首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   80098篇
  免费   12021篇
  国内免费   4020篇
电工技术   4783篇
技术理论   3篇
综合类   4959篇
化学工业   15356篇
金属工艺   3199篇
机械仪表   4772篇
建筑科学   5781篇
矿业工程   2518篇
能源动力   1822篇
轻工业   8328篇
水利工程   2221篇
石油天然气   4130篇
武器工业   1010篇
无线电   12925篇
一般工业技术   11551篇
冶金工业   3026篇
原子能技术   1441篇
自动化技术   8314篇
  2024年   174篇
  2023年   1573篇
  2022年   2899篇
  2021年   4789篇
  2020年   2959篇
  2019年   2889篇
  2018年   3037篇
  2017年   3712篇
  2016年   5007篇
  2015年   5490篇
  2014年   6089篇
  2013年   6034篇
  2012年   5198篇
  2011年   4674篇
  2010年   3728篇
  2009年   3824篇
  2008年   3496篇
  2007年   4922篇
  2006年   4978篇
  2005年   4097篇
  2004年   2969篇
  2003年   2765篇
  2002年   1930篇
  2001年   1334篇
  2000年   1141篇
  1999年   1029篇
  1998年   724篇
  1997年   626篇
  1996年   638篇
  1995年   494篇
  1994年   477篇
  1993年   399篇
  1992年   311篇
  1991年   245篇
  1990年   250篇
  1989年   199篇
  1988年   124篇
  1987年   90篇
  1986年   85篇
  1985年   85篇
  1984年   93篇
  1983年   56篇
  1982年   53篇
  1981年   42篇
  1980年   51篇
  1966年   25篇
  1964年   34篇
  1962年   64篇
  1959年   24篇
  1955年   22篇
排序方式: 共有10000条查询结果,搜索用时 102 毫秒
61.
移动边缘云是公司“云+5G”双引擎战略的最佳契合点,边缘网络是发挥移动云“大云”产品和5G网络融合优势,实现云网统筹、构建运营商“连接+计算”核心能力的关键。运营商传统接入网存在云网割裂、分段入云和组网复杂等突出问题,难以适应边缘业务敏捷交付要求。本文通过深入分析边缘云业务特征和技术架构,对标业界主流云商建设实践,研究基于云网PoP网的边缘网络建设思路,创新性提出云网一体化规划设计和建设交付流程变革,基于云网POP统一网络和业务锚点,构建Overlay和Underlay融合双层加速网络架构,探索Spine-leaf化的新型城域接入网实现L3下沉和弹性扩容等方法,实现“云+网+应用”一体化敏捷交付的边缘网络能力。  相似文献   
62.
在“移动互联网+课堂”的大势趋动下,针对现在“数字电子技术实验”教学存在的教学模式落后,教学手段单一,教学内容简单、以及考核不够全面等问题,借助超星泛雅 “一平三端”平台进行“线上-线下混合教学”改革。通过课前发布任务、课中有效组织课堂活动、课后发布作业、统计数据和教学反思进行。实践表明:该方法提高了学生的自主学习能力,并且增强了教师对学生学习情况的动态跟踪和过程性指导,同时也让课堂教学更有效,教学评价方式更有针对性、更精准,最终达到知识、技能和情感态度价值观的培养。  相似文献   
63.
Terahertz (THz) imaging is expected to become powerful tools for non-destructive inspections. To ensure the practical use of THz non-destructive monitoring, versatile THz imagers with adjustable designs that can eliminate the complexities and the bulkiness of the device are urgently required. Herein, a self-aligned filtration process for a 2D, free-standing carbon nanotube film array and its application to a THz video camera patch are reported. The presented techniques enable a) to freely design the camera size, sensor array pattern, and suspended shape according to its applications, b) to cut the camera patch into desired shapes, and c) to attach them to the objects that are intended to be measured. Real-time, non-destructive monitoring of various infrastructures is demonstrated. These results indicate that it can function regardless of restrictions, such as the shapes and locations of the measurement samples, thus providing a strong possibility for use in future non-destructive sensor networks.  相似文献   
64.
65.
66.
67.
68.
The growth in the number of chronic non-communicable diseases in the second half of the past century and in the first two decades of the new century is largely due to the disruption of the relationship between the human body and its symbiotic microbiota, and not pathogens. The interaction of the human immune system with symbionts is not accompanied by inflammation, but is a physiological norm. This is achieved via microbiota control by the immune system through a complex balance of pro-inflammatory and suppressive responses, and only a disturbance of this balance can trigger pathophysiological mechanisms. This review discusses the establishment of homeostatic relationships during immune system development and intestinal bacterial colonization through the interaction of milk glycans, mucins, and secretory immunoglobulins. In particular, the role of fucose and fucosylated glycans in the mechanism of interactions between host epithelial and immune cells is discussed.  相似文献   
69.
Mesenchymal stem cells (MSCs) are the main cell players in tissue repair and thanks to their self-renewal and multi-lineage differentiation capabilities, they gained significant attention as cell source for tissue engineering (TE) approaches aimed at restoring bone and cartilage defects. Despite significant progress, their therapeutic application remains debated: the TE construct often fails to completely restore the biomechanical properties of the native tissue, leading to poor clinical outcomes in the long term. Pulsed electromagnetic fields (PEMFs) are currently used as a safe and non-invasive treatment to enhance bone healing and to provide joint protection. PEMFs enhance both osteogenic and chondrogenic differentiation of MSCs. Here, we provide extensive review of the signaling pathways modulated by PEMFs during MSCs osteogenic and chondrogenic differentiation. Particular attention has been given to the PEMF-mediated activation of the adenosine signaling and their regulation of the inflammatory response as key player in TE approaches. Overall, the application of PEMFs in tissue repair is foreseen: (1) in vitro: to improve the functional and mechanical properties of the engineered construct; (2) in vivo: (i) to favor graft integration, (ii) to control the local inflammatory response, and (iii) to foster tissue repair from both implanted and resident MSCs cells.  相似文献   
70.
Several studies, including genome wide association studies (GWAS), have strongly suggested a central role for the ATP-binding cassette transporter subfamily A member 7 (ABCA7) in Alzheimer’s disease (AD). This ABC transporter is now considered as an important genetic determinant for late onset Alzheimer disease (LOAD) by regulating several molecular processes such as cholesterol metabolism and amyloid processing and clearance. In this review we shed light on these new functions and their cross-talk, explaining its implication in brain functioning, and therefore in AD onset and development.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号