全文获取类型
收费全文 | 103052篇 |
免费 | 6007篇 |
国内免费 | 3855篇 |
专业分类
电工技术 | 6005篇 |
技术理论 | 27篇 |
综合类 | 9353篇 |
化学工业 | 12082篇 |
金属工艺 | 4450篇 |
机械仪表 | 5981篇 |
建筑科学 | 13187篇 |
矿业工程 | 5736篇 |
能源动力 | 2973篇 |
轻工业 | 8611篇 |
水利工程 | 3075篇 |
石油天然气 | 5039篇 |
武器工业 | 2323篇 |
无线电 | 9869篇 |
一般工业技术 | 5859篇 |
冶金工业 | 5098篇 |
原子能技术 | 528篇 |
自动化技术 | 12718篇 |
出版年
2024年 | 245篇 |
2023年 | 842篇 |
2022年 | 1950篇 |
2021年 | 2551篇 |
2020年 | 2548篇 |
2019年 | 1600篇 |
2018年 | 1445篇 |
2017年 | 2224篇 |
2016年 | 2637篇 |
2015年 | 3010篇 |
2014年 | 7532篇 |
2013年 | 5423篇 |
2012年 | 7385篇 |
2011年 | 8020篇 |
2010年 | 6201篇 |
2009年 | 6391篇 |
2008年 | 5954篇 |
2007年 | 7262篇 |
2006年 | 6663篇 |
2005年 | 5810篇 |
2004年 | 5145篇 |
2003年 | 4708篇 |
2002年 | 3854篇 |
2001年 | 3211篇 |
2000年 | 2428篇 |
1999年 | 1942篇 |
1998年 | 1299篇 |
1997年 | 972篇 |
1996年 | 822篇 |
1995年 | 644篇 |
1994年 | 466篇 |
1993年 | 374篇 |
1992年 | 295篇 |
1991年 | 220篇 |
1990年 | 190篇 |
1989年 | 131篇 |
1988年 | 102篇 |
1987年 | 63篇 |
1986年 | 67篇 |
1985年 | 45篇 |
1984年 | 49篇 |
1983年 | 23篇 |
1982年 | 20篇 |
1981年 | 26篇 |
1980年 | 18篇 |
1979年 | 16篇 |
1978年 | 7篇 |
1975年 | 7篇 |
1968年 | 8篇 |
1958年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
2.
文章首先对智能化电子信息技术进行了深入的研究,而后分析了该技术在应用过程中出现的问题,最后结合该技术的相关特点给出了相应的问题解决措施,希望能够对智能化电子信息技术的发展提供帮助。 相似文献
3.
4.
Software is a central component in the modern world and vastly affects the environment’s sustainability. The demand for energy and resource requirements is rising when producing hardware and software units. Literature study reveals that many studies focused on green hardware; however, limited efforts were made in the greenness of software products. Green software products are necessary to solve the issues and problems related to the long-term use of software, especially from a sustainability perspective. Without a proper mechanism for measuring the greenness of a particular software product executed in a specific environment, the mentioned benefits will not be attained. Currently, there are not enough works to address this problem, and the green status of software products is uncertain and unsure. This paper aims to identify the green measurements based on sustainable dimensions in a software product. The second objective is to reveal the relationships between the elements and measurements through empirical study. The study is conducted in two phases. The first phase is the theoretical phase, where the main components, measurements and practices that influence the sustainability of a software product are identified. The second phase is the empirical study that involved 103 respondents in Malaysia investigating current practices of green software in the industrial environment and further identifying the main sustainability dimensions and measurements and their impact on achieving green software products. This study has revealed seven green measurements of software product: Productivity, Usability, Cost Reduction, Employee Support, Energy Efficiency, Resource Efficiency and Tool Support. The relationships are statistically significant, with a significance level of less than 0.01 (p = 0.000). Thus, the hypothesised relationships were all accepted. The contributions of this study revolve around the research perspectives of the measurements to attain a green software product. 相似文献
5.
