全文获取类型
收费全文 | 14335篇 |
免费 | 1541篇 |
国内免费 | 663篇 |
专业分类
电工技术 | 1139篇 |
综合类 | 840篇 |
化学工业 | 2451篇 |
金属工艺 | 784篇 |
机械仪表 | 915篇 |
建筑科学 | 1187篇 |
矿业工程 | 408篇 |
能源动力 | 506篇 |
轻工业 | 1227篇 |
水利工程 | 371篇 |
石油天然气 | 792篇 |
武器工业 | 101篇 |
无线电 | 1518篇 |
一般工业技术 | 1630篇 |
冶金工业 | 612篇 |
原子能技术 | 151篇 |
自动化技术 | 1907篇 |
出版年
2024年 | 69篇 |
2023年 | 269篇 |
2022年 | 532篇 |
2021年 | 766篇 |
2020年 | 564篇 |
2019年 | 444篇 |
2018年 | 501篇 |
2017年 | 560篇 |
2016年 | 508篇 |
2015年 | 676篇 |
2014年 | 819篇 |
2013年 | 933篇 |
2012年 | 967篇 |
2011年 | 1081篇 |
2010年 | 872篇 |
2009年 | 830篇 |
2008年 | 778篇 |
2007年 | 764篇 |
2006年 | 761篇 |
2005年 | 594篇 |
2004年 | 411篇 |
2003年 | 342篇 |
2002年 | 320篇 |
2001年 | 280篇 |
2000年 | 272篇 |
1999年 | 303篇 |
1998年 | 259篇 |
1997年 | 214篇 |
1996年 | 183篇 |
1995年 | 134篇 |
1994年 | 124篇 |
1993年 | 95篇 |
1992年 | 68篇 |
1991年 | 57篇 |
1990年 | 36篇 |
1989年 | 42篇 |
1988年 | 25篇 |
1987年 | 19篇 |
1986年 | 14篇 |
1985年 | 15篇 |
1984年 | 7篇 |
1983年 | 6篇 |
1982年 | 3篇 |
1981年 | 5篇 |
1980年 | 7篇 |
1978年 | 4篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1965年 | 1篇 |
1951年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
胶莱盆地在胶东半岛地质构造及造山带研究中占有重要地位,其巨厚的白垩系陆相沉积是石油系统多年的研究目标。胶莱盆地南部白垩纪的岩石地层序列较其北部更为复杂,其认识几经反复,其中尤以大盛群与王氏群和莱阳群的部分单位的关系为甚。本次工作通过详细对比其沉积层序、相互关系、古生物组合、岩石学特征及同位素年龄等因素,认为大盛群与王氏群属同一沉积层序,沉积基底相同、沉积环境相似、古生物群落时代一致,二者具有同时代、同沉积相、同岩石组合的一致性,应是一套地层,建议今后使用统一地层名称。 相似文献
2.
3.
4.
World Wide Web - The wide spread use of positioning and photographing devices gives rise to a deluge of traffic trajectory data (e.g., vehicle passage records and taxi trajectory data), with each... 相似文献
5.
As a solid state joining process, ultrasonic spot welding has been proven to be a promising technique for joining copper alloys. However, challenges still remain in employing ultrasonic spot welding to join copper alloys. This article comprehensively reviews the current state of ultrasonic spot welding of copper alloys with a number of critical issues including materials flow, plastic deformation, temperature distribution, vibration, relative motion, vertical displacement, interface friction coefficient, online monitoring technique, coupled with the macrostructure and microstructure, the mechanical properties and electrical conductivity. In addition, the future trends in this field are provided. 相似文献
6.
Xiaohui Hu Li Cheng Yan Hong Zhaofeng Li Caiming Li Zhengbiao Gu 《International Journal of Food Science & Technology》2021,56(8):4149-4158
Incorporating high level of potato flour into wheat flour enhances nutritional values of bread but induces a series of problems that lead to the decline of the bread quality. To overcome the barrier, wheat gluten and carboxymethylcellulose (CMC) were added into potato–wheat composite flour to improve dough machinability and bread quality. The rheological properties, thermo-mechanical properties and microstructures of dough were investigated. The results showed that the interaction between gluten and CMC mitigated the discontinuity of gluten matrix and gluten protein aggregation caused by the addition of potato flour, which yielded a more branched and compact gluten network. The compact three-dimensional viscoelastic structure induced improvements of gas retention capacity and dough stability, making it mimic the machinability properties of wheat flour dough. Bread qualities were apparently improved with the combined use of 4% gluten and 6% CMC, of which specific volume increased by 42.86%, and simultaneously, hardness reduced by 75.93%. 相似文献
8.
Qinhua Wang Xiaofeng Pan Xinpin Wang Shilin Cao Lihui Chen Xiaojuan Ma Liulian Huang Yonghao Ni 《Ceramics International》2021,47(4):4398-4403
Ti3C2Tx (MXene), a new kind of 2D ceramic nanosheets, is receiving more and more attention in the fields of medicine, biology, energy, electronics, etc. However, the preparation and application of MXene in hydrogel is still in its infancy period. Here, we review the latest progress (after 2018) related to MXene hydrogels in time. Aiming at the key issue of the dispersion stability of MXene in hydrogel systems, the preparation strategy, mechanism, advantages and disadvantages of MXene hydrogels are sorted out in detail, and the potential application prospects of MXene composite hydrogel are introduced. Finally, future viewpoints are put forward for the dispersion stability challenges that need solving in the design of MXene hydrogel. 相似文献
9.
Biyun Fang Chuanfeng Zhang Zeliang Qi Chunyan Li Jun Ni Xiuyun Wang Jianxin Lin Chak-Tong Au Bingyu Lin Lilong Jiang 《American Institute of Chemical Engineers》2022,68(11):e17849
The design of an efficient non-noble metal catalyst is of burgeoning interest for ammonia synthesis. Herein, we report a Mo2C/CeO2 catalyst that is superior in ammonia synthesis activity. In this catalyst, molybdenum carbide coexisted with the ceria overlayers which is from the ceria support as the strong metal–support interaction. There is a high proportion of low-valent Mo species, as well as high concentration of Ce3+ and surface oxygen species. The presence of Mo2C and CeO2 overlayers not only leads to enhancement of hydrogen and nitrogen adsorption, but also facilitates the desorption and exchange of adsorbed species with the gaseous reagents. Compared with the Mo/CeO2 catalyst prepared without carbonization, the Mo2C/CeO2 catalyst is more than sevenfold higher in ammonia synthesis rate. This work not only presents an explicit example of designing Mo-based catalyst that is highly efficient for ammonia synthesis by tuning the adsorption and desorption properties of the reactant gases, but opens a perspective for other elements in ammonia synthesis. 相似文献
10.
Zhang Huawei Yang Zhi Wu Zhaoyu Hong Xiaoyu Li Zhong Xu Yulai Li Jun Ni Gaojin Xiao Xueshan 《Oxidation of Metals》2019,92(1-2):49-65
Oxidation of Metals - The isothermal oxidation behavior and oxide-scale evolution on a newly developed Ni–Fe-based superalloy were investigated. Three oxidation stages were generally... 相似文献