全文获取类型
收费全文 | 217469篇 |
免费 | 21721篇 |
国内免费 | 7439篇 |
专业分类
电工技术 | 17659篇 |
技术理论 | 10篇 |
综合类 | 16027篇 |
化学工业 | 34969篇 |
金属工艺 | 12427篇 |
机械仪表 | 13706篇 |
建筑科学 | 17347篇 |
矿业工程 | 6814篇 |
能源动力 | 6344篇 |
轻工业 | 16838篇 |
水利工程 | 4878篇 |
石油天然气 | 9915篇 |
武器工业 | 2180篇 |
无线电 | 24440篇 |
一般工业技术 | 23073篇 |
冶金工业 | 7860篇 |
原子能技术 | 2417篇 |
自动化技术 | 29725篇 |
出版年
2025年 | 1011篇 |
2024年 | 4544篇 |
2023年 | 5000篇 |
2022年 | 6901篇 |
2021年 | 9734篇 |
2020年 | 8170篇 |
2019年 | 6408篇 |
2018年 | 6249篇 |
2017年 | 7077篇 |
2016年 | 6587篇 |
2015年 | 9326篇 |
2014年 | 11477篇 |
2013年 | 13833篇 |
2012年 | 14841篇 |
2011年 | 15290篇 |
2010年 | 14539篇 |
2009年 | 13931篇 |
2008年 | 13243篇 |
2007年 | 12542篇 |
2006年 | 11454篇 |
2005年 | 9161篇 |
2004年 | 6348篇 |
2003年 | 5427篇 |
2002年 | 5124篇 |
2001年 | 4467篇 |
2000年 | 3611篇 |
1999年 | 3003篇 |
1998年 | 2122篇 |
1997年 | 1737篇 |
1996年 | 1679篇 |
1995年 | 1450篇 |
1994年 | 1181篇 |
1993年 | 853篇 |
1992年 | 669篇 |
1991年 | 499篇 |
1990年 | 459篇 |
1989年 | 444篇 |
1988年 | 325篇 |
1987年 | 283篇 |
1986年 | 290篇 |
1985年 | 214篇 |
1984年 | 213篇 |
1983年 | 208篇 |
1982年 | 202篇 |
1981年 | 254篇 |
1980年 | 209篇 |
1975年 | 210篇 |
1974年 | 195篇 |
1973年 | 370篇 |
1972年 | 213篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Conventional drying, dehumidification drying, and combined conventional-dehumidification drying of wood were experimentally studied in this article. The results showed that the energy consumption in the dehumidification drying is the least but its drying time is the longest. The energy consumption in the combined drying is more than that in the dehumidification drying but less than that in the conventional drying, and the drying time is half of that in the dehumidification drying. The advantages of the combined conventional and dehumidification drying are discussed from the experiments results. 相似文献
32.
Prof. Dr. S. M. Rump 《Computing》1989,42(2-3):225-238
A method is described which produces guaranteed bounds for a solution of the generalized complex eigenproblem. The method extends a similar approach for general systems of nonlinear equations to the special case of complex pencils, where under weaker assumptions stronger assertions can be proved. 相似文献
33.
The Santa Amalia building in Barcelona is a block of six flats incorporating a duct by which ligth is sent to the kitchens - previously without natural ligthing- and also allows natural ventilation. Moreover, the passive solar gains obtained from the extensive glazed surfaces and the conservation of internal heat gains, along with a high degree of isulation, give energy saving of 68% for heating. 相似文献
34.
The iron rhenate was compounded by chemical method, which may be generated during wear process of Fe-Re alloys at elevated
temperature. The friction coefficient of iron rhenate has been determined by a pin-on-disc device. The results show that iron
rhenate plays role of lubricating at RT-600 °C. The lubricating behavior is related to the matching pairs. The hardness of
the materials of matching pairs, compatibility of iron rhenate with materials of matching pairs and surface roughness of disc
affect the lubricating behavior of iron rhenate mostly. The principle of matching pairs is proposed.
Project supported by the National Natural Science Foundation of China
Synopsis of the first author Xiong Dangsheng. associated professor, born in 1960. Current research fields include high-temperature self-lubricating alloys
and tribological properties of material. 相似文献
35.
张振伟 《消防技术与产品信息》2005,(2):28-32
通过科研成果转化的气体灭火系统目前己成为我所科技产业中的主导产品。其控制装置是其中关键配套设备。本文就其开发设计中的设计思想、技术原理、技术设计特色等作一阐述 相似文献
36.
Summary Stability of a twisted and axially compressed elastic rod is analysed using the Euler method of adjacent equilibrium configuration. The constitutive equations of the rod are assumed in the form that takes into account both shear of the cross-sections and compressibility of the rod axis. It is shown that bifurcation points of the non-linear system of equations describing equilibrium are determined from the linearized system of equations. The influence of shear and compressibility on the critical values of twisting couple and compressive force is obtained. Moreover, the bifurcation pattern is examined by using the Liapunov-Schmidt method. 相似文献
37.
Dr. H. Ploss 《Computing》1987,38(2):101-115
We will give an overview of the problem and then show how to modify an already present algorithm, so that it is also useful from a practical point of view. Further we will show that this algorithm is suitable for parallel computing and prove by means of an example that it can compete with the Bird algorithm, which is almost always applied by engineers but has only a heuristic base. 相似文献
38.
Experimental studies were made of the influence of mixing and casting techniques and of curing time upon the compressive strength and hardness of methyl methacrylate based polymer concrete. The Rockwell K and F scales were found to be suitable for the hardness determinations. Over a wide range of hardness and strength values, the average compressive strength (fc) varied linearly with the average hardness (RK) according to the relation fc (psi) = 560 RK - 12000, irrespective of casting and curing variables. The weaker materials exhibited greater variations in hardness. Hardness testing is found to provide a meaningful and convenient method for evaluating the quality of polymer concrete. 相似文献
39.
40.
Dr. W. Mack 《Acta Mechanica》1989,77(1-2):91-99
Summary The axisymmetric bulging of circular cylindrical rubber bars under end thrust is investigated. The results for different forms of the strain energy function are compared with experimental results.With 2 Figures 相似文献