全文获取类型
收费全文 | 156492篇 |
免费 | 13834篇 |
国内免费 | 7393篇 |
专业分类
电工技术 | 10473篇 |
技术理论 | 11篇 |
综合类 | 10561篇 |
化学工业 | 24983篇 |
金属工艺 | 9068篇 |
机械仪表 | 10143篇 |
建筑科学 | 12294篇 |
矿业工程 | 4160篇 |
能源动力 | 4719篇 |
轻工业 | 9681篇 |
水利工程 | 3313篇 |
石油天然气 | 7900篇 |
武器工业 | 1481篇 |
无线电 | 18826篇 |
一般工业技术 | 18325篇 |
冶金工业 | 7931篇 |
原子能技术 | 1728篇 |
自动化技术 | 22122篇 |
出版年
2024年 | 582篇 |
2023年 | 2121篇 |
2022年 | 4079篇 |
2021年 | 5692篇 |
2020年 | 4304篇 |
2019年 | 3539篇 |
2018年 | 3943篇 |
2017年 | 4632篇 |
2016年 | 4379篇 |
2015年 | 5825篇 |
2014年 | 7762篇 |
2013年 | 9383篇 |
2012年 | 10755篇 |
2011年 | 11284篇 |
2010年 | 10431篇 |
2009年 | 10022篇 |
2008年 | 9676篇 |
2007年 | 9314篇 |
2006年 | 9157篇 |
2005年 | 7813篇 |
2004年 | 5658篇 |
2003年 | 5150篇 |
2002年 | 5019篇 |
2001年 | 4463篇 |
2000年 | 3752篇 |
1999年 | 3575篇 |
1998年 | 2916篇 |
1997年 | 2366篇 |
1996年 | 2142篇 |
1995年 | 1755篇 |
1994年 | 1449篇 |
1993年 | 1035篇 |
1992年 | 768篇 |
1991年 | 629篇 |
1990年 | 489篇 |
1989年 | 428篇 |
1988年 | 356篇 |
1987年 | 210篇 |
1986年 | 190篇 |
1985年 | 119篇 |
1984年 | 110篇 |
1983年 | 76篇 |
1982年 | 70篇 |
1981年 | 63篇 |
1980年 | 46篇 |
1979年 | 37篇 |
1978年 | 15篇 |
1977年 | 34篇 |
1976年 | 16篇 |
1975年 | 18篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Qiang Wang Lei Shen Tong Xue Gao Cheng Cheng Zhi Huang Hong Jin Fan Yuan Ping Feng 《Advanced functional materials》2021,31(2):2002187
The {100} facet of single-crystalline TiO2(B) is an ideal platform for inserting Li ions, but it is hard to be obtained due to its high surface energy. Here, the single-crystalline TiO2(B) nanobelts from H2Ti3O7 with nearly 70% {100} facets exposed are synthesized, which significantly enhances Li-storage capacity. The first-principle calculations demonstrate an ab in-plane 2D diffusion through the exposed {100} facets. As a consequence, the nanobelts can significantly accommodate Li ions in LiTiO2 formula with specific capacity up to 335 mAh g−1, which is in good agreement with the electrochemical characterizations. Coating with conductive and protective poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate), the cut-off discharge voltage is as low as 0.5 V, leading to a capacity of 160.7 mAh g−1 after 1500 cycles with a retention rate of 66% at 1C. This work provides a practical strategy to increase the Li-ion capacity and cycle stability by tailoring the crystal orientation and nanostructures. 相似文献
102.
Neural Computing and Applications - More and more enterprises hope to achieve cooperation and win–win. However, many companies often have problems such as insufficient partner credit, which... 相似文献
103.
Petre Badica Dan Batalu Mihail Burdusel Mihai A. Grigoroscuta Gheorghe V. Aldica Monica Enculescu Raluca A. Gabor Zhiyong Wang Ruoxuan Huang Peifeng Li 《Ceramics International》2018,44(9):10181-10191
Pristine and (SiC+Te)-added MgB2 powders, green and spark plasma sintered (SPS) compacts were investigated from the viewpoint of quasi-static and dynamic (Split-Hopkinson Pressure Bar, SHPB) compressive mechanical properties The amount of the additive (SiC+Te) was selected to be the optimum one for maximization of the superconducting functional parameters. Pristine and added MgB2 show very similar compressive parameters (tan δ, fracture strength, Vickers hardness, others) and fragment size in the SHPB test. However, for the bulk SPSed samples the ratio of intergranular to transgranular fracturing changes, the first one being stronger in the added sample. This is reflected in the quasi-static KIC that is higher for the added sample. Despite this result, sintered samples are brittle and have roughly similar fragmentation behavior as for brittle engineering ceramics. In the fragmentation process, the composite nature of our samples should be considered with a special focus on MgB2 blocks (colonies) that show the major contribution to fracturing. The Glenn-Chudnovsky model of fracturing under dynamic load provides the closest values to our experimental fragment size data. 相似文献
104.
105.
106.
107.
109.
Wei-Cheng Tang Yi-Che Su Yun-Shan Huang Ya-Tin Yu Hsin-Lung Chen I-Ming Chu 《应用聚合物科学杂志》2019,136(39):48003
While perfluoroalkyl acids (PFAAs), also known as C8s, are used extensively in textile repellent coatings, concerns have arisen for their carcinogenicity and hazardous effects on the environment. In this study, a novel water-based, nonfluoro, and nanobrush textile repelling agent was prepared by conventional sol–gel chemistry using amorphous fumed silica and n-octyltriethoxysilane as the starting materials. Minimal interaction between the designed repelling agent and marketed water-based resins was confirmed using linear viscosity region (LVR) analysis and asymmetric-flow field-flow fractionation (AF4), suggesting the self-stratification potential of the repelling agent. More specifically, the repelling agent exhibited excellent compatibility and self-stratifying ability with a force-emulsified acrylic-based resin, affording a water contact angle of 104.3° when incorporated at 7% solid content. Performance tests carried out on thermoplastic polyurethane (TPU) revealed excellent adhesion (100/100) of a final formulation, and a significant increase in water contact angle from 80.1° to 103.8° after treatment. In addition, the fouling area after the removal of a submerged sample from a mixture of slurry, polymer, and oil decreased from 48 to 1% when the repelling agent was added. Moreover, the sludge-fouling property remained unchanged after 1000 cycles of abrasion. These findings demonstrate the potential of the described nonfluoro, nanobrush repelling agent as an environmentally safe alternative for use with commercial resins, in turn realizing a fully water-based hydrophobic coating. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48003. 相似文献
110.
Siqi Yu Qin Wang Jianwei Wang Yong Xiang Xiaobin Niu Tingshuai Li 《International Journal of Hydrogen Energy》2021,46(27):14331-14337
Artificial nitrogen fixation is emerging as a promising approach for synthesis of ammonia at mild conditions. Inspired by biological nitrogen fixation based on bacteria containing iron, zinc doped Fe2O3 nanoparticles are proposed as an efficient and earth abundant electrocatalyst for converting N2 to NH3. In neutral media, it achieves a maximum Faradaic efficiency (FE) of 10.4% and a large NH3 yield rate of 15.1 μg h?1 mg?1cat. at ?0.5 V vs. reversible hydrogen electrode. This catalyst also exhibits excellent selectivity and stability. Theoretical calculations suggest the reaction follows the associative enzymatic mechanism and it has a barrier of as low as 0.68 eV. 相似文献