全文获取类型
收费全文 | 60329篇 |
免费 | 4611篇 |
国内免费 | 2036篇 |
专业分类
电工技术 | 726篇 |
技术理论 | 1篇 |
综合类 | 7922篇 |
化学工业 | 3210篇 |
金属工艺 | 1933篇 |
机械仪表 | 1611篇 |
建筑科学 | 30215篇 |
矿业工程 | 1245篇 |
能源动力 | 714篇 |
轻工业 | 338篇 |
水利工程 | 5022篇 |
石油天然气 | 476篇 |
武器工业 | 270篇 |
无线电 | 4020篇 |
一般工业技术 | 5997篇 |
冶金工业 | 1198篇 |
原子能技术 | 1166篇 |
自动化技术 | 912篇 |
出版年
2024年 | 164篇 |
2023年 | 444篇 |
2022年 | 1018篇 |
2021年 | 1228篇 |
2020年 | 1353篇 |
2019年 | 1003篇 |
2018年 | 1146篇 |
2017年 | 1478篇 |
2016年 | 1581篇 |
2015年 | 1952篇 |
2014年 | 3792篇 |
2013年 | 2836篇 |
2012年 | 4144篇 |
2011年 | 4611篇 |
2010年 | 3534篇 |
2009年 | 4332篇 |
2008年 | 4129篇 |
2007年 | 4927篇 |
2006年 | 4049篇 |
2005年 | 3514篇 |
2004年 | 2741篇 |
2003年 | 2434篇 |
2002年 | 2113篇 |
2001年 | 1706篇 |
2000年 | 1446篇 |
1999年 | 1132篇 |
1998年 | 842篇 |
1997年 | 689篇 |
1996年 | 566篇 |
1995年 | 439篇 |
1994年 | 391篇 |
1993年 | 271篇 |
1992年 | 212篇 |
1991年 | 164篇 |
1990年 | 130篇 |
1989年 | 103篇 |
1988年 | 89篇 |
1987年 | 67篇 |
1986年 | 46篇 |
1985年 | 21篇 |
1984年 | 28篇 |
1983年 | 21篇 |
1982年 | 28篇 |
1981年 | 5篇 |
1980年 | 32篇 |
1979年 | 5篇 |
1975年 | 2篇 |
1962年 | 1篇 |
1959年 | 13篇 |
1957年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Yoshiyuki Uno Akira Okada Kensuke Uemura Purwadi Raharjo Toshihiko Furukawa Kosaku Karato 《Precision Engineering》2005,29(4):171-455
A new finishing process for metal molds by large-area electron beam (EB) irradiation is proposed in this study. In the large-area EB irradiation equipment used here, an EB with high-energy density is irradiated without focusing the beam, and so the EB with a maximum diameter of 60 mm can be used for melting or evaporating metal surface instantly. Experimental results show that the surface roughness decreases from 6 μmRz to less than 1 μmRz in just a few minutes under proper machining conditions. The corrosion resistance of metal mold surface also could be greatly improved by large-area EB irradiation. Furthermore, the surface roughness of tilting surface close to 90° could be well improved. Therefore, large-area EB irradiation method has a possibility to become a high-efficiency finishing process for metal molds. 相似文献
82.
83.
对气囊在路基压实密度检测、空心板梁制作和大型混凝土构件搬运中的运用进行了分析,指出将气囊这种先进的施工工艺应用到建筑施工中,加快了施工进度,确保了工程施工质量,并降低了工程施工成本,值得推广使用。 相似文献
84.
正交频分多址(OFDM:orthogonal frequency division multiplexing)技术由于其在多径环境下克服码间干扰的固有特点,在移动通信中已得到广泛地应用。利用阵列天线上行链路信号到达角估计实时信息,计算OFDM系统下行链路阵列天线权重,将阵列天线应用于下行链路中,最后给出系统误码率性能的计算机仿真结果。 相似文献
85.
It is essential to automate the scanning path generation process to effectively implement the micro-stereolithography. However, a scanning path that is generated based only on a 3D CAD model introduces dimensional inaccuracies. In micro-stereolithography, the photopolymer solidification is affected by fabrication conditions, such as the optical properties (laser power, laser scanning speed, laser scanning pitch focusing condition, etc.) and material properties of the photopolymer. Thus, the photopolymer solidification phenomena must be considered when generating a laser scanning path. In this paper, a scanning path generation algorithm that uses 3D CAD data and considers the photopolymer solidification phenomena is proposed to improve the dimensional accuracy in micro-stereolithography. Multi-line photopolymer solidification experiments were performed for various laser scanning conditions to examine the photopolymer solidification phenomena. From these experiments, linear relations between the solidification length (width) and scanning length (width) were acquired and stored in a database. Subsequently, these data were utilized to compensate the scanning path of the laser beam. In addition, experiments for determining the layer thickness in the z-direction were performed and these results were also used in the scanning path generation algorithm.This research was supported by the Highly Advanced National Project (http://www.most.go.kr), which performs some of the National R&D Program, and sponsored by the Korean Ministry of Science and Technology under the contract project code M10214000116-02B1500-02010. 相似文献
86.
Olaf Kessler 《Surface & coatings technology》2006,201(7):4046-4051
For a proper use of coated tools and components excellent coating properties as well as excellent substrate properties of the coating/substrate composite are necessary. A well known example is the load support of hard steel substrates for thin wear resistant coatings. Therefore coating processes must be combined with heat treatment processes of the substrates, whereby several practical processing constraints like order and compatibility of the applied treatment procedures must be considered. The combination of CVD-coating plus laser beam hardening is an example of a post coating heat treatment. Applications may be possible for large forming tools made of high alloyed tool steels, which nowadays are usually through hardened after CVD-coating. Laser beam hardening offers the possibility, to harden only the highly loaded edges of the tools. The advantages of this combination are short process time, less distortion and compressive residual stresses in the substrate surface. CVD-coatings can endure laser beam hardening with suitable parameters. The influence of CVD TiN-coated steel substrates and laser beam hardening parameters on microstructures and properties of coating/substrate compounds have been investigated. Special attention was paid to overlapping hardening zones, which may occur at the start and end points of a laser hardened track. In summary, the combination of coating and heat treatment processes show a high potential to produce coating/substrate compounds with excellent coating properties as well as excellent substrate properties. 相似文献
87.
运用Excel软件,高效解决了混凝土结构计算中较复杂的圆形截面偏压构件的承载力计算问题。该编程计算方法同样适用于土力学、水力学、钢结构等领域。对于解决工程中的各种学科计算问题有着广阔的应用前景。 相似文献
88.
混凝土浇筑质量对钢管混凝土性能的影响 总被引:3,自引:0,他引:3
着重阐述钢管与其核心砼粘结强度对钢管砼承载影响问题 ,并介绍三种常用浇筑方式和检测方法。 相似文献
89.
提出了一种应用于电子束曝光机束流测量中的自动跟踪工频陷波器,给出电路结构,基于对其工作原理的分析,介绍了提高陷波器跟踪精度的设计要点及调试方法。 相似文献
90.
大体积砼裂缝问题是建筑业普通关心的问题.对砼裂缝进行控制,就必须研究砼结构中裂缝产生的原因以及在实际的设计和施工过程中采取合理的、经济的措施来控制裂缝.本文通过对大体积砼裂缝成因的理论研究,提出了合理的裂缝控制的设计和施工措施. 相似文献