s. The transmission
variation at the wavelength of 550 nm was about 15%. The cyclic voltammograms showed a very good reversibility of the cathodic/anodic
processes, and the charge density was about 3.5 mC/cm2. The memory tests showed that the transmittance in the colored state increased by 8% in 90 min after removing the potential. 相似文献
83.
Amal Halder Sandip K. Nayak Subrata Chattopadhyay Sumanta Bhattacharya 《Journal of Molecular Liquids》2010,151(2-3):125-129
Ground state non-covalent interactions between a macro cyclic calixarene receptor, namely, 4-tert-butylcalix[6]arene (1), and fullerenes (C60 and C70) were studied in toluene medium by absorption spectrophotometric method. Absorption band due to the charge transfer (CT) transition have been observed in the visible region between fullerenes and 1. Utilizing the CT absorption bands, various important physicochemical parameters like oscillator strength, resonance energy, transition dipole strength of the fullerene-1 complexes and ionization potential of 1 is determined in present investigations. From Jobs method of continuous variation, it is observed that both C60 and C70 form stable 1:1 complexes with 1. The most fascinating feature of the present study is that 1 binds selectively C70 compared to C60 as obtained from binding constant (K) data of C60–1 (KC60–1) and C70–1 (KC70–1) complexes, i.e., KC60–1 = 32,400 dm3·mol? 1 and KC70–1 = 110,000 dm3.mol? 1 and selectivity (KC70–1/KC60–1) = 3.4. 1H NMR analysis provides very good support in favor of strong binding between C70 and 1. 相似文献
84.
Amal H. Ismail Nadeen H. Nsouli Michael H. Dickman Jakša Knez Ulrich Kortz 《Journal of Cluster Science》2009,20(2):453-465
The 20-tungsto-4-tellurate(IV) polyanion [H2Te4W20O80]22? (1) has been synthesized and isolated in the form of its hydrated sodium salt Na22[H2Te4W20O80]·64H2O (Na-1). Na-1 has been characterized in the solid state by FTIR and TGA. Single-crystal X-ray diffraction analysis revealed that Na-1 crystallizes in the triclinic space group P ${\bar 1}The 20-tungsto-4-tellurate(IV) polyanion [H2Te4W20O80]22− (1) has been synthesized and isolated in the form of its hydrated sodium salt Na22[H2Te4W20O80]·64H2O (Na-1). Na-1 has been characterized in the solid state by FTIR and TGA. Single-crystal X-ray diffraction analysis revealed that Na-1 crystallizes in the triclinic space group P
, with a = 12.741(2) ?, b = 16.842(3) ?, c = 17.197(4) ?, α = 93.961(10)°, β = 107.466(8)°, γ = 108.548(8)°, V = 3281.5(11) ?3 and Z = 1. The polyanion 1 comprises two [HTe2W10O40]11− fragments, connected through Te−O–W μ2-oxo bridges, and each containing a pair of face-shared WO6 octahedra. Furthermore, the 15-tungstotellurate(IV) polyanion [NaTeW15O54]13− (2) was synthesized and crystallized as a sodium salt in the orthorhombic space group Pccn, with a = 11.8841(5) ?, b = 20.8934(11) ?, c = 31.801(2) ?, V = 7896.3(7) ?3 and Z = 4.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
Dedicated to Professor C. N. R. Rao on the occasion of his 75th birthday 相似文献
85.
Amal Halder Dulal C. Mukherjee Sumanta Bhattacharya 《Journal of solution chemistry》2010,39(9):1327-1340
Ground state non-covalent interactions between a macrocyclic receptor, C-methylcalix[4]resorcinarene (1) and fullerenes (C60 and C70) have been studied in benzonitrile by an absorption spectrophotometric method. Absorption bands are located in the visible
region due to the charge transfer (CT) transition between 1 and various electron acceptors (including fullerenes), namely, 2,3-dichloro-5,6-dicyano-p-benzoquinone, tetracyanoquinodimethane and p-chloranil. Utilizing the CT absorption bands, various important physicochemical parameters, including oscillator strength,
resonance energy, transition dipole strength of all the acceptor-1 complexes and vertical ionization potential of 1 are determined. Job’s method of continuous variation reveals 1:1 stoichiometry between fullerenes and 1. The most fascinating feature of the present study is that 1 binds selectively to C70 compared to C60 as obtained from binding constant (K) data of C60-1 (KC60-1K_{\mathrm{C}60\mbox{-}\mathbf{1}}) and C70-1 (KC70-1K_{\mathrm{C}70\mbox{-}\mathbf{1}}) complexes, i.e., KC60-1=190K_{\mathrm{C}60\mbox{-}\mathbf{1}}=190 dm3⋅mol−1 and KC70-1=5,800K_{\mathrm{C}70\mbox{-}\mathbf{1}}=5{,}800 dm3⋅mol−1 and selectivity (KC70-1
/KC60-1
) ∼30. Quantum chemical calculations based on hybrid density functional theory estimate the enthalpies of formation of the
fullerene-1 complexes in vacuo and provide very good support for selectivity in the K values of the C70 and C60 complexes of 1. The exchange and correlation energies have been calculated using a hybrid DFT functional method. We have opted to use the
hybrid DFT functional over the Hartree-Fock method, as it can account for correlation effects also. Molecular electrostatic
potential map calculations give a clear picture on the electronic structures of the fullerene-1 complexes. 相似文献
86.
