全文获取类型
收费全文 | 52965篇 |
免费 | 4702篇 |
国内免费 | 2369篇 |
专业分类
电工技术 | 3080篇 |
技术理论 | 1篇 |
综合类 | 3465篇 |
化学工业 | 8650篇 |
金属工艺 | 2648篇 |
机械仪表 | 3230篇 |
建筑科学 | 4574篇 |
矿业工程 | 1235篇 |
能源动力 | 1694篇 |
轻工业 | 3308篇 |
水利工程 | 1065篇 |
石油天然气 | 2681篇 |
武器工业 | 374篇 |
无线电 | 6612篇 |
一般工业技术 | 6605篇 |
冶金工业 | 2514篇 |
原子能技术 | 837篇 |
自动化技术 | 7463篇 |
出版年
2024年 | 103篇 |
2023年 | 737篇 |
2022年 | 1189篇 |
2021年 | 1914篇 |
2020年 | 1472篇 |
2019年 | 1335篇 |
2018年 | 1350篇 |
2017年 | 1578篇 |
2016年 | 1494篇 |
2015年 | 1905篇 |
2014年 | 2514篇 |
2013年 | 3065篇 |
2012年 | 3300篇 |
2011年 | 3658篇 |
2010年 | 3185篇 |
2009年 | 3123篇 |
2008年 | 2967篇 |
2007年 | 2905篇 |
2006年 | 2973篇 |
2005年 | 2491篇 |
2004年 | 1868篇 |
2003年 | 1769篇 |
2002年 | 1904篇 |
2001年 | 1542篇 |
2000年 | 1358篇 |
1999年 | 1385篇 |
1998年 | 1206篇 |
1997年 | 977篇 |
1996年 | 933篇 |
1995年 | 772篇 |
1994年 | 617篇 |
1993年 | 548篇 |
1992年 | 393篇 |
1991年 | 296篇 |
1990年 | 293篇 |
1989年 | 202篇 |
1988年 | 171篇 |
1987年 | 105篇 |
1986年 | 90篇 |
1985年 | 59篇 |
1984年 | 53篇 |
1983年 | 35篇 |
1982年 | 38篇 |
1981年 | 19篇 |
1980年 | 23篇 |
1979年 | 18篇 |
1978年 | 14篇 |
1977年 | 13篇 |
1976年 | 15篇 |
1973年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Mobile Networks and Applications - In order to realize the best matching search of mobile intelligent education system resources, a resource search method of mobile intelligent education system... 相似文献
2.
3.
Liu Yang Pengfei Yu Wenyuan Li Fengliang Cao Xin Jin Sheng Xue Xianglong Zhang Tingwei Zhang Mingbo Wu Wenting Wu 《American Institute of Chemical Engineers》2022,68(9):e17760
Hydrogen peroxide (H2O2) has been listed as one of the 100 most important chemicals in the world. However, huge amount of residual H2O2 is hard to timely decomposed into O2 and H2O under acidic condition, easily resulting in explosion hazard. Here, we reported a core–shell structure catalyst, that is graphene with Co N structure encapsulated Co nanoparticles. Co N graphene shell serves as the active site for the H2O2 decomposition, and Co core further enhance this decomposition. Benefiting from it, the H2O2 decomposition were close to 100% after 6 cycles without pH adjustment, which increased 6 orders of magnitude compared with no catalyst. At the same time, the O2 generation reached 99.67% in 2 h with little metal leaching, and ·OH has been greatly inhibited to only 0.08%. This work can cleanly remove H2O2 with little deep oxidation and protect the process of H2O2 utilization to achieve a safer world. 相似文献
4.
Wireless Personal Communications - The Internet of Medical Things (IoMT) is the array of medical instruments and related technologies that link Information Technology (IT) systems in... 相似文献
5.
Feng Yingrui Hu Kang Zhang Min Ding Wei Kong Xiangkai Sheng Zhigao Liu Qiangchun 《Journal of Materials Science》2022,57(1):204-216
Journal of Materials Science - Rationally designing microwave absorption materials with highly efficient and tunable bandwidth is in great demand but remains a huge challenge. In this study,... 相似文献
6.
