全文获取类型
收费全文 | 719篇 |
免费 | 24篇 |
国内免费 | 23篇 |
专业分类
电工技术 | 15篇 |
综合类 | 3篇 |
化学工业 | 59篇 |
金属工艺 | 14篇 |
机械仪表 | 8篇 |
建筑科学 | 17篇 |
矿业工程 | 2篇 |
能源动力 | 16篇 |
轻工业 | 64篇 |
水利工程 | 4篇 |
石油天然气 | 7篇 |
武器工业 | 4篇 |
无线电 | 37篇 |
一般工业技术 | 118篇 |
冶金工业 | 311篇 |
原子能技术 | 17篇 |
自动化技术 | 70篇 |
出版年
2022年 | 5篇 |
2021年 | 2篇 |
2020年 | 2篇 |
2018年 | 5篇 |
2017年 | 12篇 |
2016年 | 6篇 |
2015年 | 4篇 |
2014年 | 10篇 |
2013年 | 15篇 |
2012年 | 19篇 |
2011年 | 33篇 |
2010年 | 31篇 |
2009年 | 18篇 |
2008年 | 29篇 |
2007年 | 18篇 |
2006年 | 23篇 |
2005年 | 10篇 |
2004年 | 34篇 |
2003年 | 9篇 |
2002年 | 20篇 |
2001年 | 11篇 |
2000年 | 13篇 |
1999年 | 29篇 |
1998年 | 69篇 |
1997年 | 54篇 |
1996年 | 44篇 |
1995年 | 31篇 |
1994年 | 65篇 |
1993年 | 20篇 |
1992年 | 9篇 |
1991年 | 12篇 |
1990年 | 10篇 |
1989年 | 11篇 |
1988年 | 8篇 |
1987年 | 6篇 |
1986年 | 7篇 |
1985年 | 2篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1977年 | 10篇 |
1976年 | 23篇 |
1972年 | 1篇 |
1968年 | 1篇 |
1967年 | 1篇 |
1960年 | 2篇 |
1959年 | 2篇 |
1958年 | 1篇 |
1943年 | 1篇 |
1882年 | 3篇 |
排序方式: 共有766条查询结果,搜索用时 31 毫秒
21.
G. Garib C. Vial F. Negroni E. G. Thomsen 《Journal of Materials Shaping Technology》1988,5(3):191-195
A hollow punch-torque method was used to measure friction between tough pitch copper and three different lubricants. The tests indicated that the coefficient μ is not a function of the applied pressure, while the friction factorm is. Both μ andm depend only slightly on the degree of prior deformation. The range of pressure investigated was that encountered in drawing operations and is below that for lubricated sliding surfaces where sublayer plastic flow occurs. 相似文献
22.
在自然崩落法相关研究的基础上,探讨了自然崩落法放矿控制的排产优化问题;给出了正向优化和逆向优化的数学模型,为实现均匀放矿提供了一种理想的理论方法。对充分发挥自然崩落法的优越性和提高矿产资源的回收率具有重要的理论和现实意义 相似文献
23.
24.
The aim of this project was to investigate the potential of reducing number of mixers in the biological treatment process and thereby achieve energy and economical savings and contribute to cleaner environment. The project was carried out at Avedoere wastewater treatment plant and a full scale investigation was conducted to study the effect of reduced mixing on flow velocity, suspended solid sedimentation, concentration gradients of oxygen and SS with depth and treatment efficiency. The only negative effect observed was on flow velocity; however the velocity was above the critical velocity. The plant has been operating with 50% of its designed number of mixers since September 2007 and long term results also confirm that reduced mixing did not have any negative effect on treatment efficiency. The estimated yearly electricity saving is 0.75 GWh/year. 相似文献
25.
A. P. Litvinchuk C. Thomsen M. Cardona L. Börjesson M. Käll P. Berastegui L. -G. Johansson 《Journal of Superconductivity》1994,7(1):113-116
We report a reflectivity study of thez-polarized TO-phonons of Pr
x
Y1–x
Ba2Cu4O8 and YBa2–y
Sr
y
Cu4O8 alloys in the temperature range 10–300 K. Anomalies of the frequency and linewidth of the plane-oxygen vibration at300 cm–1 due to the opening of the superconducting gap are found to occur upon crossing the superconducting transition temperatureT
c
. Phonon self-energy effects are strongly dependent onT
c
, providing evidence for a relative shift of the gap with respect to the energy of phonon.On leave from the Institute for Semiconductor Physics, Ukrainian Academy of Sciences, 252650 Kiev-28, Ukraine. 相似文献
26.
Six hooded crows (Corvus cornix) were trained in alternative simultaneous matching-to-sample and oddity-from-sample tasks with visual stimuli. Bird's ability to acquire the abstract same/different concept was investigated. For this purpose three stimulus sets of the following categories were used: color (black and white cards), shape (Arabic numerals "1" and "2"), and numerousness (heterogeneous arrays of 1 or 2 elements). These three sets were used for training successively and repeatedly; each time the stimulus set was changed for the next one after the criterion (80% correct or better over 30 successive trials) was reached with the previous one. The training procedure was repeated until the criterion could be reached for each of the three stimulus sets within the initial 30-50 trials. After that, the abstractness of the rule acquired by birds was tested. First, the "partial" transfer tests were conducted, which consisted in presentation of novel stimuli with familiar ones (numerals and arrays in the range from 1 to 4). At the final stage, only sets of novel numerals and arrays in the range from 5 to 8 were presented. The crows demonstrated successful transfer in all of these tests, including the test with absolutely novel stimuli (in the first 24 presentations: min 75.0%, p < 0.02; max 83.3%, p < 0.01). The level of correct choices did not differ from the baseline (p > 0.05). This allows us to conclude that birds are capable for formation of the abstract same/different concept. 相似文献
27.
RIa Vovin IIa Gurovich OF Eryshev SG Za?tsev AIu Magalif 《Canadian Metallurgical Quarterly》1977,77(5):743-749
The authors studied the effectiveness of out-patient treatment by Moditen-Deppt of 128 schizophrenic patients. A comparison of the previous remissions appearing during usual pharmacotherapy and remissions seen during Moditen-Depot treatment depicted statistically significant differences, indicating a distinct prevention of exacerbations due to this preparation, an increase in the duration and improved quality of remissions. Such improved remissions were expressed in lesser severity, in a decrease of psychopathological disturbances, changes qualified as a "mollification of a defect" and an improvement of some socio-clinical indices. 相似文献
28.
外流降膜板式蒸发器作为替代列管式蒸发器的新设备应用于氧化铝行业,其板片材质处于一个摸索选择的过程。本文就高合金不锈钢板片的失败事例进行分析,通过试验、试用,最终找到较为理想的材质。 相似文献
29.
30.
针对德兴铜矿设备状态监测的实际情况,论述了矿山设备润滑磨损状态监测系统,利用VB语言结合SQL Senrer开发设备润滑磨损状态分析系统。 相似文献