全文获取类型
收费全文 | 88764篇 |
免费 | 9814篇 |
国内免费 | 5361篇 |
专业分类
电工技术 | 13538篇 |
技术理论 | 15篇 |
综合类 | 6897篇 |
化学工业 | 9511篇 |
金属工艺 | 2812篇 |
机械仪表 | 4002篇 |
建筑科学 | 11407篇 |
矿业工程 | 2716篇 |
能源动力 | 13118篇 |
轻工业 | 2519篇 |
水利工程 | 2857篇 |
石油天然气 | 2638篇 |
武器工业 | 823篇 |
无线电 | 7371篇 |
一般工业技术 | 8849篇 |
冶金工业 | 4362篇 |
原子能技术 | 1633篇 |
自动化技术 | 8871篇 |
出版年
2024年 | 560篇 |
2023年 | 1844篇 |
2022年 | 3032篇 |
2021年 | 3364篇 |
2020年 | 3630篇 |
2019年 | 3203篇 |
2018年 | 2731篇 |
2017年 | 3345篇 |
2016年 | 3749篇 |
2015年 | 3722篇 |
2014年 | 6171篇 |
2013年 | 5898篇 |
2012年 | 6576篇 |
2011年 | 7249篇 |
2010年 | 5515篇 |
2009年 | 5643篇 |
2008年 | 5184篇 |
2007年 | 5672篇 |
2006年 | 4629篇 |
2005年 | 3663篇 |
2004年 | 3003篇 |
2003年 | 2609篇 |
2002年 | 2265篇 |
2001年 | 1908篇 |
2000年 | 1635篇 |
1999年 | 1306篇 |
1998年 | 991篇 |
1997年 | 788篇 |
1996年 | 708篇 |
1995年 | 538篇 |
1994年 | 512篇 |
1993年 | 384篇 |
1992年 | 302篇 |
1991年 | 267篇 |
1990年 | 209篇 |
1989年 | 188篇 |
1988年 | 149篇 |
1987年 | 106篇 |
1986年 | 83篇 |
1985年 | 109篇 |
1984年 | 96篇 |
1983年 | 59篇 |
1982年 | 77篇 |
1981年 | 36篇 |
1980年 | 49篇 |
1979年 | 33篇 |
1978年 | 17篇 |
1977年 | 13篇 |
1964年 | 22篇 |
1951年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
Bar-Anan Yoav; Liberman Nira; Trope Yaacov; Algom Daniel 《Canadian Metallurgical Quarterly》2007,136(4):610
A picture-word version of the Stroop task was used to test the automatic activation of psychological distance by words carrying various senses of psychological distance: temporal (tomorrow, in a year), social (friend, enemy), and hypotheticality (sure, maybe). The pictures implied depth, with the words appearing relatively close to or distant from the observer. The participants classified the spatial distance of words faster when the word's implicit psychological distance matched its spatial distance (e.g., a geographically close word was classified faster when it was "friend" than when it was "enemy"). The findings are consistent with the idea that psychological distance is accessed automatically, even when it is not directly related to people's current goals, and suggest that psychological distance is an important dimension of meaning, common to spatial distance, temporal distance, social distance, and hypotheticality. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
92.
冷弯型钢纵向变形的理论分析及计算 总被引:5,自引:0,他引:5
对冷弯型钢的纵向变形过程进行了力学分析,得到了变形微分方程,求得了转动角的理论公式,并对其变形形状进行了分析计算。 相似文献
93.
热处理工艺对冲击曲线的影响 总被引:1,自引:0,他引:1
通过SA515Gr.70钢的不同温度正火和13MnNiMoNbR钢正火不同温度回火试样的示波冲击试验,研究了不同热处理工艺对冲击曲线的影响。 相似文献
94.
K.K. Padmanabhan 《Tribology International》1992,25(5)
Metallic mating surfaces in structural joints offer a good source of frictional energy dissipation resulting in a damped dynamic structural response. This paper reports the results of experiments where the energy dissipation per cycle occurring at a preloaded flat metallic annular interface subjected to cyclic tangential forces is measured. The effects of certain pertinent joint variables on this frictional energy dissipation are investigated by the application of Response Surface Methodology. A central composite rotatable design was utilized for developing empirical expressions for energy loss. The methodology presented suggests a useful technique for tribological research. 相似文献
95.
The change in the internal energy during uniaxial tensile deformation of austenitic stainless steels EN 1.4301 (AISI 304) and EN 1.4318 (AISI 301LN) was determined by measuring the extent of γ→α'‐martensite transformation and the temperature increase of the samples. From the results the fraction of the stored energy of cold work and the free energy change related to the strain‐induced γ→α'‐martensite transformation were determined. The fraction of stored energy varied around 0.4. With the metastable steel grades the free energy change related to the γ→α'‐martensite transformation was found to vary between ‐98 MJ/m3 and ‐206 MJ/m3 depending on the austenite stability of the steel. Furthermore, the magnitude of the mechanical driving force was estimated by comparing the results with the free energy change of thermally induced transformation. 相似文献
96.
Precise timing and asynchronous I/O are appealing features for many applications. Unix kernels provide such features on a per‐process basis, using signals to communicate asynchronous events to applications. Per‐process signals and timers are grossly inadequate for complex multithreaded applications that require per‐thread signals and timers that operate at finer granularity. To respond to this need, we present a scheme that integrates asynchronous (Unix) signals with user‐level threads, using the ARIADNE system as a platform. This is done with a view towards support for portable, multithreaded, and multiprotocol distributed applications, namely the CLAM (connectionless, lightweight, and multiway) communications library. In the same context, we propose the use of continuations as an efficient mechanism for reducing thread context‐switching and busy‐wait overheads in multithreaded protocols. Our proposal for integrating timers and signal‐handling mechanisms not only solves problems related to race conditions, but also offers an efficient and flexible interface for timing and signalling threads. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
97.
A complete mathematicalhumerical model is proposed, in order to simulate the performance characteristics of a novel concept of a drying heat pump based on the theory of minimum energy cyclcs. The drying heat pump involvcs vapour condensation in a Lava1 nozzle. removal of the liquid phase in a supersonic separator as well as compression of the working medium. which is superheared vapour. 相似文献
98.
99.
高能粒子辐照对零膨胀微晶玻璃光学性质和面形光学稳定性的影响 总被引:2,自引:1,他引:1
研究了高能电子,高能质子对VO2微晶玻璃辐照前后光性质和面形光学稳定性的影响,研究结果表明,高能电子辐照能引起微晶玻璃面形明显变化,且使VO2微晶玻璃强烈着色。高能质子辐照没引起面形明显变化,高能质子辐照对反射光谱特性没有影响。 相似文献
100.
介绍了中国铝业贵州分公司在能源统计和管理、节能技术改造、资源综合利用和清洁生产方面所采取的措施和取得的效果。 相似文献