Hu Zhaoyang Suo Xufei Shen Yongxing Jiang Yu-Xi Cheng Jun-Bo 《International Journal of Fracture》2022,235(2):231-242
International Journal of Fracture - Adiabatic shear band (ASB) is one of the most important failure modes under high strain-rate deformation. In this work, we propose a hybrid damage model to... 相似文献
7.
Scientometrics - Governments typically formulate sets of policies to guide the direction of scientific research. And the possible effects of these policies on scientific research have been... 相似文献
8.
Qing Li Jun Wang Jie Ma Meng Ni Fan Yang Peng Liu Kuo Yang Lee Hsing-I Hsiang Deyuan Shen Dingyuan Tang 《Journal of the American Ceramic Society》2022,105(5):3375-3381
High-efficiency Yb:Y2O3 laser ceramics were fabricated using the vacuum-sintering plus hot isostatic pressing (HIP) without sintering additives. High-purity well-dispersed nanocrystalline Yb:Y2O3 powder was synthesized using a modified co-precipitation method in-house. The green bodies were first vacuum sintered at a temperature as low as 1430°C and then HIPed at 1450°C. Finally, the samples were air annealed at 800°C for 10 h. Although no sintering aids were used, full density of the samples with excellent optical homogeneity and an inline transmission of 80% at 400 nm could be obtained. Moreover, photodarkening phenomenon was not detected in the ceramics. Preliminary laser experiment with the fabricated ceramics in a two-mirror cavity has demonstrated 32 W continuous-wave (CW) output at ∼1077 nm with an optical-to-optical conversion efficiency of 58.2%. To the best of our knowledge, this is so far the highest CW output power and optical-to-optical conversion efficiency achieved with the Yb3+-doped sesquioxide ceramics in a simple two-mirror cavity. 相似文献
9.
Kelin Hu Feipeng Wang Yuyang Yan Hongcheng Liu Zijia Shen 《Ceramics International》2021,47(11):15228-15236
In this paper, a novel hybrid structure of Pd doped ZnO/SnO2 heterojunction nanofibers with hexagonal ZnO columns was one step synthesized from electrospun precursor nanofibers. Due to the synergistic effect of hexagonal ZnO, SnO2 and Pd, the structure exhibited excellent hydrogen (H2) gas sensing properties. At low-temperature of 120 °C, the response (Ra/Rg) to 100 ppm H2 gas exceeded 160, the response/recovery time was only 20 s and 6 s respectively and the limit of detection was only 0.5 ppm. Meanwhile, it also had good selectivity for H2 gas and excellent linearity. In addition, the materials were characterized by XRD, FESEM, HRTEM, XPS, and the synthesis mechanism and gas sensing mechanism were proposed. 相似文献
10.
Dr. Dae-Shik Kim Dr. Atsushi Endo Dr. Francis G. Fang Dr. Kuan-Chun Huang Dr. Xingfeng Bao Dr. Hyeong-wook Choi Dr. Utpal Majumder Dr. Young Y. Shen Steven Mathieu Xiaojie Zhu Kristen Sanders Dr. Thomas Noland Dr. Ming-Hong Hao Dr. Yu Chen Dr. John Y. Wang So Yasui Karen TenDyke Jiayi Wu Christy Ingersoll Kara A. Loiacono Dr. Janna E. Hutz Dr. Nadeem Sarwar 《ChemMedChem》2021,16(11):1741-1744
A strategy for creating potent and pan-genotypic stimulator of interferon genes (STING) agonists is described. Locking a bioactive U-shaped conformation of cyclic dinucleotides by introducing a transannular macrocyclic bridge between the nucleic acid bases leads to a topologically novel macrocycle-bridged STING agonist (MBSA). In addition to substantially enhanced potency, the newly designed MBSAs, exemplified by clinical candidate E7766 , exhibit broad pan-genotypic activity in all major human STING variants. E7766 is shown to have potent antitumor activity with long lasting immune memory response in a mouse liver metastatic tumor model. Two complementary stereoselective synthetic routes to E7766 are also described. 相似文献