全文获取类型
收费全文 | 48169篇 |
免费 | 4324篇 |
国内免费 | 2587篇 |
专业分类
电工技术 | 2153篇 |
技术理论 | 1篇 |
综合类 | 3578篇 |
化学工业 | 10732篇 |
金属工艺 | 3505篇 |
机械仪表 | 2722篇 |
建筑科学 | 5249篇 |
矿业工程 | 2118篇 |
能源动力 | 2405篇 |
轻工业 | 2748篇 |
水利工程 | 1027篇 |
石油天然气 | 1694篇 |
武器工业 | 785篇 |
无线电 | 2887篇 |
一般工业技术 | 8733篇 |
冶金工业 | 3023篇 |
原子能技术 | 503篇 |
自动化技术 | 1217篇 |
出版年
2024年 | 222篇 |
2023年 | 756篇 |
2022年 | 1331篇 |
2021年 | 1686篇 |
2020年 | 1603篇 |
2019年 | 1340篇 |
2018年 | 1269篇 |
2017年 | 1640篇 |
2016年 | 1606篇 |
2015年 | 1573篇 |
2014年 | 2443篇 |
2013年 | 2521篇 |
2012年 | 2955篇 |
2011年 | 3240篇 |
2010年 | 2493篇 |
2009年 | 2876篇 |
2008年 | 2388篇 |
2007年 | 3464篇 |
2006年 | 3117篇 |
2005年 | 2813篇 |
2004年 | 2336篇 |
2003年 | 2150篇 |
2002年 | 1766篇 |
2001年 | 1487篇 |
2000年 | 1350篇 |
1999年 | 989篇 |
1998年 | 748篇 |
1997年 | 609篇 |
1996年 | 536篇 |
1995年 | 432篇 |
1994年 | 379篇 |
1993年 | 265篇 |
1992年 | 172篇 |
1991年 | 112篇 |
1990年 | 94篇 |
1989年 | 97篇 |
1988年 | 69篇 |
1987年 | 25篇 |
1986年 | 16篇 |
1985年 | 20篇 |
1984年 | 12篇 |
1983年 | 11篇 |
1982年 | 5篇 |
1981年 | 4篇 |
1980年 | 7篇 |
1979年 | 4篇 |
1959年 | 5篇 |
1956年 | 3篇 |
1955年 | 4篇 |
1951年 | 15篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
WANG Jiqing 《声学技术》2004,23(Z3)
This paper gives an overview of the research at Institute of Acoustics, Tongji University, on functional absorbers and experience acquired in practical applications over the past three decades. Experiments and analysis of the absorption characteristics of three different geometrical forms of functional absorbers, i.e., panels, cubes and tubes, were conducted with different arrangements. The resulting esthetical effects are illustrated with pictures. Several non-fiber materials are used to compose functional absorbers with advantages both in acoustic properties and in architectural features. Cost effectiveness analysis is also given in order to provide design guidelines. 相似文献
92.
A new interaction integral formulation is developed for evaluating the elastic T-stress for mixed-mode crack problems with
arbitrarily oriented straight or curved cracks in orthotropic nonhomogeneous materials. The development includes both the
Lekhnitskii and Stroh formalisms. The former is physical and relatively simple, and the latter is mathematically elegant.
The gradation of orthotropic material properties is integrated into the element stiffness matrix using a “generalized isoparametric
formulation” and (special) graded elements. The specific types of material gradation considered include exponential and hyperbolic-tangent
functions, but micromechanics models can also be considered within the scope of the present formulation. This paper investigates
several fracture problems to validate the proposed method and also provides numerical solutions, which can be used as benchmark
results (e.g. investigation of fracture specimens). The accuracy of results is verified by comparison with analytical solutions. 相似文献
93.
94.
95.
The research was conducted to evaluate the effects of cellulose and polyester fibers on the properties of porous asphalt mixes, using the tests of draindown, abrasion, volumetric properties, rutting, and moisture damage. Images of scanning electron microscopy and X-ray computerized tomography were adopted to identify the microstructure of the fiber and inner stone skeleton of porous asphalt. The influence of rutting parameter (G*/sin δ) of asphalt modified by different fibers on the rutting resistance of the mixes was investigated. Based upon MOHR-COULOMB theory, the cohesion and the angle of internal friction of the mixes were derived from both indirect tension and unconfined compression strength. The experimental results indicate that fibers mainly stabilize asphalt binder and thicken asphalt film around aggregates. Furthermore, they result in the improved mechanical strength of porous asphalt mixes at high temperature slightly. From comparison analysis, cellulose fibers appear to perform better than polyester fibers in porous asphalt mixes. 相似文献
96.
阐述了硅铁生产中焦碳生产输送系统的工作原理和工艺要求,介绍了PLC在原料输送系统中的应用,给出了PLC的I/O接线图及程序框图,提出了工业原料生产输送控制系统的设计特点。 相似文献
97.
98.
Stress analysis of pin-loaded woven-glass fiber reinforced epoxy laminate conveying chain components
The aim of this study is to examine the effects of various loading conditions on the stress of a pin-loaded woven-glass fiber reinforced epoxy laminate conveying chain component. A numerical and experimental study was carried out to determine the stress distribution of composite conveying chain components used to convey loads. For the experimental study, an apparatus was developed to simulate chain components in real motion. Two different working conditions of the chain component were investigated. The first condition represents the movement of the chain components without loading. In the second condition, the chain component touches and moves the load. The commercial finite element package ANSYS was used to perform the numerical analysis using a three dimensional eight-noded layered structural solid elements. Chain tensile forces were loaded through pins and chosen as 250, 500, 750, 1000 and 1250 N for the two conditions of chain components. Experimental and numerical studies were compared and discussed for two conditions and five different tensile forces. A good agreement between experimental results and numerical predictions is obtained. 相似文献
99.
国家粮储库屋面防水APP卷材施工技术 总被引:1,自引:0,他引:1
针对国家粮食储备库的特点,就屋面防水APP卷材热熔法施工的施工准备及工艺流程进行了介绍,提出了具体的施工技术要点及质量通病的防治措施,取得了良好的施工效果。 相似文献
100.
赵惠琴 《有色冶金设计与研究》2004,25(4):4-8
根据所使用的低水泥浇注料的性能,对中铝山西分公司检修厂4号焙烧炉制定了合理的烘烤曲线,提高了耐火内衬的质量,延长了内衬的使用寿命。 相似文献