全文获取类型
收费全文 | 11855篇 |
免费 | 1214篇 |
国内免费 | 599篇 |
专业分类
电工技术 | 715篇 |
综合类 | 631篇 |
化学工业 | 1923篇 |
金属工艺 | 788篇 |
机械仪表 | 829篇 |
建筑科学 | 942篇 |
矿业工程 | 392篇 |
能源动力 | 306篇 |
轻工业 | 701篇 |
水利工程 | 249篇 |
石油天然气 | 885篇 |
武器工业 | 121篇 |
无线电 | 1400篇 |
一般工业技术 | 1424篇 |
冶金工业 | 680篇 |
原子能技术 | 150篇 |
自动化技术 | 1532篇 |
出版年
2024年 | 73篇 |
2023年 | 255篇 |
2022年 | 460篇 |
2021年 | 632篇 |
2020年 | 476篇 |
2019年 | 347篇 |
2018年 | 368篇 |
2017年 | 377篇 |
2016年 | 407篇 |
2015年 | 576篇 |
2014年 | 670篇 |
2013年 | 749篇 |
2012年 | 763篇 |
2011年 | 851篇 |
2010年 | 712篇 |
2009年 | 619篇 |
2008年 | 704篇 |
2007年 | 602篇 |
2006年 | 626篇 |
2005年 | 514篇 |
2004年 | 319篇 |
2003年 | 282篇 |
2002年 | 233篇 |
2001年 | 224篇 |
2000年 | 263篇 |
1999年 | 290篇 |
1998年 | 275篇 |
1997年 | 197篇 |
1996年 | 164篇 |
1995年 | 145篇 |
1994年 | 134篇 |
1993年 | 88篇 |
1992年 | 75篇 |
1991年 | 50篇 |
1990年 | 26篇 |
1989年 | 31篇 |
1988年 | 15篇 |
1987年 | 13篇 |
1986年 | 10篇 |
1985年 | 8篇 |
1984年 | 5篇 |
1983年 | 7篇 |
1982年 | 4篇 |
1981年 | 6篇 |
1980年 | 6篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1975年 | 3篇 |
1971年 | 3篇 |
1951年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Xiaoyan Dong Xu Li Xiuli Chen Hongyun Chen Congcong Sun Junpeng Shi Feihong Pang Huanfu Zhou 《Ceramics International》2021,47(3):3079-3088
Dielectric capacitors with decent energy storage and fast charge-discharge performances are essential in advanced pulsed power systems. In this study, novel ceramics (1-x)NaNbO3-xBi(Ni2/3Nb1/3)O3(xBNN, x = 0.05, 0.1, 0.15 and 0.20) with high energy storage capability, large power density and ultrafast discharge speed were designed and prepared. The impedance analysis proves that the introducing an appropriate amount of Bi(Ni0·5Nb0.5)O3 boosts the insulation ability, thus obtaining a high breakdown strength (Eb) of 440 kV/cm in xBNN ceramics. A high energy storage density (Wtotal) of 4.09 J/cm3, recoverable energy storage density (Wrec) of 3.31 J/cm3, and efficiency (η) of 80.9% were attained in the 0.15BNN ceramics. Furthermore, frequency and temperature stability (fluctuations of Wrec ≤ 0.4% over 5–100 Hz and Wrec ≤ 12.3% over 20–120 °C) were also observed. The 0.15BNN ceramics exhibited a large power density (19 MW/cm3) and ultrafast discharge time (~37 ns) over the range of ambient temperature to 120 °C. These enhanced performances may be attributed to the improved breakdown strength and relaxor behavior through the incorporation of BNN. In conclusion, these findings indicate that 0.15BNN ceramics may serve as promising materials for pulsed power systems. 相似文献
2.
3.
