全文获取类型
收费全文 | 32130篇 |
免费 | 4148篇 |
国内免费 | 2538篇 |
专业分类
电工技术 | 5143篇 |
技术理论 | 1篇 |
综合类 | 3013篇 |
化学工业 | 1858篇 |
金属工艺 | 1979篇 |
机械仪表 | 4758篇 |
建筑科学 | 3067篇 |
矿业工程 | 1943篇 |
能源动力 | 1198篇 |
轻工业 | 309篇 |
水利工程 | 959篇 |
石油天然气 | 1129篇 |
武器工业 | 601篇 |
无线电 | 2021篇 |
一般工业技术 | 3730篇 |
冶金工业 | 1169篇 |
原子能技术 | 392篇 |
自动化技术 | 5546篇 |
出版年
2024年 | 202篇 |
2023年 | 547篇 |
2022年 | 1120篇 |
2021年 | 1260篇 |
2020年 | 1184篇 |
2019年 | 991篇 |
2018年 | 840篇 |
2017年 | 1093篇 |
2016年 | 1229篇 |
2015年 | 1352篇 |
2014年 | 2029篇 |
2013年 | 1881篇 |
2012年 | 2351篇 |
2011年 | 2579篇 |
2010年 | 1951篇 |
2009年 | 1960篇 |
2008年 | 1843篇 |
2007年 | 2224篇 |
2006年 | 2134篇 |
2005年 | 1705篇 |
2004年 | 1469篇 |
2003年 | 1271篇 |
2002年 | 1053篇 |
2001年 | 869篇 |
2000年 | 652篇 |
1999年 | 601篇 |
1998年 | 442篇 |
1997年 | 392篇 |
1996年 | 309篇 |
1995年 | 269篇 |
1994年 | 203篇 |
1993年 | 168篇 |
1992年 | 120篇 |
1991年 | 101篇 |
1990年 | 75篇 |
1989年 | 65篇 |
1988年 | 59篇 |
1987年 | 24篇 |
1986年 | 19篇 |
1985年 | 27篇 |
1984年 | 15篇 |
1983年 | 17篇 |
1982年 | 9篇 |
1980年 | 11篇 |
1979年 | 15篇 |
1963年 | 6篇 |
1961年 | 8篇 |
1960年 | 6篇 |
1959年 | 8篇 |
1955年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
82.
83.
84.
85.
乙烯装置失效模式分析及基于风险的检验 总被引:1,自引:0,他引:1
简述了乙烯装置的工艺流程,分析了装置中常见的几种失效模式及其分布;以乙烯裂解装置为例,简述了RBI的执行过程和结果,从基于风险的检验理念,对制订设备检验策略提出了几点建议。 相似文献
86.
Uncertainty of Predictions of Embankment Dam Breach Parameters 总被引:3,自引:0,他引:3
Tony L. Wahl 《Canadian Metallurgical Quarterly》2004,130(5):389-397
Risk assessment studies considering the failure of embankment dams often require the prediction of basic geometric and temporal parameters of a breach, or the estimation of peak breach outflows. Many of the relations most commonly used to make these predictions were developed from statistical analyses of data collected from historic dam failures. The prediction uncertainties of these methods are widely recognized to be very large, but have never been specifically quantified. This paper presents an analysis of the uncertainty of many of these breach parameter and peak flow prediction methods. Application of the methods and the uncertainty analysis are illustrated through a case study of a risk assessment recently performed by the Bureau of Reclamation for a large embankment dam in North Dakota. 相似文献
87.
通过现场振动故障诊断案例的分析,找出了炼油企业中泵振动故障的原因主要是泵转子不平衡、小流量、泵转子与壳体不同心、泵轴承故障等。并在停机检修后发现故障产生的原因与诊断的相符,大大降低了故障诊断的难度,快捷、准确地解决问题,为企业效益最大化奠定了基础。 相似文献
88.
W. J. PLUMBRIDGE Y. KARIYA 《Fatigue & Fracture of Engineering Materials & Structures》2004,27(8):723-734
With continuing miniaturisation, increased performance demands and the requirement to remove lead from solder alloys, the challenges to structural integrity and reliability of electronic equipment are substantial and increasing. This paper outlines typical features in electronic equipment of which the structural integrity community may be generally unaware. Potential failure modes in service are described, and the problems of scale and material characteristics are considered. Progress in the application of fracture mechanics to the life prediction of interconnections is reviewed. The limited evidence available suggests that the crack growth resistance of silver‐containing lead‐free solders is superior to that of the traditional Sn‐37Pb under cycle‐controlled conditions but there is no difference when time‐dependent conditions prevail. In several respects, it is contended that the electronics sector is faced with challenges at least equivalent to those encountered in gas turbines and nuclear power generation. 相似文献
89.
The apparent tensile strength of technical flax fibers was determined in single‐fiber tests at various clamping lengths (20, 40, and 80 mm) and the outcome was compared with literature data. It was demonstrated that the strength of flax at each clamping length obeyed the two‐parameter Weibull model. The failure mode and sequence were studied in situ (i.e., during loading) by SEM and acoustic emission (AE). The failure sequence (axial splitting of the technical fiber along its elementary constituents, radial cracking of the elementary fibers, multiple fracture of the elementary fibers) concluded reflected the hierarchical build‐up of the flax bast fibers. To the above failure events AE amplitude ranges were assigned. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3638–3645, 2003 相似文献
90.
Stress Heterogeneity Effect on the Strength of Silicon Nitride 总被引:1,自引:0,他引:1
François Hild Elisabeth Amer Didier Marquis 《Journal of the American Ceramic Society》1992,75(3):700-702
The experiments reported in this paper demonstrate the causes of the failure of monolithic ceramics. The specimens are made of silicon nitride and tested at room temperature. The stress field within the specimen is different for each of four series of tests that have been conducted. Fractographic observations have also been made to identify the causes of the failures. A size effect analysis is performed. 相似文献