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   1765037篇
  免费   44909篇
  国内免费   15836篇
电工技术   46619篇
技术理论   24篇
综合类   20204篇
化学工业   309436篇
金属工艺   77167篇
机械仪表   57743篇
建筑科学   64167篇
矿业工程   18941篇
能源动力   56304篇
轻工业   129796篇
水利工程   19316篇
石油天然气   53095篇
武器工业   1777篇
无线电   219886篇
一般工业技术   312553篇
冶金工业   199433篇
原子能技术   36330篇
自动化技术   202991篇
  2022年   16485篇
  2021年   24300篇
  2020年   18662篇
  2019年   20293篇
  2018年   22481篇
  2017年   22615篇
  2016年   27922篇
  2015年   25993篇
  2014年   39651篇
  2013年   100612篇
  2012年   50323篇
  2011年   65604篇
  2010年   56721篇
  2009年   63822篇
  2008年   57869篇
  2007年   54671篇
  2006年   57147篇
  2005年   50675篇
  2004年   48975篇
  2003年   47795篇
  2002年   46093篇
  2001年   42432篇
  2000年   41207篇
  1999年   41759篇
  1998年   56687篇
  1997年   47534篇
  1996年   42041篇
  1995年   35692篇
  1994年   32753篇
  1993年   31769篇
  1992年   27939篇
  1991年   24993篇
  1990年   24897篇
  1989年   23927篇
  1988年   22307篇
  1987年   20256篇
  1986年   19613篇
  1985年   22842篇
  1984年   22747篇
  1983年   20687篇
  1982年   19627篇
  1981年   19714篇
  1980年   18341篇
  1979年   18732篇
  1978年   18036篇
  1977年   18378篇
  1976年   20494篇
  1975年   16246篇
  1974年   15683篇
  1973年   15760篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Elevated activation of the autophagy pathway is currently thought to be one of the survival mechanisms allowing therapy-resistant cancer cells to escape elimination, including for cytarabine (AraC)-resistant acute myeloid leukemia (AML) patients. Consequently, the use of autophagy inhibitors such as chloroquine (CQ) is being explored for the re-sensitization of AraC-resistant cells. In our study, no difference in the activity of the autophagy pathway was detected when comparing AraC-Res AML cell lines to parental AraC-sensitive AML cell lines. Furthermore, treatment with autophagy inhibitors CQ, 3-Methyladenine (3-MA), and bafilomycin A1 (BafA1) did not re-sensitize AraC-Res AML cell lines to AraC treatment. However, in parental AraC-sensitive AML cells, treatment with AraC did activate autophagy and, correspondingly, combination of AraC with autophagy inhibitors strongly reduced cell viability. Notably, the combination of these drugs also yielded the highest level of cell death in a panel of patient-derived AML samples even though not being additive. Furthermore, there was no difference in the cytotoxic effect of autophagy inhibition during AraC treatment in matched de novo and relapse samples with differential sensitivity to AraC. Thus, inhibition of autophagy may improve AraC efficacy in AML patients, but does not seem warranted for the treatment of AML patients that have relapsed with AraC-resistant disease.  相似文献   
52.
To investigate the evolution of the structural and enhanced magnetic properties of GdMnO3 systems induced by the substitution of Mn with Cr, polycrystalline GdMn1-xCrxO3 samples were synthesized via solid-state reactions. XRD characterization shows that all GdMn1-xCrxO3 compounds with single-phase structures crystallize well and that Cr3+ ions entering the lattice sites of GdMnO3 induce structural distortion. SEM results indicate that the grain size of the synthesized samples (a few microns) decreases as the Cr substitution concentration increases. Positron annihilation lifetime spectroscopy reveals that vacancy-type defects occur in GdMn1-xCrxO3 ceramics and that the vacancy size and concentration clearly change with the Cr content. The temperature and field dependence of the magnetization curves show that Cr substitution significantly influences the magnetic ordering of the gadolinium sublattice, improving the weak ferromagnetic transition temperature and magnetization of GdMn1-xCrxO3. The enhanced magnetization of GdMn1-xCrxO3 is closely related to the vacancy defect concentration.  相似文献   
53.
Wireless Personal Communications - Besides anti-malware usage for the eradication of malicious attacks, researchers have developed epidemic models in order to gain more insights into the spread...  相似文献   
54.
Telecommunication Systems - Energy saving in User Equipment (UE) is one of the important issues for limited sources of power in the device. It is critical for the UE to maximize its energy...  相似文献   
55.
Semiconductors - Abstract—In our work, we carry out a structural-spectroscopic study of AlGaN/GaN epitaxial layers grown by molecular-beam epitaxy with nitrogen-plasma activation on a hybrid...  相似文献   
56.
Journal of Communications Technology and Electronics - A new design of wavelets based on the convolution of a compactly supported function with a rectangular pulse is proposed and theoretically...  相似文献   
57.
Journal of Communications Technology and Electronics - A statistical study of the effectiveness of the non-threshold search procedure for a noise-like phase-shift keyed signal by the delay time is...  相似文献   
58.
Journal of Communications Technology and Electronics - In recent years, there has been a rapid improvement in photonics products due to the use of multilayer heterostructures grown on the basis of...  相似文献   
59.
Mobile Networks and Applications - Project MindCatcher is an art/research project which has the intention to explore the potential of interactive artistic environments for measuring and a better...  相似文献   
60.
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