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31.
Vijaya Kumar Ambarisha 《Journal of sound and vibration》2007,302(3):577-595
Vibration-induced gear noise and dynamic loads remain key concerns in many transmission applications that use planetary gears. Tooth separations at large vibrations introduce nonlinearity in geared systems. The present work examines the complex, nonlinear dynamic behavior of spur planetary gears using two models: (i) a lumped-parameter model, and (ii) a finite element model. The two-dimensional (2D) lumped-parameter model represents the gears as lumped inertias, the gear meshes as nonlinear springs with tooth contact loss and periodically varying stiffness due to changing tooth contact conditions, and the supports as linear springs. The 2D finite element model is developed from a unique finite element-contact analysis solver specialized for gear dynamics. Mesh stiffness variation excitation, corner contact, and gear tooth contact loss are all intrinsically considered in the finite element analysis. The dynamics of planetary gears show a rich spectrum of nonlinear phenomena. Nonlinear jumps, chaotic motions, and period-doubling bifurcations occur when the mesh frequency or any of its higher harmonics are near a natural frequency of the system. Responses from the dynamic analysis using analytical and finite element models are successfully compared qualitatively and quantitatively. These comparisons validate the effectiveness of the lumped-parameter model to simulate the dynamics of planetary gears. Mesh phasing rules to suppress rotational and translational vibrations in planetary gears are valid even when nonlinearity from tooth contact loss occurs. These mesh phasing rules, however, are not valid in the chaotic and period-doubling regions. 相似文献
32.
The removal of Ce(III) from aqueous solutions by hydrous manganese oxide (HMO) and hydrous stannic oxide (HSO) was studied
as a function of concentrations (10−2−10−7 mol·dm−3) and pH (1.2–10.0) by using the radiotracer technique. The effects of co-ions and irradiation of HMO and HSO were also studied.
The uptake of Ce(III) fitted well with the Freundlich adsorption isotherm. No significant desorption of pre-adsorbed Ce(III)
in the studied temperature range (303–333 K) indicates that both the solids may be good adsorbents for the removal of Ce(III). 相似文献
33.
34.
D. Vijaya Bharathi Kishore Kumar Hotha B. Jagadeesh Pankaj K. Chatki K. Thriveni Ramesh Mullangi A. Naidu 《Biomedical chromatography : BMC》2009,23(7):732-739
A highly selective, sensitive and accurate HPLC method has been developed and validated for the estimation of four proton‐pump inhibitors (PPI), lansoprazole (LPZ), omeprazole (OPZ), pantoprazole (PPZ) and rabeprazole (RPZ), with 500 µL human plasma using zonisamide as an internal standard (IS). The sample preparation involved simple liquid–liquid extraction of LPZ, OPZ, PPZ and RPZ and IS from human plasma with ethyl acetate. The baseline separation of all the peaks was achieved with 0.1% triethylamine (pH 6.0):acetonitrile (72:28, v/v) at a flow rate of 1 mL/min on a Zorbax C8 column. The total chromatographic run time was 11.0 min and the simultaneous elution of IS, OPZ, RPZ, PPZ and LPZ occurred at approximately 2.42, 4.45, 5.02 and 9.37 min, respectively. The method was proved to be accurate and precise at linearity range of 20.61–1999.79 ng/mL with a correlation coefficient (r) of ≥0.999. The limit of quantitation for each of the PPI studied was 20.61 ng/mL. The intra‐ and inter‐day precision and accuracy values were found to be within the assay variability limits as per the FDA guidelines. The developed assay method was applied to a pharmacokinetic study in human volunteers. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
35.
K. Jagadeeswara Pillai S. Vijaya Kumar Varma M. Syam Babu 《Proceedings Mathematical Sciences》1987,96(1):61-69
The aligned magnetic effects on a steady laminar, viscous, incompressible, conducting fluid down an open inclined channel
bounded below by a bed of varying permeability has been studied when the free surface is exposed to atmospheric pressure.
Beavers and Joseph slip condition at the interface of the free flow region and the fluid flow in the porous bed and the Darcy’s
law in the porous medium have been used. The expressions for velocity, magnetic strength and the mass flow across the cross-section
of the channel are obtained. 相似文献
36.
37.
Ahmed Kamal J. Surendranadha Reddy E. Vijaya Bharathi D. Dastagiri 《Tetrahedron letters》2008,49(2):348-353
A mild and efficient procedure has been developed for the monosulfonylation of various amines using mesyl or tosyl chlorides in water at room temperature to afford the corresponding sulfonamides in high yields. 相似文献
38.
Mohan Gundluru Santhisudha Sarva Madhu Kumar Reddy Kandula Vasudeva Reddy Netala Vijaya Tartte Suresh Reddy Cirandur 《Heteroatom Chemistry》2016,27(5):269-278
A series of new α‐aminophosphonates containing 1,3,4‐thiadiazole moiety (4a–l) were synthesized via a simple, efficient, and one‐pot three‐component Kabachnik–Fields reaction of 2‐amino‐5‐ethyl‐1,3,4‐thiadiazole with various aryl/heteroaryl aldehydes and diethylphosphite under solvent‐free microwave irradiation conditions using phosphosulfonic acid, as a reusable and heterogeneous solid acid catalyst. All the title compounds were screened for radical scavenging activity by DPPH and H2O2 methods, and antimicrobial activity against bacteria (Gram‐positive and Gram‐negative) and fungi using the disc diffusion technique. They exhibited potent in vitro antioxidant and moderate antimicrobial activity. 相似文献
39.
The molecular interactions between the polar systems isopropyl alcohol (IPA) and aniline for various mole fractions at different
temperatures were studied by determining the dielectric permittivity using an HP-LF impedance analyzer at radio frequencies,
the plunger method in the microwave frequency range and Abbe’s refractometer in optical region. Kirkwood effective correlation
factors, corrective Kirkwood correlation factors, excess permittivities, Bruggeman parameters, excess Helmholtz free energy,
relaxation time, dipole moment and excessive dipole moment were calculated using the experimental data. Optimized geometries
were calculated using Spartan Modeling software for both pure and equimolar systems of isopropyl alcohol and aniline for Hamiltonian
quantum mechanical calculations. Conformational analysis of the formation of hydrogen bond between the two systems is supported
by the FT-IR spectra. 相似文献
40.