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991.
The danger of the appearance of fibre segments of increased linear density over the ends of cylindrical packs in winding of
mineral fibres was substantiated. Dependences were obtained that allow determining the helix angle of the loops at which the
linear density of the fibre will not exceed the acceptable values when the direction of movement changes.
__________
Translated from Khimicheskie Volokna, No. 6, pp. 44–45, November–December, 2007. 相似文献
992.
V. P. Sinditskii 《Combustion, Explosion, and Shock Waves》2007,43(3):297-308
For model systems with known kinetics of elementary reactions (CH3NO2 and HN3), temperature ranges are established in which the rate-controlling reactions are the initial endothermic decomposition of
the starting material or the subsequent secondary reactions. Heat release in reactions of NO2, NO, and N2O with various fuels, such as CH2O, CO, H2, and HCN, is modeled to establish the kinetic parameters and nature of the rate-controlling reactions in gas flames of nitro
compounds. It is shown that the activation energy of the heat-release reaction due to the interaction of NO2 with a hydrocarbon fuel (which is characteristic of the first flame of nitro compounds) is in the range of 29–33 kcal/mole,
depending on the type of fuel. According to the calculations performed, the activation energy of the rate-controlling heat-releasing
process due to the deoxidation of NO and N2O (which is typical of the second flame of nitro compounds) is 43–58 kcal/mole. In the range of high pressures, where the
flames merge, the kinetic parameters of heat release are determined by the reactions of the most reactive nitrogen oxide NO2.
__________
Translated from Fizika Goreniya i Vzryva, Vol. 43, No. 3, pp. 59–71, May–June, 2007. 相似文献
993.
A. N. Zolotko Ya. I. Vovchuk V. G. Shevchuk N. I. Poletaev 《Combustion, Explosion, and Shock Waves》2005,41(6):611-621
The ignition and combustion of dust-gas suspensions are considered. It is shown that the ability of these systems to accumulate
heat is determined not only by their kinetic and thermal properties but also by the relation between their reaction surface
and the heat-removal surface (f). Experimental information on flame temperatures, ignition delays, and flame propagation over gas suspensions is processed
using the parameter f, and the postulate on the stimulating role of the developed reaction surface in activating these processes is validated.
It is shown that during overall burning, diffusion combustion of particles occurs only for rather small values of f. The ambiguous effect of the parameter f on the ignition and combustion processes leads to the necessity of optimizing the fuel size distribution and concentration
for the effective operation of the power devices. The role of the macroparameters of two-phase flames of refractory metals
in the synthesis of combustion nanoproducts is analyzed.
__________
Translated from Fizika Goreniya i Vzryva, Vol. 41, No. 6, pp. 3–14, November–December, 2005. 相似文献
994.
V. A. Strunin A. V. Fedorychev S. V. Gunin A. N. Klyuchnikov Yu. M. Milekhin G. B. Manelis 《Combustion, Explosion, and Shock Waves》2007,43(6):664-673
The model of combustion of a composition consisting of a quasi-homogeneous composite propellant (matrix) and coolant particles
is considered. The model is based on the leading role of exothermal decomposition of the matrix and on the cooling effect
of the second component by virtue of transverse heat transfer between the components in the condensed and gas phases. Formulas
for combustion characteristics (temperature, burning rate, its sensitivity to pressure, and initial temperature) are derived
and analyzed. The calculated dependences of these characteristics on pressure, particle size, concentration, and thermal effects
of decomposition of the components show that transitional regimes with a stronger dependence of the burning rate on pressure
than that of the initial propellant are reached in a certain range of parameters. An algorithm is proposed, and a parametric
identification of the model on the basis of experimental data is performed.
__________
Translated from Fizika Goreniya i Vzryva, Vol. 43, No. 6, pp. 51–60, November–December, 2007. 相似文献
995.
