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481.
Vinod Kumari R. C. Sharma Dr. G. K. Chaturvedi 《Monatshefte für Chemie / Chemical Monthly》1974,105(3):629-636
Potentiometric evidences have been cited for the formation of 1∶1∶1 ternary complexes in the systems: Cu(II)/Ni(II)-glycine-diamines [where diamines = ethylenediamine (en), propylenediamine (pn), o-phenylenediamine (phenen) and 1.8-naphthalenediamine (naphen)]. 相似文献
482.
ESR investigations on exchange coupled pairs of Cu ions in single crystals of Cu(dtc)2, isomorphously diluted with the corresponding diamagnetic zinc salt, are reported. The spin Hamiltonian parameters for the
coupled species (S=1) are:g
‖=2.1025,g
+=2.031,A=75.1×10−4 cm−1,B=14.8×10−4,D=276.0×10−4 cm−1 andE=46.7×10−4 cm−1. While theg andA tensors show tetragonal symmetry, the zeor-field splitting tensor is rhombic and has principal axes different from those
of theg andA tensors. Intensity measurements made down to 4.2 K indicate that the exchange is ferromagnetic with |FFF| ∼ 10 cm−1. Direct dipole-dipole interaction appears to be the major contribution to the zero-field splitting. A calculation on the
distributed point dipole model shows that dipolar interaction is considerably modified by the high covalency of the Cu-S bond
and accounts for the rhombic nature of the tensor. The possible exchange mechanisms in Cu(dtc)2—direct exchange and superexchange through the bridging sulphurs—are discussed. 相似文献
483.
P. Venkataiah Y. Laxmi Kumari M. Srinivas Mohan Harinath B. Bathina 《Journal of Chemical Sciences》1994,106(4):813-818
Interaction of adenosine-5′-triphosphate (ATP) with a series of binary Cu(II) complexes (ML) (where L =o-phenanthroline (Phen), 5-nitrophenanthroline (NPhen), 5-methyl phenanthroline (MPhen), 2,9-dimethylphenanthroline (DPhen),
2,9-dimethyl-4,7-diphenylphenanthroline (DPhPhen), 2,2′-bipyridyl (Bipy), bis(imidazol-2-yl) methane (BIM), oxalic acid (Ox),
glycine (Gly), alanine (Ala), valine (Val), phenylalanine (Phe), tryptophan (Trp), methionine (Met), histidine (His) or aspartic
acid (Asp) to form ternary complexes (MLA) was investigated by a pH-metric technique and the formation constants were evaluated
at 35.0°C and μ = 0.2 M (KNO3). The influence exerted by ligand L on the binding of ATP to Cu(II) was quantitatively assessed and ATP was found to bind
more strongly when L = bidentate nitrogen donors, relatively less strongly when L = amino acids and least strongly when L
= a bidentate oxygen donor. With respect to the nitrogen donor ligands the stability of the ternary complexes decreases in
the order NPhen > Phen > Bipy > MPhen > DPhen > BIM ≈ DPhPhen, whereas in ternary complexes containing amino acids the stability
decreases in the order: Phe ≈ Trp > Ala > Gly ≈ Val ≈ Met > His > Asp. The trends in the stability of the various complexes
are discussed in terms of the nature of the metal ion and the two ligands in its coordination sphere. 相似文献
484.
Kumari H Kline SR Schuster NJ Barnes CL Atwood JL 《Journal of the American Chemical Society》2011,133(45):18102-18105
Small-angle neutron scattering (SANS) studies were used to probe the stability and geometry of copper-seamed C-alkylpyrogallol[4]arene (PgC(n)Cu; n = 11, 13, 17) hexamers in solution. Novel structural features are observed at chain lengths greater than 10 in both solid and solution phase. Scattering data for the PgC(11)Cu and PgC(13)Cu in chloroform fitted as core-shell spheres with a total spherical radius of about 22.7 and 22.9 ? respectively. On the other hand, the scattering curve for the PgC(17)Cu hexamer at both 1% and 5% mass fractions in o-xylene did not fit as a discrete sphere but rather as a uniform ellipsoid. The geometric dimensions of the ellipsoid radii are 24 ? along the minor axis and 115 ? along the major axis. It is expected that an individual hexamer with heptadecyl chains would exhibit a uniform radius of ca. 24 ?. However, an approximate ratio of 1:5 between radii lengths for the minor axis and major axis is consistent with interpenetration of the heptadceyl chains of adjacent hexamers to form a single ellipsoidal assembly. 相似文献
485.
The biochemical cues and topographical architecture of the extracellular environment extensively influence ES cell fate. The microenvironment surrounding the developing embryo presents these instructive cues in a complex and interactive manner in order to guide cell fate decisions. Current stem cell research aims to reconstruct this multifaceted embryonic niche to recapitulate development in vitro. This review focuses on 2D and 3D differentiation niches created from natural and synthetic biomaterials to guide the differentiation of ES cells toward specific lineages. Biomaterials engineered to present specific physical constraints are also reviewed for their role in differentiation. 相似文献
486.
