全文获取类型
收费全文 | 62391篇 |
免费 | 5740篇 |
国内免费 | 2758篇 |
专业分类
电工技术 | 3491篇 |
技术理论 | 2篇 |
综合类 | 4097篇 |
化学工业 | 10278篇 |
金属工艺 | 3676篇 |
机械仪表 | 4041篇 |
建筑科学 | 4638篇 |
矿业工程 | 2110篇 |
能源动力 | 1685篇 |
轻工业 | 3950篇 |
水利工程 | 1054篇 |
石油天然气 | 3865篇 |
武器工业 | 524篇 |
无线电 | 7605篇 |
一般工业技术 | 7586篇 |
冶金工业 | 2950篇 |
原子能技术 | 631篇 |
自动化技术 | 8706篇 |
出版年
2024年 | 142篇 |
2023年 | 1072篇 |
2022年 | 1497篇 |
2021年 | 2436篇 |
2020年 | 1922篇 |
2019年 | 1719篇 |
2018年 | 1884篇 |
2017年 | 2078篇 |
2016年 | 1890篇 |
2015年 | 2455篇 |
2014年 | 3006篇 |
2013年 | 3603篇 |
2012年 | 4051篇 |
2011年 | 4443篇 |
2010年 | 3672篇 |
2009年 | 3513篇 |
2008年 | 3387篇 |
2007年 | 3287篇 |
2006年 | 3656篇 |
2005年 | 3031篇 |
2004年 | 2119篇 |
2003年 | 1791篇 |
2002年 | 1581篇 |
2001年 | 1427篇 |
2000年 | 1530篇 |
1999年 | 1667篇 |
1998年 | 1479篇 |
1997年 | 1249篇 |
1996年 | 1122篇 |
1995年 | 944篇 |
1994年 | 821篇 |
1993年 | 561篇 |
1992年 | 421篇 |
1991年 | 361篇 |
1990年 | 252篇 |
1989年 | 210篇 |
1988年 | 178篇 |
1987年 | 108篇 |
1986年 | 91篇 |
1985年 | 56篇 |
1984年 | 28篇 |
1983年 | 17篇 |
1982年 | 27篇 |
1981年 | 16篇 |
1980年 | 21篇 |
1979年 | 10篇 |
1978年 | 7篇 |
1977年 | 5篇 |
1976年 | 14篇 |
1975年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Raul D. Rodriguez Sergey Shchadenko Gennadiy Murastov Anna Lipovka Maxim Fatkullin Ilia Petrov Tuan-Hoang Tran Alimzhan Khalelov Muhammad Saqib Nelson E. Villa Vladimir Bogoslovskiy Yan Wang Chang-Gang Hu Alexey Zinovyev Wenbo Sheng Jin-Ju Chen Ihsan Amin Evgeniya Sheremet 《Advanced functional materials》2021,31(17):2008818
Polyethylene terephthalate (PET) is the most widely used polymer in the world. For the first time, the laser-driven integration of aluminum nanoparticles (Al NPs) into PET to realize a laser-induced graphene/Al NPs/polymer composite, which demonstrates excellent toughness and high electrical conductivity with the formation of aluminum carbide into the polymer is shown. The conductive structures show an impressive mechanical resistance against >10000 bending cycles, projectile impact, hammering, abrasion, and structural and chemical stability when in contact with different solvents (ethanol, water, and aqueous electrolytes). Devices including thermal heaters, carbon electrodes for energy storage, electrochemical and bending sensors show this technology's practical application for ultra-robust polymer electronics. This laser-based technology can be extended to integrating other nanomaterials and create hybrid graphene-based structures with excellent properties in a wide range of flexible electronics’ applications. 相似文献
82.
