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981.
Conclusions By use of methods of nonstationary heat flow, thermophysical characteristics (thermal conductivity, , thermal diffusivity,a, and specific heat capacity, C) have been obtained and the character of the temperature dependence, =f(T), has been established for a yarn-air composite system with a parallel disposition of elementary filaments.The character of the temperature dependence, =f(T), is supported by the results of studies of PA yarn-air composite systems having an unordered disposition of the elementary filaments, which were obtained by the method of a stationary heat flux.The dependence of the change in specific heat capacity coefficient of a composite system with an unordered disposition of elementary filaments on temperature, C = f(T), has been determined by the nonstationary heat flux method.Equations for the temperature dependences of the coefficient of specific heat capacity and the thermal conductivity coefficient of PA complex yarns have been obtained in the temperature range from 300 to 423 K.Translated from Khimicheskie Volokna, No. 4, pp. 46–48, July–August, 1987. 相似文献
982.
O. Mukbaniani G. Zaikov N. Pirckheliani T. Tatrishvili S. Meladze Z. Pachulia M. Labartkava 《应用聚合物科学杂志》2007,103(5):3243-3252
The hydrosilylation of α,ω‐bis(trimethylsiloxy) methylhydridesiloxane (degree of polymerization ≈ 53) with acrylic and methacrylic acid with various ratios of the initial compounds, in the presence of platinum hydrochloric acid, has been investigated. In the presence of platinum hydrochloric acid, competitive dehydrocondensation reactions take place with the formation of various oligomers with various chemical links. In the later stages of the reaction, three‐dimensional systems have been obtained. During dehydrocondensation, the reaction order, reaction rate constants, and activation energy have been determined. The structures of the synthesized oligomers have been determined with IR and NMR spectroscopy data. Gel permeation chromatography, differential scanning calorimetry, and X‐ray analyses of the synthesized oligomers have been carried out. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3243–3252, 2007 相似文献
983.
Yueming Wang Brian Van Devener Xiaolong Li Jost O. L. Wendt 《Aerosol science and technology》2019,53(7):783-792
Ultrafine ash particles play an important role in establishing a sticky inner deposit layer on heat transfer surface for power plants, but it is still unclear whether a thin surface alkali coating on these ultrafine particles might control this deposition behavior. In this research, we used a high resolution FE-TEM/STEM equipped with twin SDD EDX detectors for high X-ray detection efficiency, to determine the presence and absence of surface enrichment of alkali metals on ultrafine solid fuel ash samples that had low bulk alkali compositions but high deposition rates. Results from two types of combustion generated nano-sized ash particles are presented. One was from the oxy-combustion of pulverized bituminous coal, the other from oxy-combustion of pulverized rice husks, both being burned in a 100?kW rated down-flow laboratory combustor. Elemental mapping results from STEM/EDX uncovered some surface enrichment of alkali metals in ultrafine ash particles, where it existed, as it did for combustion of rice husks. However, it was not able to discern similar alkali metal surface enrichment for the bituminous coal ultrafines that had resulted in even higher deposition rates. Since deposition rates from both of these cases lie on the same correlation with PM1, one can conclude that although surface enrichment of alkali metals is present for some ~100?nm particles, it is not a prerequisite to achieve high inner surface deposition rates. This is in contrast to prevailing theories that point to alkali metals as “bad actors” as far as the sticky inner deposition rate is concerned.
Copyright © 2019 American Association for Aerosol Research 相似文献
984.
The concept of non-faradaic electrochemical modification of catalytic activity (NEMCA) has been applied for the in situ control of catalytic activity of a rhodium film deposited on YSZ (yttria stabilized zirconia) solid electrolyte towards reduction of 1000 ppm NO by 1000 ppm C3H6 in presence of excess (5000 ppm) O2 at 300 °C. A temporary heating at this feed composition results in a long-lasting deactivation of the catalyst under open circuit conditions due to partial oxidation of the rhodium surface. Positive current application (5 A) over both the active and the deactivated catalysts gives rise to an enhancement of N2 and CO2 production, the latter exceeding several hundred times the faradaic rate. While active rhodium exhibits a reversible behaviour, electrochemical promotion on the deactivated catalyst is composed of a reversible and an irreversible part. The reversible promotion results from the steady-state accumulation of current-generated active species at the gas exposed catalyst surface whereas the irreversible effect is due to the progressive reduction of the catalyst resulting in an increased recovery rate of lost catalytic activity. The results are encouraging with respect to application of rhodium for the catalytic removal of NO from auto-exhaust gases under lean-burn conditions. 相似文献
985.
