全文获取类型
收费全文 | 171455篇 |
免费 | 19996篇 |
国内免费 | 8477篇 |
专业分类
电工技术 | 56202篇 |
技术理论 | 3篇 |
综合类 | 13407篇 |
化学工业 | 14503篇 |
金属工艺 | 9433篇 |
机械仪表 | 8256篇 |
建筑科学 | 9382篇 |
矿业工程 | 3916篇 |
能源动力 | 13885篇 |
轻工业 | 5389篇 |
水利工程 | 4397篇 |
石油天然气 | 5030篇 |
武器工业 | 1264篇 |
无线电 | 19328篇 |
一般工业技术 | 11398篇 |
冶金工业 | 6561篇 |
原子能技术 | 3430篇 |
自动化技术 | 14144篇 |
出版年
2024年 | 342篇 |
2023年 | 2365篇 |
2022年 | 4457篇 |
2021年 | 5310篇 |
2020年 | 5806篇 |
2019年 | 4805篇 |
2018年 | 4343篇 |
2017年 | 6049篇 |
2016年 | 6477篇 |
2015年 | 7064篇 |
2014年 | 11586篇 |
2013年 | 10375篇 |
2012年 | 13448篇 |
2011年 | 14595篇 |
2010年 | 10486篇 |
2009年 | 10759篇 |
2008年 | 10118篇 |
2007年 | 12160篇 |
2006年 | 10925篇 |
2005年 | 8849篇 |
2004年 | 7441篇 |
2003年 | 6150篇 |
2002年 | 4887篇 |
2001年 | 4276篇 |
2000年 | 3464篇 |
1999年 | 2579篇 |
1998年 | 1898篇 |
1997年 | 1563篇 |
1996年 | 1507篇 |
1995年 | 1180篇 |
1994年 | 1036篇 |
1993年 | 692篇 |
1992年 | 633篇 |
1991年 | 485篇 |
1990年 | 381篇 |
1989年 | 275篇 |
1988年 | 210篇 |
1987年 | 139篇 |
1986年 | 123篇 |
1985年 | 115篇 |
1984年 | 133篇 |
1983年 | 99篇 |
1982年 | 88篇 |
1981年 | 45篇 |
1980年 | 46篇 |
1979年 | 33篇 |
1978年 | 17篇 |
1977年 | 20篇 |
1959年 | 27篇 |
1951年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 158 毫秒
1.
海上风电作为可再生清洁能源之一,受到世界各国的高度重视与大力发展。我国将海上风电提升至解决能源危机、减缓气候变化、调整能源结构的国家战略高度,到2030年我国单位国内生产总值二氧化碳排放将比2005年下降65%以上,非化石能源占一次能源消费比重将达到25%左右。安装平台不足将是我国海上风电场无法如期建成投产的主要障碍。对自升自航式海上风电安装平台系列高端装备及其设计制造的三大技术难题——腿站立作业易“失稳”、大平台大跨距大倾覆力矩自升易“失控”、高空吊装巨型叶片逾百螺栓精准定位易“失准”,以及焊缝缺陷修复和局部裂纹损伤的激光锻造修复再制造进行了介绍,研制的具有不同规格的系列装备在中国、英国、丹麦、德国等国家的著名海上风电场建设应用情况良好。 相似文献
2.
Dr. Elena Petit Dr. Lluís Bosch Prof. Anna M. Costa Ignacio Rodríguez-Izquierdo Dr. Daniel Sepúlveda-Crespo Prof. M. Angeles Muñoz-Fernández Prof. Jaume Vilarrasa 《ChemMedChem》2021,16(14):2217-2222
Amides from indole-3-glyoxylic acid and 4-benzoyl-2-methylpiperazine, which are related to entry inhibitors developed by Bristol-Myers Squibb (BMS), have been synthesized with aliphatic chains located at the C7 position of the indole ring. These spacers contain an azido group suitable for the well-known Cu(I)-catalyzed (3+2)-cycloaddition or an activated triple bond for the nucleophilic addition of thiols under physiological conditions. Reaction with polyols (β-cyclodextrin and hyperbranched polyglycerol) decorated with complementary click partners has afforded polyol-BMS-like conjugates that are not cytotoxic (TZM.bl cells) and retain the activity against R5-HIV-1NLAD8 isolates. Thus, potential vaginal microbicides based on entry inhibitors, which can be called of 4th generation, are reported here for the first time. 相似文献
3.
