全文获取类型
收费全文 | 27584篇 |
免费 | 2156篇 |
国内免费 | 682篇 |
专业分类
电工技术 | 981篇 |
技术理论 | 1篇 |
综合类 | 1258篇 |
化学工业 | 5781篇 |
金属工艺 | 1123篇 |
机械仪表 | 1456篇 |
建筑科学 | 1210篇 |
矿业工程 | 324篇 |
能源动力 | 877篇 |
轻工业 | 3513篇 |
水利工程 | 325篇 |
石油天然气 | 502篇 |
武器工业 | 95篇 |
无线电 | 3179篇 |
一般工业技术 | 4227篇 |
冶金工业 | 2138篇 |
原子能技术 | 285篇 |
自动化技术 | 3147篇 |
出版年
2024年 | 76篇 |
2023年 | 339篇 |
2022年 | 755篇 |
2021年 | 1083篇 |
2020年 | 795篇 |
2019年 | 704篇 |
2018年 | 821篇 |
2017年 | 958篇 |
2016年 | 932篇 |
2015年 | 1164篇 |
2014年 | 1524篇 |
2013年 | 2030篇 |
2012年 | 2057篇 |
2011年 | 2311篇 |
2010年 | 1851篇 |
2009年 | 1825篇 |
2008年 | 1718篇 |
2007年 | 1415篇 |
2006年 | 1167篇 |
2005年 | 816篇 |
2004年 | 638篇 |
2003年 | 521篇 |
2002年 | 455篇 |
2001年 | 354篇 |
2000年 | 313篇 |
1999年 | 325篇 |
1998年 | 618篇 |
1997年 | 456篇 |
1996年 | 290篇 |
1995年 | 229篇 |
1994年 | 220篇 |
1993年 | 199篇 |
1992年 | 155篇 |
1991年 | 124篇 |
1990年 | 110篇 |
1989年 | 112篇 |
1988年 | 77篇 |
1987年 | 65篇 |
1986年 | 66篇 |
1985年 | 81篇 |
1984年 | 74篇 |
1983年 | 51篇 |
1982年 | 45篇 |
1981年 | 47篇 |
1980年 | 49篇 |
1979年 | 43篇 |
1978年 | 33篇 |
1977年 | 57篇 |
1976年 | 87篇 |
1975年 | 41篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Harmonic cavities (HCs) are widely used in electron storage rings, mainly to increase the Touschek lifetime by lengthening bunches. HCs have become critical com... 相似文献
82.
Na Li Guangyi Liu Huimin Zhang Quan Zhao Yun Zhao Zhou Tong Yingying Wang Junshuai Sun 《中国通信》2022,(3):1-15
The convergence of information, communication, and data technologies(ICDT) has been identified as one of the developing trends of the sixth generation(6G) network. Service-based architecture(SBA) as one of the promising information technology, has been preliminarily introduced into the fifth generation(5G) core network(CN) and successfully commercialized, which verifies its feasibility and effectiveness. However, SBA mainly focuses on the control plane of CN at present and the SBA-CN user plane ... 相似文献
83.
城市燃气公司为防止出现储气量过剩或不足等问题,必须要对天然气负荷量进行预测.对此,提出一种基于小波变换和长短期记忆网络的深度学习模型(wavelet_LSTM),对未来一年的天然气日负荷量进行预测.在某市燃气公司真实数据集上的实验结果表明,该模型有较高的准确性,可以较好地满足城市燃气公司的业务需求. 相似文献
84.
作为电力系统的重要特征之一,无功辅助服务与电力系统的安全可靠运行紧密相关.在厂网分开、产权多元化和市场竞争的环境下,为了体现发电厂间的公平竞争和优质优价,无功定价研究具有重要的现实意义.考虑无功成本分摊、系统的输电线损及合同交易偏差,建立了基于成本最小化、输电线损最小化、交易偏差最小化的无功定价模型;由于以上3个目标函数相互制约,将其整合为解调函数,获得了无功定价模型的全局最优解;通过CIGRE32-bus测试系统结合情景模数分析了基础算例、所有机组参与竞争和单一机组参与竞争时各机组对无功价格的影响. 相似文献
85.
86.
87.
通过对泸型不同档次的成品酒在货架期间的酒体进行理化、色谱分析以及感官鉴评跟踪比较,初步得出:随货架时间的增加,总酸呈增加趋势,总酯呈降低趋势,尤以低度、低档次的成品酒更加突出;感官鉴评也表现出,随货架时间的增加,酒体后味现短淡,尤以低度、低档次的成品酒更显著。在此基础上,提出了在酒体设计中应采取的质量对策措施。 相似文献
88.