A. G. Fedorenko M. A. Syrunin A. G. Ivanov 《Combustion, Explosion, and Shock Waves》2005,41(5):487-495
Experimental data on the dynamic response and strength of simple shells of fiber composites are used to justify the choice
of these materials for the load-bearing shells of blast-proof structures. It is shown that in such structures composites are
preferred to homogeneous metal alloys (structural steels) to eliminate strong scale effects of an energetic nature. A criterion
for selecting fibers is proposed and justified experimentally, and reinforcement patterns are determined to obtain optimal
(in the strength-mass ratio) compositions for the load-bearing shells of blast-proof containers and chambers.
__________
Translated from Fizika Goreniya i Vzryva, Vol. 41, No. 5, pp. 3–13, September–October, 2005. 相似文献
996.
D. Kim N. Yuzh B. K. Kim E. S. Vasil’eva E. A. Kaidash O. V. Tolochko 《Glass Physics and Chemistry》2007,33(3):214-216
Nanoparticles in the iron-cobalt system with an average size ranging from 8 to 30 nm were prepared by the gaseous-phase synthesis. Iron and cobalt carbonyls were used as starting precursors. The nanoparticles were synthesized through codecomposition of iron and cobalt carbonyl vapors in the flow of an inert gas in a flow-type reactor. The cobalt content was varied in the range 0–52 wt % with independent control of the evaporation rate of the starting precursors. The magnetic hysteresis characteristics of the nanoparticles as functions of the particle size and the cobalt content were examined by vibrating-sample magnetometry. 相似文献
997.
A range of ceramic materials with low sintering temperature have been developed using ceramic and glass wastes (up to 70%). Properties of the newly synthesized materials are given, and areas of application and fabrication methods are discussed.__________Translated from Novye Ogneupory, No. 10, pp. 39 – 41, October, 2004. 相似文献
998.
T. V. Barinova I. P. Borovinskaya V. I. Ratnikov T. I. Ignat’eva 《International Journal of Self-Propagating High-Temperature Synthesis》2007,16(2):92-95
Synthetic analogs of titanate ceramics (perovskite and zirconolite) designed for use as a matrix for immobilization of high-level
nuclear fuel reprocessing wastes (HLW). Such ceramics have been prepared by SHS method from a mixture of titanate ceramics
and non-radioactive model oxides. Synthesis conditions have been optimized. The synthesized low-porosity cylindrical compacts
exhibited a high strength and low rate for leaching Cs, Sr, Y, Ce, and La in bidistilled water. The phase composition and
microstructure of synthesized products have been characterized. The immobilization of Cs was found to be accompanied by a
marked loss of this element.
The text was submitted by the authors in English. 相似文献
999.
The concentration of uniformly distributed particles in a fluid changes with time in the direction of gravitational or centrifugal
force to form a concentration gradient. The change in the concentration is an outcome of velocity variation of particles in
a fluid. A modified equation for terminal velocity, v
m of particles in polymerizing-fluid under centrifugal force is proposed to estimate the changes in the volume fraction of
particles in the graded composites. The proposed equation introduces the effect of cure kinetics of polymer and its effect
on particle movement in the model that was based on the modified Stoke’s law, considering the parameters related to particle
hindrance, centrifugal force, particle dimensions, viscosity variation etc. The model predictions of concentration changes
at the different locations of samples were compared with calcium carbonate filled polysulphide-modified-epoxy graded composites
prepared by centrifugal casting.. The effect of particle size, delayed curing rate of matrix were explored. The simulated
results are in good agreement with those of experiments. 相似文献
1000.
The early stage of velocity relaxation of nonspherical particles in a flow behind an incident shock wave is considered by the method of multiframe shadowgraphy. A procedure of processing the data on the motion of a free body for determining its acceleration is proposed; in combination with the diagnostic method used, the procedure forms something like a noncontact aerodynamic balance. Novel data on the drag of bodies of irregular shape in a flow behind a shock wave with Mach numbers of 0.5–1.5 and Reynolds numbers of 105 typical of dust explosions are obtained. It is found that the values of drag of a nonspherical bluff body and a sphere under these conditions are similar and exceed the drag of a sphere in a steady flow by a factor of 2 to 3.Translated from Fizika Goreniya i Vzryva, Vol. 41, No. 1, pp. 81–88, January–February, 2005. 相似文献