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   487931篇
  免费   4761篇
  国内免费   692篇
电工技术   8299篇
综合类   420篇
化学工业   76843篇
金属工艺   25877篇
机械仪表   17696篇
建筑科学   9938篇
矿业工程   4841篇
能源动力   9012篇
轻工业   33662篇
水利工程   6691篇
石油天然气   15798篇
武器工业   55篇
无线电   45115篇
一般工业技术   108136篇
冶金工业   74873篇
原子能技术   15078篇
自动化技术   41050篇
  2021年   4224篇
  2019年   4088篇
  2018年   12447篇
  2017年   12798篇
  2016年   11317篇
  2015年   4925篇
  2014年   8130篇
  2013年   18442篇
  2012年   13528篇
  2011年   20272篇
  2010年   17153篇
  2009年   17373篇
  2008年   18186篇
  2007年   19299篇
  2006年   12001篇
  2005年   12356篇
  2004年   11503篇
  2003年   11129篇
  2002年   10407篇
  2001年   9679篇
  2000年   9564篇
  1999年   8871篇
  1998年   18666篇
  1997年   13817篇
  1996年   10642篇
  1995年   8480篇
  1994年   7731篇
  1993年   7740篇
  1992年   6393篇
  1991年   6214篇
  1990年   6452篇
  1989年   6261篇
  1988年   6025篇
  1987年   5631篇
  1986年   5583篇
  1985年   6138篇
  1984年   5927篇
  1983年   5564篇
  1982年   5251篇
  1981年   5347篇
  1980年   5274篇
  1979年   5381篇
  1978年   5569篇
  1977年   5881篇
  1976年   7093篇
  1975年   5031篇
  1974年   5038篇
  1973年   5153篇
  1972年   4494篇
  1971年   4143篇
排序方式: 共有10000条查询结果,搜索用时 843 毫秒
201.
202.
Powder Metallurgy and Metal Ceramics - The mechanisms of phase interactions in granular media were studied to elaborate the results obtained previously at the Nekrasov Iron and Steel Institute of...  相似文献   
203.
Tsyplenkov  V. V.  Shastin  V. N. 《Semiconductors》2019,53(10):1334-1339
Semiconductors - Long-wavelength acoustic phonon-assisted relaxation rates for the excited 1s(T), 2p0, 2s, 3p0, 2p±, 4p0, and 3p± states of antimony donors in a germanium crystal are...  相似文献   
204.
Two-dimensional MoS2 nanoparticles (2D-nps) exhibit artificial enzyme properties that can be regulated at bio-nanointerfaces. We discovered that protein lipase is able to tune the peroxidase-like activity of MoS2 2D-nps, offering low-nanomolar, label-free detection and identification in samples with unknown identity. The inhibition of the peroxidase-like activity of the MoS2 2D-nps was demonstrated to be concentration dependent, and as low as 5 nm lipase was detected with this approach. The results were compared with those obtained with several other proteins that did not display any significant interference with the nanozyme behavior of the MoS2 2D-nps. This unique response of lipase was characterized and exploited for the successful identification of lipase in six unknown samples by using qualitative visual inspection and a quantitative statistical analysis method. The developed methodology in this approach is noteworthy for many aspects; MoS2 2D-nps are neither labeled with a signaling moiety nor modified with any ligands for signal readout. Only the intrinsic nanozyme activity of the MoS2 2D-nps is exploited for this detection approach. No analytical equipment is necessary for the visual detection of lipase. The synthesis of the water-soluble MoS2 2D-nps is low costing and can be performed in bulk scale. Exploring the properties of 2D-nps and their interactions with biological materials reveals highly interesting yet instrumental features that offer the development of novel bioanalytical approaches.  相似文献   
205.
The data on the use of solar photovoltaic plants (PVPs) for providing a reliable and guaranteed power supply to telecommunication systems and cellular communication systems in the conditions prevalent in Uzbekistan are given. The research-based structures developed by OOO MIR SOLAR and the selection of PVP elements ensuring their reliable operation are described. The main influencing factors are discussed, and the use of effective combinations of different types of panels (from monocrystalline and polycrystalline silicon) and a specially developed controller are considered.  相似文献   
206.
Protein trafficking is altered when normal cells acquire a tumor phenotype. A key subcellular compartment in regulating protein trafficking is the Golgi apparatus, but its role in carcinogenesis is still not well defined. Golgi phosphoprotein 3 (GOLPH3), a peripheral membrane protein mostly localized at the trans-Golgi network, is overexpressed in several tumor types including glioblastoma multiforme (GBM), the most lethal primary brain tumor. Moreover, GOLPH3 is currently considered an oncoprotein, however its precise function in GBM is not fully understood. Here, we analyzed in T98G cells of GBM, which express high levels of epidermal growth factor receptor (EGFR), the effect of stable RNAi-mediated knockdown of GOLPH3. We found that silencing GOLPH3 caused a significant reduction in the proliferation of T98G cells and an unexpected increase in total EGFR levels, even at the cell surface, which was however less prone to ligand-induced autophosphorylation. Furthermore, silencing GOLPH3 decreased EGFR sialylation and fucosylation, which correlated with delayed ligand-induced EGFR downregulation and its accumulation at endo-lysosomal compartments. Finally, we found that EGF failed at promoting EGFR ubiquitylation when the levels of GOLPH3 were reduced. Altogether, our results show that GOLPH3 in T98G cells regulates the endocytic trafficking and activation of EGFR likely by affecting its extent of glycosylation and ubiquitylation.  相似文献   
207.
This work presents simulation of microstructure evolution in the nugget zone (NZ) of a AZ31-Mg-alloy friction stir weld. The process parameters (tool geometrical characteristics, rotational speed, travel speed, applied load) have been correlated with the resulting microstructural features in the NZ of the weld (grain size and population) with the aid of the MICRESS software, which provides the ability to simulate both nucleation and grain growth during dynamic recrystallization phenomena evolving in the NZ during the weld thermal cycle. The input parameters of the developed model include the tool geometry, the welding conditions as well as the recrystallization energy, the grain boundary mobility and specific material properties. NZ microstructure obtained by simulation shows good agreement with experimental measurements for both grain population and size.  相似文献   
208.
209.
210.
Technical Physics Letters - The influence of excitation photons energy on the relaxation times of photoexcited carriers is studied. The involved relaxation mechanisms are evaluated and the...  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