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61.
Bis-dithianylalkanols and dimers are formed in preparation of 2-lithio-1,3-dithianes due to the presence of oxidising impurity in n-BuLi (perhaps n-BuOOLi). 相似文献
62.
Ghanshyam V. Joshi Bhavesh D. Kevadiya Haresh M. Mody Hari C. Bajaj 《Journal of polymer science. Part A, Polymer chemistry》2012,50(3):423-430
To accomplish the controlled‐release systems based on layered clay minerals, one of the best ways is to intercalate organic molecules into the interlayer gallery of clay minerals. Into a series of chitosan (CS) intercalated montmorillonite (MMT) nanocomposites, prepared via ion‐exchange route, antimalarial drug [quinine (QUI)] was loaded to act as effective drug delivery systems. Among the CS–MMT nanocomposites, higher drug adsorption with decreasing CS concentration was observed. CS–MMT and CS–MMT/QUI intercalated compounds were characterized by powder X‐ray diffraction, Fourier transform infrared spectroscopy, and thermal analysis. The synthesized nanocomposites, filled in the gelatin capsules followed by coating of Eudragit® L 100, were tested for in vitro drug release performance in the sequential buffer environments at 37 ± 0.5 °C. As no drug release (0%) was observed in the gastric fluid, the coating of Eudragit® L 100 to the capsules is highly adequate. However, the drug release rate was comparatively faster from the CS intercalated clay with compare with pure clay. The drug release kinetic data revealed that the release of QUI from the nanocomposites can be explained by modified Freundlich model. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
63.
Balakrishna Kolli Sarada P. Mishra M. P. Joshi S. Raj Mohan T. S. Dhami A. B. Samui 《Journal of polymer science. Part A, Polymer chemistry》2012,50(8):1572-1578
Four linear polymers containing pendant azo moiety were synthesized through click chemistry for second‐order nonlinear optical study. The polymers were found soluble in most of the polar organic solvents such as tetrahydrofuran (THF), chloroform, and dimethyl formamide (DMF). The polymers showed thermal stability up to 300 °C and glass transition temperatures (Tg) in the range of 120–140 °C. The molecular weights (Mw) of these polymers (measured by gel permeation chromatography) were in the range 37,900–55,000 g/mol. The polymers were found to form optically transparent films by solution casting from THF solution. Order parameters were calculated from UV–vis absorption spectra. The morphology changes in the films after poling were characterized by atomic force microscopy. The angular dependence, temperature dependence, and time dependence of second harmonic generation (SHG) intensity were obtained by using 1064 nm Nd:YAG laser. The SHG intensity remained unchanged up to 95 °C. At room temperature, it remained stable up to 8 days after initial drop of about 14%. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 相似文献
64.
Copper(II) complexes of the type [Cu(SPF)(Ln)Cl] (where SPF is sparfloxacin and Ln = substituted terpyridines) were synthesized and found to have a distorted octahedral geometry. Superoxide dismutase‐like activity of the complexes was measured using a nitroblue tetrazolium/reduced nicotinamide adenine dinucleotide/phenazine methosulfate system and expressed in terms of the concentration of complex which terminates the formation of formazan by 50% (IC50 value), which was found to range from 0.572 to 1.522 µm . Interactions of the complexes with herring sperm DNA were studied by absorption titration, viscosity measurement and gel electrophoresis under physiological conditions. The antimicrobial efficiency of the complexes was tested against five different microorganisms and showed good biological activity. All the complexes showed good cytotoxic activity, with LC50 values ranging from 4.01 to 9.64 µg ml?1. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
65.
66.
