全文获取类型
收费全文 | 116875篇 |
免费 | 12725篇 |
国内免费 | 8986篇 |
专业分类
电工技术 | 9962篇 |
技术理论 | 3篇 |
综合类 | 11811篇 |
化学工业 | 14640篇 |
金属工艺 | 8062篇 |
机械仪表 | 8452篇 |
建筑科学 | 8861篇 |
矿业工程 | 4109篇 |
能源动力 | 2912篇 |
轻工业 | 11986篇 |
水利工程 | 3966篇 |
石油天然气 | 4682篇 |
武器工业 | 1574篇 |
无线电 | 12336篇 |
一般工业技术 | 10406篇 |
冶金工业 | 5698篇 |
原子能技术 | 2042篇 |
自动化技术 | 17084篇 |
出版年
2024年 | 604篇 |
2023年 | 1604篇 |
2022年 | 4039篇 |
2021年 | 5227篇 |
2020年 | 3769篇 |
2019年 | 2766篇 |
2018年 | 2950篇 |
2017年 | 3485篇 |
2016年 | 3136篇 |
2015年 | 5004篇 |
2014年 | 6288篇 |
2013年 | 7544篇 |
2012年 | 9321篇 |
2011年 | 9963篇 |
2010年 | 9720篇 |
2009年 | 9067篇 |
2008年 | 9367篇 |
2007年 | 8975篇 |
2006年 | 8025篇 |
2005年 | 6523篇 |
2004年 | 4676篇 |
2003年 | 3291篇 |
2002年 | 3215篇 |
2001年 | 2896篇 |
2000年 | 2162篇 |
1999年 | 1169篇 |
1998年 | 798篇 |
1997年 | 582篇 |
1996年 | 469篇 |
1995年 | 342篇 |
1994年 | 292篇 |
1993年 | 251篇 |
1992年 | 163篇 |
1991年 | 151篇 |
1990年 | 111篇 |
1989年 | 132篇 |
1988年 | 74篇 |
1987年 | 48篇 |
1986年 | 45篇 |
1985年 | 35篇 |
1984年 | 16篇 |
1983年 | 19篇 |
1982年 | 15篇 |
1981年 | 27篇 |
1980年 | 37篇 |
1979年 | 20篇 |
1977年 | 43篇 |
1976年 | 83篇 |
1959年 | 15篇 |
1951年 | 18篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Hua Zhu Hai Zhang Tian-hao Zhang Shi-jin Yu Ping-chun Guo Yan-xiang Wang Zhi-sheng Yang 《Ceramics International》2021,47(12):16980-16985
Indium Tin Oxide (ITO) films were prepared, at room temperature, on a fluorphlogopite substrate using magnetron sputtering technology. At various temperatures of 500 °C, 600 °C, 700 °C, 800 °C, and 900 °C, the samples were (had) annealed for 2 h (a 2-h duration). The results showed improvement in the crystalline performance of ITO film at selected annealing temperatures, with a significant reduction in resistivity at 800 °C. The lowest resistivity is 4.08 × 10?4 Ω-cm, which is nearly an order of magnitude lower than the unannealed sample. All samples have an average light transmittance above 85% in the visible light range (400–800 nm), and with increasing annealing temperature, the average light transmittance tends to decrease. Besides, at the sensitive wavelength of 550 nm, the light transmittance is as high as 93.74%. The sheet resistance testing of the sample was through the number of bending times, which revealed that with the increase of the number of bending, the sheet resistance increases. However, after 1200 bending times, the change rate of the sheet resistance remains below 5%. Thus, the ITO film prepared on the flexible fluorphlogopite substrate revealed excellent optical and electrical properties, good flexibility, and improved stability after high-temperature annealing, which guarantees successful application in flexible electronic devices. 相似文献
2.
分析目前工程总承包其他费的现状及问题,并对比研究工程总承包其他费与施工管理措施费、工程建设其他费的区别和联系,探讨工程总承包其他费的构成内容与计取规则. 相似文献
3.
4.
Peng Li Haibin Jiang Ariel Barr Zhichu Ren Rui Gao Hua Wang Weiwei Fan Meifang Zhu Guiyin Xu Ju Li 《Advanced functional materials》2021,31(51):2105845
Mercury, lead, and cadmium are among the most toxic and carcinogenic heavy metal ions (HMIs), posing serious threats to the sustainability of aquatic ecosystems and public health. There is an urgent need to remove these ions from water by a cheap but green process. Traditional methods have insufficient removal efficiency and reusability. Structurally robust, large surface-area adsorbents functionalized with high-selectivity affinity to HMIs are attractive filter materials. Here, an adsorbent prepared by vulcanization of polyacrylonitrile (PAN), a nitrogen-rich polymer, is reported, giving rise to PAN-S nanoparticles with cyclic π-conjugated backbone and electronic conductivity. PAN-S can be coated on ultra-robust melamine (ML) foam by simple dipping and drying. In agreement with hard/soft acid/base theory, N- and S-containing soft Lewis bases have strong binding to Hg2+, Pb2+, Cu2+, and Cd2+, with extraordinary capture efficiency and performance stability. Furthermore, the used filters, when collected and electrochemically biased in a recycling bath, can release the HMIs into the bath and electrodeposit on the counter-electrode as metallic Hg0, Pb0, Cu0, and Cd0, and the PAN-S@ML filter can then be reused at least 6 times as new. The electronically conductive PAN-S@ML filter can be fabricated cheaply and holds promise for scale-up applications. 相似文献
5.
A new aqueous slurry-based laminated object manufacturing process for porous ceramics is proposed: firstly, an organic mesh sheet is pre-paved as a pore-forming template before slurry layer scraping; secondly, the 2D pattern is built with laser outline cutting of the dried mesh–ceramic composite layer; finally, the pore structure is formed after degreasing and sintering. Alumina parts with porosities of 51.5 %, round hole diameters of 80 ± 5 μm were fabricated using 70 wt. % solid content slurry and 100 mesh nylon net. Using an organic mesh as the framework and template not only reduces the risk of damage of the green body but also ensures the regularity, uniformity and connectivity of the micron scaled pore network. The layer-by-layer drying method avoids the delamination phenomenon and improves the paving density. The new method can realize the flexible design of the pore structure by using various organic mesh templates. 相似文献
6.
在公交时间表下给定起始和目标站点,路径规划查询返回一组到达时间早和换乘次数少的帕雷托最优路径.现有的索引方法需要大量运行时内存.本文提出主存空间高效的索引方法(a-)PAINT.(a-)PAINT对每个站点v预计算一组标签,使得对于从站点s到站点d的查询可以通过匹配s和d相关的标签高效地生成查询结果的一条路径.PAINT对任意查询返回最优路径.a-PAINT只需要很小的预处理开销,但可能返回多一趟换乘的次优路径.用真实的公交时间表与模拟查询测试,PAINT具有合理的预处理开销.a-PAINT需要更少量的预处理开销,在大规模公交网络下准确率达90%. 相似文献
7.
不同给液方式对铜电解过程中有重要的影响,不同的循环方式会影响槽内温度分布、电解液成分及阳极泥沉降等,因此,根据铜电解生产不同情况的需要,分析对比了多种给液方式在贵冶电解车间的应用,总结了这几种给液方式的优缺点和适用条件。 相似文献
8.
9.
10.