全文获取类型
收费全文 | 29104篇 |
免费 | 2121篇 |
国内免费 | 1670篇 |
专业分类
电工技术 | 475篇 |
技术理论 | 1篇 |
综合类 | 1311篇 |
化学工业 | 9707篇 |
金属工艺 | 7077篇 |
机械仪表 | 1217篇 |
建筑科学 | 1294篇 |
矿业工程 | 412篇 |
能源动力 | 675篇 |
轻工业 | 1671篇 |
水利工程 | 106篇 |
石油天然气 | 794篇 |
武器工业 | 216篇 |
无线电 | 1156篇 |
一般工业技术 | 5242篇 |
冶金工业 | 1239篇 |
原子能技术 | 172篇 |
自动化技术 | 130篇 |
出版年
2024年 | 156篇 |
2023年 | 576篇 |
2022年 | 849篇 |
2021年 | 947篇 |
2020年 | 936篇 |
2019年 | 858篇 |
2018年 | 894篇 |
2017年 | 1098篇 |
2016年 | 952篇 |
2015年 | 1017篇 |
2014年 | 1487篇 |
2013年 | 1599篇 |
2012年 | 1943篇 |
2011年 | 2184篇 |
2010年 | 1717篇 |
2009年 | 1726篇 |
2008年 | 1437篇 |
2007年 | 1758篇 |
2006年 | 1754篇 |
2005年 | 1494篇 |
2004年 | 1289篇 |
2003年 | 1069篇 |
2002年 | 948篇 |
2001年 | 763篇 |
2000年 | 696篇 |
1999年 | 512篇 |
1998年 | 437篇 |
1997年 | 331篇 |
1996年 | 311篇 |
1995年 | 254篇 |
1994年 | 199篇 |
1993年 | 166篇 |
1992年 | 162篇 |
1991年 | 100篇 |
1990年 | 92篇 |
1989年 | 80篇 |
1988年 | 21篇 |
1987年 | 12篇 |
1986年 | 19篇 |
1985年 | 8篇 |
1984年 | 8篇 |
1983年 | 10篇 |
1982年 | 6篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1959年 | 4篇 |
1951年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
利用AES、WDS和x-射线衍射等方法,研究了杜美丝表面层、铁镍芯与覆铜层界面的微观结构与特性。结果表明:良好的表面层应由Cu2O和非晶态的硼砂构成;玻璃与杜美丝的润湿性决定于表面层的净化程度和构成及加热条件。 相似文献
42.
43.
Y.L. Yang D. Zhang H.S. Kou C. S. Liu 《金属学报(英文版)》2007,20(3):210-216
Laser cladded coatings of TiCN were produced on the surface of titanium. To obtain the optimal techniques, several conditions were tested by varying the laser scanning rate. The choice of shielding gas was also studied. The cladded coatings were then evaluated from the surface mechanics point of view based on their microhardness. The microstructure of some interesting samples was investigated by optical micrographs (OM). The results showed that under the condition of fixed pulse frequency and pulse width, the laser scanning rate and the shielding gas are the main factors influencing the components of coatings. TiCN coatings were decompounded and oxidized during the cladding process in the condition of no shielding gas of N2. X-ray diffraction results indicated that the composite coatings composed of TiCN, TiC, Ti2N, and TiO2 were produced using appropriate techniques. The results indicated that the best condition in terms of the surface microhardness is obtained when the scanning rate is 1.5mm/s, the pulse frequency is 15Hz, the pulse width is 3.0ms, and N2 is chosen as the shielding gas. The microhardness of the composite coatings is about 1331kg · mm^-2, which is about 4 times that of the substrate. The optical micrographs indicated that the cladding zone is made up of TiCN, TiO2 and some interdendritic Ti, but the diffusion zone mainly consists of the dendrites phase, and the cladded depth is about 80μm, which is more than 2 times that of the laser nitrided sample. There were no microcracks or air bubbles in the cladded sample, which was cladded using the above optimal techniques. 相似文献
44.
Konstantinos D Demadis 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2005,80(6):630-640
Dendrimers have attracted immense attention during the last decade due to their interesting properties both from a basic and an applied research viewpoint. Encapsulation of metal nanoparticles for catalysis, drug delivery and light harvesting are only some applications of dendrimers that are breaking new ground. A novel application of dendrimer technology is described in the present paper that relates to industrial water treatment. Industrial water systems often suffer from undesirable inorganic deposits. These can form either in the bulk or on metallic surfaces, such as heat exchangers or pipelines. Silica (SiO2) scale formation and deposition is a major problem in high‐silica‐containing cooling waters. Scale prevention rather than removal is highly desired. In this paper, benchtop screening tests on various silica inhibition chemistries are reported, with emphasis on materials with a dendrimeric structure. Specifically, the inhibition properties of commercially available STARBURST® polyaminoamide (PAMAM) dendrimers generations 0.5, 1, 1.5, 2, and 2.5 are investigated in detail together with other commonly‐used scale inhibitors. Experimental results show that inhibition efficiency largely depends on structural features of PAMAM dendrimers such as generation number and nature of the end groups. PAMAM dendrimers are effective inhibitors of silica scale growth at 40 ppm dosage levels. PAMAM dendrimers also act as silica nucleators, forming SiO2–PAMAM composites. This occurs because the SiO2 formed by incomplete inhibition interacts with cationic PAMAM‐1 and ‐2. The general scope of silica formation and inhibition in industrial waters is also discussed. Copyright © 2005 Society of Chemical Industry 相似文献
45.
R. van Tijum 《Surface & coatings technology》2007,201(8):4633-4639
This paper concentrates on revealing the local deformation as a function of applied strain in a polymer coating supported by a plastically deforming and roughening metal substrate. To this end in-situ birefringence microscopy measurements have been executed. The measurements are performed in reflection and an alternative unwrapping scheme for the optical path difference is proposed. From the characterization of PET (polyethylene terephthalate) coated stainless steel it is concluded that strain localization appears below the macroscopic strain at yield and that the surface roughness of the substrate is the driving force of the localization. 相似文献
46.
邓宏勃 《石油化工腐蚀与防护》1998,15(3):44-44
详细了介绍了锦州石化公司体育馆及附属设施钢架结构的防火及防火涂料涂装;讨论了钢架结构的防火,并且制定涂层的设计方案、施工工艺及质量验收标准等。 相似文献
47.
高性能鳞片涂料在脱硫烟囱防腐蚀中的应用 总被引:1,自引:0,他引:1
李静 《有色冶金设计与研究》2006,27(6):10-12,16
分析了湿法烟气脱硫工艺对脱硫装置及烟囱的腐蚀情况,对几种典型的衬里结构进行比较,介绍了高性能防腐蚀鳞片涂料的应用要求和工程实例。 相似文献
48.
Interfaces play an important role in determining the mechanical properties of composite materials. The interfaces established between a titanium-alloy matrix (Ti-6Al-4V) and uncoated and TiB2/C-coated SiC fibres are analysed by scanning electron microscopy, transmission electron microscopy and X-ray techniques. Emphasis is placed upon the interfacial morphology and microstructure, identification of reaction products, and the stability of the coating layer. Complex multi-reaction layers are observed frequently in the interfacial zones. Previous, often contradictory, reports about the interlayers are reviewed. Experimental observation demonstrates that the type and distribution of interlayers vary in a given system, due to prolonged treatment of the samples at temperature. The formation and distribution of the interlayers are discussed further, with respect to these and previous findings. Methods of reducing interfacial reactivity are discussed. 相似文献
49.
50.