全文获取类型
收费全文 | 11577篇 |
免费 | 1441篇 |
国内免费 | 903篇 |
专业分类
电工技术 | 1080篇 |
综合类 | 1090篇 |
化学工业 | 1490篇 |
金属工艺 | 816篇 |
机械仪表 | 793篇 |
建筑科学 | 945篇 |
矿业工程 | 441篇 |
能源动力 | 264篇 |
轻工业 | 1139篇 |
水利工程 | 399篇 |
石油天然气 | 684篇 |
武器工业 | 126篇 |
无线电 | 1266篇 |
一般工业技术 | 969篇 |
冶金工业 | 391篇 |
原子能技术 | 175篇 |
自动化技术 | 1853篇 |
出版年
2024年 | 88篇 |
2023年 | 229篇 |
2022年 | 570篇 |
2021年 | 646篇 |
2020年 | 474篇 |
2019年 | 335篇 |
2018年 | 395篇 |
2017年 | 425篇 |
2016年 | 359篇 |
2015年 | 509篇 |
2014年 | 637篇 |
2013年 | 726篇 |
2012年 | 982篇 |
2011年 | 1011篇 |
2010年 | 869篇 |
2009年 | 809篇 |
2008年 | 860篇 |
2007年 | 854篇 |
2006年 | 741篇 |
2005年 | 608篇 |
2004年 | 390篇 |
2003年 | 287篇 |
2002年 | 274篇 |
2001年 | 234篇 |
2000年 | 220篇 |
1999年 | 88篇 |
1998年 | 47篇 |
1997年 | 60篇 |
1996年 | 55篇 |
1995年 | 26篇 |
1994年 | 20篇 |
1993年 | 17篇 |
1992年 | 17篇 |
1991年 | 11篇 |
1990年 | 9篇 |
1989年 | 7篇 |
1988年 | 9篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 7篇 |
1979年 | 4篇 |
1959年 | 1篇 |
1951年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
A novel CdS/CaFe2O4 (CS/CFO) heterogeneous p-n junction was created by thermal deposition of CaFe2O4 nanoparticles on CdS rods. The CS/CFO hetero-structured photocatalysts exhibited increasingly efficient visible light harvesting compared to the bare CdS. The CS/CFO composites also presented higher photocurrent and slower decay of photoluminescence, suggesting a better separation of the photo-generated electrons and holes. The photocatalytic H2 evolution quantity on the optimized CS/CFO composite from water in the presence of ethanol was up to 2200 μmol after 3-h visible light illumination, which is more than twice that of the pristine CdS. The chemical interaction between CdS and CaFe2O4 was confirmed by the shifts in the XPS peaks, which made it possible for the charge carriers to transfer across the p-n junction interface. This research highlights the importance of forming an interfacial p-n heterojunction between two semiconductors for efficient charge separation and improved photocatalytic performance. 相似文献
3.
Jieyi Yu Xianguo Liu Rui Su Xuefeng Zhang Xinglong Dong 《Ceramics International》2021,47(17):23950-23957
Increasing the dielectric loss capacity plays an important role in enhancing the electromagnetic absorption performance of materials. It remains a challenge to simultaneously introduce multiple types of dielectric losses in the material. In this work, we show that the atomic and interfacial dipole polarizations can be simultaneously enhanced by substituting N species into both carbon coating layers and bulk TiC lattices of a core-shell TiC@C material. Additionally, substitution of N species results more exposed TiC(111) facets and refines the TiC grain sizes in the bulk material, which is beneficial for enhancing the scattering of the external electromagnetic waves. The maximum reflection loss of the N substituted TiC@C material is measured as ?47.1 dB with an effective absorbing bandwidth of 4.83 GHz at 1.9 mm, which illustrates a valuable way to further tuning the electromagnetic absorption performance of this type of materials. 相似文献
5.
6.
耿琦 《机械制造与自动化》2021,50(2):197-199
以某款A0级纯电动汽车研发为例,介绍高压关键零部件在整车上的布置方案和在布置过程中应当注意的问题,包括动力电池、动力总成、高压配电盒、电机控制器、车载充电机布置方案、电动空调压缩机以及其他关键零部件的合理布置方案,为后期车型开发提供参考. 相似文献
7.
Yuxi Guo Xuefeng Chen Pin Gong Fuxin Chen Dandan Cui Mengrao Wang 《International Journal of Food Science & Technology》2021,56(10):4970-4982
In vitro digestion models are widely used to study the structural changes, digestion and release of food components under simulated gastrointestinal conditions. As compared to the in vivo digestion tests, the in vitro digestion reflects the digestion and utilisation of food after ingestion and has the advantages of being time consuming, inexpensive, reproducible and free from moral and ethical restrictions. This study reviewed the current research studies on the in vitro simulated digestion of polysaccharides conducted in the last 5 years and focused on the oral, gastric and intestinal digestion models, with the aim of providing a basis for the further testing of changes in the content, structure and active ingredients of polysaccharides before and after digestion. 相似文献
8.
9.
Feng Juanni Guo Xuefeng Xu Chunjie Zhang Zhongming 《中国稀土学报(英文版)》2006,24(1):120-120
As-east mierostruetures and their distribution of Mg-Zn-Y ternary alloy with high magnesium, low zinc and yttrium were examined using Nikon Epiphot optical microscopy (OM), RigakuD/max-3C X- ray diffraetion (XRD), and JEOL JSM-6700F scanning electron microscopy (SEM) equipped with an energydispersive X-ray spectroscopy (EDS). In the as-east mierostructures, Yttrium and zinc tend to segregate at grain boundaries, 相似文献
10.
介绍了某伪码连续波交会对接雷达信号处理机设计.在测距中,提出用噪声较小的载波相位△伪距测量值对伪距进行处理,得到高精度测距值.在测角中,提出了一种干涉仪天线阵结构和干涉仪解模糊算法,针对通道载波相位误差可能引起的解模糊错误,又提出了一种纠正方法,仿真显示,在发生解模糊错误的概率高达0.42的情况下,该方法仍然可以识别并纠正所有解模糊错误.实验表明,该信号处理机可以满足空间航天器交会对接的要求. 相似文献