《Ceramics International》2022,48(12):16877-16884
Oxygen selective membrane on the base of cermet δ-Bi2O3/Ag with an interpenetrating structure has the maximum potential efficiency of air separation. However, the degradation processes, including the phase degradation of fluorite δ-Bi2O3, do not make it possible to create a membrane with the required perfection and durability. In this work, the ordering of oxygen vacancies with the transformation of fluorite into the rhombohedral phase (S.G. R-3) was studied by powder HT XRD in situ at 600 °C on dense Bi0.78Er0.2Hf0.02O1.51 ceramics. Fast regeneration of disordered fluorite occurs at T = 640–700 °C. The phase degradation of fluorite due to the segregation of dopants at the second stage leads into stable phases - sillenite, tetragonal or rhombohedral phase (S.G. R-3m), depending on the composition of δ-Bi2O3. Fast regeneration of fluorite occurs when heated to 820 °C, which is unacceptable for membranes. Analysis of all available data allows us to propose approaches to optimize the composition of δ-Bi2O3 and technical solutions for creating durable oxygen selective membranes with promising use in distributed multigeneration. As a result of the analysis, a new solid electrolyte with better parameters was obtained. 相似文献
6.
《Ceramics International》2022,48(8):10921-10931
Coatings were obtained by vacuum electro-spark alloying (VESA), pulsed cathodic arc evaporation (PCAE), magnetron sputtering (MS) techniques and VESA-PCAE-MS hybrid technology using Cr3C2–NiAl electrodes. The structure of the coatings was analyzed using scanning and transmission electron microscopy, X-ray diffraction and energy-dispersive spectroscopy. Mechanical properties were determined by nanoindentation, while tribological properties were assessed using pin-on-disk tribometer. Corrosion resistance was estimated by voltammetry in 1 N H2SO4 and 3.5%NaCl solutions. Oxidation resistance tests were performed at 800°С in air. The VESA coating had the highest thickness, low friction coefficient and high wear resistance. PCAE coating demonstrated the highest hardness (24 GPa) and elastic recovery (59%), oxidation resistance and superior corrosion resistance both in 1 N H2SO4 (icorr = 70 μА/cm2) and 3.5%NaCl (icorr = 0.74 μА/cm2) solutions. The MS coating had average mechanical properties and low corrosion current density (71 μА/cm2) in 1 N H2SO4. Deposition of coatings using VESA-PCAE-MS hybrid technology led to an increase in corrosion and oxidation resistance at least by 1.5 times in comparison with the VESA coating. 相似文献
7.
8.
《Ceramics International》2022,48(11):15056-15063
Hydrogen (H2) sensors based on metal oxide semiconductors (MOS) are promising for many applications such as a rocket propellant, industrial gas and the safety of storage. However, poor selectivity at low analyte concentrations, and independent response on high humidity limit the practical applications. Herein, we designed rGO-wrapped SnO2–Pd porous hollow spheres composite (SnO2–Pd@rGO) for high performance H2 sensor. The porous hollow structure was from the carbon sphere template. The rGO wrapping was via self-assembly of GO on SnO2-based spheres with subsequent thermal reduction in H2 ambient. This sensor exhibited excellently selective H2 sensing performances at 390 °C, linear response over a broad concentration range (0.1–1000 ppm) with recovery time of only 3 s, a high response of ~8 to 0.1 ppm H2 in a minute, and acceptable stability under high humidity conditions (e. g. 80%). The calculated detection limit of 16.5 ppb opened up the possibility of trace H2 monitoring. Furthermore, this sensor demonstrated certain response to H2 at the minimum concentration of 50 ppm at 130 °C. These performances mainly benefited from the special hollow porous structure with abundant heterojunctions, the catalysis of the doped-PdOx, the relative hydrophobic surface from rGO, and the deoxygenation after H2 reduction. 相似文献
9.
构建工程咨询机构BIM技术应用能力评价的指标体系,提出改进的熵权TOPSIS评价模型,以4个典型的工程咨询单位为例,进行BIM技术运用能力评价。研究表明,BIM行业的整体水平已经有了明显的提升,但是区域间的发展还存在一定差距。 相似文献
10.