全文获取类型
收费全文 | 11510篇 |
免费 | 1193篇 |
国内免费 | 645篇 |
专业分类
电工技术 | 693篇 |
技术理论 | 1篇 |
综合类 | 833篇 |
化学工业 | 1941篇 |
金属工艺 | 813篇 |
机械仪表 | 748篇 |
建筑科学 | 753篇 |
矿业工程 | 373篇 |
能源动力 | 301篇 |
轻工业 | 807篇 |
水利工程 | 222篇 |
石油天然气 | 904篇 |
武器工业 | 112篇 |
无线电 | 1254篇 |
一般工业技术 | 1337篇 |
冶金工业 | 538篇 |
原子能技术 | 159篇 |
自动化技术 | 1559篇 |
出版年
2024年 | 55篇 |
2023年 | 238篇 |
2022年 | 406篇 |
2021年 | 585篇 |
2020年 | 393篇 |
2019年 | 323篇 |
2018年 | 384篇 |
2017年 | 448篇 |
2016年 | 324篇 |
2015年 | 520篇 |
2014年 | 647篇 |
2013年 | 727篇 |
2012年 | 873篇 |
2011年 | 798篇 |
2010年 | 773篇 |
2009年 | 699篇 |
2008年 | 636篇 |
2007年 | 656篇 |
2006年 | 669篇 |
2005年 | 551篇 |
2004年 | 372篇 |
2003年 | 318篇 |
2002年 | 300篇 |
2001年 | 253篇 |
2000年 | 203篇 |
1999年 | 232篇 |
1998年 | 192篇 |
1997年 | 152篇 |
1996年 | 128篇 |
1995年 | 104篇 |
1994年 | 97篇 |
1993年 | 57篇 |
1992年 | 58篇 |
1991年 | 42篇 |
1990年 | 29篇 |
1989年 | 16篇 |
1988年 | 24篇 |
1987年 | 12篇 |
1986年 | 19篇 |
1985年 | 5篇 |
1984年 | 3篇 |
1983年 | 11篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1959年 | 1篇 |
1951年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 312 毫秒
1.
2.
Lin Haicheng Huang Wantong Zhao Kun Qiao Shuang Liu Zheng Wu Jian Chen Xi Ji Shuai-Hua 《Nano Research》2020,13(1):133-137
Nano Research - The isostructural and isoelectronic transition-metal-dichalcogenides 1T-TaS2 and 1T-TaSe2 are layered materials with intricate electronic structures. Combining the molecular beam... 相似文献
3.
Mirmohseni Seyedeh Maedeh Tang Chunming Javadpour Amir 《Wireless Personal Communications》2020,115(1):653-677
Wireless Personal Communications - The integration of the Internet of Things (IoT) and cloud environment has led to the creation of Cloud of Things, which has given rise to new challenges in IoT... 相似文献
4.
5.
Zhezhe Yu Chunyan Qiao Xueru Zhang Lin Yan Linqiang Li Yongfeng Liu 《Journal of dairy science》2021,104(4):4108-4118
Frozen milk can help producers overcome the seasonality of goat milk production, low goat production and short lactation periods, and avoid discarding milk during some special periods. We investigated effects of combination between freezing (cryogenic refrigerator of ?16 to ?20°C or ultra-cryogenic refrigerator of ?76 to ?80°C) and thawing (homeothermy of 20 to 25°C or refrigeration of 2 to 4°C) on nutritive compositions and physicochemical characteristics of raw goat milk during storage period (80 d). Compared with fresh goat milk, the frozen-thawed milk decreased contents of fat, protein, and lactose, as well as surface tension and stability coefficient, whereas increased effective diameter and polydispersity index. The average values of color values (L*, a*, and b*) in 4 group samples changed from 83.01 to 82.25, ?1.40 to ?1.54, 3.51 to 3.81, respectively, and the ΔE of most samples did not exceed 2. In contrast to the other 3 frozen-thawed treatments, goat milk treated with ultra-cryogenic freezing-homeothermic thawing (UFHT) possessed higher fat (5.20 g/100 g), smaller effective particle diameter (0.32 µm), and the lowest polydispersity index value (0.26). The color and confocal laser scanning microscopy images of UFHT were similar to those of fresh goat milk, illustrating UFHT was the optimal approach to maintain the natural quality of goat milk. Our finding provides a theoretical basis for producers to freeze surplus milk. 相似文献
6.
7.
Li D. You-Song Gu Xiang-Rong Chang Fu-Shen Li Li-Jie Qiao Zhong-Zhuo Tian Fang G.-D. Qing-Shan Song 《IEEE transactions on magnetics》2003,39(6):3554-3558
We deposited Fe-Ti-N magnetic films with a high sputtering power of 7 W/cm/sup 2/. When the composition of the films was in the range of Fe-Ti(3.9 at.%)-N(8.8 at.%) to Fe-Ti(3.3 at.%)-N(13.5 at.%), the films were composed of /spl alpha/' and Ti/sub 2/N precipitates. With the addition of nitrogen, 4/spl pi/M/sub s/ became higher than that of pure iron, reaching a maximum of 23.8 kG. At the same time, H/sub c/ was reduced to a minimum of 1.12 Oe. The best films can meet the needs of the recording head in dual-element giant magnetoresistive/inductive heads, yielding high storage density (10 Gb/in/sup 2/). The incorporation of N in /spl alpha/-Fe brought about the /spl alpha/' phase with its higher saturation magnetization. Ti additions inhibited the equilibrium decomposition /spl alpha/'/spl rarr//spl alpha/+/spl gamma/'. Because H/sub C//sup D//spl prop/D/sup 6/, where D is average grain diameter, grain size control is very important. The nitrogen induces severe distortion of the /spl alpha/' lattice, which can cause the grains to break into pieces and reduce the grain size. High sputtering power also led to the formation of fine grains, with diameter in the order of 14 nm. Probably Ti/sub 2/N is preferentially precipitated on the grain boundary, pinning the grain boundary and stabilizing the grain size during high-temperature heat treatment. The temperature limit for stability of the structure and its associated low coercivity was not less than 520/spl deg/C. 相似文献
8.
Yu Zhao Zhigang Xu Zongshi Li Weihong Qiao Lubai Cheng 《Petroleum Science and Technology》2006,24(7):821-827
Heavy alkyl benzene sulfonates (HABS) were synthesized, and their interfacial tensions were measured and compared with those of petroleum sulfonates ORS-41. Effects of their coupling with lignosulfonate were also studied. The results showed that HABS exhibited good interfacial activities and the system of HABS blending with LS displayed better interfacial activities than ORS-41 and therefore reduced the prime cost. Their best proportions of synergism were from 3:1 to 4:1. HABS might be a more promising alkali-surfactant-polymer (ASP) flooding agent. 相似文献
9.
10.
由于干态聚合物电解质目前还不能满足聚合物锂离子电池的应用要求,人们致力于开发含液体增塑剂的聚合物电解质,包括凝胶型和微孔型两类体系。本文综述了含液聚合物电解质的最新进展,重点论述了各种新体系和新方法。 相似文献