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目前对聚落更新的研究往往凭借主观经验进行感性判断,缺乏科学定量分析的准确依据,难于对方案预期的效果进行科学的量化评判。通过对聚落空间形态演变内在逻辑的研究,综合理论研究与实证研究的长处,建构一个整体上生成模拟、局部量化分析,包含了建筑学的物理环境、社会行为环境的关系总和的研究方法体系。不仅仅是要获得一个良好的聚落更新的结果,更是要形成一套可以操作的科学方法,使我们能够摆脱那种仅仅依靠直觉、无法交流、难以评判的设计方法。 相似文献
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钢筋混凝土连梁抗震加固的试验研究 总被引:1,自引:0,他引:1
钢筋混凝土连梁是抗侧向力(风荷载和地震作用)结构-剪力墙或核心筒中的一个重要构件.在地震作用下,连梁的刚度、强度及延性对整个结构的行为表现有极大的影响.局部连梁的失效可引起抗侧力结构的整体失效.随着经济、社会的发展,在过去建成的没有考虑抗震设计或采用过时规范设计连梁的老旧高层建筑,不再满足安全要求以及由于时间因素,钢筋强度的退化,混凝土强度的降低;还有建筑物改变用途,需要增加结构构件强度,所有这些因素,都会要求对连梁进行加固处理.本文介绍了钢筋混凝土连梁加固的抗震试验研究.加固采用在连梁两侧用螺栓固定钢板的方法.研究结果表明,加固后的连梁在循环荷载下,具有更好的耗能性能、强度增加、延性性能增强且延性系数不降低.所以,此种连梁加固方法是一种可行的、能应用于实际建筑结构的、有待更进一步研究、完善的连梁加固方法. 相似文献
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《International Journal of Hydrogen Energy》2019,44(49):27151-27158
To detect hydrogen leakage as soon as possible, researchers try their best to improve the sensitivity and response speed of the hydrogen sensor. However, the sensitivity and response speed are two contradictive parameters. It is hard to improve them simultaneously. The transmission optical fiber sensor with multi-layer films is the only structure which can increase the response speed and enhance sensibility simultaneously. However, because of its special structure, the output signal of the sensor often drifts. This paper designed an in-situ observation system to study the reason why the sensor drifts. The in-situ observation system found a periodic oscillation pattern for the transmission spectrum which depends on the wavelength of the light source. The transmission spectrum patterns of the sensor with multi-layer Palladium–Yttrium (Pd–Y) alloy films under different hydrogen concentrations were analyzed. The source of drift error induced by the wavelength shift of the light source was confirmed. By using a moving average algorithm, the error characteristics of the sensor were analyzed and simulated. The results show that the increased sweep width of the laser can effectively restrain the signal drift of sensors. Particularly, when the sweep width of the laser just is the integer multiples of the period of the transmission spectrum, the suppression of the oscillation was optimal. A sensor with a wavelength-swept laser was implemented. For the sweep width of 1.1 nm, the maximum wavelength sensitivity of the sensor is only 0.046 mv/pm. The wavelength drift error is significantly less than that without signal processing. The sensor has achieved a detection limit of 0.05% which is identical to the sensor with the frequency-stabilized laser. Finally, a design principle was proposed to optimize the light source parameters and structure parameters of the probe for the high stability of the optical fiber hydrogen sensor. 相似文献
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《Wear》2002,252(11-12):979-984
In the present study, wear behaviour of woven 300 and 500 glass fabrics and aramid fibre-reinforced composite materials are experimentally investigated for 500 and 710 rpm speeds and at two different loads of 500 and 1000 g using a block-on-shaft wear tester. The wear in the experiments was determined as weight loss. The weight losses were measured after different sliding distance conditions. The worn surfaces were also examined by scanning electron microscope (SEM). As a result of this study, it is shown that the applied load on the specimens has more effect on the wear than the speed. Also the weight loss in the woven 500 glass fabric reinforced is more than that in the woven 300 glass fabric-reinforced composite. The weight loss of aramid fibre-reinforced composite is quite low compared with woven glass fabric-reinforced composites. 相似文献
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该研究旨在建立一种同时测定中国紫苏不同部位中代谢物含量的分析方法,明确紫苏不同部位中代谢物的种类与含量,为此类物质的高效利用提供一定科学依据。利用溶剂提取结合高效液相色谱技术,分别对紫苏叶、紫苏壳、紫苏杆中19种植物代谢物进行测定分析。结果表明,19种物质在55 min内完全分离,峰型和分离度良好,检出限在0.05~0.40 mg/L之间,标准曲线R2均在0.997 6以上,回收率和精密度分别在61.65%~111.42%和1.02%~17.20%之间。应用该方法对12种紫苏样品进行了检测,发现19种化合物在不同紫苏部位中的含量差异较大,在0.04~24.05 mg/g之间。12个样品中均检出2种酚酸和5种黄酮及黄酮苷。紫苏壳和杆中均检出木犀草素,含量为0.05~0.18 mg/g;紫苏叶中化合物含量顺序为迷迭香酸>野黄芩苷>芹菜素-7-O-葡萄糖苷。此外,在紫苏壳中首次检出HMF和糠醛两种呋喃环衍生物。该方法简单高效,仪器要求低,适用于紫苏及其他植物型样品中代谢物的定量检测。 相似文献
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Mobile battery-operated devices are becoming an essential instrument for business, communication, and social interaction. In addition to the demand for an acceptable level of performance and a comprehensive set of features, users often desire extended battery lifetime. In fact, limited battery lifetime is one of the biggest obstacles facing the current utility and future growth of increasingly sophisticated “smart” mobile devices. This paper proposes a novel application-aware and user-interaction aware energy optimization middleware framework (AURA) for pervasive mobile devices. AURA optimizes CPU and screen backlight energy consumption while maintaining a minimum acceptable level of performance. The proposed framework employs a novel Bayesian application classifier and management strategies based on Markov Decision Processes and Q-Learning to achieve energy savings. Real-world user evaluation studies on Google Android based HTC Dream and Google Nexus One smartphones running the AURA framework demonstrate promising results, with up to 29% energy savings compared to the baseline device manager, and up to 5×savings over prior work on CPU and backlight energy co-optimization. 相似文献
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《Carbon》2015
Understanding the mechanism of graphene synthesis by chemical vapor deposition and the effect of process parameters is critical for production of high-quality graphene. In the present work, we investigated the effect of H2 concentration during annealing on evolution of Cu surface morphology, and on deposited graphene characteristics. Our results revealed that H2 had a smoothening effect on Cu surface as its surface roughness was reduced significantly at high H2 concentration along with the formation of surface facets, dents and nanometer-sized particles. Furthermore, H2 content influenced the graphene morphology and its quality. A low H2 concentration (0% and 2.5%) during annealing promoted uniform and good quality bilayer graphene. In contrast, a high concentration of H2 (20% and 50%) resulted in multilayer, non-uniform and defective graphene. Interestingly, the annealed Cu surface morphology differed considerably from that obtained after deposition of graphene, indicating that graphene deposition has its own impact on Cu surface. 相似文献