全文获取类型
收费全文 | 9605篇 |
免费 | 1124篇 |
国内免费 | 430篇 |
专业分类
电工技术 | 819篇 |
技术理论 | 1篇 |
综合类 | 605篇 |
化学工业 | 1531篇 |
金属工艺 | 583篇 |
机械仪表 | 571篇 |
建筑科学 | 846篇 |
矿业工程 | 390篇 |
能源动力 | 280篇 |
轻工业 | 629篇 |
水利工程 | 268篇 |
石油天然气 | 494篇 |
武器工业 | 73篇 |
无线电 | 1170篇 |
一般工业技术 | 1152篇 |
冶金工业 | 471篇 |
原子能技术 | 142篇 |
自动化技术 | 1134篇 |
出版年
2024年 | 64篇 |
2023年 | 219篇 |
2022年 | 436篇 |
2021年 | 581篇 |
2020年 | 399篇 |
2019年 | 344篇 |
2018年 | 353篇 |
2017年 | 335篇 |
2016年 | 330篇 |
2015年 | 441篇 |
2014年 | 560篇 |
2013年 | 575篇 |
2012年 | 622篇 |
2011年 | 675篇 |
2010年 | 520篇 |
2009年 | 492篇 |
2008年 | 510篇 |
2007年 | 486篇 |
2006年 | 455篇 |
2005年 | 384篇 |
2004年 | 261篇 |
2003年 | 235篇 |
2002年 | 237篇 |
2001年 | 183篇 |
2000年 | 237篇 |
1999年 | 226篇 |
1998年 | 170篇 |
1997年 | 145篇 |
1996年 | 148篇 |
1995年 | 111篇 |
1994年 | 98篇 |
1993年 | 60篇 |
1992年 | 73篇 |
1991年 | 45篇 |
1990年 | 35篇 |
1989年 | 27篇 |
1988年 | 21篇 |
1987年 | 8篇 |
1986年 | 12篇 |
1985年 | 8篇 |
1984年 | 5篇 |
1983年 | 4篇 |
1982年 | 6篇 |
1979年 | 3篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1967年 | 1篇 |
1966年 | 2篇 |
1959年 | 2篇 |
1951年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 234 毫秒
51.
针对一起瓦斯流量计复线泄漏原因进行现场调查和原因分析,为了确保该系统长周期安全运行,提出相应的对策。 相似文献
52.
A novel Conformal Finite-Difference Time-Domain based on Alternating-Direction Implicit Method(ADI-CFDTD) used to calculate the microwave attenuation on coplanar waveguide(CPW) with complicated cross-section up to 200GHz is presented. This ADI-CFDTD algorithm is the combination of conformal algorithm dealing with the deformed cell with ADI-FDTD, and has unconditionally stable. The difference equations are derived from the Faraday's and Ampere's law. To validate its accuracy and efficiency, as an example, a CPW fabricated on lithium niobate is proposed. Numerical results demonstrate that this new ADI-CFDTD algorithm has more accuracy than that of quasi-static and CFDTD and shows good agreement with experiment data. When frequency is up to millimeter wave band the radiation loss is not negligible in total power loss. 相似文献
53.
54.
单井注水吞吐在塔河油田的应用 总被引:3,自引:0,他引:3
在塔河油田开发生产过程中,个别油井在修井作业中出现先漏后喷的现象。在修井完成后,产量较前期有大幅增加。针对这类油井进行单井注水吞吐采油试验,研究发现钻遇定容封闭性油藏的油井适合单井注水吞吐开采。一方面利用油水重力分异,抬升油水界面,增加采出量;另一方面注水补充地层能量,恢复地层压力。该方法在塔河油田实际应用中,取得了较好的效果和较高的经济效益,也为提高定容封闭性油藏油井的采收率提供了一个较好的方法。 相似文献
55.
F. Kusmanto G. Walker Q. Gan P. Walsh F. Buchanan G. Dickson M. McCaigue C. Maggs M. Dring 《Chemical engineering journal (Lausanne, Switzerland : 1996)》2008,139(2):398-407
The aims of this work were to investigate the conversion of a marine alga into hydroxyapatite (HA), and furthermore to design a composite bone tissue engineering scaffold comprising the synthesised HA within a porous bioresorbable polymer. The marine alga, Phymatolithon calcareum, which exhibits a calcium carbonate honeycomb structure, with a natural architecture of interconnecting permeable pores (microporosity 4–11 μm), provided the initial raw material for this study. The objective was to convert the alga into hydroxyapatite while maintaining its porous morphology using a sequential pyrolysis and chemical synthesis processes. Semi-quantitative XRD analysis of the post-hydrothermal material (pyrolised at 700–750 °C), indicated that the calcium phosphate (CaP) ceramic most likely consisted of a calcium carbonate macroporous lattice, with hydroxyapatite crystals on the surface of the macropores. Cell visibility (cytotoxicity) investigations of osteogenic cells were conducted on the CaP ceramic (i.e., the material post-hydrothermal analysis) which was found to be non-cytotoxic and displayed good biocompatibility when seeded with MG63 cells. Furthermore, a hot press scaffold fabrication technique was developed to produce a composite scaffold of CaP (derived from the marine alga) in a polycaprolactone (PCL) matrix. A salt leaching technique was further explored to introduce macroporosity to the structure (50–200 μm). Analysis indicated that the scaffold contained both micro/macroporosity and mechanical strength, considered necessary for bone tissue engineering applications. 相似文献
56.
用分光光度计测定了12例兔角膜和1例人角膜的吸收光谱,结果表明波长小于300nm的准分子激光和波长在1.88μm~2.64μm,2.36μm~40μm的激光,均可对角膜进行切割并可望用于激光角膜矫正术。 相似文献
57.
58.
Y.X. Gan 《Materials and Manufacturing Processes》1994,9(2):263-280
This paper concerns electrolytic metallic coatings for carbon fibers and the related processes. Plating bath design, electrolyte selection and other aspects were investigated. Experimental results especially in copper electroplating show that the uniformity of metallic coatings on carbon fibers can be improved by the modification of plating bath and the selection of electrolytes. Thus continuous and uniform metallic coatings can be obtained on carbon fibers, even if the cross section of carbon fibers has irregular shape. Polarization tests on different copper baths was performed. Electrodeposition of other metallic layers such as nickel, cobalt, and copper/tin duplex layer was also introduced. A process of two or more than two plating steps in which different electrolytes may be used for same metal deposition was proposed to expedite the coating procedure 相似文献
59.
60.
介绍了我国紫菜工业在工艺改进、资源开发、综合利用和深度加工等方面的情况,提出了提高产率、降低物耗、增进效益和增加品种的途径。 相似文献