CRAFT is a tweakable block cipher introduced in 2019 that aims to provide strong protection against differential fault analysis. In this paper, we show that CRAFT is vulnerable to side-channel cube attacks. We apply side-channel cube attacks to CRAFT with the Hamming weight leakage assumption. We found that the first half of the secret key can be recovered from the Hamming weight leakage after the first round. Next, using the recovered key bits, we continue our attack to recover the second half of the secret key. We show that the set of equations that are solvable varies depending on the value of the key bits. Our result shows that 99.90% of the key space can be fully recovered within a practical time. 相似文献
4.
Xueli Du Yuelong Wang Rongna Shi Zhiyong Mao Zhihao Yuan 《Journal of the European Ceramic Society》2018,38(10):3512-3517
The PbClxS1-x and Pb1-xBixS (x? =?0–0.05) bulks were fabricated with a facile method of hydrothermal synthesis and microwave sintering, and the effect of anionic and cationic donors on the thermoelectric performance of PbS was investigated. Although Cl? and Bi3+ both effectively improved the thermoelectric properties of n-type PbS, more excellent thermoelectric performance was obtained from Cl? doped samples because of higher electrical property and lower thermal conductivity at higher temperature (T? >?600?K). The thermoelectric figure of merit (ZT) reaches 1.04 for PbCl0.015S0.985 at 800?K and increases with temperature increasing without sign of saturation, which is probably the highest value ever reported for single-phase polycrystalline n-type PbS. The results also indicate that the hydrothermal synthesis and microwave sintering can realize anion doping as well as cation doping for n-type PbS at low cost, and PbS should be a robust alternative for PbTe thermoelectric materials. 相似文献
5.
Petre Badica Dan Batalu Mihail Burdusel Mihai A. Grigoroscuta Gheorghe V. Aldica Monica Enculescu Raluca A. Gabor Zhiyong Wang Ruoxuan Huang Peifeng Li 《Ceramics International》2018,44(9):10181-10191
Pristine and (SiC+Te)-added MgB2 powders, green and spark plasma sintered (SPS) compacts were investigated from the viewpoint of quasi-static and dynamic (Split-Hopkinson Pressure Bar, SHPB) compressive mechanical properties The amount of the additive (SiC+Te) was selected to be the optimum one for maximization of the superconducting functional parameters. Pristine and added MgB2 show very similar compressive parameters (tan δ, fracture strength, Vickers hardness, others) and fragment size in the SHPB test. However, for the bulk SPSed samples the ratio of intergranular to transgranular fracturing changes, the first one being stronger in the added sample. This is reflected in the quasi-static KIC that is higher for the added sample. Despite this result, sintered samples are brittle and have roughly similar fragmentation behavior as for brittle engineering ceramics. In the fragmentation process, the composite nature of our samples should be considered with a special focus on MgB2 blocks (colonies) that show the major contribution to fracturing. The Glenn-Chudnovsky model of fracturing under dynamic load provides the closest values to our experimental fragment size data. 相似文献
6.
通过分析石化装置施工过程中常见的现象,分析产生由这些现象加重腐蚀的原因和机理, 指出应加强施工过程中的控制,而达到预期的防腐蚀效果,消除腐蚀隐患。 相似文献
7.
8.
9.
阜阳地区石炭-二叠系煤系烃源岩特征 总被引:2,自引:0,他引:2
阜阳地区石炭-二叠系煤系地层发育,但由于勘探程度较低,对该区煤系地层烃源岩的生烃潜力认识不清,严重制约了该区的油气勘探。在已有资料的基础上,通过有机地球化学和有机岩石学方法并结合模拟实验,探讨了该区煤系烃源岩的生烃潜力。研究结果表明阜阳地区石炭-二叠系煤系烃源岩有机质丰度达到中等-好烃源岩标准,有机质类型以腐殖型为主,盆地模拟结果显示阜阳地区石炭-二叠系煤系地层油资源量为(30.47~152.33)×106t,气资源量为(266.7~1333.7)×108m3,展示阜阳地区石炭-二叠系煤系地层具有较好的生油气潜力。 相似文献
10.