全文获取类型
收费全文 | 511579篇 |
免费 | 82079篇 |
国内免费 | 51707篇 |
专业分类
电工技术 | 38268篇 |
技术理论 | 1篇 |
综合类 | 28241篇 |
化学工业 | 71794篇 |
金属工艺 | 37479篇 |
机械仪表 | 19450篇 |
建筑科学 | 25551篇 |
矿业工程 | 16298篇 |
能源动力 | 17420篇 |
轻工业 | 55004篇 |
水利工程 | 11329篇 |
石油天然气 | 17731篇 |
武器工业 | 4652篇 |
无线电 | 72273篇 |
一般工业技术 | 82529篇 |
冶金工业 | 56322篇 |
原子能技术 | 5666篇 |
自动化技术 | 85357篇 |
出版年
2024年 | 3127篇 |
2023年 | 5949篇 |
2022年 | 8457篇 |
2021年 | 10799篇 |
2020年 | 12435篇 |
2019年 | 21364篇 |
2018年 | 23854篇 |
2017年 | 25581篇 |
2016年 | 25350篇 |
2015年 | 24864篇 |
2014年 | 25817篇 |
2013年 | 34164篇 |
2012年 | 29125篇 |
2011年 | 28762篇 |
2010年 | 24959篇 |
2009年 | 23101篇 |
2008年 | 21576篇 |
2007年 | 20941篇 |
2006年 | 18621篇 |
2005年 | 16733篇 |
2004年 | 17763篇 |
2003年 | 15552篇 |
2002年 | 14632篇 |
2001年 | 14058篇 |
2000年 | 12455篇 |
1999年 | 12441篇 |
1998年 | 21150篇 |
1997年 | 15641篇 |
1996年 | 12568篇 |
1995年 | 10421篇 |
1994年 | 8912篇 |
1993年 | 8441篇 |
1992年 | 6698篇 |
1991年 | 5739篇 |
1990年 | 5094篇 |
1989年 | 4786篇 |
1988年 | 4331篇 |
1987年 | 2967篇 |
1986年 | 2818篇 |
1985年 | 3377篇 |
1984年 | 2957篇 |
1983年 | 2673篇 |
1982年 | 2504篇 |
1981年 | 2547篇 |
1980年 | 2320篇 |
1979年 | 2115篇 |
1978年 | 1967篇 |
1977年 | 2213篇 |
1976年 | 2941篇 |
1975年 | 1765篇 |
排序方式: 共有10000条查询结果,搜索用时 0 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
2.
Journal of Materials Science - 相似文献
3.
Xiao Zhu Chen Yanxun Jiang Hongbo Hu Zhenzhen Lui John C. S. Min Geyong Dustdar Schahram 《Wireless Networks》2022,28(7):3305-3322
Wireless Networks - Unmanned aerial vehicles (UAV) have been widely used in various fields because of their high mobility and portability. At the same time, due to the rapid development of... 相似文献
4.
6.
为研究织物组织结构与复合纱线线密度对织物凉爽性能的影响,将线密度为7.4和9.8 tex涤纶分别与线密度为7.8 tex锦纶反向加捻、并线后作为纬纱,以8.3 tex涤纶/竹浆纤维50/50混纺纱作经纱,设计平纹、二上一下斜纹和透孔组织织物.测试织物的瞬间接触凉感、热湿舒适性能及织物干、湿态升温曲线,并采用凉爽温度指数对织物的综合凉爽性能进行评价.研究结果表明:6种设计织物的瞬间接触凉感均高于标准,且平纹织物最好,纬纱粗细对瞬间接触凉感影响不显著;透孔织物透气性最好,且在人体出汗的状态下具有较好的导湿散热性能.平纹织物凉爽温度指数最高,最大凉爽温度为2.8℃,综合凉爽性能最好. 相似文献
7.
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
8.
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
9.
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
10.
John D. Rodney S. Deepapriya M. Cyril Robinson C. Justin Raj Suresh Perumal Byung Chul Kim S. Krishnan S. Jerome Das 《International Journal of Hydrogen Energy》2021,46(54):27585-27596
The production of hydrogen, a favourable alternative to an unsustainable fossil fuel remains as a significant hurdle with the pertaining challenge in the design of proficient, highly productive and sustainable electrocatalyst for both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Herein, the dysprosium (Dy) doped copper oxide (Cu1-xDyxO) nanoparticles were synthesized via solution combustion technique and utilized as a non-noble metal based bi-functional electrocatalyst for overall water splitting. Due to the improved surface to volume ratio and conductivity, the optimized Cu1-xDyxO (x = 0.01, 0.02) electrocatalysts exhibited impressive HER and OER performance respectively in 1 M KOH delivering a current density of 10 mAcm?2 at a potential of ?0.18 V vs RHE for HER and 1.53 V vs RHE for OER. Moreover, the Dy doped CuO electrocatalyst used as a bi-functional catalyst for overall water splitting achieved a potential of 1.56 V at a current density 10 mAcm?2 and relatively high current density of 66 mAcm?2 at a peak potential of 2 V. A long term stability of 24 h was achieved for a cell voltage of 2.2 V at a constant current density of 30 mAcm?2 with only 10% of the initial current loss. This showcases the accumulative opportunity of dysprosium as a dopant in CuO nanoparticles for fabricating a highly effective and low-cost bi-functional electrocatalyst for overall water splitting. 相似文献