全文获取类型
收费全文 | 470776篇 |
免费 | 5375篇 |
国内免费 | 1053篇 |
专业分类
电工技术 | 8567篇 |
综合类 | 469篇 |
化学工业 | 71050篇 |
金属工艺 | 21598篇 |
机械仪表 | 16890篇 |
建筑科学 | 10887篇 |
矿业工程 | 3101篇 |
能源动力 | 10250篇 |
轻工业 | 39673篇 |
水利工程 | 5308篇 |
石油天然气 | 9275篇 |
武器工业 | 39篇 |
无线电 | 50152篇 |
一般工业技术 | 94562篇 |
冶金工业 | 82332篇 |
原子能技术 | 10664篇 |
自动化技术 | 42387篇 |
出版年
2021年 | 3462篇 |
2019年 | 3331篇 |
2018年 | 12374篇 |
2017年 | 12802篇 |
2016年 | 9857篇 |
2015年 | 4166篇 |
2014年 | 6555篇 |
2013年 | 18043篇 |
2012年 | 12563篇 |
2011年 | 20972篇 |
2010年 | 17885篇 |
2009年 | 18192篇 |
2008年 | 18451篇 |
2007年 | 20311篇 |
2006年 | 11689篇 |
2005年 | 13346篇 |
2004年 | 11670篇 |
2003年 | 11165篇 |
2002年 | 10108篇 |
2001年 | 9550篇 |
2000年 | 9385篇 |
1999年 | 9336篇 |
1998年 | 22469篇 |
1997年 | 15924篇 |
1996年 | 12462篇 |
1995年 | 9397篇 |
1994年 | 8469篇 |
1993年 | 8213篇 |
1992年 | 6405篇 |
1991年 | 6018篇 |
1990年 | 6047篇 |
1989年 | 5971篇 |
1988年 | 5721篇 |
1987年 | 4964篇 |
1986年 | 4903篇 |
1985年 | 5682篇 |
1984年 | 5359篇 |
1983年 | 4907篇 |
1982年 | 4521篇 |
1981年 | 4690篇 |
1980年 | 4472篇 |
1979年 | 4449篇 |
1978年 | 4521篇 |
1977年 | 4981篇 |
1976年 | 6591篇 |
1975年 | 3914篇 |
1974年 | 3736篇 |
1973年 | 3864篇 |
1972年 | 3193篇 |
1971年 | 2975篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Machine Learning - We propose a data-driven approach to quantify the uncertainty of models constructed by kernel methods. Our approach minimizes the needed distributional assumptions, hence,... 相似文献
102.
Gavshina O. V. Doroganov V. A. Doroganov E. A. Onishchuk V. I. Trepalina Yu. N. 《Refractories and Industrial Ceramics》2019,60(4):350-354
Refractories and Industrial Ceramics - Results of studying the rheotechnological properties of moldable refractory mixes based on bauxite suspensions plasticized with refractory clay are presented.... 相似文献
103.
Manjin Kim Qinfen Gu Tanveer Hussain Yahia Ali Trevor B. Abbott Kazuhiro Nogita 《International Journal of Hydrogen Energy》2021,46(53):27096-27106
With superior properties of Mg such as high hydrogen storage capacity (7.6 wt% H/MgH2), low price, and low density, Mg has been widely studied as a promising candidate for solid-state hydrogen storage systems. However, a harsh activation procedure, slow hydrogenation/dehydrogenation process, and a high temperature for dehydrogenation prevent the use of Mg-based metal hydrides for practical applications. For these reasons, Mg-based alloys for hydrogen storage systems are generally alloyed with other elements to improve hydrogen sorption properties. In this article, we have added Na to cast Mg–La alloys and achieved a significant improvement in hydrogen absorption kinetics during the first activation cycle. The role of Na in Mg–La has been discussed based on the findings from microstructural observations, crystallography, and first principles calculations based on density functional theory. From our results in this study, we have found that the Na doped surface of Mg–La alloy systems have a lower adsorption energy for H2 compared to Na-free surfaces which facilitates adsorption and dissociation of hydrogen molecules leading to improvement of absorption kinetic. The effect of Na on the microstructure of these alloys, such as eutectic refinement and a density of twins is not highly correlated with absorption kinetics. 相似文献
104.
105.
Bellendir E. N. Aleksandrov A. V. 《Power Technology and Engineering (formerly Hydrotechnical Construction)》2021,55(2):149-154
Power Technology and Engineering - The major results from the survey and geotechnical monitoring during the leveling of the model foundation of the Zagorsk PSP-2 in test site No. 3 are presented.... 相似文献
106.
107.
P. Carrasqueira H. Rocha J. M. Dias T. Ventura B. C. Ferreira M. C. Lopes 《International Transactions in Operational Research》2023,30(1):206-223
Radiation therapy is a technology-driven cancer treatment modality that has experienced significant advances over the last decades, due to multidisciplinary contributions that include engineering and computing. Recent technological developments allow the use of noncoplanar volumetric modulated arc therapy (VMAT), one of the most recent photon treatment techniques, in clinical practice. In this work, an automated noncoplanar arc trajectory optimization framework designed in two modular phases is presented. First, a noncoplanar beam angle optimization algorithm is used to obtain a set of noncoplanar irradiation directions. Then, anchored in these directions, an optimization strategy is proposed to compute an optimal arc trajectory. The computational experiments considered a pool of twelve difficult head-and-neck tumor cases. It was possible to observe that, for some of these cases, the optimized noncoplanar arc trajectories led to significant treatment planning quality improvements, when compared with coplanar VMAT treatment plans. Although these experiments were done in a research environment treatment planning software (matRad), the conclusions can be of interest for a clinical setting: automated procedures can simplify the current treatment workflow, produce high-quality treatment plans, making better use of human resources and allowing for unbiased comparisons between different treatment techniques. 相似文献
108.
Tolmachev A. M. Kuznetsova T. A. Fomenkov P. E. 《Protection of Metals and Physical Chemistry of Surfaces》2021,57(3):433-436
Protection of Metals and Physical Chemistry of Surfaces - The conditions for carrying out molecular dynamics calculations of adsorption isotherms of gases and vapors in micropores of active carbons... 相似文献
109.
El-Denglawey A. Issa Shams A. M. Saddeek Yasser B. Tekin H. O. Zakaly Hesham M. H. 《Journal of Inorganic and Organometallic Polymers and Materials》2021,31(10):3934-3942
Journal of Inorganic and Organometallic Polymers and Materials - This work aimed to investigate the impact of Lead-fluoride based glasses via theoretical and simulation techniques on mechanical and... 相似文献
110.
Kozhitov L. V. Kiselev B. G. Raykova T. B. Popkova A. V. Kostishin V. G. Muratov D. G. Yakushko E. V. Kosushkin V. G. Bebenin V. G. 《Russian Microelectronics》2019,48(8):599-612
Russian Microelectronics - The recently developed nanomaterials and their production technologies as intellectual property objects (IPOs) are considered. The role of the informational-analytical... 相似文献