An algebraic model was derived for obtaining complex pressure swing adsorption (PSA) cycle schedules. This new approach involves
a priori specifying the cycle steps, their sequence and any constraints, and then solving a set of analytical equations. The solution
identifies all the cycle schedules for a given number of beds, the minimum number of beds required to operate the specified
cycle step sequence, the minimum number and location of idle steps to ensure alignment of coupled cycle steps, and a simple
screening technique to aid in identifying the best performing cycles that deserve further examination. The methodology was
tested successfully against 10, 12 and 16 bed PSA systems in the literature that all utilized the same 13 step cycle sequence
that has four pressure equalization steps. It completely resolved all the corresponding cycle schedules for these 13 step
multi-bed PSA systems with ease, and showed that the number of cycle schedules was hundreds to thousands of times greater
than the few ever reported in the literature for each one. Overall, this new methodology for complex PSA cycle scheduling
can be applied to any number of cycle steps, any corresponding cycle step sequence, and any number of constraints, with the
outcome being the complete set of cycle schedules for any number of beds greater than or equal to the minimum number it determines. 相似文献
87.
Pierre Pichat Henri Courbon Rosario Enriquez Timothy T. Y. Tan Rose Amal 《Research on Chemical Intermediates》2007,33(3-5):239-250
This article first indicates the various types of temperature-induced oxygen isotopic exchange (OIE) that can occur between labeled gaseous O2 and solid oxides. Earlier main results of light-induced OIE with semiconductor oxides are then briefly reviewed. The core of the article reports new results about the use of light-induced OIE to assess (i) the lability of TiO2 surface O atoms, as altered by calcination or Se deposits, via the comparison of OIE with the photocatalytic removal of methanol in air and (ii) the accessibility of TiO2 affixed on a fiberglass material by means of a silica binder. Both this overview and these novel results illustrate the interest of OIE in heterogeneous photocatalysis. 相似文献
88.
Sabrin R. M. Ibrahim Gamal A. Mohamed Rwaida A. Al Haidari Amal A. El-Kholy Mohamed F. Zayed Maan T. Khayat 《Natural product research》2020,34(4):474-481
AbstractA new peroxy fatty acid, tagetnoic acid (5) [4-((3S,6S)-6-((3E,8E)-octadeca-3,8-dien-1-yl)-3,6-dihydro-1,2-dioxin-3-yl)butanoic acid] and four known metabolites: ecliptal (5-formyl-α-terthiophene) (1), 5-(4-hydroxybut-1-ynyl)-2,2′-bithiophene (2), 22,23-dihydrospinasterone (3), and stigmasterol (4) were separated from the n-hexane fraction of the aerial parts of Tagetes minuta L. (Asteraceae). Their chemical structures were verified using IR, UV, 2D and 1D NMR, and HRMS. Compounds 3–5 displayed potent lipoxygenase inhibitory potential with IC50s 2.26, 1.83, and 1.17?μM, respectively compared to indomethacin (IC50 0.89?μM). Moreover, molecular docking study revealed that the potent activity of 5 is due to H-bonding and hydrophobic interaction. The results of this study suggested that Tagetes minuta dietary consumption would be useful for the individuals at risk of acute and chronic inflammatory disorders. 相似文献
89.
Occurrence and prevention of photodissolution at the phase junction of magnetite and titanium dioxide 总被引:12,自引:0,他引:12
Donia Beydoun Rose Amal Gary Low Stephen McEvoy 《Journal of molecular catalysis. A, Chemical》2002,180(1-2):193-200
A stable magnetic photocatalyst was prepared by coating a magnetic core with a layer of photoactive titanium dioxide. A direct deposition of titanium dioxide onto the surface of magnetic iron oxide particles proved ineffective in producing a stable magnetic photocatalyst, with high levels of photodissolution being observed with these samples. This observed photodissolution is believed to be due to the dissolution of the iron oxide phase, induced by the photoactive the titanium dioxide layer due to electronic interactions at the phase junction in these magnetic photocatalysts. The introduction of an intermediate passive SiO2 layer between the titanium dioxide phase and the iron oxide phase inhibited the direct electrical contact and hence prevented the photodissolution of the iron oxide phase. The magnetic photocatalyst is for use in slurry-type reactors from which the catalyst can be easily recovered by the application of an external magnetic field. 相似文献
90.
Amal E. M. Khaleel 《Monatshefte für Chemie / Chemical Monthly》2002,133(2):183-187
Summary. Three new 4-quinolinone alkaloids (5,6-dimethoxy-2-(3-methoxyphenyl)-1H-quinolin-4-one, 5,6-dimethoxy-2-(3,4-dimethoxyphenyl)-1H-quinolin-4-one, 5,6-dimethoxy-2-(2,5,6-trimethoxyphenyl)-1H-quinolin-4-one) were isolated from the leaves of Casimiroa edulis Llave et Lex (Rutaceae) cultivated in Egypt. Their structures were determined by UV/Vis, IR, 1H and 13C NMR, and EI mass spectroscopy. The alkaloids were also detected in the kernels of the seeds.
Received May 28, 2001. Accepted (revised) July 24, 2001 相似文献