全文获取类型
收费全文 | 4185篇 |
免费 | 255篇 |
国内免费 | 24篇 |
专业分类
电工技术 | 38篇 |
综合类 | 60篇 |
化学工业 | 930篇 |
金属工艺 | 143篇 |
机械仪表 | 134篇 |
建筑科学 | 177篇 |
矿业工程 | 32篇 |
能源动力 | 245篇 |
轻工业 | 635篇 |
水利工程 | 23篇 |
石油天然气 | 66篇 |
武器工业 | 1篇 |
无线电 | 208篇 |
一般工业技术 | 783篇 |
冶金工业 | 309篇 |
原子能技术 | 41篇 |
自动化技术 | 639篇 |
出版年
2024年 | 11篇 |
2023年 | 35篇 |
2022年 | 80篇 |
2021年 | 146篇 |
2020年 | 104篇 |
2019年 | 118篇 |
2018年 | 202篇 |
2017年 | 174篇 |
2016年 | 200篇 |
2015年 | 137篇 |
2014年 | 197篇 |
2013年 | 452篇 |
2012年 | 223篇 |
2011年 | 277篇 |
2010年 | 282篇 |
2009年 | 235篇 |
2008年 | 203篇 |
2007年 | 173篇 |
2006年 | 129篇 |
2005年 | 127篇 |
2004年 | 102篇 |
2003年 | 87篇 |
2002年 | 79篇 |
2001年 | 36篇 |
2000年 | 46篇 |
1999年 | 54篇 |
1998年 | 93篇 |
1997年 | 61篇 |
1996年 | 44篇 |
1995年 | 47篇 |
1994年 | 31篇 |
1993年 | 22篇 |
1992年 | 16篇 |
1991年 | 17篇 |
1990年 | 10篇 |
1988年 | 11篇 |
1987年 | 9篇 |
1986年 | 8篇 |
1985年 | 18篇 |
1984年 | 17篇 |
1983年 | 12篇 |
1982年 | 12篇 |
1981年 | 14篇 |
1980年 | 14篇 |
1979年 | 7篇 |
1978年 | 14篇 |
1977年 | 12篇 |
1976年 | 18篇 |
1974年 | 11篇 |
1973年 | 8篇 |
排序方式: 共有4464条查询结果,搜索用时 15 毫秒
21.
22.
23.
Guzanová Anna Draganovská Dagmar Ižaríková Gabriela Brezinová Janette Rajt’úková Viktória Živčák Jozef Hudák Radovan Janoško Erik Moro Róbert 《Journal of Mechanical Science and Technology》2021,35(10):4389-4404
Journal of Mechanical Science and Technology - The article deals with selective laser melting process using CoCrW powder. Our aim was to identify the influence of product position on the building... 相似文献
24.
The COVID-19 pandemic has affected the educational systems worldwide, leading to the near-total closures of schools, universities, and colleges. Universities need to adapt to changes to face this crisis without negatively affecting students’ performance. Accordingly, the purpose of this study is to identify and help solve to critical challenges and factors that influence the e-learning system for Computer Maintenance courses during the COVID-19 pandemic. The paper examines the effect of a hybrid modeling approach that uses Cloud Computing Services (CCS) and Virtual Reality (VR) in a Virtual Cloud Learning Environment (VCLE) system. The VCLE system provides students with various utilities and educational services such as presentation slides/text, data sharing, assignments, quizzes/tests, and chatrooms. In addition, learning through VR enables the students to simulate physical presence, and they respond well to VR environments that are closer to reality as they feel that they are an integral part of the environment. Also, the research presents a rubric assessment that the students can use to reflect on the skills they used during the course. The research findings offer useful suggestions for enabling students to become acquainted with the proposed system’s usage, especially during the COVID-19 pandemic, and for improving student achievement more than the traditional methods of learning. 相似文献
25.
26.
The breath figure (BF) method is an effective process for fabricating porous polymeric films. In this study, we fabricated porous polymer films from thermoplastic polyurethane (PU) through static BF with CHCl3 as a solvent under 55–80% relative humidity. The porous PU films were prepared within various pore structures and sizes, which were adjustable, depending on the fabrication conditions. The humidity and exposure time were examined as variable parameters affecting the surface morphology, wettability, and cytotoxicity. Atorvastatin calcium, a hyperlipidemic agent, was loaded into the porous films during the casting process, and the drug-loading and drug-releasing behaviors of the porous PU membranes were evaluated. Approximately 60–80% of the drug was released in 14 days. The films exhibited sustained drug-release performances because of the hydrophobicity and nonbiodegradable nature of PU for perivascular drug administration. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47658. 相似文献
27.
28.
A ternary ZnAl40Cu2 and a quaternary ZnAl40Cu2Si2.5 alloys were produced by permanent mold casting and subjected to T5 heat treatment at a temperature of 150 °C for 24 hours. The structural, mechanical and lubricated wear properties of these alloys were investigated in the as-cast and heat-treated conditions and the results were compared with those of SAE 65 (CuSn12) plain bearing bronze. Microstructure of the ternary alloy consisted of aluminum-rich α, eutectoid conversion product of α+η and ϵ phase located in the interdendritic channels. In addition to these phases, silicon particles were observed in the microstructure of the quaternary alloy. T5 heat treatment caused a considerable amount of reduction in the hardness, tensile strength and wear resistance of ZnAl40-based ternary and quaternary alloys, but improved their ductility and stability. These alloys in the as-cast and heat-treated conditions exhibited lower wear volume or higher wear resistance than SAE 65 bearing bronze. Among the experimental alloys, the optimum mechanical properties and wear performance were obtained from ZnAl40Cu2Si2.5 alloy in both as-cast and heat-treated conditions. Adhesion appeared to be the main wear mechanism for the ZnAl40-based alloys, but abrasion dominated the wear of SAE 65 bronze. 相似文献
29.
30.
Pamučar Dragan Sremac Siniša Stević Željko Ćirović Goran Tomić Dejan 《Neural computing & applications》2019,31(9):5045-5068
Neural Computing and Applications - Successfully organizing the transport of hazardous materials and handling them correctly is a very important logistical task that affects both the overall flow... 相似文献