全文获取类型
收费全文 | 760篇 |
免费 | 15篇 |
专业分类
电工技术 | 4篇 |
化学工业 | 112篇 |
金属工艺 | 6篇 |
机械仪表 | 13篇 |
建筑科学 | 40篇 |
能源动力 | 4篇 |
轻工业 | 85篇 |
水利工程 | 8篇 |
无线电 | 66篇 |
一般工业技术 | 135篇 |
冶金工业 | 230篇 |
原子能技术 | 1篇 |
自动化技术 | 71篇 |
出版年
2023年 | 5篇 |
2022年 | 4篇 |
2021年 | 12篇 |
2019年 | 12篇 |
2018年 | 16篇 |
2017年 | 14篇 |
2016年 | 11篇 |
2015年 | 5篇 |
2014年 | 4篇 |
2013年 | 51篇 |
2012年 | 24篇 |
2011年 | 40篇 |
2010年 | 22篇 |
2009年 | 17篇 |
2008年 | 18篇 |
2007年 | 24篇 |
2006年 | 17篇 |
2005年 | 20篇 |
2004年 | 17篇 |
2003年 | 17篇 |
2002年 | 8篇 |
2001年 | 12篇 |
2000年 | 11篇 |
1999年 | 11篇 |
1998年 | 61篇 |
1997年 | 49篇 |
1996年 | 26篇 |
1995年 | 15篇 |
1994年 | 14篇 |
1993年 | 19篇 |
1992年 | 7篇 |
1991年 | 5篇 |
1990年 | 11篇 |
1989年 | 10篇 |
1988年 | 8篇 |
1987年 | 10篇 |
1986年 | 5篇 |
1985年 | 7篇 |
1983年 | 8篇 |
1982年 | 11篇 |
1981年 | 8篇 |
1980年 | 13篇 |
1978年 | 6篇 |
1977年 | 8篇 |
1976年 | 10篇 |
1975年 | 6篇 |
1974年 | 5篇 |
1972年 | 4篇 |
1970年 | 7篇 |
1937年 | 5篇 |
排序方式: 共有775条查询结果,搜索用时 0 毫秒
121.
Measurements are reported of the properties of leaky surface waves propagating on 41° and 64° rotated cuts of LiNbO3 both on the free surface and under metal. Transducer and multistrip-coupler performance are consistent with piezo electric-coupling constants of 18° and 12%, respectively. Insertion-loss and spurious-signal-level results show that the interdigital transducer with few finger pairs is better matched to a metallised propagation path than to a free surface path for leaky waves. 相似文献
122.
A.B Newton 《International Journal of Refrigeration》1981,4(5):246-254
The history of the refrigeration compressor from 1865 onwards is described. The compressor is at the heart of almost all refrigeration systems, yet is largely taken for granted. 相似文献
123.
The paper considers the use of water and chemicals in the textile industry and the volume, nature and composition of process effluents, the effect they have on the environment and the limitations they pose on the reuse of water. An outline is given of the methods available for treatment of waste waters from the industry, on site or at a Water Authority's works and the effects that chemical constituents of the effluents have on the treatment processes and on disposal of water and sludge. The assessment and significance of biodegradability and the extent of present-day knowledge on the biodegradability of the main classes of chemicals used in textile processing are discussed. The paper concludes with a section dealing with the removal of colour from waste waters. 相似文献
124.
125.
Focused on the amount of physical activity in the recalled dreams of 27 paralyzed and 29 normal men. 1 hypothesis, derived from Rorschach's work, was that dreams are kinesthetic phenomena which continuously function to maintain body image. A 2nd, alternative hypothesis was that dreams serve an emergency repair function, buttressing body image only when the latter is in flux. While no general upsurge of kinesthetic dream content was found in the paralyzed-S group, recently paralyzed men were found to have more, and long-term paralyzed men less, kinesthetic dream content than did normal men. Results support the emergency repair theory of dream function. The necessity for a 2-factor theory of dream function is considered. (16 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
126.
127.
Tsang Leung Blanchard Andrew J. Newton Richard W. Kong Jin Au 《Geoscience and Remote Sensing, IEEE Transactions on》1982,(4):482-485
A simple approximate relation between backscattering coefficient and emissivity measurements is derived. The relation is applicable to active and passive microwave remote sensing of earth terrain where volume scattering plays a dominant role. From the relation, one can obtain a rough estimate of the backscattering coefficient from the emissivity and vice versa. Such estimation is useful in checking experimental measurements and also helps to ascertain the validity of theoretical models. It also safeguards against obtaining arbitrarily high values for both backscattering coefficients and emissivities. 相似文献
128.
The stacking fault probability, root-mean-square strain, and effective domain size are determined for pure silver and three Ag?Sn alloys using X-ray diffraction data. Both isochronal and isothermal annealing experiments were conducted to determine the nature of the recovery of plastic deformation in the filed powder specimens. An abrupt recovery of the above quantities was observed during isochronal annealing at temperatures that increased with solute concentration. Three recovery stages were observed in Ag-9 at. pct Sn annealed at 165°C for varying times. The principal stage is probably associated with recrystallization since both the stacking fault probability and rms strain recover together. An activation energy of 25 kcal per mol is determined for this stage. 相似文献
129.
This paper utilizes data from a series of worldwide surveys conducted from 1968 to 1980 for the U.S. Department of the Interior, Office of Saline Water and Office of Water Research and Technology as well as the recent literature to illustrate the improvements made in the materials selection process over the last several years. Trends in materials used for heat exchange tubing, flash chambers and components, pumps, water boxes, etc., are enumerated and evaluated with respect to likely service life as a function of the severity of operating conditions.Plant factor (percent of time operating at rated capacity) is correlated with design and to gain perspective is compared to plant factors achieved in the chemical processing industry generally.Present trade-off decisions with respect to materials, operating temperatures and conditions, performance factors, electrical energy consumption, and use of chemicals are summarized and commented upon. 相似文献
130.
Steve Newton 《Computer Communications》1985,8(3):115-120
As a result of the reduced costs of processing power and computer storage and the improvement in speech compression techniques, many new computer-based voice products have appeared. Of these, voice messaging is likely to have the most immediate impact. An explanation of the concepts involved in voice messaging systems is presented, and comparisons are made with conventional text and telephone communications systems. Some of the benefits of voice messaging systems and the ways in which they could be developed are outlined. 相似文献