全文获取类型
收费全文 | 249253篇 |
免费 | 1674篇 |
国内免费 | 265篇 |
专业分类
电工技术 | 4044篇 |
综合类 | 91篇 |
化学工业 | 40400篇 |
金属工艺 | 15147篇 |
机械仪表 | 10070篇 |
建筑科学 | 4179篇 |
矿业工程 | 3759篇 |
能源动力 | 3888篇 |
轻工业 | 9708篇 |
水利工程 | 4088篇 |
石油天然气 | 13007篇 |
武器工业 | 28篇 |
无线电 | 20235篇 |
一般工业技术 | 62801篇 |
冶金工业 | 32134篇 |
原子能技术 | 11134篇 |
自动化技术 | 16479篇 |
出版年
2021年 | 2770篇 |
2019年 | 2750篇 |
2018年 | 5457篇 |
2017年 | 5728篇 |
2016年 | 6056篇 |
2015年 | 3065篇 |
2014年 | 5336篇 |
2013年 | 10099篇 |
2012年 | 7326篇 |
2011年 | 8944篇 |
2010年 | 7305篇 |
2009年 | 8109篇 |
2008年 | 8185篇 |
2007年 | 7869篇 |
2006年 | 6360篇 |
2005年 | 5571篇 |
2004年 | 5485篇 |
2003年 | 5303篇 |
2002年 | 5134篇 |
2001年 | 4950篇 |
2000年 | 4937篇 |
1999年 | 4253篇 |
1998年 | 7174篇 |
1997年 | 5831篇 |
1996年 | 4421篇 |
1995年 | 3653篇 |
1994年 | 3422篇 |
1993年 | 3623篇 |
1992年 | 3214篇 |
1991年 | 3359篇 |
1990年 | 3481篇 |
1989年 | 3369篇 |
1988年 | 3267篇 |
1987年 | 3260篇 |
1986年 | 3156篇 |
1985年 | 3314篇 |
1984年 | 3252篇 |
1983年 | 3146篇 |
1982年 | 2993篇 |
1981年 | 3045篇 |
1980年 | 3071篇 |
1979年 | 3257篇 |
1978年 | 3490篇 |
1977年 | 3460篇 |
1976年 | 3911篇 |
1975年 | 3209篇 |
1974年 | 3293篇 |
1973年 | 3341篇 |
1972年 | 2987篇 |
1971年 | 2754篇 |
排序方式: 共有10000条查询结果,搜索用时 11 毫秒
101.
V. N. Perevezentsev M. Yu. Shcherban’ M. Yu. Murashkin R. Z. Valiev 《Technical Physics Letters》2007,33(8):648-650
The structure and mechanical properties of nanocrystalline aluminum alloy 1570 obtained by means of severe plastic deformation have been studied. Being tested in a temperature range from 300 to 400°C, the alloy exhibits high-strain-rate superplasticity. At 400°C, the superplasticity is manifested in a very broad range of strain rates, extending from 5 × 10?3 to 1 s?1. 相似文献
102.
103.
104.
O Bernard B Chachuat A Hélias B Le Dantec B Sialve J-P Steyer L Lardon P Neveu S Lambert J Gallop M Dixon P Ratini A Quintabà S Frattesi J M Lema E Roca G Ruiz J Rodriguez A Franco P Vanrolleghem U Zaher D J W De Pauw K De Neve K Lievens D Dochaine O Schoefs H Fibrianto R Farina V Alcaraz Gonzalez V Gonzalez Alvarez P Lemaire J A Martinez F Esandi O Duclaud J F Lavigne 《Water science and technology》2005,52(1-2):457-464
The TELEMAC project brings new methodologies from the Information and Science Technologies field to the world of water treatment. TELEMAC offers an advanced remote management system which adapts to most of the anaerobic wastewater treatment plants that do not benefit from a local expert in wastewater treatment. The TELEMAC system takes advantage of new sensors to better monitor the process dynamics and to run automatic controllers that stabilise the treatment plant, meet the depollution requirements and provide a biogas quality suitable for cogeneration. If the automatic system detects a failure which cannot be solved automatically or locally by a technician, then an expert from the TELEMAC Control Centre is contacted via the internet and manages the problem. 相似文献
105.
The article investigates the state of stress and strain of the surface of an elastic cylindrical shell whose outer part is subjected to the effect of an incident acoustic wave. A qualitative and quantitative analysis of the state of strain of the surface is carried out and recommendations are given for optimizing the functional purpose of the shell and minimizing the arising stresses.Translated from Problemy Prochnosti, No. 4, pp. 43–47, April, 1991. 相似文献
106.
V. I. Gorynin 《Strength of Materials》1991,23(5):524-527
The influence of the level of defectiveness of design and service origin (grooves and cracks) of a fastener and an impact specimen on the accuracy of determination of the allowable values of the ductile-to-brittle transition temperature is investigated. An evaluation of the allowable ductile-to-brittle transition temperatures making it possible to impose more soundly based requirements for effectiveness of the material in the stages of design, production, and service in relation to the production condition of the steel, the level of defectiveness of the fastener, and the specified operating life of the threaded joint is proposed.Translated from Problemy Prochnosti, No. 5, pp. 35–37, May, 1991. 相似文献
107.
J Byrne S Kienzle D Johnson G Duke V Gannon B Selinger J Thomas 《Water science and technology》2006,53(10):327-334
Long-term trends in alpine and prairie snow pack accumulation and melt are affecting streamflow within the Oldman River Basin in southern Alberta, Canada. Unchecked rural and urban development also has contributed to changes in water quality, including enhanced microbial populations and increased waterborne pathogen occurrence. In this study we look at changing environment within the Oldman River Basin and its impact on water quality and quantity. The cumulative effects include a decline in net water supplies, and declining quality resulting in increased risk of disease. Our data indicates that decreases in the rate of flow of water can result in sedimentation of bacterial contaminants within the water column. Water for ecosystems, urban consumption, recreation and distribution through irrigation is often drawn from waterholding facilities such as dams and weirs, and concern must be expressed over the potential for contaminate build-up and disproportionate potential of these structures to pose a risk to human and animal health. With disruption of natural flow rates for water resulting from environmental change such as global warming and/or human intervention, increased attention needs to be paid to use of best management practices to protect source water supplies. 相似文献
108.
Filled fibrous sorbents modified with transition metal ferro- and ferricyanides capable to recover americium(III) and rare-earth metals(III) from nitric acid solutions were prepared. The most complete and rapid recovery is attained on complex-forming and cation-exchange sorbents (as filled fibrous materials) saturated with nickel ions. The sorbents are characterized by good kinetic properties and can be used for recovery of the above metals. 相似文献
109.
A. B. Blyakhman A. V. Myakinkov A. G. Ryndyk 《Journal of Communications Technology and Electronics》2006,51(4):397-402
The maximum-likelihood technique is applied to determine the coordinates of moving targets in a three-dimensional bistatic forward-scattering radar. The potential accuracy of the coordinates’ determination is estimated. Simulation results are presented. 相似文献
110.