全文获取类型
收费全文 | 266138篇 |
免费 | 24704篇 |
国内免费 | 12716篇 |
专业分类
电工技术 | 24879篇 |
技术理论 | 32篇 |
综合类 | 26283篇 |
化学工业 | 29165篇 |
金属工艺 | 13095篇 |
机械仪表 | 18369篇 |
建筑科学 | 31901篇 |
矿业工程 | 14807篇 |
能源动力 | 9163篇 |
轻工业 | 19214篇 |
水利工程 | 11114篇 |
石油天然气 | 12565篇 |
武器工业 | 3515篇 |
无线电 | 17915篇 |
一般工业技术 | 19243篇 |
冶金工业 | 13508篇 |
原子能技术 | 1842篇 |
自动化技术 | 36948篇 |
出版年
2024年 | 1348篇 |
2023年 | 3883篇 |
2022年 | 7173篇 |
2021年 | 9174篇 |
2020年 | 9073篇 |
2019年 | 6795篇 |
2018年 | 6317篇 |
2017年 | 8065篇 |
2016年 | 9479篇 |
2015年 | 10329篇 |
2014年 | 18119篇 |
2013年 | 15720篇 |
2012年 | 19393篇 |
2011年 | 21247篇 |
2010年 | 15486篇 |
2009年 | 15674篇 |
2008年 | 14481篇 |
2007年 | 17636篇 |
2006年 | 16162篇 |
2005年 | 13992篇 |
2004年 | 11502篇 |
2003年 | 9962篇 |
2002年 | 8156篇 |
2001年 | 6801篇 |
2000年 | 5744篇 |
1999年 | 4505篇 |
1998年 | 3233篇 |
1997年 | 2802篇 |
1996年 | 2276篇 |
1995年 | 1926篇 |
1994年 | 1604篇 |
1993年 | 1147篇 |
1992年 | 900篇 |
1991年 | 642篇 |
1990年 | 553篇 |
1989年 | 530篇 |
1988年 | 316篇 |
1987年 | 214篇 |
1986年 | 192篇 |
1985年 | 200篇 |
1984年 | 141篇 |
1983年 | 129篇 |
1982年 | 74篇 |
1981年 | 81篇 |
1980年 | 87篇 |
1979年 | 44篇 |
1978年 | 26篇 |
1977年 | 24篇 |
1975年 | 17篇 |
1959年 | 29篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
本文通过焊接试验对奥氏体不锈钢绕带容器环板与绕带焊接工艺进行了研究分析,并得出了合理的焊接方法和工艺参数。 相似文献
52.
53.
Combined shape and sizing optimization of truss structures 总被引:1,自引:0,他引:1
In this paper, an evolutionary optimization method is presented for weight minimum problem of a 3-dimensional truss structure
in terms of nodal coordinates and element cross-sectional areas. The structure is subject to stress, local buckling and displacement
constraints. Two types of design variables with different natures are optimized separately: (1) a fully stressed design (FSD)
and scaling techniques are applied to sizing variables and (2) the evolutionary node shift method is applied to shape variables.
Alternating procedure is utilized to couple the two types of variables and to combine the results. The optimum solution is
achieved gradually from the initial configuration design. Two typical truss structures are examined to illustrate the validity
of the method.
Received: 22 October 2001 / Accepted: 04 June 2002
This research work is supported by the National Natural Science Foundation of China under the guarantees no. 10072050 and
10172072, respectively. 相似文献
54.
A. Rac 《Tribology International》1985,18(1):29-33
The wear of grey cast iron in dry sliding conditions has been studied with the aims of (1) finding the influence of working conditions on the wear rate, and (2) determining the region of speed and load where low wear is accomplished. Grey cast iron with flake and nodular graphite was submitted to investigation using a pin-on-disc machine. The results indicate that the flake graphite cast iron is more suitable for applications at speeds greater than 4 m s−1 and lower loads, while nodular cast iron has greater wear resistance at lower speeds in the range of loads investigated - from 50 N cm−2 to 200 N cm−2 相似文献
55.
56.
本文简要地介绍了我国几个地下矿在锚喷网联合支护的硐室工程中堵漏防渗处理所取得的良好效果,可供类似矿山参考。 相似文献
57.
This article presents a two-dimensional transient model for gas-solids flow and heat transfer through pipes using the coupled Computational Fluid Dynamics and Discrete Element Method approach. Numerical simulations have been conducted to examine the modification of fluid thermal structure due to the presence of particles in a pneumatic transport pipeline. Modeled results have demonstrated the key role of transversal motion of rebounding particles in the pipe cross section in altering fluid temperature. Further implementation of this modeling technique in air-drying processes is discussed and possible experimental methods for the measurement of in situ particle and fluid motion and temperature profile are cited. 相似文献
58.
J. C. Jones H. Rahmati T. D. H. Do 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1992,54(4):317-318
Wood shaving samples were heated in both cubic baskets and in a previously described system realising the conditions of the ‘infinite slab’ in thermal ignition. Results from the two sets of experiment were found to be totally consistent with each other. 相似文献
59.
A survey was carried out of past and current Canadian experiences with machine-aided translation (MAT) systems of non-literary texts in one government institution and three industrial settings. Each organization requires a great deal of translation and had conducted several experiments in the use of MAT. The survey supports positive conclusions about the prospects for expanded use of computers in translation.The authors express their thanks to all those who helped in the preparation of this paper. We are particularly grateful to the staff of the translation departments of the organizations mentioned in the paper for their kind cooperation and their willingness to answer our questions: Chantal Delorme ofIBM Canada, Lorraine Desmarais and Mr. Plamondon of Bell Canada, Pierre Tellier of the Department of the Secretary of State, Maria Russo and Raymond Lapointe of the Xerox Corporation. Furthermore we thank Prof. Graeme Hirst for helpful discussion. 相似文献
60.
求文针对我国天然气凝液如何利用问题,结合新技术进展,进行了初步探讨,认为原料较多的场合,应以催化脱氢或芳构化作为当前的主要加工方向。对原料较少的场合,也提出一些看法。 相似文献