Yuan-Cheng Meng Hua-Feng Zhang Xiao-Xiao Pan Nan Chen Hui-Fang Hu Saeed ul Haq Abid Khan Ru-Gang Chen 《International journal of molecular sciences》2021,22(6)
Dehydrins (DHNs) play an important role in abiotic stress tolerance in a large number of plants, but very little is known about the function of DHNs in pepper plants. Here, we isolated a Y1SK2-type DHN gene “CaDHN3” from pepper. To authenticate the function of CaDHN3 in salt and drought stresses, it was overexpressed in Arabidopsis and silenced in pepper through virus-induced gene silencing (VIGS). Sub-cellular localization showed that CaDHN3 was located in the nucleus and cell membrane. It was found that CaDHN3-overexpressed (OE) in Arabidopsis plants showed salt and drought tolerance phenotypic characteristics, i.e., increased the initial rooting length and germination rate, enhanced chlorophyll content, lowered the relative electrolyte leakage (REL) and malondialdehyde (MDA) content than the wild-type (WT) plants. Moreover, a substantial increase in the activities of antioxidant enzymes; including the superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX), and lower hydrogen peroxide (H2O2) contents and higher O2•− contents in the transgenic Arabidopsis plants. Silencing of CaDHN3 in pepper decreased the salt- and drought-stress tolerance, through a higher REL and MDA content, and there was more accumulation of reactive oxygen species (ROS) in the CaDHN3-silenced pepper plants than the control plants. Based on the yeast two-hybrid (Y2H) screening and Bimolecular Fluorescence Complementation (BiFC) results, we found that CaDHN3 interacts with CaHIRD11 protein in the plasma membrane. Correspondingly, the expressions of four osmotic-related genes were significantly up-regulated in the CaDHN3-overexpressed lines. In brief, our results manifested that CaDHN3 may play an important role in regulating the relative osmotic stress responses in plants through the ROS signaling pathway. The results of this study will provide a basis for further analyses of the function of DHN genes in pepper. 相似文献
83.
针对现有高效管生产工艺在翅片形成过程中易撕裂翅片形成毛刺,影响翅片高度进而产生质量、换热的问题,拟以19.05冷凝管为试验对象,通过对高效管用管坯进行翅片成型加工前的预硬化处理,实现高效管表面毛刺减少、换热效率提升的目的 .研究表明,管坯经过预硬化处理后的翅片成型,其翅片硬度增加,不易撕裂;和未经过预硬化处理的翅片成型相比,高效管表面毛刺减少,翅片高度提升,外表面换热面积增大,单管换热效率提升. 相似文献
84.
Catalysis Letters - For the noble-metal based catalysts, the metal dispersion and sinter resistance of the metal nanoparticles (NPs) are the most vital factors for their application in series... 相似文献
85.
86.
Lin Chen Jun Guo Yuke Zhu Mingyu Hu Jing Feng 《Journal of the American Ceramic Society》2021,104(1):404-412
The features of crystal structures, thermo-mechanical properties and their dominant mechanisms of weberites RE3NbO7 were studied as high-temperature oxides. We concentrated on connections between structures and thermo-mechanical properties, the influences of bond lengths, lattice distortion degrees and microstructures on these properties were estimated. The shortening of bond length and increment of bonding strength would lead to the increase of mechanical properties. The Vickers hardness (4.5-7.8 GPa) and toughness (0.5-1.6 MPa·m1/2) of weberites RE3NbO7 are enhanced by grain refinement and increment of bond strength, while crystal structures, bond lengths, and lattice distortion degrees influenced their Young's modulus (100-170 GPa). Nano-indentation was applied to test the influence of microstructures on modulus and hardness. The dominant mechanisms for mechanical properties and thermal conductivity were proposed, which was conducive to properties tailoring and engineering applications of weberites RE3NbO7 oxides. 相似文献
87.
Dong Liu Xia Ke Zhong-Ce Hu Yu-Guo Zheng 《Journal of Bioscience and Bioengineering》2021,131(5):518-524
88.
随着时代的发展,我国对现代化建设方面的要求也在不断提高.经济的发展与建筑施工项目有很大的联系,故对其安全管理体系的要求也越来越高.所以为使我国经济的发展更上一层楼,应更注重提高建筑施工项目的安全管理和安全生产监控. 相似文献
89.
EPC工程总承包自20世纪80年代开始,在石油化工、水电工程等大型工程项目中EPC得到了较为广泛的应用,从2003年开始我国住房与城乡建设部下发了有关工程总承包的明确制度与规定,至此工程总承包正式得到了各行业的推广性应用.现就市政工程项目实施过程中的风险及成本控制进行详细的论述,对比了地基处理工程的三种方案:空心方桩,管桩和真空预压联合堆载预压. 相似文献
90.
EPC工程总承包自20世纪80年代开始,在石油化工、水电工程等大型工程项目中EPC得到了较为广泛的应用,从2003年开始我国住房与城乡建设部下发了有关工程总承包的明确制度与规定,至此工程总承包正式得到了各行业的推广性应用.现就市政工程项目实施过程中的风险及成本控制进行详细的论述,对比了地基处理工程的三种方案:空心方桩,管桩和真空预压联合堆载预压. 相似文献