全文获取类型
收费全文 | 10496篇 |
免费 | 1393篇 |
国内免费 | 590篇 |
专业分类
电工技术 | 1445篇 |
综合类 | 998篇 |
化学工业 | 1428篇 |
金属工艺 | 774篇 |
机械仪表 | 914篇 |
建筑科学 | 1010篇 |
矿业工程 | 536篇 |
能源动力 | 502篇 |
轻工业 | 577篇 |
水利工程 | 682篇 |
石油天然气 | 606篇 |
武器工业 | 104篇 |
无线电 | 508篇 |
一般工业技术 | 764篇 |
冶金工业 | 856篇 |
原子能技术 | 127篇 |
自动化技术 | 648篇 |
出版年
2024年 | 44篇 |
2023年 | 164篇 |
2022年 | 344篇 |
2021年 | 397篇 |
2020年 | 393篇 |
2019年 | 287篇 |
2018年 | 312篇 |
2017年 | 373篇 |
2016年 | 431篇 |
2015年 | 439篇 |
2014年 | 707篇 |
2013年 | 694篇 |
2012年 | 818篇 |
2011年 | 882篇 |
2010年 | 667篇 |
2009年 | 634篇 |
2008年 | 539篇 |
2007年 | 645篇 |
2006年 | 568篇 |
2005年 | 525篇 |
2004年 | 441篇 |
2003年 | 358篇 |
2002年 | 301篇 |
2001年 | 248篇 |
2000年 | 232篇 |
1999年 | 161篇 |
1998年 | 168篇 |
1997年 | 123篇 |
1996年 | 94篇 |
1995年 | 88篇 |
1994年 | 86篇 |
1993年 | 62篇 |
1992年 | 47篇 |
1991年 | 34篇 |
1990年 | 37篇 |
1989年 | 19篇 |
1988年 | 18篇 |
1987年 | 19篇 |
1986年 | 6篇 |
1985年 | 9篇 |
1984年 | 13篇 |
1983年 | 11篇 |
1982年 | 4篇 |
1980年 | 9篇 |
1979年 | 4篇 |
1961年 | 2篇 |
1960年 | 2篇 |
1959年 | 2篇 |
1957年 | 2篇 |
1951年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
141.
随着新能源发电占比增加,发电侧的调节能力降低,挖掘负荷侧的可调节潜力是新型电力系统电力供需平衡的必然选择。针对工业用户,提出了一种基于二次聚类的可调节潜力特征提取与综合评估方法。综合考虑工业用户的可中断性、可转移性和生产属性,建立了负荷可调节潜力评估指标体系。首先,采用近邻传播(affinity propagation, AP)聚类-k均值(k-means)聚类的二次聚类方法挖掘用户可调节潜力特征,计算可调节指标。其次,基于相关性定权(criteria importance through intercriteria correlation, CRITIC)法和多准则妥协解排序(vlsekriterijumska optimizacija I kompromisno resenje, VIKOR)法分别评估工业用户可中断潜力、可转移潜力和生产潜力。然后,利用集对分析(set pair analysis, SPA)-可变模糊集(variable fuzzy set, VFS)法评估工业用户负荷综合可调节潜力,并得到优先级排序。最后,根据某地区9户工业用户历史负荷监测数据进行可调节潜力评估,通过对不同聚类方法、不同指标体系以及不同评估算法结果的对比分析,验证了所提方法在特征提取、指标定义以及评估合理性方面的优势。 相似文献
142.
二甲苯是一种重要的人为源 VOC, 也是城市地区 SOA 的重要前体物。二甲苯光氧化形成的 SOA 受多种环
境因素影响, 而 NH3 对该反应形成的 SOA 生成产率及反应机制的影响尚不清楚。基于室内烟雾箱模拟系统, 探讨了
NH3 对二甲苯光氧化形成 SOA 质量浓度、物理特性及化学组成的影响。研究表明, 在低浓度条件下, NH3 对二甲苯
光氧化生成 SOA 具有明显的促进作用, 结合气溶胶质谱结果发现 NH3 促进醛酮类物质进入颗粒相以及含氮有机物的
生成是导致 SOA 质量浓度增加的主要原因。此外, NH3 能够提高邻二甲苯生成 SOA 的吸光度, 但是对对二甲苯无明
显影响。分析表明, 相较于对二甲苯, 邻二甲苯光氧化会生成大量醛类物质, NH3 与醛类发生美拉德反应是导致 SOA
吸光性增加的主要原因。 相似文献
143.
