全文获取类型
收费全文 | 47892篇 |
免费 | 3112篇 |
国内免费 | 2537篇 |
专业分类
电工技术 | 1830篇 |
技术理论 | 2篇 |
综合类 | 3030篇 |
化学工业 | 8757篇 |
金属工艺 | 8107篇 |
机械仪表 | 2457篇 |
建筑科学 | 3987篇 |
矿业工程 | 1323篇 |
能源动力 | 1239篇 |
轻工业 | 2922篇 |
水利工程 | 911篇 |
石油天然气 | 2070篇 |
武器工业 | 804篇 |
无线电 | 4747篇 |
一般工业技术 | 6151篇 |
冶金工业 | 2285篇 |
原子能技术 | 419篇 |
自动化技术 | 2500篇 |
出版年
2024年 | 167篇 |
2023年 | 628篇 |
2022年 | 904篇 |
2021年 | 1002篇 |
2020年 | 1008篇 |
2019年 | 966篇 |
2018年 | 994篇 |
2017年 | 1309篇 |
2016年 | 1238篇 |
2015年 | 1287篇 |
2014年 | 2139篇 |
2013年 | 2203篇 |
2012年 | 2964篇 |
2011年 | 3368篇 |
2010年 | 2728篇 |
2009年 | 2763篇 |
2008年 | 2829篇 |
2007年 | 3654篇 |
2006年 | 3480篇 |
2005年 | 2999篇 |
2004年 | 2616篇 |
2003年 | 2185篇 |
2002年 | 1793篇 |
2001年 | 1562篇 |
2000年 | 1346篇 |
1999年 | 1027篇 |
1998年 | 845篇 |
1997年 | 670篇 |
1996年 | 599篇 |
1995年 | 505篇 |
1994年 | 392篇 |
1993年 | 318篇 |
1992年 | 276篇 |
1991年 | 179篇 |
1990年 | 146篇 |
1989年 | 128篇 |
1988年 | 85篇 |
1987年 | 40篇 |
1986年 | 55篇 |
1985年 | 23篇 |
1984年 | 11篇 |
1983年 | 16篇 |
1982年 | 11篇 |
1981年 | 10篇 |
1980年 | 14篇 |
1979年 | 4篇 |
1966年 | 6篇 |
1964年 | 4篇 |
1957年 | 7篇 |
1955年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
钱塘江光缆管穿越长度2454.15m,穿越深度为32m,穿越中采用了多项新技术、新工艺、新方法。文章介绍了导向孔对穿技术、套管技术、水下磁场电缆铺设技术、长距离泥浆回流技术、长距离穿越钻杆组合技术在钱塘江光缆管穿越施工中的应用。 相似文献
82.
We have assessed the antimicrobial, vapor-phase activity of the following natural essential oils (EOs) when used in paraffin-based “active coatings” for paper packaging materials intended to come into contact with foods: clove (Sygzium aromaticum), cinnamon (Cinnamomum zeylanicum), and oregano (Origanum vulgare) EOs, and cinnamaldehyde-enriched cinnamon EO. To our knowledge, this is the first time that such an approach has been presented for consideration by the scientific community. 相似文献
83.
SWRH82B冶炼过程中几个工艺问题的探讨 总被引:1,自引:0,他引:1
通过对天津钢铁有限公司在SWRH82B钢冶炼过程中工艺数据的整理分析,就转炉冶炼终点如何实现高碳低磷和优化工序操作提出一些改进措施。 相似文献
84.
85.
Thermal analysis of a ceramic coating diesel engine piston using 3-D finite element method 总被引:1,自引:0,他引:1
In this study, firstly, thermal analyses are investigated on a conventional (uncoated) diesel piston, made of aluminum silicon alloy and steel. Secondly, thermal analyses are performed on pistons, coated with MgO-ZrO2 material by means of using a commercial code, namely ANSYS. Finally, the results of four different pistons are compared with each other. The effects of coatings on the thermal behaviors of the pistons are investigated. It has been shown that the maximum surface temperature of the coated piston with material which has low thermal conductivity is improved approximately 48% for the AlSi alloy and 35% for the steel. 相似文献
86.
A nanocrystalline coating of K38G alloy was obtained by means of magnetron sputtering. The corrosion behavior of cast K38G alloy and its sputtered nanocrystalline coating with a solid NaCl deposit in dry air or wet oxygen at 600 and 700°C have been studied and compared. The results indicated that the mass gain of the coating is higher than that of the cast alloy at 600 and 700°C. Therefore, nanocrystallization reduced the corrosion resistance at these temperatures. Furthermore, the mass gains of the coating and the cast alloy with a NaCl deposit in wet oxygen were less than that with a NaCl deposit in dry air. The relevant corrosion mechanisms are discussed. 相似文献
87.
A silicide coating was prepared on Ti3SiC2-based ceramic by pack cementation to improve the oxidation resistance of Ti3SiC2, which is a technologically important material for high temperature applications. The microstructure, phase composition and
oxidation resistance of the coated sample were investigated. The results demonstrated that the silicide coating was mainly
composed of TiSi2 and SiC. A single layer of a mixture of SiO2 and TiO2 was formed on the surface of the coated sample during isothermal oxidation at 1100 °C and 1200 °C for 20h. Compared to Ti3SiC2, the parabolic rate constant of silicide coated Ti3SiC2 decreased by 2~3 orders of magnitude. Furthermore, the coated sample showed much better cyclic oxidation resistance than
Ti3SiC2 during the cyclic oxidation at 1100 °C for 400 times. However, during the preparation of the coating, a number of fine cracks
formed in the outer layer of the coating. When these cracks penetrated the whole coating during the cyclic oxidation, the
oxidation rate was accelerated, which degraded the oxidation resistance.
Electronic Publication 相似文献
88.
以乙醇为溶剂,正硅酸乙酯(TEOS,tetraethoxysilane)在氢氧化铵催化下水解缩聚为纳米尺度的无定型SiO2溶胶颗粒,二甲基二乙氧基硅烷(DDS,dimethyldiethoxysilane)在盐酸催化下水解缩聚为线状聚二甲基硅氧链.用混合溶胶在玻璃基片上旋转镀膜,然后于80℃空气气氛下热处理.实验证明通过DDS将疏水的双甲基链引入镀膜胶体,使膜兼具疏水性和减反射性能.利用激光散射粒度分析仪和电子显微镜研究了溶胶颗粒的粒度变化和聚集情况等溶胶微结构,用物理吸附仪研究了膜的孔结构,考察了热处理前后膜的疏水性和透射谱,得到了溶胶微结构与膜性能之间的关联. 相似文献
89.
90.
介绍了长江江新洲堤段应用软体排护岸新型技术的情况,结合长江江新洲护岸工程对软体排施工、工艺、设备作简要叙述。 相似文献