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141.
Glawe DD Rodríguez F Stone MO Naik RR 《Langmuir : the ACS journal of surfaces and colloids》2005,21(2):717-720
Herein, we describe the formation of silica structures on indium tin oxide (ITO) surfaces using poly-L-lysine (PLL) to template the condensation of silicic acid. Precisely controlled electrostatic fields were used to preposition PLL onto ITO surfaces. Subsequent polypeptide-mediated silicification resulted in the formation of silica with concentration gradients that followed the pattern of the externally applied electrostatic field used in the deposition of the PLL. The resulting silica structures were securely attached to the ITO surface. The technique described here offers an inexpensive and rapid method for the deposition of polypeptides on surfaces. 相似文献
142.
Peter Rogl Subhash K. Naik Erwin Rudy 《Monatshefte für Chemie / Chemical Monthly》1977,108(6):1339-1352
The system VC0.88–HfC0.98–MoC was investigated by means of melting point, differential-thermoanalytical, X-ray diffraction and metallographic techniques on hot pressed and heat treated as well as melted alloy specimens and a constitutional diagram from 1500°C through the melting range established.The small miscibility gap within the HfC–MoC system (T
c=1630°C) interacts at lower temperatures with the solvus in a monotectoid-like reaction at 1575°C. Additions of VC to the HfC–MoC solid solution gradually increase its critical temperature.Solid state phase behaviour and melting behaviour was established within the isopleths VC0.88–MoC as well as within (V0.5Hf0.5)C–MoC and (V0.75Hf0.25)C–(Hf0.75Mo0.25)C.Phase equilibria within VC0.88–HfC–MoC are characterized by an extreme large miscibility gap at 1500°C connecting the VC–HfC and HfC–MoC systems.Originating at the VC–HfC binary an eutectic trough proceeds into the VC–HfC–MoC ternary with rising temperatures, connecting the maximum critical point of the disappearing miscibility gap [(V0.31Hf0.49Mo0.20)C] by a limiting tie line (2750±20°C). Isothermal sections have been calculated assuming regular solutions.With 5 Figures 相似文献
143.
Naik GH Priyadarsini KI Maity DK Mohan H 《The journal of physical chemistry. A》2005,109(10):2062-2068
Reaction of one-electron oxidant (Br(2)(*-)) with tryptophol (TP) and 5-hydroxytryptophol (HTP) have been studied in aqueous solution in the pH range from 3 to 10, employing nanosecond pulse radiolysis technique and the transients detected by kinetic spectrophotometry. One-electron oxidation of TP has produced an indolyl radical that absorbs in the 300-600 nm region with radical pK(a) = 4.9 +/- 0.2, while the reaction with HTP has produced an indoloxyl radical with lambda(max) at 420 nm and radical pK(a) < 3. Hydroxyl radicals ((*)OH) react with these two compounds producing (*)OH radical adducts that undergo water elimination to give one-electron-oxidized indolyl and indoloxyl radical species, respectively. The indoloxyl radicals react with the parent compound to form dimer radicals with an average association constant of (6.7 +/- 0.4) x 10(4) M(-1). No such dimerization is observed with indolyl radical, indicating that the presence of the 5-hydroxy group markedly alters its ability to form a dimer. A possible explanation behind such a difference in reactivity has been supported with ab initio quantum chemical calculations. 相似文献
144.
Prashant U. Naik 《Tetrahedron letters》2004,45(9):1933-1936
The ionic liquid, 1-butyl-3-methylimidazolium chloroaluminate, [bmim]Cl·AlCl3, N=0.67 mediated syntheses of aromatic sulfonamides via electrophilic substitution of arenes is reported. The protocol serves as a distinctly expeditious and ambient route towards the syntheses of these pharmaceutically useful compounds, yielding quantitative conversions at room temperature within 5-30 min in most of the cases. The Lewis acidity and molar stoichiometry of the ionic liquid influences the extent of conversion. The method has been used for the syntheses of a diverse range of sulfonamides by variation of arenes and sulfamoyl chlorides. With monosubstituted benzenes, the protocol offers an added advantage of exclusive selectivity towards the formation of para substituted sulfonamides over the ortho products. 相似文献
145.
Vommina V. Sureshbabu Rao Venkataramanarao Shankar A. Naik G. Chennakrishnareddy 《Tetrahedron letters》2007,48(39):7038-7041
An efficient synthesis of tetrazole analogues of amino acids starting from Nα-Fmoc amino acid in a three-step protocol is reported. The free amino tetrazoles were obtained in good yields and with excellent purity after removal of the Fmoc group. The synthesis of analogues of aspartic and glutamic acids in which the 5-tetrazolyl moiety is inserted at the β/γ carboxyl group starting from Fmoc-Asn and Fmoc-Gln and the incorporation of these tetrazoles into peptides are also described. 相似文献
146.