Alternative hydrocarbon solvents for cottonseed extraction 总被引:3,自引:0,他引:3
P. J. Wan D. R. Pakarinen R. J. Hron Sr. O. L. Richard E. J. Conkerton 《Journal of the American Oil Chemists' Society》1995,72(6):653-659
Hexane has been used for decades to extract edible oil from cottonseed. However, due to increased regulations affecting hexane
because of the 1990 Clean Air Act and potential health risks, the oil-extraction industry urgently needs alternative hydrocarbon
solvents to replace hexane. Five solvents,n-heptane, isohexane, neohexane, cyclohexane, and cylopentane, were compared with commercial hexane using a benchscale extractor.
The extractions were done with a solvent to cottonseed flake ratio of 5.5 to 1 (w/w) and a miscella recycle flow rate of 36
mL/min/sq cm (9 gal/min/sq ft) at a temperature of 10 to 45°C below the boiling point of the solvent. After a 10-min single-stage
extraction, commercial hexane removed 100% of the oil from the flakes at 55°C; heptane extracted 100% at 75°C and 95.9% at
55°C; isohexane extracted 93.1% at 45°C; while cyclopentane, cyclohexane, and neohexane removed 93.3, 89.4, and 89.6% at 35,
55, and 35°C, respectively. Each solvent removed gossypol from cottonseed flakes at a different rate, with cyclopentane being
most and neohexane least effective. Based on the bench-scale extraction results and the availability of these candidate solvents,
heptane and isohexane are the alternative hydrocarbon solvents most likely to replace hexane.
Presented in part at the AOCS Annual Meeting & Expo, Atlanta, Georgia, May 1994. 相似文献
986.
L. Hernqvist O. Leissner B. Petersson 《European Journal of Lipid Science and Technology》1987,89(5):190-193
A new type of low erucic acid rapeseed oil containing high amount (11%) of palmitic acid (C16-LOBRA) was studied, both in labscale and in pilot-plant equipment. The polymorphic behaviour of fat blends and margarine emulsions consisting of C16-LOBRA, LOBRA and soybean oil and their hydrogenated fats were examined. The results clearly show the potential in the hydrogenated C16-LOBRA. The time before the stable ß-form is developed is much longer for the hydrogenated C16-LOBRA compared with the hydrogenated LOBRA and in fact similar to a hydrogenated soybean oil. The hydrogenated C16-LOBRA is therefore well suited to be used in e.g. margarine systems. 相似文献
987.
Stakheev A. Yu. Gabrielsson P. Gekas I. Teleguina N. S. Bragina G. O. Tolkachev N. N. Baeva G. N. 《Topics in Catalysis》2007,42(1-4):143-147
Pt/Al2O3 and Pt/BaO/Al2O3 catalysts (1 wt% Pt, 10 wt%BaO) were sulfated under conditions simulating a real NSR catalyst operation. Comparative TPR
and XPS studies of sulfur removal from Pt/Al2O3 and Pt/BaO/Al2O3 catalysts indicate that the sulfur removal from Al2O3 surface precedes reductive decomposition of BaSO4 (250–400 °C). Barium sulfate decomposition started with further increase in desulfation temperature at the point of surface
atomic ratio Ba:S = 1 (~450o). Simultaneously, an intensive formation of sulfide species on the catalyst surface was observed. Thermodynamic analysis
of the desulfation process allows us to hypothesize that barium sulfide formation may hinder sulfur removal under reducing
conditions. 相似文献
988.
989.
990.
Thermal behaviour of starch-graft-polyacrylamide (S-g-PAM) copolymers was evaluated. Grafting of polyacrylamide onto starch lowers the initial decomposition temperature. However, the over-all stability as assessed by the shape of thermogravimetric curve and integral procedural decomposition temperature increased with an increase in % graft-on. 相似文献