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991.
钢铁件无熔盐覆盖光亮热浸镀铝-一种无污染镀铝新工艺 总被引:1,自引:0,他引:1
提出了一种无污染光亮镀铝工艺。在熔融的热浸镀铝液中添加少量(小于0.1%)抗氧化合金以代替熔盐覆盖。观察了镀铝件的外观、微观结构,并测试了其各项性能,该工艺所得镀铝件光亮洁白,具有优良的耐磨、耐蚀及抗高温氧化性能。 相似文献
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Mixtures of tetrahydrofuran (THF) and carbon dioxide (CO2) were identified as new solvent systems for polysulfone. The miscibility and density of polysulfone in binary fluid mixtures of THF and CO2 were investigated from 300 to 425 K at pressures up to 70 MPa. The influence of the CO2 and polysulfone concentrations was studied, with the concentrations of the other two components kept constant. At a 4.5 wt % polymer concentration, the demixing pressures in a 10 wt % CO2 and 90 wt % THF mixture increased with temperature (310–425 K) from 15 to 40 MPa. With increasing CO2 concentration (from ca. 10 to 14 wt %), a significant increase (from 15 to 70 MPa at 310 K) was observed in the demixing pressures. Furthermore, with an increasing amount of CO2, the nature of the phase boundary shifted from lower critical solution temperature behavior to upper critical solution temperature behavior. The influence of the polymer concentration was studied in the 0–5 wt % range at two CO2 levels, with solvent compositions of 10 wt % CO2 and 90 wt % THF and 13 wt % CO2 and 87 wt % THF. The system with a higher level of CO2 (13 wt %) showed highly unusual phase behavior: on pressure–composition and temperature–composition diagrams, the system displayed two distinct regions of miscibility. In the system with 10 wt % CO2, the distinct regions of miscibility that were observed in the system with 13 wt % CO2 partially overlapped and led to a W‐shape phase boundary. The densities of the polymer solutions were measured from the one‐phase region through the demixing point into the two‐phase region at a constant temperature. No significant change in density was found around the phase boundary; this indicated that the coexisting phases had similar densities, as is often the case with liquid–liquid phase separation in polymer solutions under high pressure. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2357–2362, 2002 相似文献
995.
研制了以熔融合金惰性气体雾化法制备的含有大量硅化物的镍铁合金粉末为烧结粘结相的硅化物-镍铁合金/碳化钛金属陶瓷。用SEM,EDS,XRD和热重天平等测试分析了金属陶瓷的组织结构与性能。结果表明:这种硅化物-镍铁合金/碳化钛金属陶瓷具有核/环形边缘结构,硅化物-镍铁合金对碳化钛粒子有较好的润湿烧结作用。研制的金属陶瓷的抗弯强度在1000~1200MPa,硬度HRA为80~90。由于合金中含有较高的对氧有较强亲和力的元素硅,在氧化过程中形成SiO2以及一系列复合氧化物构成的致密氧化膜,使合金具有高的抗高温氧化性能。 相似文献
996.
Semih Eser Robert G. Jenkins Guangquan Wei Harold H. Schobert Joseph T. Joseph 《Fuel》1991,70(12):1445-1455
High pressure microdilatometer experiments were performed on a subbituminous (Wyodak) and a bituminous (Illinois no. 6) coal in helium and hydrogen atmospheres with and without added tetralin. Wyodak coal samples showed no swelling but contractions ranging between 24 and 40 vol% upon heating at 20 and 100 °C min− 1 under helium or hydrogen pressures between 150 and 1000 psig (˜1.0–6.9 MPa). Under the same conditions, Illinois no. 6 coals displayed contractions (25–60 vol%) prior to swelling up to 117 vol%. Upon tetralin addition (at 35–190 wt% of the coal), Wyodak coal samples did not swell but showed an increasing contraction with increasing helium or hydrogen pressure due to a slight softening and fusion of the coal particles. In contrast, addition of tetralin at much lower concentrations (5–35 wt%) had a marked effect on the contraction and swelling behaviour of Illinois no. 6. A maximum swelling of 200 vol% was obtained at a tetralin addition of 30 wt%. The increased swelling results from more extensive softening and fusion of coal particles in the presence of tetralin. Both coals showed a decreasing char yield with increasing tetralin concentration. The substantially lower extent of interaction observed between Wyodak coal samples and tetralin compared to Illinois no. 6 coal can be attributed to the differences in pore structure and/or chemical constitution of the two coal samples. Examination of the resultant solids by optical microscopy revealed the microstructural changes produced by thermal treatment in dilatometer experiments. 相似文献
997.
低粘度高固含量醋酸乙烯-丙烯酸酯共聚乳液胶粘剂的研制 总被引:3,自引:4,他引:3
介绍了一种低粘度、高固体含量的醋酸乙烯-丙烯酸丁酯-丙烯酸异辛酯共聚乳液胶粘剂的合成工艺及性能。该乳液粘度低于2500mPa.s,固体含量≥52%,较低的玻璃化温度和良好的耐水性能,应用于卷烟和防水涂料的生产。 相似文献
998.
999.
Heloise O. Pastore Alberto Frache Enrico Boccaleri Leonardo Marchese Giovanni Camino 《大分子材料与工程》2004,289(9):783-786
Summary: The success of the use of layered silicates in polymer nanocomposites, to improve physical and chemical properties is strictly related to a deeper knowledge of the mechanistic aspects on which the final features are grounded. This work shows the temperature induced structural rearrangements of nanocomposites based on poly[ethylene‐co‐(vinyl acetate)] (EVA) intercalated‐organomodified clay (at 3–30 wt.‐% silicate addition) which occur in the range between 75 and 350 °C. In situ high temperature X‐ray diffraction (HT‐XRD) studies have been performed under both nitrogen and air to monitor the modifications of the nanocomposite structure at increasing temperatures under inert/oxidative atmosphere. Heating between 75 and 225 °C, under nitrogen or air, causes the layered silicate to migrate towards the nanocomposite surface and to increase its interlayer distance. The degradation of both the clay organomodifier and the VA units of the EVA polymer seems to play a key role in driving the evolution of the silicate phase in the low temperature range. The structural modifications of the nanocomposites in the high temperature range (250–350 °C), depended on the atmosphere, either inert or oxidizing, in which the samples were heated. Heating under nitrogen led to deintercalation and thus a decrease of the silicate interlayer space, whereas exfoliation was the main process under air leading to an increase of the silicate interlayer space.
1000.