《中国有色金属学会会刊》2021,31(8):2468-2478
An acoustic emission (AE) experiment was carried out to explore the AE location accuracy influenced by temperature. A hollow hemispherical specimen was used to simulate common underground structures. In the process of heating with the flame, the pulse signal of constant frequency was stimulated as an AE source. Then AE signals received by each sensor were collected and used for comparing localization accuracy at different temperatures. Results show that location errors of AE keep the same phenomenon in the early and middle heating stages. In the later stage of heating, location errors of AE increase sharply due to the appearance of cracks. This provides some beneficial suggestions on decreasing location errors of structural cracks caused by temperature and improves the ability of underground structure disaster prevention and control. 相似文献
4.
采用沉水植物表面流湿地(沉水组)、挺水植物表面流湿地(挺水组)和浮床湿地(浮床组)3种盐沼湿地对长江口近岸低污染水体进行脱氮除磷效能的研究。结果表明,HRT为3 d时,水组、挺水组、浮床组对NO3^--N的去除率在高温时段分别为79.9%±13.2%、71.8%±15.2%、77.2%±13.2%,中温时段分别为39.4%±13.7%、31.5%±8.5%、18.4%±16.6%,低温时段分别为15.6%±14.6%、19.7%±8.6%、2.%5±8.6%。沉水组和挺水组对TP的去除率受温度影响较小,分别为66.4%±32.4%、55.5%±29.4%;而浮床组除磷效果受温度影响较大。当HRT缩短为1.5 d时,3组湿地系统在高温时段仍可达到相近的脱氮除磷效果,在中低温时段脱氮除磷效果都有不同程度的下降。 相似文献
5.
本文开发了一种新型的方舱夹芯板用室温固化高强度环氧结构胶黏剂,验证了其物化特性、相关力学性能和环境适应性。结果表明此胶黏剂具有优良性能,可以满足方舱用大板胶黏剂的使用需求。 相似文献
6.
Yujie Chen Yiping Song Zhen Zhang Yali Chen Qiliang Deng Shuo Wang 《Advanced functional materials》2021,31(41):2104885
Various products, including foods and pharmaceuticals, are sensitive to temperature fluctuations. Thus, temperature monitoring during production, transportation, and storage is critical. Facile indicators are required to monitor temperature conditions via color changes in real time. This study aimed to prepare and apply thiol-functionalized covalent organic frameworks (COFs) as a novel indicator for monitoring thermal history and temperature abuse. The COFs underwent obvious color changes from bright yellow to purple after exposure to different temperatures for varying durations. The reaction kinetics are analyzed under isothermal conditions, which reveal that the order of reaction rates is k−20°C < k4°C < k20°C < k35°C < k55°C. The activation energy (Ea) of the COFs is calculated using the Arrhenius equation as 50.71 kJ moL−1. The COFs are capable of sensitive color changes and offer a broad temperature tracking range, thereby demonstrating their application potential for the monitoring of temperature and time exposure history during production, transportation, and storage. This excellent performance thermal history indicator also shows promise for expanding the application field of COFs. 相似文献
7.
8.
Shuang Xia Yukun Chen Jinfeng Tian Jinfeng Shi Chengzhen Geng Huawei Zou Mei Liang Zhibo Li 《Advanced functional materials》2021,31(26):2101143
Gecko-inspired microfibrillar adhesives have achieved great progress in microstructure design and adhesion improvement over the past two decades. Space applications nowadays show great interest in this material for the characteristics of reversible adhesion and universal van der Waals interactions. However, the impact of harsh environment of space on the performance of microfibrillar adhesives, especially the extreme low temperature, is rarely addressed. Herein, microfibrillar adhesives fabricated by phenyl containing polydimethylsiloxane (p-PDMS) elastomers with superior low-temperature reversible adhesion is proposed. p-PDMS elastomers are synthesized through one-pot anionic ring-opening copolymerization, and the resulting elastomers become non-crystallizable with excellent low-temperature elasticity. Low-temperature adhesion tests demonstrate that the adhesion strength of microfibrillar adhesives fabricated by p-PDMS elastomers can be well maintained to as low as −120 °C. In contrast, the adhesion strength of pure PDMS microfibrillar adhesive reduces more than 50% below its crystallization temperature. The low-temperature cyclic adhesion tests further demonstrate that p-PDMS microfibrillar adhesives exhibit superior reversible adhesion compared to that of PDMS microfibrillar adhesives, owing to the sustainable conformal contact and even distribution of loads over repeated cycles. This study provides a new fabrication strategy for microfibrillar adhesives, and is beneficial for the practical application of microfibrillar adhesives. 相似文献
9.
10.