全文获取类型
收费全文 | 119937篇 |
免费 | 13828篇 |
国内免费 | 9001篇 |
专业分类
电工技术 | 10524篇 |
技术理论 | 1篇 |
综合类 | 12388篇 |
化学工业 | 16252篇 |
金属工艺 | 8120篇 |
机械仪表 | 8463篇 |
建筑科学 | 8972篇 |
矿业工程 | 4233篇 |
能源动力 | 3205篇 |
轻工业 | 12451篇 |
水利工程 | 3397篇 |
石油天然气 | 4377篇 |
武器工业 | 1587篇 |
无线电 | 13046篇 |
一般工业技术 | 11096篇 |
冶金工业 | 4620篇 |
原子能技术 | 2173篇 |
自动化技术 | 17861篇 |
出版年
2024年 | 350篇 |
2023年 | 1960篇 |
2022年 | 4589篇 |
2021年 | 5818篇 |
2020年 | 4282篇 |
2019年 | 3006篇 |
2018年 | 3335篇 |
2017年 | 3731篇 |
2016年 | 3271篇 |
2015年 | 5002篇 |
2014年 | 6500篇 |
2013年 | 7773篇 |
2012年 | 9280篇 |
2011年 | 9697篇 |
2010年 | 9220篇 |
2009年 | 8916篇 |
2008年 | 9563篇 |
2007年 | 8980篇 |
2006年 | 8086篇 |
2005年 | 6668篇 |
2004年 | 4683篇 |
2003年 | 3395篇 |
2002年 | 3184篇 |
2001年 | 2980篇 |
2000年 | 2500篇 |
1999年 | 1409篇 |
1998年 | 800篇 |
1997年 | 652篇 |
1996年 | 561篇 |
1995年 | 498篇 |
1994年 | 366篇 |
1993年 | 314篇 |
1992年 | 280篇 |
1991年 | 194篇 |
1990年 | 181篇 |
1989年 | 171篇 |
1988年 | 116篇 |
1987年 | 78篇 |
1986年 | 51篇 |
1985年 | 51篇 |
1984年 | 38篇 |
1983年 | 34篇 |
1982年 | 35篇 |
1981年 | 24篇 |
1980年 | 35篇 |
1979年 | 19篇 |
1978年 | 9篇 |
1977年 | 7篇 |
1959年 | 25篇 |
1951年 | 20篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
Kun Yang Yachun Wang Penghui Lei Tiankai Yao Dong Zhao Jie Lian 《Journal of the European Ceramic Society》2021,41(12):6018-6028
Chemical durability of lanthanide zirconates (A2Zr2O7) (A = La-Yb) under near-field environments is important for evaluating their application as potential nuclear waste forms. In this work, A2Zr2O7 (A = La-Yb) are synthesized by spark plasma sintering with controlled microstructure and their chemical durability are evaluated in a nitric acid solution (pH = 1). Scanning transmission electron microscopy analysis reveals an amorphous passivation film either enriched with Zr or lanthanide. The complex chemistry of the passivation films can be correlated with a transition in corrosion mechanisms from a preferential release of lanthanide in La2Zr2O7 to a preferential release of Zr in Er2Zr2O7 and Yb2Zr2O7. These results suggest a dominant mechanism of incongruent dissolution and surface reorganization for the formation of passivation films. Strong correlations are identified between the leaching rates and cation ionic size, ionic potential, electronegativity differences between A-site cation and Zr, and bonding valence sum of oxygen, suggesting important impacts of structural and bonding characteristics in controlling chemical durability of lanthanide zirconates. 相似文献
2.
3.
4.