Experimental investigations on ablatively accelerated thin plastic foil targets irradiated by a 6J, 5 nsec Nd: glass laser
pulse, were conducted using shadowgraphy technique. A 2 nsec, 0.53 μm probe pulse, derived from the main laser was used for
recording the foil motion. It was observed that 6 μm plastic foils could be accelerated to a velocity of about 3 × 106 cm/sec for an incident laser intensity of 5 × 1013 W/cm2 and the corresponding ablation pressure was 0.4 Mbar. Ablation pressure (P) scaling against absorbed laser intensity (I
a
) was slower (P ∝I
a
0.4
) for a smaller laser focal spot (30 μm) as compared to the scaling (P ∝I
a
0.7
) for a larger focal spot (500 μm). This result has been explained considering the loss due to lateral energy transport from
the laser plasma interaction region. 相似文献
147.
H. R. Prakash Naik H. S. Bhojya Naik T. R. Ravikumar Naik D. S. Lamani T. Aravinda 《Phosphorus, sulfur, and silicon and the related elements》2013,188(2):355-360
Quinolines/benzo[h]quinolines are associated with a broad spectrum of biological activities. In view of this, 3-(1,3-dioxolan-2-yl)quinoline/benzo[h]quinoline-2-thiol/selenols were prepared under microwave irradiation through one-pot reactions, and these quinolines/ benzo[h]quinolines were evaluated for potential antibacterial activity. Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file. 相似文献
148.
Bhojya Naik H. S. Siddaramaiah Ramappa P. G. 《Journal of Thermal Analysis and Calorimetry》1999,55(3):841-849
The complexes of cobalt(II) with dothiepin (DOT) hydrochloride have been studied for kinetics of thermal degradation by thermogravimetric
analysis (TG) and derivative thermogravimetric studies (DTG) in a static nitrogen atmosphere at a heating rate of 10° C min−1. A general mechanism of thermal decomposition is advanced involving dehydration and decomposition process for both organic
and inorganic ligands. The thermal degradation reactions were found to proceed in three steps having an activation energy
in the range 6.75–170 kJ mol−1. Thermal decomposition kinetics parameters were computed on the basis of thermal decomposition data.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
149.
The [Ag]+‐catalyzed exchange of coordinated cyanide in [Fe(CN)6]4? by phenylhydrazine (PhNHNH2) has been studied spectrophotometrically at 488 nm by monitoring increase in the absorbance for the formation of cherry red colored complex [Fe(CN)5PhNHNH2]3?. The other reaction conditions were pH 2.80±,0.02, temperature = 30.0 ± 0.1°C, and ionic strength (I) = 0.02 M (KNO3). The reaction was followed as a function of pH, ionic strength, temperature, [Fe(CN)4?6], [PhNHNH2], [Ag+] by varying one variable at a time. The initial rates were evaluated for each variation using the plane mirror method. The initial rates evaluated as a function of [Fe(CN)4?6] clearly indicate that the initial rate increases with the increase in [Fe(CN)4?6] and finally reaches to a limiting value when [Fe(CN)4?6]/[AgNO3] ? 1000. It indicates the formation of a strong adduct between [Fe(CN)6]4? and AgNO3 prior to the abstraction of CN?. The variation in initial rates with [PhNHNH2] also showed limiting values at [Fe(CN)4?6]/[PhNHNH2] ? 8.30. The complex behavior due to pH and [Ag+] variations on the rate has been explained in detail. The composition of the final reaction product [Fe(CN)5PhNHNH2] formed during the course of reaction has been found to be 1:1 using the mole ratio method. The evaluated values of activation parameters for the catalyzed reaction are Ea = 53.85 kJ mol?1, Δ H≠, = 51.33 kJ mol?1, and Δ S≠ = ?134.63 J K?1 mol?1, which suggest an interchange dissociative mechanism. A most plausible mechanistic scheme has been proposed based on the experimental observations. © 2007 Wiley Periodicals, Inc. Int J Chem Kinet 39: 447–456, 2007 相似文献
150.
R. Tackett C. Sudakar R. Naik G. Lawes C. Rablau P.P. Vaishnava 《Journal of magnetism and magnetic materials》2008
CoxFe3−xO4 (0?x?0.10) nanoparticles coated with tetramethyl ammonium hydroxide as a surfactant were synthesized by a co-precipitation technique. The Fe:Co ratio was tuned up to x=0.10 by controlling the Co2+ concentration during synthesis. The mean particle size, determined by transmission electron microscopy, ranged between 15±4 and 18±4 nm. The superparamagnetic blocking temperature and the magnetocrystalline anisotropy constant of the ferrofluids, determined using ac and dc magnetic measurements, scale approximately linearly with cobalt concentration. We also find distinct differences in the optical response of different samples under an applied magnetic field. We attribute changes in field-induced optical relaxation for the x=0 and 0.05 samples to differences in the anisotropic microstructure under an applied magnetic field. 相似文献