全文获取类型
收费全文 | 9289篇 |
免费 | 577篇 |
国内免费 | 472篇 |
专业分类
电工技术 | 454篇 |
技术理论 | 1篇 |
综合类 | 675篇 |
化学工业 | 389篇 |
金属工艺 | 650篇 |
机械仪表 | 1512篇 |
建筑科学 | 470篇 |
矿业工程 | 784篇 |
能源动力 | 286篇 |
轻工业 | 101篇 |
水利工程 | 126篇 |
石油天然气 | 201篇 |
武器工业 | 99篇 |
无线电 | 701篇 |
一般工业技术 | 2441篇 |
冶金工业 | 420篇 |
原子能技术 | 89篇 |
自动化技术 | 939篇 |
出版年
2024年 | 25篇 |
2023年 | 107篇 |
2022年 | 167篇 |
2021年 | 298篇 |
2020年 | 290篇 |
2019年 | 180篇 |
2018年 | 180篇 |
2017年 | 194篇 |
2016年 | 363篇 |
2015年 | 488篇 |
2014年 | 569篇 |
2013年 | 597篇 |
2012年 | 662篇 |
2011年 | 706篇 |
2010年 | 499篇 |
2009年 | 561篇 |
2008年 | 537篇 |
2007年 | 559篇 |
2006年 | 534篇 |
2005年 | 452篇 |
2004年 | 387篇 |
2003年 | 354篇 |
2002年 | 290篇 |
2001年 | 243篇 |
2000年 | 185篇 |
1999年 | 180篇 |
1998年 | 184篇 |
1997年 | 116篇 |
1996年 | 106篇 |
1995年 | 96篇 |
1994年 | 67篇 |
1993年 | 35篇 |
1992年 | 23篇 |
1991年 | 23篇 |
1990年 | 16篇 |
1989年 | 15篇 |
1988年 | 13篇 |
1987年 | 7篇 |
1986年 | 4篇 |
1985年 | 2篇 |
1984年 | 4篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1979年 | 2篇 |
1973年 | 3篇 |
1966年 | 2篇 |
1959年 | 1篇 |
1957年 | 2篇 |
1956年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 171 毫秒
31.
D. Srinivasa Rao H. Suresh Hebbar M. Komaraiah 《Materials and Manufacturing Processes》2007,22(7):825-829
Burnishing is used increasingly as a finishing operation which gives additional advantages such as increased hardness, fatigue strength, and wear resistance. Experimental work based on 34 factorial design was carried out to establish the effects of ball burnishing parameters on the surface hardness of high-strength low alloy steels (HSLA) dual-phase (DP) steel specimens. Statistical analysis of the results shows that the speed, feed, lubricant and ball diameter have significant effect on surface hardness. 相似文献
32.
The deformation characteristics of artificially cemented calcareous soil subjected to undrained cyclic triaxial loading are investigated at different confining pressure and cyclic stress levels. The influence of cementation on the shear stiffness is investigated by comparing the behavior of cemented and uncemented soils with similar initial conditions. It is observed that the deviator stress and the deviatoric strain at yield reduced with increasing number of cycles for cemented sand due to progressive degradation of bond, which results in significant decrease in stiffness. On the other hand, a strain-hardening effect is observed in uncemented sand and this results in increasing yield stress and strain with progressive number of cycles. A linear relationship between degradation index and number of cycles is observed for cemented sand. This relationship has been synthesized in the form of an empirical equation by modifying a previously proposed equation for cohesive soils. This empirical equation was further used to evaluate the fatigue life of soils by adopting a failure criterion. 相似文献
33.
A laboratory investigation was conducted to evaluate the fatigue behavior of an alternative pavement foundation material containing cement stabilized reclaimed crushed aggregate. Class C fly ash, and waste-plastic strip [high density polyethylene (HDPE)] reinforcement. The primary motivation for this research was to evaluate a composite that contained more than 90% recycled materials for use as an alternative foundation layer underneath conventional flexible or rigid pavement. The specific objectives of this study were (1) to evaluate the flexural fatigue behavior of the new composite, and (2) to evaluate the accumulation of fatigue damage in the material. The results indicate that the fatigue resistance of this material is similar to other traditional stabilized pavement materials. It was found that the dynamic elastic modulus remained approximately constant (degraded slowly) for most specimens up to the end of fatigue life. Fatigue damage computed using a dissipated energy approach showed that the damage accumulation in this material approximately follows Miner's rule for cumulative damage, which is often used in pavement engineering. 相似文献
34.
McKenna Frank P.; Horswill Mark S.; Alexander Jane L. 《Canadian Metallurgical Quarterly》2006,12(1):1
Skill and risk taking are argued to be independent and to require different remedial programs. However, it is possible to contend that skill-based training could be associated with an increase, a decrease, or no change in risk-taking behavior. In 3 experiments, the authors examined the influence of a skill-based training program (hazard perception) on the risk-taking behavior of car drivers (using video-based driving simulations). Experiment 1 demonstrated a decrease in risk taking for novice drivers. In Experiment 2, the authors examined the possibilities that the skills training might operate through either a nonspecific reduction in risk taking or a specific improvement in hazard perception. Evidence supported the latter. These findings were replicated in a more ecological context in Experiment 3, which compared advanced and nonadvanced police drivers. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
35.
G. Lange 《Materialwissenschaft und Werkstofftechnik》2003,34(1):80-85
Failures by notch induced fatigue fractures Notches produce local stress concentrations and promote the formation of fatigue cracks. Characteristic types of notches as a result of design, manufacturing and operation are presented and remedial measures are discussed. Examples demonstrate the effect of different kinds of notches on various components. 相似文献
36.
韩选江 《南京建筑工程学院学报》2002,(4):67-74
为有效保护地面上的生态环境,开发利用地下空间资源并营建新世纪的地下水城,在新的21世纪里将会建造更多的地下工程以满足人们生产生活的各种需要。文中介绍了地下工程施工中采用的逆作法、盾构法、新奥法、沉管隧道、顶管工程和大型沉井施工新技术,供同行们参考应用。 相似文献
37.
38.
涂层材料的断裂分析(英文) 总被引:1,自引:0,他引:1
和基体厚度相比,涂层很薄,因此细观力学模型可把基体作为半无限弹性体。由于涂层和基体材料的膨胀系数及弹性系数不匹配,涂层材料中残余热应力的解析解为 E_c/(1-γ_c)·(α_s-α_c)△T。用有限元法校核,该应力和解析解吻合得好。通过对涂层产生裂纹驱动力和断裂韧性的讨论,提出了抗裂涂层厚度公式。 相似文献
39.
本文通过对某液压挖掘机工作装置实验样本长度的研究,详细讨论了样本长度的确定方法,重点分析了趋势曲线拟合法,提出了样本长度精度区间分析的方法,并在处理大量实验数据的基础上,从载荷分布及寿命估算的角度做了实际的验证.编制了应用程序,使样本长度确定至寿命估算整个过程程序化. 相似文献
40.