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111.
具有黑漆古褐漆古表层的8种铜镜样品表面X射线衍射分析(XRDA)结果表明,在相近的2θ角位置上都有4~5个较宽的弥散峰,而基体的XRDA结果都无弥散峰。结果表明弥散峰是样品表层中具有3~5nm的SnO2微晶所引起的。而已穿透腐蚀的黑漆古铜镜残片研细的XRDA结果尚具有基体的强衍射峰,表明黑漆古表层不单含有金属氧化物(主要是SnO2),还存在未被腐蚀而被SnO2所包裹的原合金大小不等的颗粒。 相似文献
112.
The temperature dependence of the thermoelectric power of calcium substituted YBa2–x
Ca
x
Cu3O7– pellets with 0x1.5 is presented between 60 K and 300 K. A metal–insulator transition was reported earlier by us in this system and was attributed to the ionic size-dependent localization effect. While the sign of thermoelectric power of all the calcium substituted samples was found to be positive, its magnitude increases significantly with calcium content in YBCO. The normal state thermoelectric power data of substituted YBa2–x
Ca
x
Cu3O7– (0x1.5) are discussed in light of a two-band model originally proposed by Gottwick et al. for heavy fermion systems and later modified by Forro et al. 相似文献
113.
图形创意是一个需要反复试验的创意过程,它建立在对图形产生的文化背景、社会背景等因素的了解以及对图形本身形式语言分析的基础之上。此次图形创意过程力图对马克斯·比尔的设计作品进行形式语言分析,探寻构建和谐色彩的规律,并在此基础上进行再创造,将楚青铜龙纹在再创造的骨格与色彩中进行重组,从而得到全新的图形创意设计作品。 相似文献
114.
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116.
刘渝 《重庆理工大学学报(自然科学版)》2007,21(16):94-98
对虎图形的性质,学术界长期以来存在多种观点。这些观点有其出现时代的合理性,但随着虎图形兵器材料的增加和对巴蜀文化研究的不断深入,其缺陷逐渐暴露出来。通过对学术界图腾说、族徽说、文字说、虎神说4种主要观点的分析,倾向于认为兵器上的虎图形是春秋战国时期特有的,一种巫术色彩浓郁的虎神崇拜的体现,与当时的军事集团有很大关系;虎图形的主要性质一是虎神,二是在图形符号组合中表现出来的图语性质。 相似文献
117.
广州地区出土青铜器十分脆弱,强度极低。为筛选最佳的加固材料,选取水性丙烯酸乳液、水性丙烯酸树脂、有机硅、丙烯酸清漆、水性聚氨酯分散液、聚乙烯醇缩丁醛树脂、热塑性丙烯酸树脂共7类8种加固材料进行实验,通过对比粘结性、渗透性、颜色变化、耐酸碱、成膜性、耐水性等7项性能,热塑性丙烯酸树脂B48N是目前最适合广州地区出土脆弱青铜器的加固材料。 相似文献
118.
《Journal of Nuclear Science and Technology》2013,50(4):375-377
The control characteristics of the cryogenic distillation column with a feedback stream have been discussed based on computer simulation results. This column plays an important role in fusion reactor. A new control system was proposed from the simulation results. The flow rate of top product is determined from the composition and flow rate of a main feed stream by a feedforward control loop. The flow rates of the feedback stream and vapor stream within the column are proportionally changed with a corresponding change of feed flow rate. The flow rate of vapor stream within the column is further adjusted to maintain product purity by a feedback control loop. The proposed system can control the product purity for a large fluctuation of feed composition, a change of feed flow rate, and an increase or decrease of the number of total theoretical stages of the column. The control system should be designed for each column by considering its operating conditions and function. The present study gives us a basic procedure for the design method of the control system of the cryogenic distillation column. 相似文献
119.
L. Muresan S. Varvara E. Stupnišek-Lisac H. Otma?i? K. Maruši? S. Horvat-Kurbegovi? K. Rahmouni 《Electrochimica acta》2007,52(27):7770-7779
Cultural bronze artefacts are exposed in indoor or outdoor environment. They often suffer of a substantial alteration due to an increasing atmospheric pollution. In this work, we propose the use of some innoxious compounds as corrosion inhibitors of bronze objects covered with patina. The bronze used was Cu-6Sn (in wt.%). This composition was selected after a preliminary work on several archaeological bronzes found in Transylvania, Romania, dated from the Late Neolithic to Roman periods. First, an artificial patina was formed on Cu-6Sn bronze under potential regulation, in 0.2 g L−1 NaHCO3 + 0.2 g L−1 Na2SO4 aqueous solution (pH 8), during 4 days. A pale blue to green patina was obtained and characterized using EDS and Raman spectroscopy. Then, four innoxious organic substances were examined as corrosion inhibitors: 5 mM 4-methyl-1-(p-tolyl)-imidazole (TMI), 10 mM 1-phenyl 4-methyl-imidazole (PMI), 1 mM 2-mercapto 5-R-acetylamino-1,3,4-thiadiazole (MAcT), 1 mM 2-mercapto 5-R-amino-1,3,4-thiadiazole (MAT), and for comparison 1 mM benzotriazole (BTA). The impedance spectra collected showed, for all of them, three depressed capacitive loops. On the basis of these capacitance values, these loops were allocated to the surface film with ionic conduction, the double layer capacitance with the charge transfer resistance, and the oxidation-reduction process involving the surface patina. TMI and MAcT were found to be efficient inhibitors though their performances are significantly lower than that of BTA. 相似文献
120.
Ernani S. Palma Paulo C. Greco Jr. 《Journal of Materials Engineering and Performance》2000,9(6):683-687
Several approximate models have been utilized for fatigue life prediction. Some of these models are available for mean stress
(or strain) correction on fatigue life, when nonzero mean stress (or strain) is applied. In this paper, the most commonly
used empirical strain-life models for fatigue life predictions, for materials subjected to variable amplitude loads, are described.
Experimental results of fatigue tests, where the specimens of sintered steels were subjected to partial random loads, are
presented and compared with those results obtained theoretically by the models. The utilization of the various models and
their influence on results are discussed. 相似文献