Amitabh Jain 《辐射效应与固体损伤》2013,168(1-4):39-46
The potential advantages of ion implantation have been exploited in virtually every kind of semiconductor device. Several commercially important devices owe their existence to this technique. Ion implantation provides precise control over the amount of dopant, concentration profile and lateral dimensions in device fabrication. The high degree of uniformity and reproducibility have made it possible to produce sophisticated devices and integrated circuits with high yield and tight tolerances. This is a truly planar process. It is possible to achieve high doping concentrations with relatively lower processing temperatures thereby avoiding lifetime degradation. The process is carried out in an inherently clean environment. A wide range of dopants is available and one is not limited by the particular properties of the substrate. There is great flexibility in choice of masking materials and self-alignment of doped regions in MOS devices is facilitated. The increasing impact of ion implantation on device technology is discussed with reference to some recent developments. Specific commercially manufactured devices are mentioned. Ion implantation machines continue to undergo development aimed at higher throughputs and cleaner vacuum. There is the need for greater reliability of machines. Effort is also directed at the development of low cost machines for dedicated applications. Design of implanted devices continues to be an empirical process in some respects. The ability to accurately predict profile shapes in samples implanted (perhaps through a screen oxide) and subject to complicated post-implantation process steps, would cut down development time and costs. 相似文献
67.
Kinshuk Dasgupta D. Sen T. Mazumdar R. K. Lenka R. Tewari S. Mazumder J. B. Joshi S. Banerjee 《Journal of nanoparticle research》2012,14(3):728
For the first time, bamboo-shaped multiwalled carbon nanotubes, having diameter of the order of 50 nm, have been grown on
carbon black in a fluidized bed in bulk amount. The activation energy for the synthesis of the product was found out to be
around 33 kJ/mol in the temperature range of 700−900 °C. The carbon nanotubes were separated from the carbon black by preferential
oxidation of the later, the temperature of which was determined by thermogravimetry. The transmission electron microscopy
revealed different features of the nanotubes such as “Y” junction, bend, and catalyst filling inside the nanotubes. Small
angle neutron scattering was performed on the nanotubes synthesized at different temperatures. The data were fitted into a
suitable model in order to find out the average diameter, which decreases with increase in synthesis temperature. The Monte
Carlo simulation predicts the same behavior. Based on the above observations, a possible growth mechanism has been predicted.
The oscillation in carbon saturation value inside the catalyst in the fluidized bed has been indicated as the responsible
factor for the bamboo-shaped structure. 相似文献
68.
69.
Krati Joshi 《Molecular physics》2015,113(19-20):2980-2991
Finite-temperature behaviour of a hollow golden cage (HGC) plays a crucialrole in its potential applications as a catalyst, drug delivery agent, contrasting agent and so on. This physico-chemical property of HGCs is not well understood so far. In that context, Born–Oppenheimer molecular dynamics (BOMD) simulations are performed on a well-known ‘free-standing’ HGC. The cluster considered in this study is the ground state Au18 cluster (a cage with a diameter of about >5.5 Å). The results thus obtained are compared with the BOMD simulation results reported earlier on Au32 icosahedron cage, a conformation with a diameter of nearly. The sphericity of both the clusters is studied using a shape deformation parameter as a function of time and temperature. These results are supplemented by radial distribution function at various temperatures. The observations and analysis of results indicate that, both the clusters retain an HGC conformation from 300 to 400 K, admitting structural fluxionality by the Au18 cluster. Remarkably, the Au18 cluster is able to maintain its hollowness and sphericity up to a high temperature of 1000 K. Underlying structural and electronic properties influencing the individualistic behaviour of cages are highlighted. Composition of the frontier molecular orbitals and the charge distribution play a crucial role in the finite-temperature behaviour of the Au cages. The conclusions are supplemented by supporting calculations on another degenerate ground state Au18 hollow cage and a well-known pyramidal Au18 cage at 300 and 400 K. 相似文献
70.
Krishna C. Joshi Diwakar Sharma Bidya S. Joshi 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4):33-36
Abstract The synthesis of some new sulfur-containing spiroindole derivatives is reported. Fluorinated 3′-aryl-2′-phenylimino-spiro[3H-indole-3,6′[4,5′-pyrazolin][4,3-d]thiazolo]2(1H)-ones were prepared by the reaction of 5-(2-oxo-3-indolinylidene)-3-aryl-2-phenylimino-4-thiazolidinones with hydrazine hydrate. The compounds have been characterized on the basis of elemental and spectral studies. 相似文献