Disassembly–Reassembly Approach to RuO2/Graphene Composites for Ultrahigh Volumetric Capacitance Supercapacitor 下载免费PDF全文
A porous, yet compact, RuO2/graphene hybrid is successfully prepared by using a disassembly–reassembly strategy, achieving effective and uniform loading of RuO2 nanoparticles inside compact graphene monolith. The disassembly process ensures the uniform loading of RuO2 nanoparticles into graphene monolith, while the reassembly process guarantees a high density yet simultaneously unimpeded ion transport channel in the composite. The resulting RuO2/graphene hybrid possesses a density of 2.63 g cm−3, leading to a record high volumetric capacitance of 1485 F cm−3 at the current density of 0.1 A g−1. When the current density is increased to 20 A g−1, it remains a high volumetric capacitance of 1188 F cm−3. More importantly, when the single electrode mass loading is increased to 12 mg cm−2, it still delivers a high volumetric capacitance of 1415 F cm−3 at the current density of 0.1 A g−1, demonstrating the promise of this disassembly–reassembly approach to create high volumetric performance materials for energy storage applications. 相似文献
144.
Carbon Nanotubes: Carbon Nanotubes Disrupt Iron Homeostasis and Induce Anemia of Inflammation through Inflammatory Pathway as a Secondary Effect Distant to Their Portal‐of‐Entry (Small 15/2017) 下载免费PDF全文
145.
146.
Cijun Shuai Chongxian He Liang Xu Quan Li Tong Chen 《Virtual and Physical Prototyping》2018,13(4):292-300
The discrete secondary phases usually cause severe galvanic corrosion, thereby resulting in rapid degradation for Mg–Al alloys in orthopaedics application. In this study, CaO was introduced into Mg–Al–Zn (AZ61) alloy via selective laser melting (SLM) to ameliorate the characterisations of the secondary phases, with an aim to improve its corrosion behaviour. Results revealed that CaO reacted with Mg and Al in Mg–Al alloys during SLM, suppressing the formation of coarse Mg17Al12 phase and promoting the formation of (Mg, Al)2Ca phase. Meanwhile, the rapid solidification during SLM promoted the homogeneous precipitation of the second phase. As a result, inert (Mg, Al)2Ca phase homogeneously wrapped the Mg grains, which effectively protected them from the invasion of corrosion solution. Thus, the degradation rate was remarkably reduced from 0.073 to 0.031?mg?cm–2?h–1. Furthermore, AZ61-9CaO exhibited good cytocompatibility. This work suggested that AZ61-9CaO was promising candidates for orthopaedics implants. 相似文献
147.
Ceramic foams are made of zinc oxide using different amounts of Sb2O3 and Bi2O3 as sintering aids. The effect of a ball milling processing of the starting powders and the sintering temperature on the microstructure and the properties of the ZnO foams is investigated. The focus is set on the evolution of the secondary phases formed within the microstructure of ZnO. A determining effect is identified in the amount of an Al2O3 impurity which is introduced by abrasion of the milling vessels during ball milling. Alumina is partially dissolved in a spinel α–Zn7Sb2O12 secondary phase which is stabilized by a reduction of the unit cell volume. Remaining Al2O3 is incorporated into zinc oxide under formation of a defect wurtzite phase. The phase evolution is a complex function of the content of sintering aids, the Al2O3 impurity level and the sintering temperature. The shrinkage during sintering and the porosity evolution are correlated to the phase composition within the ZnO material. The thermal conductivity and the compressive strength of the foams are determined, normalized with respect to their porosity, and correlated to the microstructure and phase composition of the ZnO strut material. 相似文献
148.
149.
150.
Yusuke Fukui Yosuke Honda Yasuhiro Yamauchi Michiko Okafuji Masahiro Sakai Mikihiko Nishitani Yusuke Takata 《Journal of the Society for Information Display》2010,18(12):1090-1094
Abstract— MgO thin film is currently used as a surface protective layer for dielectric materials because MgO has a high resistance during ion sputtering and exhibits effective secondary electron emission. The secondary‐electron‐emission coefficient γ of MgO is high for Ne ions; however, it is low for Xe ions. The Xe content of the discharge gas of PDPs needs to be raised in order to increase the luminous efficiency. Thus, the development of high‐γ materials replacing MgO is required. The discharge properties and chemical surface stability of SrO containing Zr (SrZrO) as the candidate high‐γ protective layer for noble PDPs have been characterized. SrZrO films have superior chemical stability, especially the resistance to carbonation because of the existence of a few adsorption sites due to their amorphous structure. The firing voltage is 60 V lower than that of MgO films for a discharge gas of Ne/Xe = 85/15 at 60 kPa. 相似文献