凌娜 《南京工业职业技术学院学报》2006,6(3):56-57,60
从文献编目所含有的环节及编目理论的作用入手,着重论述了文献编目中题名的选取、主题词的著录和图书在版编目对书目数据的影响。 相似文献
89.
Camila I. Irion Monique Williams Jose Condor Capcha Trevor Eisenberg Guerline Lambert Lauro M. Takeuchi Grace Seo Keyvan Yousefi Rosemeire Kanashiro-Takeuchi Keith A. Webster Karen C. Young Joshua M. Hare Lina A. Shehadeh 《International journal of molecular sciences》2022,23(12)
Alport syndrome (AS) is a hereditary renal disorder with no etiological therapy. In the preclinical Col4a3-/- model of AS, disease progression and severity vary depending on mouse strain. The sodium-glucose cotransporter 2 (SGLT2) is emerging as an attractive therapeutic target in cardiac/renal pathologies, but its application to AS remains untested. This study investigates cardiorespiratory function and SGLT2 renal expression in Col4a3-/- mice from three different genetic backgrounds, 129x1/SvJ, C57Bl/6 and Balb/C. male Col4a3-/- 129x1/SvJ mice displayed alterations consistent with heart failure with preserved ejection fraction (HFpEF). Female, but not male, C57Bl/6 and Balb/C Col4a3-/- mice exhibited mild changes in systolic and diastolic function of the heart by echocardiography. Male C57Bl/6 Col4a3-/- mice presented systolic dysfunction by invasive hemodynamic analysis. All strains except Balb/C males demonstrated alterations in respiratory function. SGLT2 expression was significantly increased in AS compared to WT mice from all strains. However, cardiorespiratory abnormalities and SGLT2 over-expression were significantly less in AS Balb/C mice compared to the other two strains. Systolic blood pressure was significantly elevated only in mutant 129x1/SvJ mice. The results provide further evidence for strain-dependent cardiorespiratory and hypertensive phenotype variations in mouse AS models, corroborated by renal SGLT2 expression, and support ongoing initiatives to develop SGLT2 inhibitors for the treatment of AS. 相似文献
90.
Youngjae Ryu Yoonju Kim Hye Ryeong Lim Hyung-Joon Kim Byong Seo Park Jae Geun Kim Sang-Joon Park Chang Man Ha 《International journal of molecular sciences》2022,23(12)
Recent advances in optical clearing techniques have dramatically improved deep tissue imaging by reducing the obscuring effects of light scattering and absorption. However, these optical clearing methods require specialized equipment or a lengthy undertaking with complex protocols that can lead to sample volume changes and distortion. In addition, the imaging of cleared tissues has limitations, such as fluorescence bleaching, harmful and foul-smelling solutions, and the difficulty of handling samples in high-viscosity refractive index (RI) matching solutions. To address the various limitations of thick tissue imaging, we developed an Aqueous high refractive Index matching and tissue Clearing solution for Imaging (termed AICI) with a one-step tissue clearing protocol that was easily made at a reasonable price in our own laboratory without any equipment. AICI can rapidly clear a 1 mm thick brain slice within 90 min with simultaneous RI matching, low viscosity, and a high refractive index (RI = 1.466), allowing the imaging of the sample without additional processing. We compared AICI with commercially available RI matching solutions, including optical clear agents (OCAs), for tissue clearing. The viscosity of AICI is closer to that of water compared with other RI matching solutions, and there was a less than 2.3% expansion in the tissue linear morphology during 24 h exposure to AICI. Moreover, AICI remained fluid over 30 days of air exposure, and the EGFP fluorescence signal was only reduced to ~65% after 10 days. AICI showed a limited clearing of brain tissue >3 mm thick. However, fine neuronal structures, such as dendritic spines and axonal boutons, could still be imaged in thick brain slices treated with AICI. Therefore, AICI is useful not only for the three-dimensional (3D) high-resolution identification of neuronal structures, but also for the examination of multiple structural imaging by neuronal distribution, projection, and gene expression in deep brain tissue. AICI is applicable beyond the imaging of fluorescent antibodies and dyes, and can clear a variety of tissue types, making it broadly useful to researchers for optical imaging applications. 相似文献