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   196909篇
  免费   15850篇
  国内免费   8114篇
电工技术   11338篇
技术理论   13篇
综合类   12217篇
化学工业   31939篇
金属工艺   10452篇
机械仪表   11682篇
建筑科学   15126篇
矿业工程   4875篇
能源动力   5564篇
轻工业   13336篇
水利工程   3477篇
石油天然气   9873篇
武器工业   1353篇
无线电   25210篇
一般工业技术   24888篇
冶金工业   10310篇
原子能技术   2209篇
自动化技术   27011篇
  2024年   771篇
  2023年   2991篇
  2022年   5236篇
  2021年   7275篇
  2020年   5383篇
  2019年   4503篇
  2018年   5151篇
  2017年   5959篇
  2016年   5221篇
  2015年   7055篇
  2014年   9079篇
  2013年   11621篇
  2012年   12269篇
  2011年   13578篇
  2010年   11825篇
  2009年   11546篇
  2008年   11481篇
  2007年   10856篇
  2006年   10932篇
  2005年   9387篇
  2004年   6413篇
  2003年   5439篇
  2002年   5141篇
  2001年   4703篇
  2000年   4701篇
  1999年   5222篇
  1998年   4640篇
  1997年   4040篇
  1996年   3630篇
  1995年   3052篇
  1994年   2426篇
  1993年   1921篇
  1992年   1543篇
  1991年   1174篇
  1990年   967篇
  1989年   783篇
  1988年   635篇
  1987年   472篇
  1986年   354篇
  1985年   307篇
  1984年   202篇
  1983年   156篇
  1982年   151篇
  1981年   113篇
  1980年   96篇
  1979年   67篇
  1978年   57篇
  1977年   56篇
  1976年   94篇
  1973年   32篇
排序方式: 共有10000条查询结果,搜索用时 140 毫秒
41.
Malondialdehyde (MDA) was selected to represent a secondary by-product of lipid peroxidation during rice ageing. This study aimed to investigate the effects of MDA modification on the structural characteristics of rice protein. The results showed that as MDA concentration increased, rice protein carbonyl and disulphide groups increased, but sulphydryl content decreased. The blue shift of maximum fluorescence peak, the decrease of rice protein intrinsic fluorescence intensity and the reduction of surface hydrophobicity indicated the formation of protein aggregates caused by MDA oxidative modification. The results of molecular weight distribution and particle size distribution showed that MDA modification resulted in the formation of soluble protein aggregates, and the decrease of rice protein solubility indicated that insoluble protein aggregates were formed. Results of protein electrophoresis showed that MDA modification contributed to rice protein aggregation via non-disulphide covalent bonds. The results showed that rice protein gradually aggregated with increasing MDA concentration.  相似文献   
42.
Despite recent rapid advances in metal halide perovskites for use in optoelectronics, the fundamental understanding of the electrical-poling-induced ion migration, accounting for many unusual attributes and thus performance in perovskite-based devices, remain comparatively elusive. Herein, the electrical-poling-promoted polarization potential is reported for rendering hybrid organic–inorganic perovskite photodetectors with high photocurrent and fast response time, displaying a tenfold enhancement in the photocurrent and a twofold decrease in the response time after an external electric field poling. First, a robust meniscus-assisted solution-printing strategy is employed to facilitate the oriented perovskite crystals over a large area. Subsequently, the electrical poling invokes the ion migration within perovskite crystals, thus inducing a polarization potential, as substantiated by the surface potential change assessed by Kelvin probe force microscopy. Such electrical-poling-induced polarization potential is responsible for the markedly enhanced photocurrent and largely shortened response time. This work presents new insights into the electrical-poling-triggered ion migration and, in turn, polarization potential as well as into the implication of the latter for optoelectronic devices with greater performance. As such, the utilization of ion-migration-produced polarization potential may represent an important endeavor toward a wide range of high-performance perovskite-based photodetectors, solar cells, transistors, scintillators, etc.  相似文献   
43.
44.
徐浩  吴炜  陈浩  王子康 《电子测试》2020,(10):117-118,27
无人机技术目前的快速发展使得我们国家输电线路自身的巡检能力得到了持续的提升,基于此本文在对无人机技术给予认识的情况下,在了解了输电线路巡检过程中的使用优势之后,还总结了无人机技术在当前我国线路巡检过程中的应用路径以及应用方法;之后使用案例分析的方式分析了无人机技术在当前输电线路巡检过程中的应用方法。  相似文献   
45.
Yan  Jing  Zhu  Rongying  Wu  Fan  Zhao  Ziyin  Ye  Huan  Hou  Mengying  Liu  Yong  Yin  Lichen 《Nano Research》2020,13(10):2706-2715
Nano Research - Insufficient intratumoral penetration greatly hurdles the anticancer performance of nanomedicine. To realize highly efficient tumor penetration in a precisely and spatiotemporally...  相似文献   
46.
47.
48.
The crystallization of capped ultrathin polymer films is closely dependent on film thickness and interfacial interaction. Using dynamic Monte Carlo simulations, the crystallization behaviors of polymer films confined between two substrates were investigated. The crystallization rate of confined polymers is reduced with high interfacial interactions. Above a critical strength of interfacial interaction, polymer crystallization in the thin film is inhibited within the simulation time scales. An increase in film thickness leads to a rise in critical interfacial interaction. In thicker films, the chains have more space to change conformation to form crystal stems. In addition, there are fewer absorbed segments in confined chains for the thicker films, and thus the chains have stronger ability to adjust their conformation. Therefore an increase in film thickness can cause a reduction in the entropic barrier required for the formation of crystals and thus an increase in the critical interfacial interaction. © 2018 Society of Chemical Industry  相似文献   
49.
Wu  Li  Li  Jing  Fu  Caixia  Kühn  Bernd  Wang  Xiaolin 《Magma (New York, N.Y.)》2019,32(4):501-509
Magnetic Resonance Materials in Physics, Biology and Medicine - To investigate the value of using diffusion-weighted imaging (DWI) and intravoxel incoherent motion DWI (IVIM-DWI) to assess the...  相似文献   
50.
Lin  Haicheng  Huang  Wantong  Zhao  Kun  Qiao  Shuang  Liu  Zheng  Wu  Jian  Chen  Xi  Ji  Shuai-Hua 《Nano Research》2020,13(1):133-137
Nano Research - The isostructural and isoelectronic transition-metal-dichalcogenides 1T-TaS2 and 1T-TaSe2 are layered materials with intricate electronic structures. Combining the molecular beam...  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