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991.
煤中15种微量元素在燃烧产物中的分配 总被引:21,自引:1,他引:21
建立了燃煤中15种向量元素在悄灰和底灰中含量分布的经验公式,该公式可以估算煤中微量元素在燃烧产物中的分配及传输通量。煤中非挥发性元素大部分存在于底灰和飞灰中,挥发性元素进入大气的量较高。 相似文献
992.
Electromotive force measurements were carried out on the system KCl–KNO3–H2O at constant total ionic strengths of 0.5, 1.0, 2.0 and 3.0 mol-kg–1 and at 25, 35 and 45°C using a cell consisting of a potassium ionselective electrode and a Ag/AgCl electrode. The Harned coefficients and the Pitzer binary and ternary interaction parameters for the system have been evaluated at each temperature. The osmotic coefficients, excess free energies of mixing and heats of mixing of the system have been predicted at each of the experimental temperatures and ionic strengths. The solubility data at 25°C are also interpreted. 相似文献
993.
Javad Mostaghimi Pierre Proulx Maher I. Boulos 《Plasma Chemistry and Plasma Processing》1984,4(3):199-217
A theoretical investigation of the effect of different parameters on the flow and the temperature fields in a radiofrequency
inductively coupled plasma is carried out. The parameters studied are: central injection gas flow rate, total gas flow rate,
input power, and the type of plasma gas. The results obtained for argon and nitrogen plasmas at atmospheric pressure indicate
that the flow and the temperature fields in the coil region, as well as the heat flux to the wall of the plasma confinement
tube, are considerably altered by the changes in the torch operating conditions. 相似文献
994.
A novel instrumental technique for the direct, fast, accurate, and precise determination of uranium in concentrates and other U-rich materials (as well as to mineralized rocks) is presented. The proposed technique is an absolute methodology, based on the comparison of the fluorescence of the accurately known standard with a sample of similar but unknown concentration in the low operational range of the instrument (on same sample-dilution basis), by the use of H3PO4-NH4H2PO4 as a fluorescence-enhancing reagent. The relative standard deviation of the proposed technique was 0.5-0.9% (n=9) at 18.1, 36.2, 61.2, and 99.6% U3O8. The proposed technique is suitable for the determination of uranium in samples arising from exploration projects, ores from mining operations, mill process samples, uranium ore concentrates leading to fuel fabrication as well as samples from environmental monitoring containing up to 100% uranium. The results are in good agreement with those obtained by titrimetric, gravimetric, and TBP extraction-H2O2 spectrophotometric methods. The precision of the technique is within the acceptable ‘pure geochemistry’ type of analysis (R.S.D. ∼ 1.0%) and is comparable even those obtained with titrimetric and gravimetric assay. The proposed differential technique coupled with flow injection may open up new advancement in instrumentation leading to design and development of microchemielectronic devices for direct on-line determination, more compatible with the tools of computer age as also to help in handling of radioactive solutions in chemical laboratories in uranium processing industries. 相似文献
995.
Samaresh Jana 《Tetrahedron letters》2005,46(7):1155-1157
A novel and efficient methodology has been developed for the construction of synthetically important tri-substituted tetrahydrofuran derivatives from bromo-alkenes and bromo-alkynes by radical cyclization reactions using the radical initiator Cp2TiCl, generated in situ from commercially available titanocene dichloride and Zn dust in tetrahydrofuran under argon. 相似文献
996.
J. D. Menczel G. L. Collins S. K. Saw 《Journal of Thermal Analysis and Calorimetry》1997,49(1):201-208
Vectra® liquid crystalline polymers (LCP's) were introduced as commercial products in the mid-1980's. The first of these (Vectra A130) was a wholly aromatic thermotropic copolyester ofp-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid. Vectra A130 is a thermotropic LCP that can be melt spun into filaments that on heat treatment are characterized by high strength and high modulus. Vectra resin can also be extruded into films. In the fiber or film form this material is commercially known as Vectran®. Heat treatment enhances the tensile strength of Vectran fiber variants. Because of this, the elucidation of the physical transformations taking place in the internal structure of the material during heating has always been an important subject. Several thermal techniques are used to indicate clearly that what is observed as a glass transition is unlike the conventional glass transition in typical semicrystalline polymers. There is also an indication of the presence of multiple states of mesophase aggregation that collapse into a single state when taken to high enough temperatures. 相似文献
997.
The application of Bacillus subtilis as a flocculant for fine coal has been reported here. Zeta-potential measurements showed that both the coal and bacteria had similar surface charge as a function of pH. Surface free energy calculations showed that the coal was hydrophobic while the bacterium was hydrophilic. The adhesion of the bacteria to coal and subsequent settling was studied in detail. Adhesion of bacteria to coal surface and subsequent settling of coal was found to be quick. Both adhesion and settling were found to be independent of pH, which makes the process very attractive for field applications. The presence of an electrolyte along with the bacterium was found to not only enhance adhesion of bacteria, but also produce a clear supernatant. Further, the settled fraction was more compact than with bacteria alone. Interaction energy calculations using the extended DLVO theory showed that the electrical forces along with the acid–base interaction energy play a dominant role in the lower pH range. Above pH 7, the acid–base interaction energy is the predominant attractive force and is sufficient enough to overcome the repulsive forces due to electrical charges to bring about adhesion and thus settling of fine coal. With increase in electrolyte concentration, the change in total interaction energy with pH is minimal which probably leads to better adhesion and hence settling. 相似文献
998.
This paper deals with synthesis and assessment of the hydraulicity of C4A3Cr, analog phase C4A3S to , relevant to the phase chemistry and properties of sulfoaluminate cements. C4A3Cr, synthesized at 1250 °C is well crystallized phase, latently hydraulic, with hydration accelerated in the presence of C4A3S, or CS. Calorimetric curves show reciprocal influence of sulfate and chromate phase in hydration of C4A3S-C4A3Cr system. The total heat expressed at hydration is nearly the same for all specimens, but the rate of heat evolution depends
on the ratio of C4A3S/C4A3Cr phases. X-ray diffraction pattern and DTA curves showed that, increasing content of C4A3Cr in hydrating mixture results in a coexistence of two types of ettringite (chromate and sulfate ettringite) hydrogarnet,
gibbsite and monosulfate.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
999.
This paper mainly deals with the design and synthesis of a novel styrene-butadieneblock copolymer. When this copolymer is used in the tread portion of tyres, it can improvewet skid resistance and reduce rolling resistance without sacrificing its general physical-mechanical properties. The visco-elastic curve of tire tread using the novel copolymer asits rubber portion was showed. Reactivity ratios for two monomers in the polymerizingsystem were calculated. The diagrams of differelitial, integral and finite difference calculithroughout the whole molecular chain were presented. The influence of the micro- andmacro-structure of the copolymer chain on wet skid resistance and rolling resistance wasdiscussed 相似文献
1000.
M. Nagy 《Colloid and polymer science》1985,263(3):245-265