全文获取类型
收费全文 | 108983篇 |
免费 | 11128篇 |
国内免费 | 5645篇 |
专业分类
电工技术 | 7965篇 |
技术理论 | 11篇 |
综合类 | 8116篇 |
化学工业 | 16942篇 |
金属工艺 | 6236篇 |
机械仪表 | 7056篇 |
建筑科学 | 8935篇 |
矿业工程 | 3487篇 |
能源动力 | 3407篇 |
轻工业 | 6569篇 |
水利工程 | 2349篇 |
石油天然气 | 6271篇 |
武器工业 | 1133篇 |
无线电 | 12807篇 |
一般工业技术 | 12527篇 |
冶金工业 | 4633篇 |
原子能技术 | 1453篇 |
自动化技术 | 15859篇 |
出版年
2024年 | 435篇 |
2023年 | 1833篇 |
2022年 | 3691篇 |
2021年 | 5114篇 |
2020年 | 3826篇 |
2019年 | 3054篇 |
2018年 | 3487篇 |
2017年 | 3812篇 |
2016年 | 3498篇 |
2015年 | 4782篇 |
2014年 | 5906篇 |
2013年 | 6970篇 |
2012年 | 7650篇 |
2011年 | 8257篇 |
2010年 | 7097篇 |
2009年 | 6660篇 |
2008年 | 6559篇 |
2007年 | 6049篇 |
2006年 | 5957篇 |
2005年 | 4931篇 |
2004年 | 3435篇 |
2003年 | 3073篇 |
2002年 | 3207篇 |
2001年 | 2700篇 |
2000年 | 2299篇 |
1999年 | 2283篇 |
1998年 | 1677篇 |
1997年 | 1397篇 |
1996年 | 1420篇 |
1995年 | 1054篇 |
1994年 | 906篇 |
1993年 | 682篇 |
1992年 | 505篇 |
1991年 | 340篇 |
1990年 | 274篇 |
1989年 | 232篇 |
1988年 | 226篇 |
1987年 | 134篇 |
1986年 | 85篇 |
1985年 | 60篇 |
1984年 | 35篇 |
1983年 | 28篇 |
1982年 | 36篇 |
1981年 | 24篇 |
1980年 | 20篇 |
1979年 | 17篇 |
1976年 | 10篇 |
1971年 | 3篇 |
1959年 | 9篇 |
1951年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
91.
92.
93.
激光脉冲编码是激光制导武器的抗干扰措施之一。角度欺骗式干扰和高重频干扰是目前半主动激光制导武器的主要有源干扰来源。为研究不同激光脉冲编码方式对激光半主动制导武器抗这两种干扰性能的影响,本文针对敌方激光告警机的识别算法与我方导引头的解码过程,提出自相关函数与归一化互相关函数评价方法,并对目前主要编码方式进行仿真,仿真结果表明:激光脉冲编码的抗角度欺骗式干扰能力受编码序列周期性与脉冲间隔随机性的影响;抗高重频激光干扰能力受编码序列脉冲间隔随机性的影响;LFSR状态码的抗角度欺骗式干扰与抗高重频干扰效果均优于其他编码方式。 相似文献
94.
Linlin Zhu Liyuan Zhang Xi Li Xiaoqi Jin Tiejun Shi 《Fullerenes, Nanotubes and Carbon Nanostructures》2020,28(7):551-560
AbstractGraphene oxide (GO) was functionalized by polyether amine (PEA) via two methods which were one-pot modification in acetone (GON) and two steps with the intermediate product of GOCO-Cl generated (GONS). There were more PEA successfully grafted onto GO for GONS than GON. The onset polymerization temperatures of the benzoxazine (Bz) composites decreased by the inclusion of 1?wt% of GO, GON or GONS. Thermal stability of the polybenzoxazine (PBz) composites was significantly improved indicated from the increase of weight loss temperature. T10, T20 and T50 values of the composites with GONS were higher than that of the others. Toughness of PBzs may be enhanced by the incorporation of nanofillers, and GONS had stronger interfacial interaction with PBz matrix than GON. 相似文献
95.
Sustainable biocomposites have gained considerable interest as an alternative to conventional composites in recent years due to their cost-effectiveness and environmental friendliness. The aim of this study was to investigate the performance and durability behavior of biocomposites from sustainable biocarbon (BC) as compared to conventional established fillers. The poly(butylene terephthalate) (PBT) and its composites reinforced with BC, talc, and glass fiber (GF) were prepared and the durability performances was investigated. The study showed that BC/PBT biocomposites provided a lighter weight alternative to traditionally used fillers. After undergoes thermo-oxidative aging, the mechanical properties of BC/PBT biocomposite were deteriorated. The GF/PBT showed the most stable in retaining its mechanical properties in comparison to the talc/PBT and BC/PBT. The aging behavior and mechanism of the PBT composites were discussed. This study provides further insight on the durability-related properties progression of biocomposites as compared to traditional used fillers. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47722. 相似文献
96.
97.
Tian Xiaoying Peng Hui Luo Xuguang Nie Shiyuan Zhou Feng Peng Xiaoyan 《International Journal of Control, Automation and Systems》2020,18(4):897-910
International Journal of Control, Automation and Systems - There is a class of typical nonlinear industrial process, which can be characterized by a first-order inertia plus pure delay model in an... 相似文献
98.
Single image super resolution (SISR) is an important research content in the
field of computer vision and image processing. With the rapid development of deep
neural networks, different image super-resolution models have emerged. Compared to
some traditional SISR methods, deep learning-based methods can complete the superresolution tasks through a single image. In addition, compared with the SISR methods
using traditional convolutional neural networks, SISR based on generative adversarial
networks (GAN) has achieved the most advanced visual performance. In this review, we
first explore the challenges faced by SISR and introduce some common datasets and
evaluation metrics. Then, we review the improved network structures and loss functions
of GAN-based perceptual SISR. Subsequently, the advantages and disadvantages of
different networks are analyzed by multiple comparative experiments. Finally, we
summarize the paper and look forward to the future development trends of GAN-based
perceptual SISR. 相似文献
99.
The flame front deformation instability of low-velocity filtration combustion within an inert packed bed is studied based on the initial preheating non-uniformity. Based on the experimental phenomena, an initial thermal perturbation model is numerically proposed so as to predict the deformation behaviors of the flame front instabilities. The numerical prediction indicates that the assumption of an initial thermal perturbation is a feasible explanation as the cause of the flame front inclination instability. As the initial thermal perturbation increases, the phenomena of the flame front break and shrinking instabilities could easily occur at high filtration velocity or low equivalence ratio. Moreover, the evolutions of the flame front break rate and the shrinking rate are quantitatively analyzed. 相似文献
100.