全文获取类型
收费全文 | 2684篇 |
免费 | 11篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 7篇 |
化学工业 | 36篇 |
金属工艺 | 3篇 |
机械仪表 | 8篇 |
建筑科学 | 14篇 |
矿业工程 | 4篇 |
能源动力 | 2篇 |
轻工业 | 69篇 |
水利工程 | 2篇 |
石油天然气 | 1篇 |
无线电 | 90篇 |
一般工业技术 | 26篇 |
冶金工业 | 2404篇 |
原子能技术 | 1篇 |
自动化技术 | 31篇 |
出版年
2022年 | 7篇 |
2021年 | 5篇 |
2020年 | 8篇 |
2019年 | 4篇 |
2017年 | 8篇 |
2016年 | 4篇 |
2015年 | 4篇 |
2014年 | 3篇 |
2013年 | 14篇 |
2012年 | 4篇 |
2011年 | 11篇 |
2010年 | 20篇 |
2009年 | 9篇 |
2008年 | 12篇 |
2007年 | 8篇 |
2006年 | 13篇 |
2005年 | 7篇 |
2004年 | 3篇 |
2003年 | 11篇 |
2001年 | 6篇 |
2000年 | 3篇 |
1999年 | 69篇 |
1998年 | 726篇 |
1997年 | 411篇 |
1996年 | 284篇 |
1995年 | 173篇 |
1994年 | 117篇 |
1993年 | 168篇 |
1992年 | 21篇 |
1991年 | 19篇 |
1990年 | 36篇 |
1989年 | 31篇 |
1988年 | 35篇 |
1987年 | 20篇 |
1986年 | 26篇 |
1985年 | 22篇 |
1984年 | 8篇 |
1983年 | 10篇 |
1982年 | 19篇 |
1981年 | 22篇 |
1980年 | 33篇 |
1979年 | 2篇 |
1978年 | 12篇 |
1977年 | 77篇 |
1976年 | 181篇 |
1975年 | 3篇 |
1968年 | 1篇 |
1965年 | 2篇 |
1962年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有2698条查询结果,搜索用时 15 毫秒
141.
AS Dubuisson M Foidart-Dessalle M Reznik JC Grosdent A Stevenaert 《Canadian Metallurgical Quarterly》1997,148(1):378-387
This study reevaluated the possibility of using predegenerated nerves as donor nerve allografts for nerve repair and compared the results of functional recovery to those obtained after standard, fresh nerve allograft repair. Twenty donor rats underwent a ligature/ section of the left sciatic nerve 4 weeks before nerve graft harvesting. Forty recipient rats underwent severing of the left sciatic nerve leaving a 15-mm gap between the nerve stumps. Graft repair was undertaken using either the predegenerated left sciatic nerve of the 20 donor rats (predegenerated group, 20 recipient rats) or the normal right sciatic nerve of the 20 donor rats (fresh group, 20 recipient rats). Recovery of function was assessed by gait analysis, electrophysiologic testing and histologic studies. Walking tracks measurements at 2 and 3 months, electromyography parameters at 2 and 3 months, peroperative nerve conduction velocity and nerve action potential amplitude measurements at 3 months, as well as assessments of myelinated nerve fiber density and surface of myelination showed that fresh and predegenerated nerve grafts induced a comparable return of function although there was some trend in higher electrophysiologic values in the predegenerated group. The only slight but significant difference was a larger mean nerve fiber diameter in the nerve segment distal to a predegenerated nerve graft compared to a fresh nerve graft. Although our study does not show a dramatic long-term advantage for predegenerated nerve grafts compared to fresh nerve grafts, their use as prosthetic material is encouraging. 相似文献
142.
GP Rossi G Albertin S Bova AS Belloni F Fallo U Pagotto L Trevisi G Palù AC Pessina GG Nussdorfer 《Canadian Metallurgical Quarterly》1997,138(10):4421-4426
143.
144.
G Gourdon P Dessen AS Lia C Junien H Hofmann-Radvanyi 《Canadian Metallurgical Quarterly》1997,40(2):73-77
The ultrastructural morphology of the interface region between the stria vascularis (SV) and spiral ligament (SL) was examined in the neonatal rat cochlea via transmission electron microscopy. At postnatal day (PND) 3, morphology of both basal cells and fibrocytes was simple and immature. Only a small number of fibrocytes was observed in the SL. Intercellular junctions between basal cells and fibrocytes, and between adjacent fibrocytes, were few. At PND 7, the number of fibrocytes increased, and more organelles appeared within their cytoplasm. From PND 11 to 14, nuclei of the basal cells appeared to be more spindle-shaped and contained more heterochromatin. The cytoplasm of the fibrocytes was pale, and a greater number of cytoplasmic vesicles and mitochondria emerged. More intercellular junctions were observed between basal cells and fibrocytes at the interface region and between fibrocytes in the SL. By PND 21, the morphology of basal cells and fibrocytes and their intercellular junctions appeared to be adult-like. These morphological observations correlate with previous reports on the functional maturation of the developing rat cochlea. 相似文献
145.
This paper presents five newly developed models to predict reliability of human operators performing time continous tasks under stress. Laplace transforms of state probability equations and operator reliability are developed. Mean time to human error (MTTHE) expressions are obtained. In addition specific plots are shown for selective models. 相似文献
146.
B.S. Dhillon 《Microelectronics Reliability》1989,29(2)
This paper discusses the subject of safety factors. An extensive list of references is presented. 相似文献
147.
D Reddy AS Pollock SA Clark K Sooy RC Vasavada AF Stewart T Honeyman S Christakos 《Canadian Metallurgical Quarterly》1997,94(5):1961-1966
148.
Harinder Singh Oberoi Sunil Bansal & Gurpreet Singh Dhillon 《International Journal of Food Science & Technology》2008,43(8):1499-1504
Among the five Kluyveromyces marxianus strains tested for β-galactosidase production, K. marxianus NCIM 3465 showed maximum enzyme activity of 1.62 IU mg−1 dry weight. Different levels (5–25%, w/v) of dried cauliflower waste were incorporated into whey to evaluate the effect of its supplementation on enzyme production. Although a marginal increase in enzyme production was seen by incorporating 5% and 10% cauliflower waste in whey, nearly 15% increase in β-galactosidase production was observed when cauliflower waste level was increased to 20% compared with whey alone. Supplementing whey with 20% cauliflower waste also decreased the production time. Lactose concentration in whey, mainly responsible for increasing the biological oxygen demand load of the effluent water, decreased from 4.2% to nearly 0% at 24 h. Thus, this study demonstrated that both these by-products/residues could be effectively used for β-galactosidase production at commercial scale. 相似文献
149.
150.