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   34354篇
  免费   2629篇
  国内免费   1356篇
电工技术   1754篇
技术理论   2篇
综合类   2217篇
化学工业   6155篇
金属工艺   2012篇
机械仪表   1986篇
建筑科学   2576篇
矿业工程   1036篇
能源动力   867篇
轻工业   1902篇
水利工程   526篇
石油天然气   2564篇
武器工业   230篇
无线电   4014篇
一般工业技术   4132篇
冶金工业   1567篇
原子能技术   437篇
自动化技术   4362篇
  2024年   165篇
  2023年   578篇
  2022年   986篇
  2021年   1405篇
  2020年   1065篇
  2019年   886篇
  2018年   1046篇
  2017年   1150篇
  2016年   965篇
  2015年   1270篇
  2014年   1621篇
  2013年   2014篇
  2012年   2096篇
  2011年   2339篇
  2010年   1975篇
  2009年   1813篇
  2008年   1734篇
  2007年   1625篇
  2006年   1796篇
  2005年   1629篇
  2004年   1103篇
  2003年   937篇
  2002年   867篇
  2001年   750篇
  2000年   867篇
  1999年   1020篇
  1998年   788篇
  1997年   707篇
  1996年   687篇
  1995年   563篇
  1994年   461篇
  1993年   343篇
  1992年   262篇
  1991年   195篇
  1990年   146篇
  1989年   127篇
  1988年   112篇
  1987年   68篇
  1986年   50篇
  1985年   24篇
  1984年   18篇
  1983年   18篇
  1982年   30篇
  1981年   14篇
  1980年   11篇
  1979年   2篇
  1977年   6篇
  1976年   2篇
  1975年   1篇
  1951年   1篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
智能终端产品(包括手机、平板和混合式的移动计算设备)在个人和商业应用场合大量使用,终端在高速计算能力方面更新迅猛,处理能力军备竞赛将陷入硬件瓶颈,同质现象成为现实,而人机交互技术、终端应用开发环境、终端安全云服务等将成为影响智能终端向纵深人群渗透和更商业化应用领域发展的决定要素。本文旨在探讨、分析和展示上述几个关键技术的新进展和演进趋势。  相似文献   
102.
Tomographic perfusion imaging is a significant imaging modality for stroke diagnosis.However,the low rotational speed of the C-arm(6-8 s per circle)is a chal-le...  相似文献   
103.
The barcode probe is a convenient and efficient tool for molecular cytogenetics. Tripidium arundinaceum, as a polyploid wild allied genus of Saccharum, is a useful genetic resource that confers biotic and abiotic stress resistance for sugarcane breeding. Unfortunately, the basic cytogenetic information is still unclear due to the complex genome. We constructed the Cot-20 library for screening moderately and highly repetitive sequences from T. arundinaceum, and the chromosomal distribution of these repetitive sequences was explored. We used the barcode of repetitive sequence probes to distinguish the ten chromosome types of T. arundinaceum by fluorescence in situ hybridization (FISH) with Ea-0907, Ea-0098, and 45S rDNA. Furthermore, the distinction among homology chromosomes based on repetitive sequences was constructed in T. arundinaceum by the repeated FISH using the barcode probes including Ea-0663, Ea-0267, EaCent, 5S rDNA, Ea-0265, Ea-0070, and 45S rDNA. We combined these probes to distinguish 37 different chromosome types, suggesting that the repetitive sequences may have different distributions on homologous chromosomes of T. arundinaceum. In summary, this method provide a basis for the development of similar applications for cytogenetic analysis in other species.  相似文献   
104.
制备了国内外文献未见报道的70%稻瘟灵可湿性粉剂(WP),对该剂型的配方组成、加工工艺、贮存稳定性进行了研究,并对其各项性能进行了测试,确定了优惠配方。实验结果表明,该产品的各项指标均符合可湿性粉剂标准的要求,悬浮率在90%以上,润湿时间在1min以内,在40±2℃下贮存60天后的分解率小于5%。  相似文献   
105.
Mitochondria, as the main site of cellular energy metabolism and the generation of oxygen free radicals, are the key switch for mitochondria-mediated endogenous apoptosis. Ca2+ is not only an important messenger for cell proliferation, but it is also an indispensable signal for cell death. Ca2+ participates in and plays a crucial role in the energy metabolism, physiology, and pathology of mitochondria. Mitochondria control the uptake and release of Ca2+ through channels/transporters, such as the mitochondrial calcium uniporter (MCU), and influence the concentration of Ca2+ in both mitochondria and cytoplasm, thereby regulating cellular Ca2+ homeostasis. Mitochondrial Ca2+ transport-related processes are involved in important biological processes of tumor cells including proliferation, metabolism, and apoptosis. In particular, MCU and its regulatory proteins represent a new era in the study of MCU-mediated mitochondrial Ca2+ homeostasis in tumors. Through an in-depth analysis of the close correlation between mitochondrial Ca2+ and energy metabolism, autophagy, and apoptosis of tumor cells, we can provide a valuable reference for further understanding of how mitochondrial Ca2+ regulation helps diagnosis and therapy.  相似文献   
106.
107.
108.
109.
The influence of microstructural characteristics on Lüders strain and mechanical properties was explored by means of altering thermo-mechanical circumstances in...  相似文献   
110.
A growing body of research suggests that inflammatory insult contributes to the etiology of central nervous system diseases, such as depression, Alzheimer’s disease, and so forth. However, the effect of prenatal systemic inflammation exposure on offspring brain development and cerebral susceptibility to inflammatory insult remains unknown. In this study, we utilized the prenatal inflammatory insult model in vivo and the neuronal damage model in vitro. The results obtained show that prenatal maternal inflammation exacerbates LPS-induced memory impairment, neuronal necrosis, brain inflammatory response, and significantly increases protein expressions of COX-2, DP2, APP, and Aβ, while obviously decreasing that of DP1 and the exploratory behaviors of offspring rats. Meloxicam significantly inhibited memory impairment, neuronal necrosis, oxidative stress, and inflammatory response, and down-regulated the expressions of APP, Aβ, COX-2, and DP2, whereas significantly increased exploring behaviors and the expression of DP1 in vivo. Collectively, these findings suggested that maternal inflammation could cause offspring suffering from inflammatory and behavioral disorders and increase the susceptibility of offspring to cerebral pathological factors, accompanied by COX-2/PGD-2/DPs pathway activation, which could be ameliorated significantly by COX-2 inhibitor meloxicam treatment.  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