S. Kumari S. N. Chatterjee L. K. Jha B. N. Roy 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,61(2):355-363
H+ impact single and He2+ impact single and double electron
capture cross sections of magnesium atoms have been calculated in the
modified binary encounter approximation (BEA). The accurate expressions of
ion impact sDE\sigma _{\Delta {E}} (cross section for energy transfer
DE\Delta E) and Hartree-Fock momentum distributions of the target
electrons have been used throughout the calculations. On the basis of the
present work it is concluded that inner shell captures by H+ and
He2+ ions incident on magnesium atoms contribute partly to single
electron capture and partly to transfer ionization cross sections. The
calculated He2+ impact double electron capture cross sections of
magnesium are in reasonably good agreement with the experimental
observations. This indicates the success of the present theoretical approach
in study of charge transfer cross sections of atoms as indirect mechanisms do
not interfere with double electron capture processes in this case. 相似文献
487.
Pilli NR Inamadugu JK Kondreddy N Karra VK Damaramadugu R Rao JV 《Biomedical chromatography : BMC》2011,25(8):943-951
A rapid and sensitive liquid chromatography–tandem mass spectrometric (LC‐MS/MS) assay method has been developed and fully validated for simultaneous quantification of donepezil and its active metabolite, 6‐o‐desmethyl donepezil in human plasma. Analytes and the internal standard were extracted from human plasma by liquid–liquid extraction technique using a 30:70 v/v mixture of ethyl acetate and n‐hexane. The reconstituted samples were chromatographed on a C18 column by using a 70:30 v/v mixture of acetonitrile and ammonium formate (5 mm , pH 5.0) as the mobile phase at a flow rate of 0.6 mL/min. The calibration curve obtained was linear (r ≥ 0.99) over the concentration range of 0.09–24.2 ng/mL for donepezil and 0.03–8.13 ng/mL for 6‐o‐desmethyl donepezil. The results of the intra‐day and inter‐day precision and accuracy studies were well within the acceptable limits. The proposed method was successfully applied for the estimation of the drug in real time plasma samples for pharmacokinetic studies. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
488.
Srinivas B Shubhamangala B Lalitha K Reddy PA Kumari VD Subrahmanyam M De BR 《Photochemistry and photobiology》2011,87(5):995-1001
TiO(2) and different Cu wt% loaded TiO(2) (TC(0.5-5.0)), 10 wt% TC(2.0) supported on molecular sieve 5A (10 wt% TC(2.0)/MS) were prepared by impregnation and solid-state dispersion methods. The photocatalysts prepared were characterized using XRD, SEM, and UV-Vis DRS, TEM, XPS spectroscopy techniques. Photocatalytic reduction of CO(2) in water and alkaline solution are investigated in a batch reactor. The yield of oxalic acid increased notably when TC was supported on molecular sieve. The Cu-TiO(2) supported on molecular sieve catalyst promotes the charge separation that leads to an increase in the selective formation of oxalic acid in addition to methanol, acetic acid and traces of methane. The product formation is due to the high adsorption of CO(2), water and product shape selectivity of the composite photocatalyst. The maximum yield of oxalic acid was found to be 65.6 μg h(-1) g(-1) per cat using 0.2 N NaOH containing solution over 10 wt% TC(2.0)/MS photocatalyst. The difference in the photocatalytic activity is related to its physicochemical properties. 相似文献
489.
Nirmala Kumari Jangid Chetna Ameta Kiran Meghwal Rakshit Ameta Pinki B. Punjabi 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(8):625-632
Methyl violet–substituted polyaniline is prepared by oxidative polymerization of aniline in an aqueous acidic media using tosic acid as dopant and ammonium persulphate as oxidant. Substitution of methyl violet (dye moieties) on polyaniline backbone takes place in the presence of butyl lithium. The structures of methyl violet–substituted polyanilinewas elucidated by Fourier transform infrared (FT-IR), fluorescence spectra, XRD and differential scanning calorimetery (DSC). Molecular weight is determined by gel permeation chromatography (GPC) and viscosity method. Conductivity and band gap of methyl violet–substituted polyaniline was computed by a two-probe conductometer. 相似文献
490.
In this paper we present non-singular Bianchi types I and V cosmological models, in the presence of bulk viscous fluid and within the framework of f(R,T) gravity theory. Exact solutions to the field equations are obtained by choosing a particular form of the function f(R,T) and a special value for the average scale factor of the model, which corresponds to a time- dependent deceleration parameter. The cosmological models initially accelerate for a certain period of time and thereafter decelerate. The physical and kinematical properties of the models of the universe are discussed. 相似文献