全文获取类型
收费全文 | 288938篇 |
免费 | 80061篇 |
国内免费 | 53116篇 |
专业分类
电工技术 | 35998篇 |
技术理论 | 1篇 |
综合类 | 31020篇 |
化学工业 | 38354篇 |
金属工艺 | 31848篇 |
机械仪表 | 14239篇 |
建筑科学 | 20858篇 |
矿业工程 | 16879篇 |
能源动力 | 10956篇 |
轻工业 | 29421篇 |
水利工程 | 10113篇 |
石油天然气 | 16883篇 |
武器工业 | 4832篇 |
无线电 | 41721篇 |
一般工业技术 | 39861篇 |
冶金工业 | 10713篇 |
原子能技术 | 2974篇 |
自动化技术 | 65444篇 |
出版年
2024年 | 3224篇 |
2023年 | 5975篇 |
2022年 | 8511篇 |
2021年 | 10366篇 |
2020年 | 12126篇 |
2019年 | 20171篇 |
2018年 | 21898篇 |
2017年 | 23684篇 |
2016年 | 23049篇 |
2015年 | 23756篇 |
2014年 | 23538篇 |
2013年 | 23922篇 |
2012年 | 24674篇 |
2011年 | 21536篇 |
2010年 | 19933篇 |
2009年 | 16898篇 |
2008年 | 14723篇 |
2007年 | 14180篇 |
2006年 | 12319篇 |
2005年 | 10660篇 |
2004年 | 11566篇 |
2003年 | 9280篇 |
2002年 | 8712篇 |
2001年 | 7754篇 |
2000年 | 6780篇 |
1999年 | 5961篇 |
1998年 | 4892篇 |
1997年 | 4373篇 |
1996年 | 4130篇 |
1995年 | 4032篇 |
1994年 | 3343篇 |
1993年 | 3010篇 |
1992年 | 2851篇 |
1991年 | 2080篇 |
1990年 | 1650篇 |
1989年 | 1531篇 |
1988年 | 1162篇 |
1987年 | 396篇 |
1986年 | 342篇 |
1985年 | 237篇 |
1984年 | 165篇 |
1983年 | 108篇 |
1982年 | 171篇 |
1981年 | 161篇 |
1980年 | 126篇 |
1976年 | 230篇 |
1975年 | 206篇 |
1972年 | 237篇 |
1971年 | 128篇 |
1960年 | 205篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Feng Wenran Li Zhen Chen Yingying Chen Jinyang Lang Haoze Wan Jianghong Gao Yan Dong Haitao 《Journal of Materials Science》2022,57(3):1881-1889
Journal of Materials Science - Although chalcogenide materials continue to generate considerable interest due to great potentials for various optoelectronic devices, annealing for a long time in... 相似文献
4.
调度作为计划层和执行层的纽带,是智能型工厂的主要组成部分.对此,从炼油生产装置调度的角度,对炼油调度问题进行综述与分析.首先对炼油生产调度建模问题的研究现状进行阐述,介绍目前该领域建模方面考虑的因素;其次,对炼油生产调度的各种优化方法进行总结综述;最后,结合目前的信息技术和智能制造的发展趋势,分析炼油生产调度所面临的挑战和未来的研究方向. 相似文献
5.
边坡位移的时间序列曲线存在复杂的非线性特性,传统的预测模型精度不足以满足预测要求。为此提出了基于变分模态分解的鸟群优化-核极限学习机的预测模型,并用于河北省某水泥厂的边坡位移预测。该方法首先采用VMD把边坡位移序列分解为一系列的有限带宽的子序列,再对各子序列分别采用相空间重构并用核极限学习机预测,采用鸟群算法优化相空间重构的嵌入维度和KELM中惩罚系数和核参数三个数值,以取得最优预测模型。最后将各个子序列预测值叠加,得到边坡位移的最终预测值。结果表明:和KELM、BSA-KELM、EEMD-BSA-KELM模型相比,基于VMD的BSA-KELM预测精度更高,为边坡位移的预测提供一种有效的方法。 相似文献
6.
Photoresponsive biomaterials are experiencing a transition from in vitro models to in vivo demonstrations that point toward clinical translation. Dynamic hydrogels for cell encapsulation, light-responsive carriers for controlled drug delivery, and nanomaterials containing photosensitizers for photodynamic therapy are relevant examples. Nonetheless, the step to the clinic largely depends on their combination with technologies to bring light into the body. This review highlights the challenge of photoactivation in vivo, and presents strategies for light management that can be adopted for this purpose. The authors’ focus is on technologies that are materials-driven, particularly upconversion nanoparticles that assist in “direct path” light delivery through tissue, and optical waveguides that “clear the path” between external light source and in vivo target. The authors’ intention is to assist the photoresponsive biomaterials community transition toward medical technologies by presenting light delivery concepts that can be integrated with the photoresponsive targets. The authors also aim to stimulate further innovation in materials-based light delivery platforms by highlighting needs and opportunities for in vivo photoactivation of biomaterials. 相似文献
7.
Tao Feng Mingde Tong Shuotian Yao Hejun Li Shifeng Wen Hongjiao Lin 《Journal of the European Ceramic Society》2021,41(1):158-166
Composites based on hafnium carbide and reinforced with continuous naked carbon fiber with and without PyC interface were prepared at low temperature by precursor infiltration and pyrolysis and chemical vapor deposition method. The microstructure, mechanical property, cyclic ablation and fiber bundle push-in tests of the composites were investigated. The results show that after three times ablation cycles, the bending strength of samples without PyC interface decreased by 63.6 %; the bending strength of samples with PyC interface only decreased by 37.8 %. The force displacement curve of the samples with PyC interface presented a well pseudoplastic deformation state. The mechanical behavior difference of two kinds of composites was due to crucial function of PyC interface phase including protection of fiber and weakening of fiber/matrix interface. 相似文献
8.
9.
Fenqi Du Dongmei Yang Yue Sun Yang Jiao Feng Teng Haibo Fan 《Ceramics International》2021,47(4):4963-4971
Ultrawide band gap semiconductor materials have attracted considerable attention in recent years owing to their great potential in the photocatalytic field. In this study, Zn-doped Ga2O3 nanofibers with various concentrations were synthesized via electrospinning; they exhibited a superior photocatalytic degradation performance of rhodamine B dye compared to that of undoped Ga2O3 nanofibers. The Zn dopant replaced Ga sites via replacement doping, which could increase the concentration of oxygen vacancies and lead to enhanced photocatalytic properties. When the Zn concentration increased, a Ga2O3/ZnGa2O4 hybrid structure formed, which could further enhance the photocatalytic performance. The separation of photogenerated carriers due to Zn doping and heterojunctions were the primary causes of the enhanced photocatalytic performance. This study provides experimental data for the fabrication of high-performance photocatalysts based on Ga2O3 nanomaterials. 相似文献
10.