Matrix Manipulation of Directly-Synthesized PbS Quantum Dot Inks Enabled by Coordination Engineering
Fei Li Yang Liu Guozheng Shi Wei Chen Renjun Guo Dong Liu Yaohong Zhang Yongjie Wang Xing Meng Xuliang Zhang You Lv Wei Deng Qing Zhang Yao Shi Yifan Chen Kai Wang Qing Shen Zeke Liu Peter Müller-Buschbaum Wanli Ma 《Advanced functional materials》2021,31(45):2104457
The direct-synthesis of conductive PbS quantum dot (QD) ink is facile, scalable, and low-cost, boosting the future commercialization of optoelectronics based on colloidal QDs. However, manipulating the QD matrix structures still is a challenge, which limits the corresponding QD solar cell performance. Here, for the first time a coordination-engineering strategy to finely adjust the matrix thickness around the QDs is presented, in which halogen salts are introduced into the reaction to convert the excessive insulating lead iodide into soluble iodoplumbate species. As a result, the obtained QD film exhibits shrunk insulating shells, leading to higher charge carrier transport and superior surface passivation compared to the control devices. A significantly improved power-conversion efficiency from 10.52% to 12.12% can be achieved after the matrix engineering. Therefore, the work shows high significance in promoting the practical application of directly synthesized PbS QD inks in large-area low-cost optoelectronic devices. 相似文献
5.
良好的负荷预测模型能够精准且快速地计算预测值,有利于合理地规划分配电能,提升电网运行稳定性.基于MATLAB搭建灰色Elman网络电力负荷预测模型,参考安徽省淮南市"十三五"能源规划[1],以对淮南市进行中长期电力负荷预测为例,同时设置基于MATLAB搭建的Elman网络和灰色理论中的GM(1,1)模型为对照组进行对比仿真实验.提出灰色Elman网络相比对照组具有更高的运算精度,灰色Elman网络对比Elman网络有更好的训练效果. 相似文献
6.
于潞璐 《辽东学院学报(自然科学版)》2021,28(3):207-210
运用八段锦进行女大学生篮球教学后疲劳恢复,并与传统恢复手段拉伸运动进行比较实验,探索快速消除运动性疲劳的方法.研究结果显示:女大学生运用八段锦进行篮球教学后的疲劳恢复,其心率恢复明显的优于传统拉伸运动;学生的主观感觉疲劳恢复程度也明显的优于传统拉伸运动.结果表明,八段锦能够有效促进女大学生生理和心理疲劳的恢复. 相似文献
7.
8.
9.
Yunyan Liu Ning Jiang Yao Liu Dawei Cui Chang-Feng Yu Huiqiang Liu Zhao Li 《Ceramics International》2021,47(16):22416-22423
Pulsed laser deposition (PLD) was used to prepare tungsten trioxide (WO3) films on ITO substrates with a varying laser power density of 4.0–5.5 W/cm2. XPS indicated that when the laser power density decreased, the peak positions of the W 4f and O 1s orbits shifted slightly to low energy due to the difference in oxygen vacancies. As the laser power density decreased, W6+ gradually replaced the lattice position of O2?, increasing oxygen vacancies in the lattice. The transmittance modulated values (ΔT) were over 44% at 830 nm, indicating strong absorption by the WO3 thin films in the near-infrared ray. The switching time of the WO3 thin films between bleached states and coloured states decreased as the laser power density increased due to the amorphous structure, morphology, and lower oxygen deficiency at a high power density. The high ΔT and very fast switching time of tb (1.09 s) and tc (6.01 s) demonstrated the excellent electrochromic (EC) properties of the WO3 films prepared by PLD. 相似文献
10.
建立高效液相色谱法检测伐地昔布的有关物质.采用α-酸性糖蛋白键合硅胶的手性色谱柱,以乙腈-醋酸铵缓冲液(0.01 mol/L,pH4.0)作为流动相进行梯度洗脱,检测波长215 nm.伐地昔布与5个已知杂质均可达到基线分离,在各自浓度范围内线性关系良好,平均回收率95.13%~99.77%,RSD1.10%~1.77%,检测限0.017 9~0.060 1 μg/mL,定量限0.059 7~0.200 0 μg/mL.方法专属性强,准确度好,灵敏度高,可为伐地昔布的质量控制及后续分离提纯和帕瑞昔布的质量控制提供指导. 相似文献