全文获取类型
收费全文 | 1235篇 |
免费 | 12篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 2篇 |
综合类 | 3篇 |
化学工业 | 220篇 |
金属工艺 | 108篇 |
机械仪表 | 12篇 |
建筑科学 | 9篇 |
矿业工程 | 10篇 |
能源动力 | 1篇 |
轻工业 | 51篇 |
水利工程 | 8篇 |
石油天然气 | 64篇 |
无线电 | 32篇 |
一般工业技术 | 107篇 |
冶金工业 | 576篇 |
原子能技术 | 14篇 |
自动化技术 | 34篇 |
出版年
2021年 | 12篇 |
2019年 | 20篇 |
2018年 | 22篇 |
2017年 | 22篇 |
2016年 | 30篇 |
2015年 | 15篇 |
2014年 | 14篇 |
2013年 | 22篇 |
2012年 | 14篇 |
2011年 | 30篇 |
2010年 | 27篇 |
2009年 | 23篇 |
2008年 | 24篇 |
2007年 | 25篇 |
2006年 | 14篇 |
2005年 | 28篇 |
2004年 | 15篇 |
2003年 | 18篇 |
2002年 | 9篇 |
2001年 | 9篇 |
2000年 | 18篇 |
1998年 | 131篇 |
1997年 | 86篇 |
1996年 | 71篇 |
1995年 | 38篇 |
1994年 | 25篇 |
1993年 | 33篇 |
1992年 | 14篇 |
1991年 | 13篇 |
1990年 | 16篇 |
1989年 | 12篇 |
1988年 | 12篇 |
1987年 | 15篇 |
1986年 | 16篇 |
1985年 | 9篇 |
1984年 | 13篇 |
1983年 | 11篇 |
1982年 | 14篇 |
1981年 | 10篇 |
1979年 | 8篇 |
1978年 | 19篇 |
1977年 | 43篇 |
1976年 | 85篇 |
1975年 | 13篇 |
1974年 | 16篇 |
1972年 | 15篇 |
1971年 | 9篇 |
1968年 | 9篇 |
1967年 | 8篇 |
1966年 | 8篇 |
排序方式: 共有1251条查询结果,搜索用时 15 毫秒
11.
12.
13.
14.
Nickel-titanium instruments purportedly resist deformation and loss of sharpness better than do stainless steel instruments but may be more susceptible to breakage. The processes of wear and breakage of nickel-titanium and stainless steel instruments were examined. Sixty files of five types (12 each) and three manufacturers were used. All were used repeatedly in curved canals until failure or for a maximum of 22 minutes. Each instrument was examined with scanning electron microscopy both new (control) and at spaced intervals for evidence of wear and fatigue. All new instruments were of good quality. Stainless steel instrument tended to wear the most rapidly, and next were nickel-titanium rotary instruments; the most resistant to wear were nickel-titanium hand instruments. There were few instrument separations. In general, nickel-titanium (particularly hand) instruments resisted deterioration better than did stainless steel. Nickel-titanium rotary instruments (2 of 12) had the most breakage. 相似文献
15.
16.
R. G. Grebenshchikov V. F. Popova A. K. Shirvinskaya 《Glass Physics and Chemistry》2003,29(5):479-483
The phase equilibria in the LnAlO3–CaTiO3 (Ln = Dy, Y, Lu) systems are investigated and their phase diagrams are constructed for the first time. The thermal stability of the prepared solid solutions with a perovskite structure is studied. 相似文献
17.
18.
V. Z. Kutsova N. V. Popova A. G. Krimmel T. P. Chaikovskaya 《Metal Science and Heat Treatment》1992,34(11):704-707
Dnepropetrovsk Metallurgical Institute. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 11, pp. 31–33, November, 1992. 相似文献
19.
K Ivanov M Popova P Denev C Kratchanov 《Zeitschrift für Lebensmittel-Untersuchung und -Forschung》1992,195(5):455-458
Laboratory experiments have been carried out for the removal of heavy metals from hydrogenated vegetable oils using hydrated polyuronides (degree of swelling from 4 to 12.8 ml/g) such as alginic acid, pectic and pectinic acids. The effect of the type of polyuronide, degree of esterification and oil treatment on the degree of demetalization has been studied. It has been shown that with increase in the degree of esterification of the polyuronide the efficiency of demetalization decreases. The second and third treatment of the hydrogenated oil with pectinic acid resulted in a high degree of heavy metal removal. The possibility of efficient demetalization of hydrogenated oils by treatment with water solutions of pectinic acids has also been demonstrated. The degree of metal ion removal increases with decreasing concentration of pectinic acids in the water solution. 相似文献
20.
The authors assessed the method for life-time study of the biomechanical characteristics of ocular tissues in 281 children (562 eyes) aged 7 to 14 years. The method for assessing the biomechanics of the eyelids is described. In detail. The rates of propagation of acoustic waves in normal tissue and in 1.0 to 6.0 diopters myopia are presented. A correlation has been revealed between the increase of the velocity of acoustic surface waves, propagating in the horizontal direction in the internal segment of the orbital area of the upper eyelids, and the value of clinical refraction in myopia. The authors consider clinical signs of myopia-screwing up one's eyes and a wider lid slit-from a biomechanical viewpoint. 相似文献