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   1473篇
  免费   222篇
  国内免费   108篇
电工技术   39篇
综合类   180篇
化学工业   78篇
金属工艺   27篇
机械仪表   50篇
建筑科学   41篇
矿业工程   20篇
能源动力   25篇
轻工业   34篇
水利工程   12篇
石油天然气   23篇
武器工业   156篇
无线电   577篇
一般工业技术   102篇
冶金工业   60篇
原子能技术   36篇
自动化技术   343篇
  2024年   2篇
  2023年   17篇
  2022年   21篇
  2021年   54篇
  2020年   32篇
  2019年   44篇
  2018年   41篇
  2017年   45篇
  2016年   73篇
  2015年   76篇
  2014年   96篇
  2013年   106篇
  2012年   127篇
  2011年   162篇
  2010年   91篇
  2009年   107篇
  2008年   101篇
  2007年   110篇
  2006年   97篇
  2005年   63篇
  2004年   57篇
  2003年   47篇
  2002年   47篇
  2001年   35篇
  2000年   27篇
  1999年   26篇
  1998年   24篇
  1997年   13篇
  1996年   14篇
  1995年   15篇
  1994年   5篇
  1993年   4篇
  1992年   4篇
  1991年   4篇
  1990年   3篇
  1989年   3篇
  1988年   2篇
  1987年   3篇
  1986年   1篇
  1977年   1篇
  1975年   1篇
  1957年   1篇
  1954年   1篇
排序方式: 共有1803条查询结果,搜索用时 125 毫秒
1.
Pancreatic ductal adenocarcinoma (PDAC), an extremely aggressive invasive cancer, is the fourth most common cause of cancer-related death in the United States. The higher mortality in PDAC is often attributed to the inability to detect it until it has reached advanced stages. The major challenge in tackling PDAC is due to its elusive pathology, minimal effectiveness, and resistance to existing therapeutics. The aggressiveness of PDAC is due to the capacity of tumor cells to alter their metabolism, utilize the diverse available fuel sources to adapt and grow in a hypoxic and harsh environment. Therapeutic resistance is due to the presence of thick stroma with poor angiogenesis, thus making drug delivery to tumor cells difficult. Investigating the metabolic mediators and enzymes involved in metabolic reprogramming may lead to the identification of novel therapeutic targets. The metabolic mediators of glucose, glutamine, lipids, nucleotides, amino acids and mitochondrial metabolism have emerged as novel therapeutic targets. Additionally, the role of autophagy, macropinocytosis, lysosomal transport, recycling, amino acid transport, lipid transport, and the role of reactive oxygen species has also been discussed. The role of various pro-inflammatory cytokines and immune cells in the pathogenesis of PDAC and the metabolites involved in the signaling pathways as therapeutic targets have been previously discussed. This review focuses on the therapeutic potential of metabolic mediators in PDAC along with stemness due to metabolic alterations and their therapeutic importance.  相似文献   
2.
3.
Xanthohumol (XH) is an important prenylated flavonoid that is found within the inflorescence of Humulus lupulus L. (Hop plant). XH is an important ingredient in beer and is considered a significant bioactive agent due to its diverse medicinal applications, which include anti-inflammatory, antimicrobial, antioxidant, immunomodulatory, antiviral, antifungal, antigenotoxic, antiangiogenic, and antimalarial effects as well as strong anticancer activity towards various types of cancer cells. XH acts as a wide ranging chemopreventive and anticancer agent, and its isomer, 8-prenylnaringenin, is a phytoestrogen with strong estrogenic activity. The present review focuses on the bioactivity of XH on various types of cancers and its pharmacokinetics. In this paper, we first highlight, in brief, the history and use of hops and then the chemistry and structure–activity relationship of XH. Lastly, we focus on its prominent effects and mechanisms of action on various cancers and its possible use in cancer prevention and treatment. Considering the limited number of available reviews on this subject, our goal is to provide a complete and detailed understanding of the anticancer effects of XH against different cancers.  相似文献   
4.
Osteosarcoma (OS) is a rare condition with very poor prognosis in a metastatic setting. Basic research has enabled a better understanding of OS pathogenesis and the discovery of new potential therapeutic targets. Phase I and II clinical trials are already ongoing, with some promising results for these patients. This article reviews OS pathogenesis and new potential therapeutic targets.  相似文献   
5.
Cannabidiol (CBD), the major nonpsychoactive Cannabis constituent, has been proposed for the treatment of a wide panel of neurological and neuropsychiatric disorders, including anxiety, schizophrenia, epilepsy and drug addiction due to the ability of its versatile scaffold to interact with diverse molecular targets that are not restricted to the endocannabinoid system. Albeit the molecular mechanisms responsible for the therapeutic effects of CBD have yet to be fully elucidated, many efforts have been devoted in the last decades to shed light on its complex pharmacological profile. In particular, an ever-increasing number of molecular targets linked to those disorders have been identified for this phytocannabinoid, along with the modulatory effects of CBD on their cascade signaling. In this view, here we will try to provide a comprehensive and up-to-date overview of the molecular basis underlying the therapeutic effects of CBD involved in the treatment of neurological and neuropsychiatric disorders.  相似文献   
6.
本文回顾和总结了晋煤集团煤层气的开发历程和煤层气利用情况,分析了晋煤集团煤层气开发利用的方向和市场,详细阐明了晋煤集团的近期规划和发展前景。  相似文献   
7.
将神经网络与传统专家系统有机地结合,建立了用于浮选过程中浮选指标预测与判断的神经网络专家系统,该系统适应性强,且具有良好的自学习功能。  相似文献   
8.
针对传统目标排序方法忽略了现实中不确定因素和对立因素的缺点,基于集对分析理论建立了炮兵远程精确打击目标排序指标体系。从同、异、反3个方面研究打击目标的确定性与不确定性,运用联系度的概念从全局角度对目标排序问题进行集对分析,并以实例进行目标排序。结果表明,该方法简单易行、思路新颖、易于编程,适合处理大量数据,能较好解决定性分析时认识判读偏差的问题。  相似文献   
9.
陈晓娟  史震  冯屾 《航空兵器》2011,(5):23-25,55
为了适应未来海战的特点和要求,如何提高反舰导弹的突防能力,已经成为各国研究的一项重点。本文在采用过载控制方案的基础上,采用非线性控制方法,设计了反舰导弹线性自适应变结构复合控制器。在过载稳定回路的基础上,通过对导弹高度和侧向偏移的控制实现了导弹的飞行控制系统设计。通过对导弹的末端机动信号的设计,实现了导弹纵向跃升和航向...  相似文献   
10.
针对低信噪比下机动目标的调频步进雷达成像问题,提出基于Radon-分数阶模糊函数(RFRAF)的方法进行积累成像的方法.在分析了机动目标的调频步进雷达回波信号特征的基础上,将目标回波信号在RFRAF域进行匹配和积累,通过峰值搜索出目标的运动参数,并构建补偿函数实现机动目标运动补偿,从而获得目标精确ISAR像.计算机仿真结果进一步表明了该方法能在低信噪比下稳健成像.  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